Early-age shrinkage properties of eco-friendly reactive powder concrete with reduced cement content

Abstract

Reactive powder concrete (RPC) is an ultra-high strength and high ductility cement-based composite. Associated with early-age shrinkage, high cement dosage may reduce the mechanical and durability performance of RPC. This study aims to clarify the influence of high volume mineral admixtures, aggregate restraint and fibre reinforcement on early-age autogenous and drying shrinkage of eco-friendly RPC at early-age (<24 h). To assess the effect of aggregates and fibres on shrinkage behaviour, neat paste, mortar phase without steel micro-fibre and RPC with steel micro-fibre were produced. Portland cement was partially replaced by 50% fly ash (FA) or ground granulated blast furnace slag (GGBFS). As a result, the following four major conclusions were obtained: (1) autogenous and drying shrinkage of the paste were decreased by FA replacement, but increased by GGBFS replacement, (2) aggregate restraint on early-age shrinkage was more pronounced in the case of high volume replacement of mineral admixtures, and more effective to reduce autogenous shrinkage compared to drying deformation, (3) neither autogenous nor drying shrinkage were importantly reduced by steel micro-fibre reinforcement and (4) eco-friendly RPC with a lower shrinkage can be produced by using high volume FA replacement.