Free Concrete Technology MCQs with Answers
80 Concrete Technology MCQs from Civil Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Concrete technology covers cement, aggregates, water and admixtures, including their properties, proportioning and effect on fresh and hardened concrete. It explains workability, water-cement ratio, setting, hydration, strength, durability, curing, mix design and common defects, while distinguishing segregation and bleeding from general loss of workability.
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80 questions · page 3 of 4
- A. Capillary pores after evaporation
- B. Additional cementing compounds
- C. Higher aggregate strength
- D. Greater resistance to carbonation
Explanation: Excess mixing water eventually leaves the paste and forms capillary voids.
Correct answer: Capillary pores after evaporation- A. 1.15
- B. 2.15
- C. 3.15
- D. 4.15
Explanation: Ordinary Portland cement has a specific gravity of about 3.15. This value is used in absolute volume calculations during concrete mix…
Correct answer: 3.15- A. Surface polishing
- B. Sudden impact loading
- C. Gradual compressive loading
- D. Chemical weathering
Explanation: The aggregate crushing value indicates resistance to crushing under a gradually applied compressive load.
Correct answer: Gradual compressive loading- A. Improved cement hydration
- B. Delayed cement expansion
- C. Reduced aggregate absorption
- D. Segregation of the mix
Explanation: Over-vibration can drive coarse aggregate downward and bring mortar or water upward, producing segregation.
Correct answer: Segregation of the mix- A. Calcium hydroxide to form binding compounds
- B. Gypsum to form extra sand
- C. Coarse aggregate to form air voids
- D. Mixing water to form free lime
Explanation: Pozzolanic materials react with calcium hydroxide released during cement hydration.
Correct answer: Calcium hydroxide to form binding compounds- A. Decrease to zero
- B. Increase
- C. Remain exactly constant
- D. Change only during mixing
Explanation: A higher water-cement ratio leaves more capillary pores after evaporation, so permeability generally increases.
Correct answer: Increase- A. Abrasion under rubbing
- B. Absorption of mixing water
- C. Sudden shock or impact
- D. Chemical attack by sulphates
Explanation: The aggregate impact value assesses how well aggregate resists sudden blows or shock.
Correct answer: Sudden shock or impact48. If concrete is placed and cured at a substantially higher temperature, cement hydration generally
- A. Stops completely
- B. Changes aggregate into cement
- C. Becomes independent of water
- D. Proceeds more rapidly at early ages
Explanation: Higher temperature generally accelerates hydration and early strength development.
Correct answer: Proceeds more rapidly at early ages- A. 10
- B. 50
- C. 100
- D. 1000
Explanation: Fineness modulus is calculated by adding the cumulative percentages retained on the specified sieves and dividing the sum by 100.
Correct answer: 100- A. Eliminates the need for cement
- B. Provides high early strength
- C. Prevents every type of shrinkage
- D. Makes aggregate grading unnecessary
Explanation: Steam curing raises the temperature and moisture available for hydration, allowing precast units to achieve useful early strength quickly.
Correct answer: Provides high early strength- A. It prevents carbonation of concrete
- B. It increases the density of aggregates
- C. It controls the setting time of cement
- D. It provides most of the cement colour
Explanation: Gypsum is added to Portland cement to regulate the rapid reaction of tricalcium aluminate and prevent flash set.
Correct answer: It controls the setting time of cement- A. Constant temperature
- B. Specified compressive strength
- C. Maximum expansion
- D. Standard penetration
Explanation: Normal consistency is the water content that allows the Vicat plunger to penetrate the cement paste to a specified depth.
Correct answer: Standard penetration- A. Greater surface area and interlocking
- B. Lower specific gravity and absorption
- C. Higher cement content and fineness
- D. Greater elasticity and thermal resistance
Explanation: Angular and rough particles have greater surface area and interlock more strongly, increasing internal friction and water demand for the…
Correct answer: Greater surface area and interlocking- A. Increase the specific gravity of cement
- B. Promote corrosion of embedded steel
- C. Prevent aggregate interlocking
- D. Eliminate cement hydration
Explanation: Chloride ions can break down the passive protective film around reinforcing steel and promote corrosion when sufficient moisture and…
Correct answer: Promote corrosion of embedded steel- A. Resistance to aggregate crushing
- B. Resistance to cement setting
- C. Flexural tensile strength
- D. Elastic recovery after unloading
Explanation: The modulus of rupture is the flexural tensile strength obtained from a bending test on a concrete beam or prism.
Correct answer: Flexural tensile strength- A. Initial setting time
- B. Cement fineness before mixing
- C. Exact water-cement ratio
- D. Uniformity and internal defects
Explanation: Ultrasonic pulse velocity helps identify variations in quality, cracks, voids and internal discontinuities in hardened concrete.
Correct answer: Uniformity and internal defects- A. Drying shrinkage
- B. Aggregate crushing
- C. Flash setting
- D. Loss of cement hydration
Explanation: More paste can lubricate aggregate particles and improve workability, but the larger volume of cement paste can increase drying shrinkage.
Correct answer: Drying shrinkage- A. Evaporation from an exposed surface
- B. Self desiccation during cement hydration
- C. Settlement of coarse aggregate
- D. Expansion caused by wetting
Explanation: Autogenous shrinkage results from internal moisture consumption during hydration, especially in low water-cement ratio concrete, which…
Correct answer: Self desiccation during cement hydration- A. To delay cement hydration in lower layers
- B. To increase the water-cement ratio gradually
- C. To ensure each layer is properly compacted
- D. To prevent all contact between adjacent layers
Explanation: Placing manageable layers allows vibration or other compaction to remove entrapped air throughout the depth.
Correct answer: To ensure each layer is properly compacted- A. Stop hydration of the cement paste
- B. Decrease the total aggregate surface area
- C. Eliminate the need for compaction
- D. Increase the surface area requiring paste
Explanation: Smaller aggregate particles provide a greater total surface area, so more paste is needed to coat them and maintain comparable…
Correct answer: Increase the surface area requiring paste