Experimental investigation on engineered cementitious composites (ECC) incorporating recycled autoclaved aerated concrete aggregate (RAACA)

Engineered Cementitious Composites (ECC) are typically produced with ultrafine silica or quartz sand as fine aggregates, which not only consumes natural resources but also increases material costs and limits their practical applications. To enhance the sustainability and cost-effectiveness of ECC, this study proposes a methodology for preparing ECC by replacing ultrafine sand with recycled autoclaved aerated concrete aggregate (RAACA). The effect of RAACA with three particle sizes and different aggregate dosages on the mechanical and shrinkage performances in ECC was studied. The results revealed that all the RAACA-ECC behaved high ductility, with an ultimate tensile strain of 3.28 % at the 100–200 mesh RAACA replacement, representing a 30.7 % increase compared to the control. Meanwhile, it exhibited comparable compressive strength to the conventional ECC made with silica sand , even though RAACA pre-absorbed a significant amount of additional water. Scanning electron microscopy (SEM) analysis revealed a sufficiently dense interfacial transition zone (ITZ) between the matrices and the RAACA particles (100–200mesh). The incorporation of RAACA notably enhanced the tensile strain-hardening and multiple cracking behavior in ECC while also mitigating the autogenous shrinkage in matrix, but negatively affecting the drying shrinkage . Additionally, the polyolefin fiber adopted is proved to be capable of producing ECC with high quality. • A series of polyolefin fiber ECCs were developed. • RAACA used as an ultrafine sand substitute in ECC was investigated. • The ECCs with RAACA exhibited favorable tensile strain-hardening properties. • The presence of gypsum in RAACA reduced the autogenous shrinkage of ECC.