MCQs on Ingredients of Concrete
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Q1: The Los Angeles testing machine is commonly used to determine which property of the coarse aggregate?
Difficulty: Medium
Solution:
The Los Angeles abrasion test is used to find the hardness and abrasion resistance of coarse aggregates by measuring the wear due to attrition and impact.
Q2: As specified in IS 2386 (Part IV): 1963, which of the following set of sieves are used to find the crushing value of coarse aggregates?
Difficulty: Hard
Solution:
For the aggregate crushing value test (IS 2386), the aggregate must pass a 12.5 mm sieve and be retained on a 10 mm sieve. After crushing, the material is sieved through a 2.36 mm sieve to find the crushing value.
Q3: Proper experimental knowledge about the porosity and water absorption capacity of a coarse aggregate is required as its affects the durability of concrete because of:
I. Freezing and thawing
II. Reaction with chemically reactive fluids
III. Increasing the workability of concrete
Difficulty: Medium
Solution:
Porosity and water absorption affect concrete durability due to freezing and thawing (absorbed water expands when frozen, causing cracks), chemical reactions (porous aggregates allow reactive fluids to penetrate), and workability (highly porous aggregates absorb mixing water, reducing the intended workability).
Q4: As per IS 2386 (1963), the aggregate crushing value is calculated by using a single sized aggregate, which is:
Difficulty: Medium
Solution:
According to IS 2386 (1963), the ACV test requires a single-sized aggregate that passes through a 12.5 mm IS sieve and is retained on a 10 mm IS sieve.
Q5: Under properly controlled combustion and temperature, what is the percentage of silica content that can be obtained from rice husk ash?
Difficulty: Hard
Solution:
Rice Husk Ash (RHA) contains about 85% to 95% silica when burnt under properly controlled combustion (around 800 degrees C) and temperature.
Q6: Pycnometer, wire mesh bucket and water are used to calculate which characteristic property of the coarse aggregate?
Difficulty: Easy
Solution:
A Pycnometer, wire mesh bucket, and water are the standard apparatuses used to determine the specific gravity and water absorption of coarse aggregates (IS 2386 Part III).
Q7: The total amount of dissolved salts allowable concentrations in mixing water in order to obtain a good strength concrete in terms of parts per million (ppm) as per IS 456 is __.
Difficulty: Medium
Solution:
According to IS 456:2000 guidelines for mixing water, the allowable concentration limit for total dissolved salts in mixing water is 15000 ppm.
Q8: Super plasticisers are also called
Difficulty: Easy
Solution:
Super plasticisers are also known as high-range water reducers (HRWR). They can reduce the water content by up to 30% while maintaining or improving workability without affecting setting time.
Q9: For estimating the water absorption of 4.75 mm aggregate used for concrete, the prescribed oven drying temperature (°C) is:
Difficulty: Easy
Solution:
As per IS 2386 (Part III), the prescribed oven-drying temperature for estimating the water absorption of aggregates is strictly maintained between 100 degrees C and 110 degrees C.
Q10: The impact value of aggregate is calculated for understanding which one of the following characteristic property of aggregate?
Difficulty: Easy
Solution:
The aggregate impact test is conducted to determine its toughness, which represents its resistance to sudden dynamic loads or impact.
Q11: As per IS 383 (1970), the grading limit percentage of fine aggregates in Zone II which are passing through a 4.75 mm IS sieve is
Difficulty: Hard
Solution:
According to IS 383:1970, for Zone II fine aggregates, the percentage passing through a 4.75 mm IS sieve is 90% to 100%.
Q12: Based on coarse aggregate’s shape, what shape is mostly recommended for good bonding and high strength in concrete?
Difficulty: Easy
Solution:
Angular aggregates have rough surfaces and sharp edges which provide better interlocking and superior bonding with the cement matrix, making them the most recommended shape for high-strength concrete.
Q13: As per IS 383 (1970), the percentage passing of fine aggregates under a 2.36 mm IS sieve during grading Zone I is
Difficulty: Hard
Solution:
According to IS 383:1970, fine aggregates falling under Zone I must have 60% to 95% passing through a 2.36 mm IS sieve.
Q14: The aggregates which are available near the river front are found to have a rounded shape due to
Difficulty: Medium
Solution:
Aggregates near riverfronts obtain their rounded shape primarily due to attrition, which is the mutual rubbing, grinding, and wearing down of particles as they are transported by water over time.
Q15: As per IS 383 (1970), the passing percentage of fine aggregates under Zone IV from an IS 600 microns sieve is
Difficulty: Hard
Solution:
According to IS 383:1970, for an IS 600 microns sieve, the passing percentage for Zone IV fine aggregates is 80% to 100%.