Multi-property response and optimisation of lightweight self-consolidating mortar containing silica fume and nano silica

Abstract

This article aims to investigate and optimise the properties of lightweight self-consolidating mortar (LSCM) by using the response surface method (RSM). Silica fume (SF), nano silica (NS), water-cement ratio (W/C) and superplasticiser (SP) were chosen as variables. Also, part of the aggregates was replaced with lightweight expanded clay aggregate (LECA). Due to the advantages of RSM in accommodating multi-response optimisation of LSCM properties, the investigation and analysis were carried out for the stability, segregation and compressive strength. The optimised results recommended acceptable ranges of the required rheological and hardened criteria for LSCM. The mixtures achieved in these ranges include an LSCM with sufficient stability and low segregation. In particular, the results showed that the ultimate segregation must be < 8% for structural concrete. In addition, the results proved that increasing the fraction of NS and SF improves the properties of the LSCM by reducing the segregation and increasing the stability and compressive strength. It was found that adding 6% of NS at a high W/C ratio decreased the segregation by at least 15%. Adding 6% NS and %SF to LSCM within 0.5 W/C increased the compressive strength up to 15.1 MPa for the former and 3.8 MPa for the latter.