Improving the hardened and transport properties of perlite incorporated mixture through different solutions: Surface area increase, nanosilica incorporation or both

Abstract

Abstract This study investigates the effect of the synergetic incorporation of perlite powder and nanosilica (NS) on mechanical and transport properties of mortar. Inherently, perlite possesses a slow pozzolanic activity, which can prolong the improvement in mechanical and transport properties of concrete. As such, in this study, perlite powder was ground to fine particles with the specific surface area (SSA) of 3100 cm2/g and 3900 cm2/g and was added to the mixture with 10% and 15% replacement level, respectively. Moreover, NS, which is found to accelerate the pozzolanic reaction in cement matrix due to the high surface area, with dosage of 1%, 2%, 3%, and 4% was added to the mixtures in conjunction with the ground perlite to further overcome the slow reactivity of perlite at early ages and improve mechanical and transport properties. The compressive strength of the samples was assessed, and it was found that 15% replacement of Ordinary Portland Cement (OPC) with perlite, with the SSA of 3900 cm2/g, and 2% NS led to the highest compressive strength of 68.3 MPa. Transport properties such as electrical resistivity, rapid chloride migration, and capillary water absorption of the samples were assessed. It was observed that the mixture with 2% NS and 15% replacement of OPC with perlite could increase the electrical resistivity to 35.2 kΩ·cm and reduce the migration coefficient to 4.1*10−12 m2/s at 91 days. Moreover, this mixture decreased the water absorption at 28 days to the extent of 43% in comparison with the control mixture.