Engineers Daily

Overview - Aggregates for Concrete

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The importance of using the right type and quality of aggregates cannot be overemphasized. The fine and coarse <a href="http://www.engineersdaily.com/2012/03/preplaced-aggregate-concrete.html" target="_blank">aggregates</a> generally occupy 60% to 75% of the concrete volume (70% to 85% by mass) and strongly influence the concrete’s freshly mixed and hardened properties, mixture proportions, and economy. Fine aggregates (Fig. 1) generally consist of natural sand or crushed stone with most particles smaller than 5 mm (0.2 in.).</div>
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<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-hv6Rj-JqfWI/V39kPN9_yvI/AAAAAAAAGwI/42T1oIZVRtULi_xc_kTcfhcFWqxPbp5QwCLcB/s1600/fine%2Bagg%2528engineersdaily.com%2529.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Overview - Aggregates for Concrete" border="0" height="204" src="https://4.bp.blogspot.com/-hv6Rj-JqfWI/V39kPN9_yvI/AAAAAAAAGwI/42T1oIZVRtULi_xc_kTcfhcFWqxPbp5QwCLcB/s320/fine%2Bagg%2528engineersdaily.com%2529.jpg" title="Overview - Aggregates for Concrete" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">Fig. 1. Closeup of fine aggregate (sand). </span></b><br />
<b><span style="font-size: small;">Image courtesy: University of Memphis</span></b></td></tr>
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Coarse aggregates (Fig. 2) consist of one or a combination of gravels or crushed stone with particles predominantly larger than 5 mm (0.2 in.) and generally between 9.5 mm and 37.5 mm (3⁄8 in. and 1 1⁄2 in.). Some natural aggregate deposits, called pit-run gravel, consist of gravel and sand that can be readily used in concrete after minimal processing. Natural gravel and sand are usually dug or dredged from a pit, river, lake, or seabed.</div>
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-MAuBeaMoZnk/V39kbJVV2XI/AAAAAAAAGwM/mRK_TMJ2QyQ-8mSOtYOnApeBmtsi6B43gCLcB/s1600/stones%2528engineersdaily.com%2529.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Overview - Aggregates for Concrete" border="0" height="266" src="https://1.bp.blogspot.com/-MAuBeaMoZnk/V39kbJVV2XI/AAAAAAAAGwM/mRK_TMJ2QyQ-8mSOtYOnApeBmtsi6B43gCLcB/s400/stones%2528engineersdaily.com%2529.jpg" title="Overview - Aggregates for Concrete" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">Fig. 2. Coarse aggregate. Rounded gravel (left) and<br />crushed stone (right).</span></b><b><span style="font-size: small;"> Image courtesy: University of Memphis</span></b></td></tr>
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Crushed stone is produced by crushing quarry rock, boulders, cobbles, or large-size gravel. Crushed air-cooled blast-furnace slag is also used as fine or coarse aggregate. The aggregates are usually washed and graded at the pit or plant. Some variation in the type, quality, cleanliness, grading, moisture content, and other properties is expected. Close to half of the coarse aggregates used in <a href="http://www.engineersdaily.com/2011/02/properties-of-ordinary-portland-cement.html" target="_blank">Portland</a> cement concrete in North America are gravels; most of the remainder are crushed stones.</div>
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Naturally occurring concrete aggregates are a mixture of rocks and minerals (see Table 1). A mineral is a naturally occurring solid substance with an orderly internal structure and a chemical composition that ranges within narrow limits. Rocks, which are classified as igneous, sedimentary, or metamorphic, depending on origin, are generally composed of several minerals. For example, granite<br />
contains quartz, feldspar, mica, and a few other minerals; most limestones consist of calcite, dolomite, and minor amounts of quartz, feldspar, and clay. Weathering and erosion of rocks produce particles of stone, gravel, sand, silt, and clay.</div>
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<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-iQpcvIyzgx8/V39k4dznEMI/AAAAAAAAGwQ/DmOUep3srmce_S_S8b6sruqaaYUKOdK4QCLcB/s1600/Table1%2528engineersdaily.com%2529.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Overview - Aggregates for Concrete" border="0" height="640" src="https://4.bp.blogspot.com/-iQpcvIyzgx8/V39k4dznEMI/AAAAAAAAGwQ/DmOUep3srmce_S_S8b6sruqaaYUKOdK4QCLcB/s640/Table1%2528engineersdaily.com%2529.jpg" title="Overview - Aggregates for Concrete" width="396" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><span style="font-size: small;">Table 1: Rock and Mineral Constituents in<br />Aggregates</span></b></td></tr>
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Recycled <a href="http://www.engineersdaily.com/2011/01/concrete-degradation.html" target="_blank">concrete</a>, or crushed waste concrete, is a feasible source of aggregates and an economic reality, especially where good aggregates are scarce. Conventional stone crushing equipment can be used, and new equipment has been developed to reduce noise and dust</div>
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Aggregates must conform to certain standards for optimum engineering use: they must be clean, hard, strong, durable particles free of absorbed chemicals, coatings of clay, and other fine materials in amounts that could affect hydration and bond of the cement paste. Aggregate particles that are friable or capable of being split are undesirable. Aggregates containing any appreciable amounts of shale or other shaly rocks, soft and porous materials, should be avoided; certain types of chert should be especially avoided since they have low resistance to weathering and can cause surface defects such as pop outs.</div>
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Identification of the constituents of an aggregate cannot alone provide a basis for predicting the behavior of aggregates in service. Visual inspection will often disclose weaknesses in coarse aggregates. Service records are invaluable in evaluating aggregates. In the absence of a performance record, the aggregates should be tested before they are used in concrete. The most commonly used aggregates—sand, gravel, crushed stone, and air-cooled blast-furnace slag—produce freshly mixed normal-weight concrete with a density (unit weight) of 2200 to 2400 kg/m<sup>3</sup> (140 to 150 lb/ft<sup>3</sup>). </div>
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Aggregates of expanded shale, clay, slate, and slag (Fig. 3) are used to produce structural lightweight concrete with a freshly mixed density ranging from about 1350 to 1850 kg/m<sup>3</sup> (90 to 120lb/ft<sup>3</sup>).</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-7XcDSnUqbZM/V39lStXmzfI/AAAAAAAAGwY/pCFX4Xx7d14kBUIFF79bqPW-CYXW555YQCLcB/s1600/lightweigh_aggregates%2528engineersdaily.com%2529.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Fig. 3. Lightweight aggregate. Expanded clay (left) and expanded shale (right)." border="0" height="216" src="https://4.bp.blogspot.com/-7XcDSnUqbZM/V39lStXmzfI/AAAAAAAAGwY/pCFX4Xx7d14kBUIFF79bqPW-CYXW555YQCLcB/s400/lightweigh_aggregates%2528engineersdaily.com%2529.jpg" title="Fig. 3. Lightweight aggregate. Expanded clay (left) and expanded shale (right)." width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;"><b>Fig. 3. Lightweight aggregate. Expanded clay (left) and<br />expanded shale (right). </b></span><br />
<b><span style="font-size: small;">Image courtesy: University of Memphis</span></b></td></tr>
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Other lightweight materials such as pumice, scoria, perlite, vermiculite, and diatomite are used to produce insulating lightweight concretes ranging in density from about 250 to 1450 kg/m<sup>3</sup> (15 to 90 lb/ft3). Heavyweight materials such as barite, limonite, magnetite, ilmenite, hematite, iron, and steel punchings or shot are used to produce heavyweight concrete and radiation-shielding concrete (ASTM C 637 and C 638). Only normal-weightaggregates are discussed in this article</div>
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Normal-weight aggregates should meet the requirements of ASTM C 33 or AASHTO M 6/M 80. These specifications limit the permissible amounts of deleterious substances and provide requirements for aggregate characteristics. Compliance is determined by using one or more of the several standard tests cited in the following sections and tables. However, the fact that aggregates<br />
satisfy ASTM C 33 or AASHTO M 6/M 80 requirements does not necessarily assure defect-free concrete.</div>
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For adequate consolidation of concrete, the desirable amount of air, water, cement, and fine aggregate (that is, the mortar fraction) should be about 50% to 65% by absolute volume (45% to 60% by mass). Rounded aggregate, such as gravel, requires slightly lower values, while crushed aggregate requires slightly higher values. Fine aggregate content is usually 35% to 45% by mass or volume of the total aggregate content.<br />
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By Kieu Hai Dang</div>

Overview - Aggregates for Concrete

The importance of using the right type and quality of aggregates cannot be overemphasized. The fine...

