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.

Keywords:

• Reactive powder concrete
• early-age shrinkage
• admixture
• aggregate
• drying

Acknowledgments

The authors gratefully acknowledge to TÜBİTAK. The authors would like to thank Assoc. Prof. (Ph.D.) Burak Felekoğlu for his valuable assistance for developing the shrinkage test setup, and Mr. Ümit Ürün from Pomza-Export, Mr. Mehmet Yerlikaya from Bekaert, Mr. Okan Duyar and Mr. Cevdet Kumaş from BASF and OYAK Cement Group for materials support. The first author would like to give special thanks to Turkish Cement Manufacturers’ Association (TCMA).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by The Scientific and Technological Research Council of Turkey (TÜBİTAK) under grant number 110M691.