Use of slag to improve mechanical properties of engineered cementitious composites (ECCs) with high volumes of fly ash

Fly ash (FA) has been a necessary ingredient for engineered cementitious composites (ECCs) with excellent tensile strain capacity and multiple cracking. However, ECC with high volumes of FA has lower matrix strength, especially at early age. The purpose of this paper is to develop a kind of green ECC with high tensile ductility and strong enough matrix strength, especially at early age. A series of investigations has carried out to evaluate mechanical properties and drying shrinkage of ECC with 70% combination mineral admixtures of FA and ground granulated blast furnace slag (SL). The experimental results show that ECC with combination mineral admixtures can achieve strain hardening behavior, tensile capacity of ECC can be more than 2.5% at 90 days. Meanwhile, compared to ECC only with FA, SL and FA can effectively increase compressive strength of ECC, especially at early age. Incorporating SL into matrix can slightly increase drying shrinkage of ECC. However, among four ECC mixtures, ECC with 30% SL and 40% FA presents the lowest drying shrinkage at later ages.