Which of the following is not true in general about self-compacting concrete?
- ASuperplasticizer is used
- BProductivity is increased
- CHas low density and provides thermal insulationCorrect
- DQuality of labour does not affect the durability of self-compacting concreteM
Solution
Concept
Properties and characteristics of Self-Compacting Concrete (SCC), including its high flowability, use of superplasticizers, and high density/durability.
Explanation
Self-Compacting Concrete (SCC) is designed to flow under its own weight without requiring any vibration, filling all gaps and heavily reinforced formwork. It has a high density and low porosity due to proper packing, rather than low density and thermal insulation (which are properties of lightweight concrete). Therefore, statement C is not true.
Why the other options are wrong
A: Superplasticizers are essential for achieving the high flowability of SCC without segregation. B: Productivity increases because placing SCC is faster and requires no external vibration. D: While SCC reduces labor effort for compaction, overall quality control remains important, but option C is definitively false as SCC has high density, not low density.
Shortcut
Remember SCC: flows under own weight, needs superplasticizers and viscosity modifying agents, highly dense and durable, eliminates need for vibrators.
Common mistake
Confusing Self-Compacting Concrete (SCC) with lightweight insulating concrete.
Correct answer: C) Has low density and provides thermal insulation