Q. In a concrete mix design, what does the term 'water-cement ratio' refer to?
A.The ratio of water to the total volume of concrete
B.The ratio of water to the weight of cement
C.The ratio of cement to the weight of aggregates
D.The ratio of fine aggregates to coarse aggregates
Solution
The water-cement ratio is defined as the weight of water divided by the weight of cement in a concrete mix, which significantly affects the strength and durability of the concrete.
Correct Answer: B — The ratio of water to the weight of cement
Q. What is the primary benefit of using lightweight aggregates in concrete?
A.Increased compressive strength
B.Reduced thermal conductivity
C.Lower cost of materials
D.Improved aesthetic appeal
Solution
Lightweight aggregates reduce the overall density of concrete, which can lead to increased compressive strength and improved thermal insulation properties.
Q. What is the primary purpose of using water in concrete mix design?
A.To enhance the color of the concrete
B.To facilitate the chemical reaction of hydration
C.To reduce the weight of the concrete
D.To increase the setting time
Solution
Water is essential for the hydration process, which is the chemical reaction that occurs when cement and water are mixed, leading to the hardening of concrete.
Correct Answer: B — To facilitate the chemical reaction of hydration
Q. What is the significance of the 'f' value in concrete mix design?
A.It represents the maximum aggregate size
B.It indicates the compressive strength of concrete
C.It denotes the water-cement ratio
D.It measures the workability of the mix
Solution
The 'f' value, often referred to as the characteristic compressive strength of concrete, indicates the strength that the concrete is expected to achieve at 28 days.
Correct Answer: B — It indicates the compressive strength of concrete
Q. Which type of aggregate is typically used to improve the workability of concrete?
A.Coarse aggregate
B.Fine aggregate
C.Recycled aggregate
D.Lightweight aggregate
Solution
Fine aggregates, such as sand, are used to improve the workability of concrete by filling the voids between coarse aggregates and providing a smoother mix.
