Grade 80-100 self-consolidating concrete for Hong Kong

Abstract

Compared to normal concrete mixes, high-strength concrete mixes are more cohesive and sticky, and would in general require a larger slump for proper consolidation. On the other hand, apart from high strength, high workability is also desired because it would allow faster and quieter concreting operation and reduce the risk of incomplete consolidation. However, it is not easy to achieve both high strength, which demands a low water/binder ratio, and high workability, which demands a high water content, without increasing the binder paste volume, which may lead to thermal and shrinkage cracking problems. In this study, the feasibility of producing high-strength, self-consolidating concrete with a binder paste volume of not more than 35% in Hong Kong was investigated by trial concrete mixing. A new polycarboxylate-based superplasticiser was used. In total, 18 trial mixes have been cast. All of them have slump higher than 200 mm and 28-day cube strength ranging from 80 to 117 M Pa. Some of them are suitable for making grade 80-100, self-consolidating concrete in Hong Kong.