Which of the following statement(s) is/are true regarding steam curing in precast concrete? (i) It accelerates strength gain. (ii) It is commonly used in factory production of precast elements.
- AOnly (i)
- BOnly (ii)
- CBoth (i) and (ii)Correct
- DNeither (i) nor (ii)
Solution
Concept
Steam curing in precast manufacturing
Formula
NONE
Step-by-step solution
1. Steam curing introduces elevated temperatures (typically 65 to 80 °C) and 100% relative humidity to accelerate the hydration of tricalcium silicate (C3S). 2. This thermal acceleration promotes rapid early strength development within hours; statement (i) is true. 3. Commercial precast plants rely on rapid cycle times to demold, prestress, and reuse forms daily, making steam curing standard practice; statement (ii) is true. 4. Consequently, both statements (i) and (ii) are true. Answer: C
Explanation
Steam curing supplies high thermal energy along with moisture to fresh concrete, drastically accelerating cement hydration reactions to achieve required 28-day strengths in 12 to 24 hours. Because rapid mold turnaround and early handling are crucial to commercial efficiency, steam curing is universally utilized in precast concrete factory manufacturing.
Why the other options are wrong
A) Statement (ii) is also true because steam curing is the standard industrial curing method in precast plants. B) Statement (i) is also true as thermal excitation drastically accelerates early strength gain. D) Both statements describe standardized precast industry procedures.
Shortcut
Steam curing = Accelerated hydration + Rapid turnover in precast concrete factories.
Common mistake
Assuming steam curing is primarily used for in-situ cast construction rather than precast plants.
Correct answer: C) Both (i) and (ii)