Redispersible Polymer Powder-Modified Sulphoaluminate Cement Mortar

Abstract

The super-softening property of redispersible polymer powder can improve the flexibility of cement-based materials while guarantees other work performances. In this study, the influences of different mixing amounts of redispersible polymer powders on the compressive strength, flexural strength, flexural compression ratio and bonding strength of sulphoaluminate cement mortar were investigated. The microscopic morphological structure of redispersible polymer powder-modified sulphoaluminate cement mortar was also observed through SEM to analyse the influence mechanism. Results show that, with the mixing amount of 2.0%, the compressive strength of cement mortar was improved. This mixing amount also increased the 28d flexural strength to 8.21 MPa (5.0% improvement) and 14d bonding strength to 5.6 MPa (27.3% improvement). Addition of more redispersible polymer powder resulted in the increase in flexural compression ratio because the powder particles formed water-insoluble continuous polymer colloidal film in hardened paste. This film generated a network with cement dydration products throughout the paste, consequently promoting the flexibility of cement.