Effects of halloysite nanotube, nano-silica and micro-silica on rheology, hardened properties and fracture energy of SCLC

In this paper, the effects of different replacement levels of halloysite nanotube (HNT), colloidal nano-silica (CS), micro-silica (MS), and the combination of them on the fresh and hardened properties of self-compacting lightweight concrete (SCLC) are studied. Four factors including water to binder ratio (w/b) with two levels of 0.35 and 0.45, CS with three replacement levels of 1, 3 and 5%, MS with the replacement level of 10% and HNT with three replacement levels of 1, 2 and 3% were chosen. The fresh properties of SCLCs were observed in terms of slump flow diameter and time, J-ring diameter, Vfunnel time and U-box tests. The hardened properties were determined through mechanical properties including compressive strength, tensile strength, modulus of elasticity and flexural strength. The non-destructive tests including electrical resistivity and water absorption were executed too. Moreover, the effects of MS, CS and HNT contents on the fracture energy of SCLC samples were studied. The results displayed that the mentioned properties for the SCLC specimens containingMS, CS and HNT improved, but the superior performance was obtained in binary mixes, which were created by adding both MS and CS simultaneously. The optimal conditions for having the best results were obtained when the amounts of MS and CS were 10% and 3%, respectively.