Waterproof properties of thermal insulation mortar containing vitrified microsphere

• Effect of the content of vitrified microsphere on the waterproof properties.
• Effect of hydrophobically-modified aggregate on the waterproof properties.
• Effect of hydrophobically-modified cementing material on the waterproof properties.
• Comparison of two methods of hydrophobically-modified.

The waterproof indicators including water absorption, impermeability and wettability were evaluated in this paper. First, the optimum vitrified microsphere (VM) content was determined according to the fundamental performance, water absorption and impermeability of the thermal insulation mortar. The influence of water to cement ratio (w/c) on consistency of the mortar was then investigated. The results indicated that when w/c was 1.4, the mortar was favorable in terms of workability, strength and durability. The test results showed that the hydrophobic treatment of VM surface was beneficial to the reduction of water absorption. Two hydrophobic treatment methods, i.e., coating with organosilicon hydrophobic agent (OHA) on VM or blended OHA with cement were compared. According to the testing results of water absorption, the water level decline and water seepage depth, blending OHA with cement was more effective to improve the waterproof performance of the thermal insulation mortar.