Effects of a novel hydrophobic admixture on the sulfate attack resistance of the mortar in the wet-dry cycling environment.

• A new type of integral hydrophobic admixture was developed. • The durability of HA and mortar with HA was systematically investigated. • The inhibition mechanism of bi-directional water migration was revealed. The sulfate attack tends to cause deterioration in the performance of cement-based materials. An innovative hydrophobic agent named Yellow River Engineering Consulting (YREC) was developed to improve the resistance of the mortar to sulfate attack in wet-dry cycling environment. In this study, an investigation was conducted to investigate the effects of the acid, alkali and salt solutions on the durability of the YREC. Meanwhile, a series of hydrophobic mortars with varying YREC mass fractions were prepared to explore the sulfate resistance in the wet-dry cycling environment. The water migration in wet and dry process was compared by conducting the water absorption and desorption tests. In addition, the XRD, FTIR, ESEM and MIP were applied to further analyze the properties of the YREC. According to the analytical results, the microstructure and hydrophobic functional group of the YREC remained unchanged under the erosion of the acid, alkali and salt solutions. The YREC could significantly reduce the surface cracking, strength loss and structural loosening of the mortar under the wet-dry cycling sulfate attack. In addition, the YREC played a role in reducing the rate of the water absorption and desorption, resulting in a decrease in the sulfate concentration and penetration depth. Finally, the mechanism analysis showed that the YREC could enhance the inhibitory effect on bi-directional water migration through hydrophobization and refining the pore structure of the mortar. [ABSTRACT FROM AUTHOR]