How to do quick multiplication without a calculator? The method of lines

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<span style="font-size: small;">If you grew up memorizing multiplication tables, you know the 
struggle of elementary mathematics students. Math isn’t meant to be 
about memorizing, it is supposed to be about problem-solving.</span><br />
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<a href="https://3.bp.blogspot.com/-T1V_N62xHI0/V2bUxPm0qSI/AAAAAAAAGvk/G_Oq0ylFDBUajI_7haktp1EKk_tZa9LAgCLcB/s1600/multiply%2528engineersdaily.com%2529.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="How to do quick multiplication without a calculator? The method of lines" border="0" height="240" src="https://3.bp.blogspot.com/-T1V_N62xHI0/V2bUxPm0qSI/AAAAAAAAGvk/G_Oq0ylFDBUajI_7haktp1EKk_tZa9LAgCLcB/s320/multiply%2528engineersdaily.com%2529.png" title="How to do quick multiplication without a calculator? The method of lines" width="320" /></a></div>
<span style="font-size: small;">One Japanese method of multiplication teaches kids to both visualize 
how numbers multiply together and provides a quick and easy method to 
solve large multiplication problems. The best part? This technique 
involves absolutely no numbers in the solving stage, so no more 
forgetting to carry the one and getting the answer wrong. Check out the 
short video below to learn a little more.</span><br />
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<span style="font-size: small;"><iframe allowfullscreen="" frameborder="0" height="452" src="https://www.youtube.com/embed/e-P5RGdjICo" width="750"></iframe></span>

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<span style="font-size: small;">Most commonly, this method is believed to have <a href="http://www.archimedes-lab.org/Maths2_Multiplication.html" rel="external nofollow">originated in Japan</a>,
 but it is an underutilized tool in the realm of teaching kids 
mathematics. By drawing parallel lines for each number slot in one 
number then drawing perpendicular lines that are parallel to each other 
in another direction you end up with a series of intersection points. By
 separating these intersections into sections, just count the points and
 you have your final answer. For problems that involve multiplication of
 numbers involving tens and hundreds places, this method proves faster 
than doing it the old fashioned way.</span></div>
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<span style="font-size: small;">Not only is this a cool trick, but it actually visualizes what is 
happening when you multiply 2 numbers together. Each place (ones, tens, 
hundreds) is symbolized by an intersection location created by the 
actual numbers in the problem. To explain further, for the problem of 
123×321, the 1 line crosses the 3 lines creating a total of 3 intersections
 in the thousands place. This means that the first number is 3, and you 
know the answer will be to the magnitude of thousands by the number of 
intersection locations. Still not getting it? Check out the explanatory 
video below for further help.</span><br />
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<span style="font-size: small;"><iframe allowfullscreen="" frameborder="0" height="452" src="https://www.youtube.com/embed/_AJvshZmYPs" width="750"></iframe></span>

How to do quick multiplication without a calculator? The method of lines

If you grew up memorizing multiplication tables, you know the struggle of elementary mathematics s...

Rolls-Royce Unveils 103EX Concept in Stunning 360˚ VR

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<span style="font-size: xx-small;"><span style="color: #cc0000;"><i><b><span style="font-family: "helvetica neue" , "arial" , "helvetica" , sans-serif;">June, 2016</span></b></i></span></span></div>
<span style="font-size: small;"><span style="font-family: "helvetica neue" , "arial" , "helvetica" , sans-serif;">Rolls-Royce just unveiled a concept car, and it is one of the most 
spectacular, yet vastly unusual, concept automobiles that has ever been 
seen. The unveil took place as a <b>360˚</b> Youtube video 
that takes you through a virtual reality experience with the help of the
 virtual assistant named “Eleanor.” The car resembles something straight
 out of Tron, and it is fully autonomous. Enter the <b>103EX</b>, an ambitious design that Rolls-Royce wants you to make your grand entrance in. Check out the immersive video below, and don’t forget that you can control the perspective in this 360˚ experience.</span></span><br />
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<iframe allowfullscreen="" frameborder="0" height="452" src="https://www.youtube.com/embed/q7gygumHoos" width="750"></iframe>

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<span style="font-size: small;"><span style="font-family: "helvetica neue" , "arial" , "helvetica" , sans-serif;">When you first get a glimpse of the car,
 you have to stop and wonder if Rolls-Royce is serious, because of just 
how different it looks. The goal of the new concept isn’t to display one
 singular car, rather a vision of inspiring the driver to break down the
 boundaries of what they think a luxury car is, according to the <a href="http://www.theverge.com/2016/6/16/11956484/rolls-royce-vision-100-concept-360-degree-video-tour" rel="external nofollow">Verge</a>.</span></span></div>
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<span style="font-size: small;"><span style="font-family: "helvetica neue" , "arial" , "helvetica" , sans-serif;">“Looking towards the next <b>100 years</b>, 
each and every Rolls-Royce will be a unique work of art. Shape, size and
 silhouette – you will be able to craft your vision entirely from the 
wheels up.” ~ <a href="https://www.rolls-roycemotorcars.com/en-GB/103ex.html" rel="external nofollow">Rolls-Royce</a></span></span></blockquote>
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<span style="font-size: small;"><span style="font-family: "helvetica neue" , "arial" , "helvetica" , sans-serif;">For another look at the car, watch the below video guided again by that mysterious AI voice, Eleanor.</span></span><br />
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<iframe allowfullscreen="" frameborder="0" height="452" src="https://www.youtube.com/embed/dGSm082ELXY" width="750"></iframe>

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<span style="font-size: small;"><span style="font-family: "helvetica neue" , "arial" , "helvetica" , sans-serif;">These fully autonomous luxurious cars are what Rolls-Royce believes 
the visionaries of the future will be riding in. You have to admit, the 103EX concept does look like something straight out of a science fiction movie. The car looks massive, and it is. Stretching <b>over 20 feet</b>
 for a car that only holds 2 people on a fancy couch, whoever rides 
inside will make quite the entrance wherever they arrive, according to 
the <a href="http://qz.com/709642/rolls-royce-just-unveiled-the-most-amazingly-ludicrous-self-driving-luxury-vehicle/" rel="external nofollow">Quartz</a>.
 All-electric is the vision of the future of Rolls-Royce vehicles, along
 with a luggage storage compartment and interior design rivaling many 
foreign palaces.</span></span><br />
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<a href="https://2.bp.blogspot.com/-pGtOJTZx6Ak/V2bRUMEd7QI/AAAAAAAAGvY/ssEHCmU0LrUWsswZh6zbRLHbrmJZr2kegCLcB/s1600/rolls-royce-100%2528engineersdaily.com%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Rolls-Royce Unveils 103EX Concept in Stunning 360˚ VR" border="0" height="454" src="https://2.bp.blogspot.com/-pGtOJTZx6Ak/V2bRUMEd7QI/AAAAAAAAGvY/ssEHCmU0LrUWsswZh6zbRLHbrmJZr2kegCLcB/s640/rolls-royce-100%2528engineersdaily.com%2529.jpg" title="Rolls-Royce Unveils 103EX Concept in Stunning 360˚ VR" width="640" /></a></div>
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<span style="font-size: small;"><span style="font-family: "helvetica neue" , "arial" , "helvetica" , sans-serif;">[Image Source: <a href="https://www.rolls-roycemotorcars.com/en-GB/103ex.html" rel="external nofollow"><i>Rolls-Royce</i></a>]</span></span></div>
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<span style="font-size: small;"><span style="font-family: "helvetica neue" , "arial" , "helvetica" , sans-serif;">All of this futuristic technology is part of Rolls-Royce’s parent 
company BMW’s centennial celebration. The company also unveiled a <a href="https://www.youtube.com/watch?v=N3XasCh2evc" rel="external nofollow">transparent Mini Cooper concept</a> which is equally as stunning as the Rolls-Royce 103EX. The future of luxury is going to look, well,<i> futuristic</i>.</span></span></div>

Rolls-Royce Unveils 103EX Concept in Stunning 360˚ VR

June, 2016 Rolls-Royce just unveiled a concept car, and it is one of the most spectacular, yet v...

Germany Banning all Vehicle Emissions by 2030

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<span style="font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"><span style="font-size: small;">Many European countries have been making the shift to electric 
vehicles and Germany has just stated that they plan to ban the sale of 
gasoline and diesel powered vehicles by <strong>2030</strong>. The country is also planning to reduce its carbon footprint by<strong> 80-95% by 2050</strong>,
 sparking a shift to green energy in the country. Effectively, the ban 
will encompass the registration of new cars in the country as they will 
not allow any gasoline powered vehicle to be registered after 2030, 
according to <a href="http://www.theglobeandmail.com/globe-drive/news/industry-news/all-cars-in-germany-need-to-be-emissions-free-by-2030-official-says/article30446032/" rel="external nofollow">The Globe and Mail</a>.</span></span></div>
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<span style="font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"><span style="font-size: small;">
</span></span><div style="text-align: justify;">
<span style="font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"><span style="font-size: small;">Part of the reason this ban is being discussed and implemented is 
because energy officials see that they will not reach their emissions 
goals by 2050 if they do not eliminate a large portion of vehicle 
emissions. The country is still hopeful that it will meet its emissions 
goals, like reducing emissions by <strong>40% by 2020</strong>, but the acceptance of electric cars in the country has not occurred as fast as expected.</span></span></div>
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<span style="font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"><span style="font-size: small;">Other efforts to increase the use of electric vehicles include plans to build over <strong>1 million </strong>hybrid
 and electric battery plugins across the country. By 2030, Germany plans
 on having over 6 million plugins installed. According to the <a href="http://www.ibtimes.co.uk/germany-targets-2030-ban-new-petrol-diesel-car-sales-1565570" rel="external nofollow">International Business Times</a>, electric car sales are expected to increase as Volkswagen is still recovering from its emissions scandal.</span></span></div>
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<tr><td style="text-align: center;"><span style="font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"><span style="font-size: small;"><a href="https://4.bp.blogspot.com/-ne7OwTKfFbk/V2bNbdzV6AI/AAAAAAAAGvM/RNxAI1V1hpcVJeDdwFABY2i6O8bZhDSCQCLcB/s1600/test%2528engineersdaily.com%2529.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Germany Banning all Vehicle Emissions by 2030" border="0" height="380" src="https://4.bp.blogspot.com/-ne7OwTKfFbk/V2bNbdzV6AI/AAAAAAAAGvM/RNxAI1V1hpcVJeDdwFABY2i6O8bZhDSCQCLcB/s640/test%2528engineersdaily.com%2529.jpg" title="Germany Banning all Vehicle Emissions by 2030" width="640" /></a></span></span></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"><span style="font-size: small;">A test device checks exhaust emissions of a VW Golf 2.0 TDI car in Frankfurt/Oder, Germany.
Photograph courtesy: Patrick Pleul/EPA
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<span style="font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"><span style="font-size: small;">
</span></span><div style="text-align: justify;">
<span style="font-family: "Helvetica Neue",Arial,Helvetica,sans-serif;"><span style="font-size: small;">Currently, there are only around <strong>155,000</strong> registered hybrid and electric vehicles on German roads, dwarfed by the <strong>45 million</strong>
 gasoline and diesel cars currently driving there too. As countries 
continue setting goals of reducing emissions, greater steps are going to
 need to be taken to have a noticeable effect on the surrounding 
environment. While the efforts are certainly not futile, the results of 
such bans will likely only start to be seen by generations down the 
line, bettering the world for the future.</span></span></div>
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Germany Banning all Vehicle Emissions by 2030

Many European countries have been making the shift to electric vehicles and Germany has just state...

Standard Test Method for Density and Unit Weight of Soil by Sand Replacement Method

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<span style="font-family: "verdana" , sans-serif;">Sand replacement test method is used to determine the field density or 
in-place density of earth embankments, road fills, sub-grade, sub-base 
or any of compacted material. This method serves as base upon which one 
can accept the density of a compacted material to a specified magnitude 
or to a percentage of maximum unit dry density determined as proctor.</span></div>
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<span style="font-family: "verdana" , sans-serif;">As we know that moisture content of the <a href="http://www.engineersdaily.com/2011/03/aashto-soil-classification-system.html" target="_blank">soil</a> vary from time to time and 
hence the field density also, so we are required to report the test 
result in terms of dry density. In order to determine the dry density we
 must have to examine the moisture content in the <a href="http://www.engineersdaily.com/2011/03/introduction-to-soil-classification.html" target="_blank">soil</a> by using general 
method.<br />
Moisture content (%) = m = ((wt. of wet soil – wt of dry soil) / wt of dry soil)  x 100<br />
Dry density = (bulk density ) / (1 + w)</span>
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<span style="color: #990000;">Apparatus Required</span></span></h2>
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Sand pouring cylinder</span></li>
<li><span style="font-family: "verdana" , sans-serif;">Calibrating</span></li>
<li><span style="font-family: "verdana" , sans-serif;">Metal tray</span></li>
<li><span style="font-family: "verdana" , sans-serif;">Excavating tool</span></li>
<li><span style="font-family: "verdana" , sans-serif;">Balance</span></li>
<li><span style="font-family: "verdana" , sans-serif;">Glass plate</span></li>
<li><span style="font-family: "verdana" , sans-serif;">Metal tray</span></li>
<li><span style="font-family: "verdana" , sans-serif;">Clean uniform sand (1mm pass 600 mirco retain)</span></li>
<li><span style="font-family: "verdana" , sans-serif;">Water content determination apparatus</span></li>
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<span style="color: #990000;">Theory</span></span></h2>
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The dry density of the sample obtained as a result is divided by the 
proctor test result i.e. the maximum dry obtained of the sample that can
 be obtained in the laboratory by using standard AASHTO compaction test 
or Modified AASHTO compaction test and the result is reported as 
percentage.<br /><br />
The acceptance criteria for these percentages depend on the 
specification requirements and generally following rules is followed;<br /><br />
No less than 98% within 150 mm below formation level<br />
No less than 95% between 150 mm and 1200 mm below formation<br />
No less than 90% beyond 1200 mm below formation level</span></div>
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<span style="color: #990000;">Background</span></span></h2>
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As we know density means weight per unit volume or in other words how 
much mass is being enclosed in a specific quantum of volume. We can 
easily determine the mass of <a href="http://www.engineersdaily.com/2011/03/massachusetts-institute-of-technology.html" target="_blank">soil</a> by using the physical balance or 
digital balance, but the problem lies in finding the volume of the hole 
dug.<br />
This problem is solved with the help of a calibrated sand whose unit 
weight or density is already being determined and thus if we could 
determine how much weight of calibrated sand is going to rest in the dug
 hole we can find the volume of the hole by using following formula;<br />
Volume of dug hole = weight of soil in hole dug  / unit weight of calibrated soil</span></div>
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<span style="color: #990000;">Procedure</span></span></h2>
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The standard procedure of this test is being divided in two parts in 
first part we will find the unit weight of the standard <a href="http://www.engineersdaily.com/2014/01/principles-of-geotechnical-engineering.html" target="_blank">soil</a> by 
calibration process described  as follows;</span></div>
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<span style="color: #990000;">Calibration</span></span></h2>
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>Determine the internal volume of the calibrating container by using the dimensions as follows;<br />
                                                    <b>V = πd<sup>2</sup>h/4</b><br />
2.<span class="Apple-tab-span" style="white-space: pre;"> </span>Now 
fill the sand pouring cylinder with the sand to be calibrated within 
about 10 mm of its top left vacant and then determine the mass of the 
sand pouring cylinder along with sand and note it as w1.<br /><br />
3.<span class="Apple-tab-span" style="white-space: pre;"> </span>Now 
place the sand pouring cylinder on top of calibrating cylinder of known 
volume and open the shutter to allow the sand to fall in to the cylinder
 after no more sand is falling close the shutter and determine the mass 
of the calibrating cylinder filled with sand and note it as W2<br /><br />
4.<span class="Apple-tab-span" style="white-space: pre;"> </span>Now as 
we also have the weight of the sand in the conical portion of the sand 
pouring cylinder, we must subtract the weight of sand that can 
accumulate within that conical portion. For that take a flat glass plate
 and place the sand pouring cylinder. Open the shutter till no more sand
 falls and determine the mass of sand in the conical portion and note it
 as W3.<br /><br />
5.<span class="Apple-tab-span" style="white-space: pre;"> </span>Now the weight of the sand in the calibrating cylinder is determined as<br />
                        Wa = W1 – W2 – W3<br /><br />
6.<span class="Apple-tab-span" style="white-space: pre;"> </span>The 
bulk density of the sand is determined by dividing the mass of sand in 
the calibrating cylinder with the volume of the calibrating cylinder.</span></div>
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<span style="color: #990000;">Determine the Dry density of the soil under sample</span></span></h2>
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>Prepare the area of the embankment subject to test, level the top of the soil using the scrapper tool.<br /><br />
2.<span class="Apple-tab-span" style="white-space: pre;"> </span>Place the metal tray on the flat surface, if required insert the nails into the small holes of the metal tray.<br /><br />
3.<span class="Apple-tab-span" style="white-space: pre;"> </span>Trace the circular hole of the tray on the ground and excavate the soil carefully without loosing any of<br />
the soil fragment. Dig a hole of approximately 150 mm in the ground.<br /><br />
4.<span class="Apple-tab-span" style="white-space: pre;"> </span>Collect all the excavated material in a metal container and clear the hole using a brush.<br /><br />
5.<span class="Apple-tab-span" style="white-space: pre;"> </span>Determine the mass of this soil as weight of wet soil from hole Ww.<br /><br />
6.<span class="Apple-tab-span" style="white-space: pre;"> </span>Fill the sand pouring cylinder with the calibrated sand and determine its mass as W1.<br /><br />
7.<span class="Apple-tab-span" style="white-space: pre;"> </span>Place 
the cylinder directly over the excavated hole. Allow the sand to run out
 the cylinder by opening the shutter. Close the shutter when the hole is
 completely filled and no further movement of sand is observed.<br /><br />
8.<span class="Apple-tab-span" style="white-space: pre;"> </span>Now weigh the remaining sand in the sand pouring cylinder and note it as w4.<br /><br />
9.<span class="Apple-tab-span" style="white-space: pre;"> </span>Take a sample of the excavated soil in an air tight sampler for the determination of the water content or moisture content.<br /><br />
10.<span class="Apple-tab-span" style="white-space: pre;"> </span>Volume of the hole is determined by using the unit weight of the calibrated sand already known;</span></div>
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<span style="color: #990000;">Observations and Calculations</span></span></h2>
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Volume of calibrating container = V (cm<sup>3</sup>) = 1000 cm<sup>3</sup><br />
Weight of cylinder + sand (before pouring) , W1(g) = 7476 g<br />
Mean weight of cylinder + sand (after pouring), W2 (g) = 5610 g<br />
Mean weight of sand in cone (of pouring cylinder), W3 (g) = 436 g<br />
Weight of sand to fill calibrating container Wa = w1 – w2 – w3 = 1430 g<br />
Bulk density of sand = Gamma b = Wa / v (g/cm<sup>3</sup>) = 1.43</span></div>
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<span style="color: #990000;">Dry Density</span></span></h2>
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Weight of calibrated sand in hole wb = W1 – W4 – W2<br />
Volume of hole = Vh = Wb  / Unit weight of sand<br />
Dry density of soil = ww / vh<br />
% compaction = (dry density / proctor density )  x 100</span></div>
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Standard Test Method for Density and Unit Weight of Soil by Sand Replacement Method

Sand replacement test method is used to determine the field density or in-place density of earth e...

Network Security Engineer Resume

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(Article added on special request.) </div>
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A nice and well organized resume plays a pivotal role in getting your documents through the first phase of recruitment. It not only shows one's credentials but also how one organizes information, how presentable he or she is and many other traits preferred by the recruiters. Below are some concise segments for network security engineer resume. Of course they can be tailored or expanded to fulfill individual requirements.<br />
<br />
<span style="color: #990000;"><span style="font-size: large;">OBJECTIVE</span></span><br />
<br />
Seeking a challenging, growth-oriented position where an intimate knowledge of network security can effectively contribute to the successful and profitable operation of an organization.<br />
<br />
QUALIFICATIONS SUMMARY<br />
Highly creative and client-focused Information Technology Professional with over four years of industry experience spanning the design, implementation, configuration, and support of LAN/WAN network security solutions for companies. Knowledge of TCP/IP, relationship management, security event analysis, and problem resolution skills as well as outstanding organizational, multitasking, and team building skills. Proven ability as a resourceful coordinator, quick to learn new skills in fast-paced IT environments. <br />
<br />
<span style="color: #990000;"><span style="font-size: large;">PROFESSIONAL EXPERIENCE</span></span><br />
<br />
Network Security<br />
Analyst June 2010 - PRESENT<br />
XYZ Consultants<br />
Proficient in researching traffic patterns to identify false-positives and/or malicious traffic within IDS (Intrushield, TippingPoint, etc), IPS (Snort), scanners (Qualis), proxy (BlueCoat) and firewalls (CheckPoint, ASA, PIX, and Netscreen)<br />
Ability to analyze a large volume of security events while maintaining a high quality of analysis<br />
Identified data in firewall events to assist in troubleshooting<br />
Assisted with IDS and IPS Security Event tuning and noise reduction<br />
Proficient in suppressing messages on Firewall modules per customer and/or internal request<br />
Proficient with the SourceFire IDS/IPS to update devices and perform health checks<br />
Worked out of a SOC inbox and organized and routed issues to appropriate party in priority<br />
Performed searches within Remedy to identify historical traffic for customer requests and/or internal needs<br />
Worked out of Remedy on a daily basis to manage ticket, customer accounts, and device inventory<br />
Proficient in handling multiple work queues in priority and escalated matters when appropriate<br />
Provide excellent customer service and always receive positive feedback from management<br />
Strong documentation and report creation skills<br />
Act as a mentor to others on shift<br />
<br />
HELP SUPPORT OCTOBER 2009 - June 2010<br />
XYZ Consultants<br />
<br />
Installed and troubleshot Snare Syslog configurations on high valued windows machines<br />
Installed new servers / new applications on existing servers in support of internet and intranet environment<br />
Install, configure, troubleshoot and maintain local area networks including workstation connectivity via hardware and software<br />
Built and fixed computers by assembling and replacing components<br />
Submitted firewall policy change requests to the firewall administrators<br />
Developed system/network documentation<br />
Received employee-of-the-month for providing excellent customer service<br />
<br />
ADMINISTRATOR (Five Month Contract) APRIL 2009 - AUGUST 2009<br />
XYZ Consultants <br />
<br />
Responsible for troubleshooting network connectivity issues between client and partner machines<br />
Addressed network topology and architectural issues<br />
Responsible for installing Windows XP on new hire and client machines<br />
Installed and configured network printers, fax machines, and projectors<br />
Performed network administration and solve miscellaneous PC hardware and software issues. <br />
Kept inventory for all office devices and machines<br />
Follow all policies, procedures, and practices for office maintenance and operations<br />
<br />
TECHNICIAN JULY 2008 - APRIL 2009<br />
STU Consultants<br />
Deliver and picked up, troubleshot, diagnose, and perform basic repairs on computer components<br />
Staged mail servers with Windows 2003 Server<br />
Participated in the conversion of 100 PCs from Windows 2000 to Windows 2003<br />
Troubleshot local area network configurations and resolved hardware & software setups<br />
Recommended policies and procedures for managing, maintaining, and supporting the Intranet/ Internet usage<br />
Supported local area networks. Provided technical support and conducted test evaluation of new systems.<br />
Provided hardware specifications for purchase orders<br />
<br />
ADMIN ASSISTANT (INTERNSHIP) <br />
JULY 2007 - JULY 2008 <br />
BRACTECH - SPRINGFIELD, VA <br />
Designed and installed small Windows XP based LANs for business clients<br />
Performed PC and network repairs on equipment<br />
loaded software and upgraded user workstations as needed<br />
Troubleshot and resolved many user issues<br />
Maintained documentation on all completed assignments and configuration changes<br />
Performed network testing and base lining<br />
<br />
<span style="color: #990000;"><span style="font-size: large;">EDUCATION</span></span><br />
Planning to pursue a Information Security degree at ABC College <br />
o August 2005 - May 2006<br />
o Pursued an education in Business Administration with a concentration in Management<br />
<span style="color: #990000;"><span style="font-size: large;"><br />REFERENCES</span></span><br />
Available upon request</div>
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Don't forget to drop your comments below with your valuable feedback. </div>

Network Security Engineer Resume

(Article added on special request.) A nice and well organized resume plays a pivotal role in ...

Moment of Inertia

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<a href="https://2.bp.blogspot.com/-kHYPRPs-m5w/V1gKPpe87JI/AAAAAAAAGuE/KgEktkbDoycM2RQ_kirZaVMtB8JuCJabgCLcB/s1600/Spherical_shell_moment_of_inertia.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="Moment of Inertia" border="0" height="293" src="https://2.bp.blogspot.com/-kHYPRPs-m5w/V1gKPpe87JI/AAAAAAAAGuE/KgEktkbDoycM2RQ_kirZaVMtB8JuCJabgCLcB/s320/Spherical_shell_moment_of_inertia.png" title="Moment of Inertia" width="320" /></a></div>
The moment of inertia of an area is the capacity of a cross section to resist bending or buckling. It represents a mathematical concept that is dependent on the size and shape of the section of the member. The bending axis of a member is also the centroidal axis; therefore, the ability to locate the centroid of a shape is closely associated with moment of inertia. Engineers use the moment of inertia to determine the state of stress in a section, and determine the amount of deflection in a beam.</div>
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The definition of the <a href="http://www.engineersdaily.com/2014/11/basic-concepts-of-moment-of-intertia.html" target="_blank">moment of inertia</a> of an area can be thought of as the sum of the products of all the small areas and the squares of their distances from the axis being considered. This gives</div>
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If we represent the moment of inertia by the letter I, then the moments of inertia with respect to the x and y axis axis are</div>
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<span style="color: #990000;"><b><span style="font-size: large;">Units</span></b></span></div>
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Moment of inertia is expressed in units of length to the fourth power. Although dimensionally speaking it seems unusual, it is just a mathematical abstract and is an important property in the design of beams and columns. We will see in the following examples the methods of calculating the moment of inertia for a given beam section subjected to bending. If we choose the unit of length as mm., then the unit of the moment of inertia is</div>
<div style="text-align: justify;">
<span style="color: #990000;"></span><br /></div>
<div style="text-align: center;">
mm<sup>2</sup> x mm<sup>2</sup> = mm<sup>4</sup></div>

Moment of Inertia

The moment of inertia of an area is the capacity of a cross section to resist bending or buckling...

Overview: Deflection in Beams

<div style="text-align: justify;">
While the elongation or contraction of axially loaded members along their longitudinal axes is usually of little consequence, beams may experience excessive <a href="http://www.engineersdaily.com/2016/02/deflection-formulae-for-beams.html" target="_blank">deflection</a> perpendicular to their longitudinal axes, making them unserviceable. Limits on deflection are based on several considerations, including minimizing vibrations, thereby improving occupant comfort; preventing cracking of ceiling materials, partitions, or cladding supported by the <a href="http://www.engineersdaily.com/2011/01/design-of-reinforced-concrete-beams-per.html" target="_blank">beams</a>; and promoting positive drainage (for roof beams) in order to avoid ponding of water at midspan. These limits are generally expressed as a fraction of the span, L (Table 1). <br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-jdmK1WmaCXM/V1P85k9oF6I/AAAAAAAAGtE/Ix0xaAuAPz4ATh801uduXoSrdHF0UfWUQCLcB/s1600/table1%2528www.engineersdaily.com%2529.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Overview: Deflection in Beams" border="0" height="358" src="https://1.bp.blogspot.com/-jdmK1WmaCXM/V1P85k9oF6I/AAAAAAAAGtE/Ix0xaAuAPz4ATh801uduXoSrdHF0UfWUQCLcB/s640/table1%2528www.engineersdaily.com%2529.png" title="Overview: Deflection in Beams" width="640" /></a></div>
<br />
Formulas for the calculation of maximum deflection are shown in Table 2, along with additional values for the recommended minimum depth of reinforced concrete spanning elements.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-Dj5ruLr7yyg/V1P9rHaeYYI/AAAAAAAAGtQ/vOK0Mhd2cyMHMFIBhGWbUxHsyKrU45GNACLcB/s1600/table2%2528www.engineersdaily.com%2529.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Overview: Deflection in Beams" border="0" height="640" src="https://4.bp.blogspot.com/-Dj5ruLr7yyg/V1P9rHaeYYI/AAAAAAAAGtQ/vOK0Mhd2cyMHMFIBhGWbUxHsyKrU45GNACLcB/s640/table2%2528www.engineersdaily.com%2529.png" title="Overview: Deflection in Beams" width="570" /></a></div>
<br />
The maximum (mid span) deflection, <b>Δ</b>, of a uniformly loaded simple span can also be found from the equation:</div>
<div class="separator" style="clear: both; text-align: center;">
<img border="0" src="https://3.bp.blogspot.com/-3g1WjXhMlwg/V1P7sanAsTI/AAAAAAAAGs4/0w4l2G5oSjUmo_qk9wL7xmFzCGzRyDjqwCLcB/s1600/fmla.png" /></div>
<div style="text-align: justify;">
where w   distributed load (lb/in. or kips/in.), L   span (in.), E   modulus of elasticity (psi or ksi), and I   moment of inertia (in 4 ). When using Equation 8.1 with L in feet, w in lb/ft or kips/ft, E in psi or ksi (compatible with load, w ), and I in in<sup>4</sup>, as is most commonly done, multiply the expression by 12<sup>3</sup> to make the units consistent.<br />
  </div>

Overview: Deflection in Beams

While the elongation or contraction of axially loaded members along their longitudinal axes is usua...

