Research on the Effectiveness of Tetraethoxysilane-Reinforced Earthen Site: Influence of Soil Water Content and Curing Humidity

To investigate the influence of soil water content and curing humidity conditions on the reinforcement effect of tetraethoxysilane on earthen sites, remolded rammed earth samples with 0%, 5%, 10%, and 14.5% water content were prepared and reinforced by tetraethoxysilane and then placed in the relative humidity conditions of 35%, 65%, and 85% for 28 days. The basic physical, mechanical, and durability properties of samples before and after reinforcement were evaluated, and the mechanism was clarified through microscopic analysis. Results showed that tetraethoxysilane strengthened the connection between soil particles and filled the pores by generating Si-O-Si groups mainly through a hydrolysis reaction. Under the same humidity condition, tetraethoxysilane had a better effect on the mechanical and durability properties of samples with low water content (0% and 5% in this paper), while it generated a weak reinforcement effect on the samples with high water content (10% and 14.5% in this paper). For samples with the same water content, too high a curing humidity condition (85% in this paper) was not favorable to the reinforcement effect of tetraethoxysilane. These conclusions were confirmed by microscopic analysis, including scanning electron microscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy.