Durability of concrete with nano-particles under combined action of carbonation and alkali silica reaction

Abstract

Subway concrete is easy to be attacked by carbonation in the relatively closed space, and alkali silica reaction (ASR) is a serious durability problem of concrete, which is difficult to find and repair. The damage caused by carbonation and ASR seriously affects the durability of subway concrete. Two kinds of nano-particles (nano-SiO2 and nano-Fe2O3) are mixed into plain subway concrete in this paper, and their effects on the durability of concrete under the combined action of carbonation and ASR are studied experimentally. The test results show that, after mixing with nano-particles, the carbonation depth and expansion of subway concrete are decreased, as well as the sonic velocity of subway concrete is increased obviously, which demonstrate the durability of subway concrete with nano-particles is better than plain subway concrete. The enhancement of durability is due to the special physical and chemical properties of nanoparticles, which can improve the microstructure of concrete and the chemical composition of pore solution in concrete.

Keywords

• subway concrete
• nano-particles
• carbonation
• alkali silica reaction
• combined action