Allowable Stress

<div style="text-align: justify;">
If a member is loaded beyond its ultimate stress, it will fail or rupture. In engineering <a href="http://www.engineersdaily.com/search/label/structures" target="_blank">structures</a>, it is essential that the structure not fail. Thus, the design is based on some lower value called allowable stress or design stress. If, for example, a certain type of steel is known to have an ultimate strength of 110,000 psi, a lower allowable stress would be used for <a href="http://www.engineersdaily.com/2014/02/thesis-design-of-structural-mechanisms.html" target="_blank">design</a>, say 55,000 psi. This allowable stress would allow only half the load the ultimate stress would allow. Allowable stress values are different for different materials, and they are tabulated and recommended by the International Building Code Association.<br />
The ratio of the ultimate stress to the allowable stress is known as the factor of safety.</div>
<div style="text-align: justify;">
<br />
<span style="font-size: large;"><span style="color: #cc0000;"><b>factor of safety = ultimate strength / allowable stress</b></span></span><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-xUykZnYD7tA/V1PzZtjB6_I/AAAAAAAAGrM/yDUGJtzQxoQaMehZJos-49irYPLPx33yACLcB/s1600/stress%2528engineersdaily.com%2529.JPG" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Allowable Stress" border="0" height="187" src="https://2.bp.blogspot.com/-xUykZnYD7tA/V1PzZtjB6_I/AAAAAAAAGrM/yDUGJtzQxoQaMehZJos-49irYPLPx33yACLcB/s400/stress%2528engineersdaily.com%2529.JPG" title="Allowable Stress" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Image courtesy: http://www.smpes.com</td></tr>
</tbody></table>
</div>
<div style="text-align: justify;">
</div>
<div style="text-align: justify;">
<b>Example</b></div>
<div style="text-align: justify;">
Determine the required size for a steel rod to support a tensile load of 50,000 lb if the allowable tensile stress of the steel is 25, 000 psi.</div>
<div style="text-align: justify;">
<br />
<b>Solution</b></div>
<div style="text-align: justify;">
σ = F/A</div>
<div style="text-align: justify;">
or</div>
<div style="text-align: justify;">
A = F/σ = 50, 000lb/25, 000psi = 2in<sup>2</sup><br />
A = πD2/4 = 2in<sup>2</sup><br />
Solving for D, we have:<br />
D = 1.6 in</div>

Allowable Stress

If a member is loaded beyond its ultimate stress, it will fail or rupture. In engineering structure...

5 Handy Tips for Anyone Starting an Engineering Business

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<a href="https://1.bp.blogspot.com/-HnJzP0hfz_M/VwqIRVQxUoI/AAAAAAAAGqA/Qy4POwXkuqopL7jD3egw92n-9FDc95IVQ/s1600/business%2528engineersdaily.com%2529.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="5 Handy Tips for Anyone Starting an Engineering Business" border="0" height="213" src="https://1.bp.blogspot.com/-HnJzP0hfz_M/VwqIRVQxUoI/AAAAAAAAGqA/Qy4POwXkuqopL7jD3egw92n-9FDc95IVQ/s320/business%2528engineersdaily.com%2529.png" title="5 Handy Tips for Anyone Starting an Engineering Business" width="320" /></a></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">If you have decided to start an <a href="http://www.engineersdaily.com/2016/04/5-signs-you-should-invest-in-construction-industry.html" target="_blank">engineering business</a>, you are about to embark on an exciting journey into the unknown. Working for yourself
 is different to working for a boss. You are now the master of 
everything you do. You decide what happens to you and how much money you
 make. For some, that freedom is liberating, for others, it is 
terrifying. Becoming a boss won’t be easy. You have loads of things to 
consider before you make it big. Here are five super tips that you 
should keep in mind.<strong></strong></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><strong><strong></strong></strong></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: large;"><span style="color: #cc0000;"><b>Make a financial budget before every quote</b></span></span><strong><strong><span style="font-size: large;"><span style="color: #cc0000;"> </span></span></strong></strong></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">When you get your first job, it is easy 
to let it excite you. Many new businessmen rush into quoting people for a
 job, before doing their research. Don’t think that taking a little 
extra time to complete your budget will lose you a client. Many people 
worry that if they take too long getting back to the client, the client 
will go with another <a href="http://www.engineersdaily.com/2014/04/types-of-construction-companies.html" target="_blank">company</a>. It is your duty to make a budget before 
you set a quote. If you don’t do that, you could end up losing money on 
jobs.<strong><strong> </strong></strong></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: large;"><span style="color: #cc0000;"><b>Time <a href="http://www.engineersdaily.com/2014/03/book-construction-management-and-design-industrial-steel-concrete-el.reedy.html" target="_blank">management</a> will be your best tool</b><strong><strong> </strong></strong></span></span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">Engineering jobs always run longer than 
they should. You can set yourself aside from the majority of engineering
 companies by completing jobs on time. Time management
 is not easy. You need to have great organizational and planning skills.
 You should make sure that you make a detailed schedule of each day. 
That means you can plan everybody’s roles and responsibilities before 
they start work. Usually, engineering companies get just one fee for the
 entire job. That means that when you are wasting time, you’re also 
wasting money.<strong><strong> </strong></strong></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: large;"><b><span style="color: #cc0000;">Every employee plays an integral role</span></b><span style="color: #cc0000;"><strong><strong> </strong></strong></span></span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">Don’t dismiss anyone’s ability or 
skills. In an <a href="http://www.engineersdaily.com/2014/03/book-construction-contracts-4th-edition-murdoch-hughes.html" target="_blank">engineering company</a>, there is a hierarchy system that 
works within every group. There is no such thing as a small job. Make 
sure that you appreciate the hard work that everybody is putting into 
your company. It is vital that you let your staff know how much you 
appreciate them. It can be easy to take staff for granted. If you do 
that, your staff will likely find another company for which to work. 
Take the time to get to know your staff so that you create a strong working relationship with them.<strong><strong> </strong></strong></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: large;"><span style="color: #cc0000;"><b>Choose your material and tools with care</b><strong><strong> </strong></strong></span></span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">When you are buying your materials and 
tools for each job, you might find buying the cheapest items is 
tempting. Remember, cheap materials never last. You want people to 
remember you as a quality company. That means that you need to ensure 
that you get quality materials so that they last. For example, when 
you’re buying a drawn seamless tube
 for a job, make sure that it comes with great reviews. Finding the 
right material for each job is vital to the success of your business, 
and so you need to make sure that you choose with care.<strong><strong> </strong></strong></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: large;"><span style="color: #cc0000;"><b>Start small and think big later</b><strong><strong> </strong></strong></span></span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">You might want to dive into <a href="http://www.engineersdaily.com/2014/03/book-project-management-for-engineering-construction-oberlender.html" target="_blank">large engineering jobs</a> and take on the world. As with everything, though, 
you’re going to need to start small. You can’t expect to land a massive 
job when you first start your business. Your clients want to see a track
 record of great work from you. That means that you won’t get the big 
jobs until you have proved you can handle them. No job is ever too small
 for you to take on when you start your company. Thinking that you’re 
above certain jobs won’t win you friends or clients. Take any job you 
can get so that you can start building your portfolio.</span></div>

5 Handy Tips for Anyone Starting an Engineering Business

If you have decided to start an engineering business , you are about to embark on an exciting jou...

