Experimental Study on the Influence of Particle Size of the SiO2 Aerogel on Properties of Silica Aerogel Tunnel Fireproof Mortar

Abstract

The influence rule of different particle sizes of the SiO 2 aerogel played on the high performance concrete-special fire retardant coating mortar was tested, so was strength, resistance to water and heat conduction performance. The design of mortar mix ratio was based on volume method, the total volume of the aerogel and sand was fixed to 60%, two kinds of particle size of commercial SiO 2 aerogel were used to replace the fine aggregate which are 0.5-2mm and 0.5-4mm and the replace rate were 0%, 20%, 40%, 60%, 80% respectively. The performance of fire retardant mortar has been improved through adding TiO 2 , renewable disperse latex powder, methyl cellulose ether and polypropylene fiber. The result was indicated that the strength, water resistance and thermal conductivity of two kinds of particle size of mortar meet the requirements of fireproof material. The 28d compressive strength, 28d flexural strength and thermal conductivity of aerogel mortar 0.5~2mm were less 32%, 37% and 7% than that of aerogel mortar with 0.5~4mm, while the softening coefficient of aerogel mortar with 0.5~2mm was more 8% than that of aerogel mortar with 0.5~4mm respectively. The structure of aerogel mortar with 0.5~2mm is uniform and loose, and it is more suitable for the preparation of fire retardant mortar, alongside scanning electron microscopy (SEM) analyses.