Development of very high strength concrete for Hong Kong

Abstract

In order to explore the feasibility and means of producing very high strength concrete (with mean cube strength > 100 MPa) in Hong Kong, extensive trial mixing and testing have been conducted. The conditions adopted for the very high strength concretes described here are that only locally available materials and conventional production and curing methods can be used and that the heat of hydration and shrinkage should not be excessive. To satisfy these conditions, all ingredients were obtained from the local market and the mixes were designed to have a binder paste volume of not more than 35%. Because of the high strength requirement, volcanic aggregates, which are generally stronger, were used instead of the more commonly used granitic aggregates. In the testing programme, the effects of various mix parameters including binder paste volume, fine to total aggregates ratio, dosage of condensed silica fume, and combined usage of condensed silica fume and pulverized fuel ash etc. were studied. Based on the test results, several selected mixes which may be considered for the production of Grade 90-100 concrete are recommended.