Lec 2 mcqs easy
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Lec 2 mcqs easy

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Questions and Answers

What is the percentage weight of soil retained on the 4.75 sieve?

9.71%

In the combined grading of fine and coarse aggregate, what properties of concrete can be better controlled?

Workability and Shrinkage

What does the reduction of voids achieve in concrete when different aggregate sizes are combined?

Decreased Void-Content

The Fine Module (FM) value falls within which range for medium aggregate according to the example provided?

<p>2.5 – 2.8</p> Signup and view all the answers

Why is it important to determine the absorption and surface moisture of aggregates in concrete?

<p>To control water content and batch weights</p> Signup and view all the answers

What is the purpose of limestone sweetening in concrete production?

<p>To enhance the ASR resistance by replacing 30% of the reactive aggregate with limestone</p> Signup and view all the answers

Which factor does NOT influence the Alkali-Carbonate Reaction (ACR)?

<p>Moisture content in concrete</p> Signup and view all the answers

Which testing method is NOT used for Alkali-Carbonate Reaction (ACR) assessment?

<p>Moisture absorption test</p> Signup and view all the answers

What is the main effect of lithium-based admixtures in concrete?

<p>To reduce ASR expansion</p> Signup and view all the answers

How does spraying a 30% LiNO3 solution with a tanker truck contribute to concrete production?

<p>It enhances ASR resistance</p> Signup and view all the answers

Why is particle size important in concrete?

<p>It influences the surface area available for cement paste interaction</p> Signup and view all the answers

How does the particle size affect the surface area in concrete?

<p>Bigger particles result in higher surface area</p> Signup and view all the answers

What is the effect of larger coarse aggregate on cement requirement in concrete?

<p>Less cement is required</p> Signup and view all the answers

How does larger coarse aggregate influence water requirement in concrete mixtures?

<p>Less water is required</p> Signup and view all the answers

What does Fineness Modulus (FM) measure in aggregates?

<p>Particle size distribution of aggregates</p> Signup and view all the answers

What is the maximum percentage of particles that should pass through the 4.75 mm sieve according to ASTM C33 grading limits?

<p>95%</p> Signup and view all the answers

What is the purpose of the Nominal Maximum Size of an aggregate?

<p>It determines the maximum size of aggregate to ensure proper concrete properties.</p> Signup and view all the answers

What does it mean if an aggregate has a percentage of retained aggregate at 0% on a sieve analysis?

<p>All particles passed through the sieve.</p> Signup and view all the answers

How does the Nominal Maximum Size relate to the dimensions of forms in a construction project?

<p>It should not exceed 1/5 the narrowest dimension between sides of forms.</p> Signup and view all the answers

Why is Alkali-Silica Reaction (ASR) more concerning than Alkali-Carbonate Reaction (ACR)?

<p>ASR aggregates have a more common occurrence of reactive silica minerals.</p> Signup and view all the answers

What does it mean in aggregate grading if the percentage passing a certain sieve is below the ASTM lower limit?

<p>The aggregate is too fine.</p> Signup and view all the answers

Which visual symptom is associated with Alkali-Silica Reaction (ASR)?

<p>Fragments breaking out of the surface (popouts)</p> Signup and view all the answers

What is the mechanism behind Alkali-Silica Reaction (ASR)?

<p>Alkali hydroxide + Reactive silica + Moisture -&gt; Alkali Silica Gel + Alkali Silica gel filling microcracks</p> Signup and view all the answers

Which testing method is used for detecting Alkali-Silica Reaction (ASR)?

<p>Concrete Prism Test (ASTM C 1293)</p> Signup and view all the answers

What condition must be present for Alkali-Silica Reaction (ASR) to occur?

<p>Alkali + Reactive silica + Moisture</p> Signup and view all the answers

What is the main cause of D-cracking in concrete pavements?

<p>Failure of carbonate coarse aggregate</p> Signup and view all the answers

Which of the following describes a popout in concrete?

<p>Breaking away of a small fragment of concrete due to internal pressure</p> Signup and view all the answers

What can potentially make aggregates harmful if they react chemically with concrete?

<p>Interfering with the normal hydration of cement</p> Signup and view all the answers

What is Alkali-Aggregate Reactivity (AAR) defined as?

<p>A chemical reaction between aggregates and alkali hydroxides in concrete</p> Signup and view all the answers

What does combined grading aim to achieve in aggregates?

<p>Reduction of voids in concrete</p> Signup and view all the answers

What is the particle size range for fine aggregate, according to ASTM Sieve Sizes?

<p>150 μm to 9.5 mm</p> Signup and view all the answers

Which type of aggregate is Rocks and minerals classified as?

<p>Coarse aggregate</p> Signup and view all the answers

What does grading of aggregate refer to?

<p>Particle size distribution</p> Signup and view all the answers

What type of sieve analysis is used for determining the grading of aggregate?

<p>Wire mesh sieves with square openings</p> Signup and view all the answers

Which sieve sizes are used for determining the particle size distribution of fine aggregate?

<p>7 standard sieves from 150 μm to 9.5 mm</p> Signup and view all the answers

Which type of aggregate is Crushed blast-furnace slag classified as?

<p>Heavy aggregate</p> Signup and view all the answers

What do the curves on the particle size distribution curve indicate?

<p>Particle size limits specified in ASTM C 33</p> Signup and view all the answers

What does the square grid in sieve analysis allow through?

<p>Smaller particles</p> Signup and view all the answers

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