Classification of Soil Shear Tests According to Drainage Conditions

<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-EoRyIALOkDc/VwqET_IwgGI/AAAAAAAAGp0/r5WvI8fikVEM9AIJH7UPTEdD_HmTCiP5A/s1600/triaxial%2528engineersdaily.com%2529.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="Classification of Soil Shear Tests According to Drainage Conditions" border="0" height="266" src="https://3.bp.blogspot.com/-EoRyIALOkDc/VwqET_IwgGI/AAAAAAAAGp0/r5WvI8fikVEM9AIJH7UPTEdD_HmTCiP5A/s400/triaxial%2528engineersdaily.com%2529.png" title="Classification of Soil Shear Tests According to Drainage Conditions" width="400" /></a></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">The shear strength parameters in the case of saturated <a href="http://www.engineersdaily.com/2011/03/introduction-to-soil-classification.html" target="_blank">soils</a> depend 
very much upon the drainage conditions and therefore in the laboratory 
shear test, the drainage condition expected in the field for a 
particular problem should be simulated. Based on drainage condition the 
shear tests are classified as following 3 types.</span></span></div>
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span>
<br />
<ol style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;">Unconsolidated Undrained Test (UU test)</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Consolidated Undrained Test (CU test)</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Consolidated Drained Test (CD test) </span></span></li>
</ol>
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span>
<br />
<div style="text-align: justify;">
<b> 
<span style="color: #cc0000;"><span style="font-size: large;"><span style="font-family: inherit;">1. Unconsolidated Undrained Test (UU)</span></span></span></b></div>
<div style="text-align: justify;">
<br /></div>
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span>
<br />
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">Drainage is not permitted throughout the test. In the case of direct 
shear test drainage is not permitted during the application of both 
normal stress and shear stress. In the case of triaxial compression test
 drainage is not permitted during the application of both cell pressure 
and deviator stress. Since the test is conducted fast allowing no time 
for either consolidation of sample initially or dissipation of pore 
pressure in later stage, the test is also called <b>quick test</b>.</span></span><br />
</div>
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span>
<br />
<div style="text-align: justify;">
<b><span style="color: #cc0000;"><span style="font-size: large;"><span style="font-family: inherit;">2. Consolidated Undrained Test (CU)</span></span></span></b></div>
<div style="text-align: justify;">
<br /></div>
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span>
<br />
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">In this type of shear test the <a href="http://www.engineersdaily.com/2011/03/massachusetts-institute-of-technology.html" target="_blank">soil</a> specimen is allowed to 
consolidate fully under initially applied stress and then sheared 
quickly without allowing dissipation of pore pressure. In the case of 
direct shear test the specimen is allowed to consolidate fully under 
applied normal stress and then sheared at high rate of strain to prevent
 dissipation of pore pressure during shearing. In the case of triaxial 
compression test the specimen is allowed to consolidate fully under the 
applied cell pressure and then the pore water outlet is closed and the 
specimen is subjected to increasing <a href="http://www.engineersdaily.com/2014/01/principles-of-geotechnical-engineering.html" target="_blank">deviator stress</a> at higher rate of 
strain.</span></span><br />
</div>
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span>
<br />
<div style="text-align: justify;">
<b><span style="color: #cc0000;"><span style="font-size: large;"><span style="font-family: inherit;">3. Consolidated Drained Test (CD)</span></span></span></b></div>
<div style="text-align: justify;">
<br /></div>
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span>
<br />
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">In this type of shear test drainage is allowed throughout the test. 
The specimen is allowed to consolidate fully under the applied initial 
stress and then sheared at low rate of strain giving sufficient time for
 the pore water to drain out at all stages. The test may continue for 
several hours to several days.</span></span></div>

Classification of Soil Shear Tests According to Drainage Conditions

The shear strength parameters in the case of saturated soils depend very much upon the drainage...

Causes of Cracks in Concrete

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<a href="https://2.bp.blogspot.com/-mECk6G6wWXU/VwZ3t3ezR-I/AAAAAAAAGpk/Q90Zd42NQnAl0DYabUHSspSnqdD9FTf-g/s1600/crack%2528engineersdaily.com%2529.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="Causes of Cracks in Concrete" border="0" height="213" src="https://2.bp.blogspot.com/-mECk6G6wWXU/VwZ3t3ezR-I/AAAAAAAAGpk/Q90Zd42NQnAl0DYabUHSspSnqdD9FTf-g/s320/crack%2528engineersdaily.com%2529.png" title="Causes of Cracks in Concrete" width="320" /></a></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">Cracks in concrete are caused due to following factors.</span></span></div>
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span><ol style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;">One of the main <a href="http://www.engineersdaily.com/2011/01/concrete-degradation.html" target="_blank">causes of cracks</a> in concrete is the cooling and 
contraction due to setting of concrete. Volume change and stresses due 
to shrinkage are independent of any external load or stress applied.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Cracks may develop in a smaller section attached to a large section 
due to differential expansion and contraction. Therefore a joint should 
be provided at the change of section. There is more possibility of 
cracking of fixed members than those which are free to expand and 
contract as simply supported beams.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Repeated expansion and contraction or alternate wetting and drying which may result in gradual disintegration of poor concrete.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Rapid drying due to hot weather and high speed winds or absorption 
of water from the concrete by wooden forms also a cause of cracking in <a href="http://www.engineersdaily.com/2013/12/advanced-concrete-technology-by-zongjin.html" target="_blank">concrete</a>. Therefore the form work on which fresh concrete is placed must
 be damped, or it should be waterproof so that it does not absorb water 
from fresh concrete.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Loose form work can also lead to cracks in concrete. so form work 
should be of adequate strength to bear the pressure of the wet concrete 
without swelling, spreading or any movement.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Concentration of tensile reinforcement at square openings or 
re-entrant angles (as in corners of door and window openings) causes 
cracks. This can be avoided by suitably placing reinforcements having 
adequate covering. Sufficient thickness of concrete should be given at 
the points where bars are bent up and anchored.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Minute cracks on the tension side of a <a href="http://www.engineersdaily.com/2011/02/properties-of-ordinary-portland-cement.html" target="_blank">reinforced concrete</a> member 
are unavoidable due to poor tensile strength of concrete as compared to 
steel and which must crack when steel reinforcement taken its load. 
Those cracks, however, should be fine enough for moisture penetration to
 prevent corrosion of the reinforcement.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Hair cracks are the result of unequal shrinkage of the surface 
concrete and the mass behind it. Delayed finishing and final floating of
 concrete can avoid these cracks up t o a certain limit.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Surface cracks are also caused by surface dressing with a mortar 
having too rich in cement. Too much water, insufficient curing, or from 
over trowelling. One method of avoiding such hair cracks is to remove 
the surface skin of the concrete by brushing it with a stiff brush soon 
after setting.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Contraction of <a href="http://www.engineersdaily.com/2013/08/what-is-concrete.html" target="_blank">concrete</a> is more harmful than expansion as it sets up
 tensile stresses in the structure, particularly those with a large 
surface area and thus form cracks. Such contracting cracks may be 
prevented by inserting reinforcement near the surface. Closely spaced 
reinforcement of small diameter and near the surface is more effective 
than large diameter bars further apart from the surface.</span></span></li>
</ol>

Causes of Cracks in Concrete

Cracks in concrete are caused due to following factors. One of the main causes of cracks in c...

How to Protect Concrete Against Weathering?

<div style="text-align: justify;">
<span style="font-size: small;">Concrete structures which are subjected to freezing and thawing are 
likely to <a href="http://www.engineersdaily.com/2011/01/concrete-degradation.html" target="_blank">deteriorate</a> earlier. Structures which are mostly affected 
under similar climatic conditions due to freezing and thawing are the 
exposed surfaces of the top 60 cm of walls, piers, parapets, cornices 
etc. the durability of such structures can be improved by adopting 
certain weather proofing measures. It has been observed that concrete 
surface if applied with curing compounds, linseed oil, epoxies etc, last
 longer.</span></div>
<span style="font-size: small;">
</span><div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-U0zwU_K9dW0/VwUrlnSk8sI/AAAAAAAAGpU/AZPeWa5A-BckhoQTaMXXxEN0-0wEVQ1Sg/s1600/degrade%2528engineersdaily.com%2529.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="How to Protect Concrete Against Weathering?" border="0" height="213" src="https://2.bp.blogspot.com/-U0zwU_K9dW0/VwUrlnSk8sI/AAAAAAAAGpU/AZPeWa5A-BckhoQTaMXXxEN0-0wEVQ1Sg/s320/degrade%2528engineersdaily.com%2529.jpg" title="How to Protect Concrete Against Weathering?" width="320" /></a></div>
<div style="text-align: justify;">
<span style="font-size: small;">In general protection measures against weathering are not adopted for
 new concrete surface unless they show some signs of deterioration, 
which is evident by the formation of fine cracks, close and parallel to 
edges and corners. It is better to treat such surfaces in earlier stages
 to avoid later uneconomical and difficult repairs. Concrete should be 
made waterproof to make it durable against freezing and thawing. The 
following methods of protection against weathering are known to have 
given good results.</span></div>
<span style="font-size: small;">
</span><ol style="text-align: justify;">
<li><span style="font-size: small;">Application of oils & paints</span></li>
<li><span style="font-size: small;">Application of varnishes</span></li>
<li><span style="font-size: small;">Application of chemical solutions</span></li>
</ol>
<span style="font-size: small;">
</span><h2 style="text-align: justify;">
<span style="color: #cc0000;"><b><span style="font-size: large;">1. Application of Oils & Paints</span></b></span></h2>
<span style="font-size: small;">
</span><div style="text-align: justify;">
<span style="font-size: small;">New concrete surfaces after completion of the curing should be 
allowed to dry for 1 or 2 weeks before waterproofing treatment is 
applied. Such new surfaces are brushed with a solution of 40 gm of 
phosphoric acid and 16 gm of zinc chloride to a liter of water. This is 
done to prevent the saponification of linseed oil. This treatment is not
 necessary for old concrete surfaces. Before adopting waterproofing 
measures the surface must be made clean and dry. After it apply two 
coats of linseed oil as mentioned below.</span></div>
<span style="font-size: small;">
</span><ul style="text-align: justify;">
<li><span style="font-size: small;">A mixture of 50% raw linseed oil and 50% turpentine heated to a temperature of 80<sup>0</sup>C is applied with ordinary brush as first coat</span></li>
<li><span style="font-size: small;">Raw linseed oil heated to 80<sup>0</sup>C is applied as a second coat with ordinary brush after 24 hours of application of the first coat.</span></li>
</ul>
<span style="font-size: small;">
</span><div style="text-align: justify;">
<span style="font-size: small;">After the second coat waterproofing coat becomes thoroughly dry, the 
entire treated surface is given two coats of standard white lead and oil
 paint. The application of the paint is necessary otherwise the 
previously applied oil treatment will deteriorate. In order that the 
colour of oil paint should match with the colour of concrete surface, 
lamp black or burnt sienna is added to the paint.</span></div>
<span style="font-size: small;">
</span><div style="text-align: justify;">
<span style="font-size: small;">In case any open cracks formed in the surface area to be treated, 
these should be first repaired by filling the cracks and then the 
surface is brushed with oil.</span></div>
<span style="font-size: small;">
</span><h2 style="text-align: justify;">
<span style="color: #cc0000;"><b><span style="font-size: large;">2. Application of Varnishes</span></b></span></h2>
<span style="font-size: small;">
</span><div style="text-align: justify;">
<span style="font-size: small;">Sometimes varnishes are applied to concrete surfaces which are 
effective against attacks due to mineral and vegetable oils. There are 
various bituminous paints, pitches and mastics available these days. 
They save the surface against acid attacks.</span></div>
<span style="font-size: small;">
</span><h2 style="text-align: justify;">
<span style="color: #cc0000;"><b><span style="font-size: large;">3. Application of Chemical Solutions</span></b></span></h2>
<span style="font-size: small;">
</span><h3 style="text-align: justify;">
<span style="font-size: small;">Magnesium or Zinc Fluosilicate Solution</span></h3>
<span style="font-size: small;">
</span><div style="text-align: justify;">
<span style="font-size: small;">The treatment consists of applying two or more coats of the compound.
 For the first coat, a solution of 1 kg of the compound per 10 liters of
 water is used. For subsequent coats, about 2 kg of the compound per 10 
liters of water are used. The solution is painted on the surface and 
each coat is allowed to dry before the next coat is applied. At the end,
 the surface is brushed and washed with water. This treatment hardens 
the surface and makes it impervious by chemical action. It protects 
<a href="http://www.engineersdaily.com/2011/02/properties-of-ordinary-portland-cement.html" target="_blank">concrete</a> against the attack of all mineral and vegetable oils, salts and
 alkalies.</span></div>
<span style="font-size: small;">
</span><h3 style="text-align: justify;">
<span style="font-size: small;">Sodium Silicate Solution</span></h3>
<span style="font-size: small;">
</span><div style="text-align: justify;">
<span style="font-size: small;">It is a viscous liquid and should be diluted with three times its 
volume of water. It should also be applied as above. It is better to 
scrub each coat with water after it has hardened before applying the 
next coat. The later coats are of a stronger solution. It also protects 
concrete against the same attacks as Fluosilicate.</span></div>

