Effect of nano-SiO_2 on properties and microstructure of polymer modified cementitious materials at different temperatures

摘要

In this study, the effect of nano-SiO_2 on mechanical properties and microstructure of polymer modified cementitious (PMC) materials under 20 and 6°C was studied through strength test, X-ray Diffraction Analysis, Mercury Intrusion Porosimetry, and Scanning Electron Microscopy. Results showed that the flexural and compres-sive strength of cement mortar was influenced seriously by polymer especially under low temperature condition. And nano-SiO_2 was contributed to enhance the flexural and compressive strength of PMC materials at early age under 20°C while the enhancement still existed at later age under 6°C. The disadvantage of polymer on the properties and microstructure of PMC materials at low temperature was modified by nano-SiO_2 due to the increase of hydration rate of cement, the decrease of the Ca(OH)_2 (CH) orientation aggregation, the modification of pore structure, and the promotion of polymer film formation. This study provides a prospective method on the performance optimization of PMC materials.