The following statements pertain to mass concreting. Which are correct? S1: Preferred materials are low-heat Portland cement, pozzolanas, aggregates, water, admixture and coolants. S2: Slump of mass concrete shall be the same as or more than ordinary concrete work. S3: Concrete with a low water-cement ratio, correctly consolidated and properly cured provides durability to mass concrete work.
Try it first: pick an option, then read the explanation.
Statements on Mass Concreting
S1 is correct. Low-heat Portland cement, pozzolanas, aggregates, water, admixtures and coolants are all standard materials for mass concrete, used to reduce heat of hydration.
S2 is wrong. Mass concrete uses a lower slump than ordinary concrete, not the same or higher. A higher slump would increase water content, raise the heat of hydration, and increase shrinkage — exactly what mass concreting tries to avoid.
S3 is correct. A low water-cement ratio combined with correct consolidation and proper curing are the key factors that produce a durable mass concrete section.
Key takeaway
S2 is the trick option. “Same or more slump” sounds reasonable, but mass concrete always uses less workability to keep temperature rise and cracking under control.