How to Protect Concrete Against Weathering?

Concrete structures which are subjected to freezing and thawing are likely to deteriorate earlier...

How to Prevent Plastic Shrinkage Cracking of Concrete?

<div style="text-align: justify;">
Plastic shrinkage cracking (as shown below) is caused by rapid drying
 of the concrete surface. They can occur at any time of the year, from 
cooler low-humidity weather conditions to, in particular, hot weather 
conditions involving any one or a combination of high temperature, low 
humidity and wind. These types of cracks occur while the concrete is bleeding and during
 the finishing operation. Fresh concrete may be exposed to the elements 
for a considerable time during these stages, causing the concrete at the
 surface to dry and shrink before it has any strength to resist the 
shrinkage forces.
</div>
<div style="text-align: justify;">
<a href="http://www.engineersdaily.com/2016/04/factors-affecting-durability-of-concrete.html" target="_blank">Concrete</a> cracks in much the same way as clay soils.</div>
<div class="separator" style="clear: both; text-align: justify;">
</div>
<h1 style="text-align: justify;">
<span style="color: #cc0000;"><strong>Methods of Preventing Plastic Shrinkage Cracking of Concrete</strong></span></h1>
<div class="separator" style="clear: both; text-align: justify;">
<a href="https://3.bp.blogspot.com/-_2MnSIEP2nQ/VwUo0NhS5fI/AAAAAAAAGpI/LWRuoyMJBaQQ5WVomi7EdXf74CbhMm_JA/s1600/Plastic-Shrinkage-Cracking-of-Concrete%2528engineersdaily.com%2529.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="How to Prevent Plastic Shrinkage Cracking of Concrete?" border="0" height="229" src="https://3.bp.blogspot.com/-_2MnSIEP2nQ/VwUo0NhS5fI/AAAAAAAAGpI/LWRuoyMJBaQQ5WVomi7EdXf74CbhMm_JA/s320/Plastic-Shrinkage-Cracking-of-Concrete%2528engineersdaily.com%2529.jpg" title="How to Prevent Plastic Shrinkage Cracking of Concrete?" width="320" /></a></div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">1. Erecting Temporary Wind Breaks</span></h2>
<div style="text-align: justify;">
Higher wind velocities can greatly affect the rate of evaporation of 
water from the concrete being placed. This in turn will result is 
plastic shrinkage cracking of concrete. Therefore erect temporary wind 
breaks to reduce the wind velocity over the surface of the concrete.</div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">2. Providing Sunshades</span></h2>
<div style="text-align: justify;">
In case of construction of concrete slabs, it is very effective to 
provide sunshades over the concrete slabs and thereby controlling the 
surface temperature of the slab.</div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">3. Proper Placement Timing</span></h2>
<div style="text-align: justify;">
In very hot weather conditions, concrete should not be placed in the 
afternoon, because it can lead to plastic shrinkage cracks on concrete 
due to loss of water. Therefore it is a good practice to schedule 
concrete placement in early morning or early evening. This way we can 
have better control over concrete temperature.</div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">4. Using Fog Sprays</span></h2>
<div style="text-align: justify;">
In very hot and dry periods the wind is very hot. Therefore use fog 
sprays to spray fog into the air over the concrete surface and in the 
direction opposite to the direction the wind is blowing. Using of fog 
sprays reduce the rate of evaporation from the concrete surface.</div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">5. Dampening the Subgrade</span></h2>
<div style="text-align: justify;">
During construction of concrete pavement in hot and dry weather, 
dampen the subgrade which is liable to water absorption from concrete. 
But remember the subgrade should not be over dampened. The formwork and 
the reinforcement should also be dampened.</div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">6. Using Evaporation Retarder</span></h2>
<div style="text-align: justify;">
Spray an evaporation retarder such as aliphatic alcohol over the 
freshly screeded <a href="http://www.engineersdaily.com/2016/04/4-main-factors-affecting-concrete-mix-proportions.html" target="_blank">concrete</a> surface. Surfaces can dry prematurely when the
 rate of evaporation is greater than the rate of bleeding. These 
products form a film on the surface that reduces the rate of evaporation
 of water, thus allowing time for all the bleed water to rise to the 
surface. In extreme conditions, re-application of the evaporation 
retarder may be necessary both before and during trowelling. These 
products do not affect the strength or performance of the concrete and 
can act as a finishing aid.</div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">7. Start Curing Immediately</span></h2>
<div style="text-align: justify;">
Commence curing as soon as possible after finishing. Spray the 
surface with liquid membrane curing compound or cover the surface with 
wet burlap or start water curing after concrete placement.</div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">8. Accelerating Setting Time of Concrete</span></h2>
<div style="text-align: justify;">
Use some form of chemical admixture in concrete to accelerate the 
setting time of concrete and avoid large temperature differences between
 concrete and air temperature.</div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">9. Adding Polypropylene Fibres in Concrete Mix</span></h2>
<div style="text-align: justify;">
Polypropylene fibres can be added to the concrete mix to reduce the 
incidence of plastic <a href="http://www.engineersdaily.com/2011/04/shrinkage-and-temperature-reinforcement.html" target="_blank">shrinkage</a> cracking. Fibres tend to bind the surface
 of the concrete together and provide some strength to the plastic 
concrete to resist the shrinkage forces.</div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;">10. Be Ready</span></h2>
<div style="text-align: justify;">
Have proper manpower, equipment and supplies on hand so that the concrete can be placed and finished promptly.</div>

How to Prevent Plastic Shrinkage Cracking of Concrete?

Plastic shrinkage cracking (as shown below) is caused by rapid drying of the concrete surface. The...

