Preparation and properties of nanosilica-doped polycarboxylate superplasticizer

Abstract Combination of nanoparticles and polycarboxylate superplasticizers (PCE) is expected to synchronously improve the workability, mechanical properties and durability of the mortars and concretes. In this study, nanosilica (NS) has been introduced and grafted onto PCE molecular chains through radical polymerization. Nanosilica-doped polycarboxylate superplasticizer (NS/PCE) was thus obtained and used as the modified water reducer in cement pastes and mortars. The effect of NS/PCE on adsorption, dispersion and mechanical properties of cement pastes or mortars has also been investigated. Results showed that PCE had been chemically bonded to anchor onto the surface of NS by Si-O-. NS was uniformly dispersed in PCE due to the steric resistance and electrostatic repulsive force. The as-obtained NS/PCE had better dispersion and enhanced adsorption performance compared to that of the undoped PCE. NS/PCE can effectively reduce the amount and orientation coefficient of Ca(OH)2 crystals in cement-based materials, which is beneficial to the microstructure refinement and the mechanical properties improvement of cement matrix.