Improving the performance of cement-based composites containing superabsorbent polymers by utilization of nano-SiO_2 particles

摘要

The application of superabsorbent polymer (SAP) as an internal curing agent for cement based composites results in benefits such as reduced autogenous shrinkage and cracking. However, a reduction in compres sive and flexural strength usually occurs due to the empty voids remained in the matrix after deswelling of SAP particles. Nanoparticles are good candidates for improving the mechanical performance of cementi tious materials, due to their multiple mechanisms of action, not the least their high pozzolanic activity. In the present work, the capability of amorphous nano-SiO_2 (NS) as the most widely used nanoparticle in cementitious materials, for retrieving mechanical properties of SAP-containing pastes was evaluated, and its impact on setting time and Theological properties was measured. It was found that small dosages of NS could offset the negative effect of SAP on compressive strength but flexural strength was not fully compen sated. Optimization of the dosages of NS and SAP could reduce the negative influences on the yield stress and viscosity whilst improving mechanical performance. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were used to monitor the changes in microstructure and composition.