Precautions During Concrete Placement

<div style="text-align: justify;">
<span style="font-family: inherit;">The concrete, as it comes out of the mixer or as it is ready for use 
on the platform, is to be transported and placed on the formwork.</span></div>
<div style="text-align: justify;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-VjixBwDN-Vs/VwUlom9tv9I/AAAAAAAAGo8/NwPAeEyQQEQtrovXgj7tcMiQtBfS18KbQ/s1600/Concrete_pump%2528engineersdaily.com%2529.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="Precautions While Concrete Placement" border="0" height="240" src="https://3.bp.blogspot.com/-VjixBwDN-Vs/VwUlom9tv9I/AAAAAAAAGo8/NwPAeEyQQEQtrovXgj7tcMiQtBfS18KbQ/s320/Concrete_pump%2528engineersdaily.com%2529.JPG" title="Precautions While Concrete Placement" width="320" /></a></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">Following precautions should be taken during placing of concrete.</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">
</span></div>
<ol style="text-align: justify;">
<li><span style="font-family: inherit;">The formwork or the surface which is to receive the fresh concrete should be properly cleaned, prepared and well watered.</span></li>
<li><span style="font-family: inherit;">It is desirable to deposit concrete as near as practicable to its final position.</span></li>
<li><span style="font-family: inherit;">The large quantities of concrete should not be deposited at a time. 
Otherwise the concrete will start to flow along the formwork and 
consequently the resulting concrete will not have uniform composition.</span></li>
<li><span style="font-family: inherit;">The concrete should be dropped vertically from a reasonable height. 
For vertical laying of concrete, care should be taken to use stiff mix. 
Otherwise the bleeding of concrete through cracks in forms will take 
place. The term bleeding is used to mean the diffusion or running of 
concrete through formwork.</span></li>
<li><span style="font-family: inherit;">The concrete should be deposited in horizontal layers of about 150 
mm height. For mass <a href="http://www.engineersdaily.com/2016/04/concrete-mixed-proportioning-methods.html" target="_blank">concrete</a>, the layers may be of 400 mm to 500 mm 
height. The accumulation of excess water in upper layers is known as the
 laitance and it should be prevented by using shallow layers with stiff 
mix or by putting dry batches of concrete to absorb the excess water.</span></li>
<li><span style="font-family: inherit;">As far as possible, the concrete should be placed in single 
thickness. In case of deep sections, the concrete should be placed in 
successive horizontal layers and proper care should be taken to develop 
enough bond between successive layers.</span></li>
<li><span style="font-family: inherit;">The concrete should be thoroughly worked around the reinforcement 
and tapped in such a way that no honeycombed surface appears on removal 
of the formwork. The term honeycomb is used to mean comb or mass of waxy
 cells formed by bees in which they store their honey. Hence, if this 
precaution is not taken, the concrete surface so formed would have a 
honeycomb like surface.</span></li>
<li><span style="font-family: inherit;">The concrete should be placed on the formwork as soon as possible. 
But in no case, it should be <a href="http://www.engineersdaily.com/2011/05/placing-of-concrete.html" target="_blank">placed</a> after 30 minutes of its preparation.</span></li>
<li><span style="font-family: inherit;">During placing, it should be seen that all edges and corners of concrete surface remain unbroken, sharp and straight in line.</span></li>
<li><span style="font-family: inherit;">The placing of concrete should be carries out uninterrupted between predetermined construction joints.</span></li>
</ol>

Precautions During Concrete Placement

The concrete, as it comes out of the mixer or as it is ready for use on the platform, is to be tra...

3 Common Causes of Failure of Flexible Pavements

<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">A typical flexible pavement consist of following 4 layers</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ul style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;">Soil subgrade</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Sub-base course</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Base course</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Surface or wearing course</span></span></li>
</ul>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-pEjb6LKgbsY/VwUjLxiRSfI/AAAAAAAAGow/o0AlpVn1NWwozNzf5LpD_3dG8loNtS6gw/s1600/pav%2528engineersdaily.com%2529.gif" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="3 Common Causes of Failure of Flexible Pavements" border="0" height="113" src="https://1.bp.blogspot.com/-pEjb6LKgbsY/VwUjLxiRSfI/AAAAAAAAGow/o0AlpVn1NWwozNzf5LpD_3dG8loNtS6gw/s400/pav%2528engineersdaily.com%2529.gif" title="3 Common Causes of Failure of Flexible Pavements" width="400" /></a></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">If due to any reason, any of the above mentioned layers loses its stability, it will lead to failure of the whole pavement.</span></span><span style="font-family: inherit;"></span><span style="font-family: inherit;"><span style="font-size: small;"> There are many types of failures of flexible pavement, such as 
formation of pot holes, ruts, cracks, localized depression etc. when any
 one form of failure found on the surface, then it is an indication of 
failure of pavement.</span></span><span style="font-family: inherit;"></span><span style="font-family: inherit;"><span style="font-size: small;"> Therefore it is essential that each layer of the pavement should be 
carefully designed and constructed to maintain its stability.</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<h1 style="text-align: justify;">
<span style="color: #cc0000;"><span style="font-size: large;"><span style="font-family: inherit;">What Causes Failure of Flexible Pavement?</span></span></span></h1>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">The 3 common causes of failure of flexible pavement are as follow</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ol style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;">Failure of subgrade</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Failure of sub-base or base course</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Failure of surface or wearing course</span></span></li>
</ol>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;"><span style="font-family: inherit;"><span style="font-size: small;">1. Failure of Subgrade</span></span></span></h2>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">This is the main cause of flexible pavement failure. When there is 
excessive deformation in subgrade <a href="http://www.engineersdaily.com/2011/03/aashto-soil-classification-system.html" target="_blank">soil</a>, it will result in failure of 
whole pavement. The failure of subgrade soil can be detected by the 
following forms of defects causing unevenness of pavement surface.</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ul style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;">Excessive undulation & corrugation on surface</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Depression followed by heaving at surface</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Lateral shoving of pavement near the edge along the wheel path</span></span></li>
</ul>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">The two primary reasons of failure of subgrade soil are</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ul style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;">Inadequate stability</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Excessive stress application</span></span></li>
</ul>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ol style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;"><strong> Inadequate stability:</strong> Stability is the 
resistance to deformation under stress. When soil used for construction 
of subgrade is of inferior quality, it will not be able to resist the 
load coming from wheel, and ultimately it will fail.</span></span></li>
</ol>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">Another reason causing loss of stability of subgrade soil is improper
 compaction of soil during construction. Presence of excessive moisture 
at subgrade level without proper drainage control also affects the 
stability of subgrade.</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ol start="2" style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;"><strong> Excessive stress application:</strong> Thickness of 
the pavement should be so designed, that it can distribute the wheel 
load properly. If pavement thickness becomes less than that of the 
required value, then it will result in failure of subgrade. Also if the 
wheel load applied on pavement is in excess of design value, it will 
result in failure of subgrade.</span></span></li>
</ol>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;"><span style="font-family: inherit;"><span style="font-size: small;">2. Failure of Sub-base or Base Course</span></span></span></h2>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">There are 5 primary reasons behind failure of sub-base or base course as described below.</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ol style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;"><strong> Inadequate stability or strength:</strong> Role of a
 sub-base or base course is to transform the wheel load from surface 
course or wearing course to the subgrade. Therefore the strength of the 
sub-base or base course is always higher than that of subgrade. Strength
 of the sub-base or base course can be achieved by taking following 
measures.</span></span></li>
</ol>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ul style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;">Using good quality of aggregate</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Proper mix design</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Providing sufficient thickness</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Proper quality control</span></span></li>
</ul>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">If there is any deviation occurs in any of the above mentioned factors, it will lead to failure of pavement.</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ol start="2" style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;"><strong> Loss of binding action:</strong> When wheel load is 
repeatedly applied on road surface, it causes internal movement of 
particles in the sub-base or base course. This results in relative 
movement between surface course and sub-base or base course. In other 
word, instead of acting as whole, different layer acts separately. This 
is the cause of alligator or map cracking on bituminous surface.</span></span></li>
</ol>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">Therefore a layer of <strong>tack coat</strong> or <strong>prime coat</strong> is applied on top of the base course before placing surface course. This creates a better bonding of these two layers.</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ol start="3" style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;"><strong> Loss of base course materials:</strong> When there 
is no wearing course or surface course on the base course, or if the 
wearing course has completely worn out, that will result in loss of base
 course material. This happens because of suction caused by the tyre and
 exposed base course materials. Also loss of stone aggregate creates pot
 holes on surface course.</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;"><strong> Inadequate wearing course:</strong> If the thickness of wearing course is less, then water will find its way to the base course causing damage to it.</span></span></li>
</ol>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">Therefore it is essential to consider type, intensity and volume of traffic before deciding thickness of wearing course.</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ol start="5" style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;"><strong> Use of inferior material:</strong> The materials to 
be used for construction of base course should be so chosen in a manner 
so that it can resist the wheel load and weathering actions. Inferior 
quality of material should not be used.</span></span></li>
</ol>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<h2 style="text-align: justify;">
<span style="color: #cc0000;"><span style="font-family: inherit;"><span style="font-size: small;">3. Failure of Wearing Course</span></span></span></h2>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">Wearing course or surface course is the layer having more strength 
than all the other pavement layers. This is because the wheel load is 
directly applied on this layer. Along with the vertical load, it has 
also to resist the abrading effect of wheel and weathering effect of 
climate.</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">Therefore design and construction of wearing course should be done 
properly. A pervious layer of wearing course can damage all the 
underlying layers. The following measure should be employed during 
design and construction of wearing courses</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<ul style="text-align: justify;">
<li><span style="font-family: inherit;"><span style="font-size: small;">Proper mix design</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Sufficient thickness</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Good quality of binder</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Proper amount of binder</span></span></li>
<li><span style="font-family: inherit;"><span style="font-size: small;">Good quality aggregate</span></span></li>
</ul>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">High degree of quality control should be employed during construction of wearing course.</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">
</span></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><span style="font-size: small;">Oxidation or aging of binder, also make the bituminous surface 
brittle and creates cracks on pavement surface. This results in ingress 
of moisture to underlying layers and weakening of the layers.</span></span></div>

3 Common Causes of Failure of Flexible Pavements

A typical flexible pavement consist of following 4 layers Soil subgrade Sub-base course Base...