Effects of aggregate type, aggregate pretreatment method, supplementary cementitious materials, and macro fibers on fresh and hardened properties of high-strength all-lightweight self-compacting concrete

In this research, a new high-strength all-lightweight self-compacting concrete (HALSCC) was developed with a density less than 1760 kg/m(3) and a compressive strength of more than 40 MPa. The effects of different parameters were investigated: pretreatment methods, binders, type of aggregates, and hybrid steel fibers on the properties of HALSCC. The experimental investigation evaluated the properties of fresh, mechanical, and microstructure of several concrete mixtures that incorporate low-C(3)A cement, silica fume, metakaolin, and hybrid steel fibers. The results show that HALSCC can be developed. The binder pretreatment method could improve the compressive strength by 14.1% compared with the water pretreatment method through the strengthening of Zone 1 and Zone 2 of interfacial transition zone. Also, the mixes incorporating stalite could improve the compressive strength by 40.8% and 106% compared to the mixes with scoria and leca respectively. Hybrid length steel fibers could increase the mechanical properties when compared to a single type of fiber.