Properties of compound hydrophobic agent for corn stover-based Portland cement wall material

With the growing emphasis on the circular economy, agricultural wastes have been increasingly exploited to mitigate resource constraints. Corn stover, as a highly abundant agricultural residue, is rich in cellulose sugar. When blended with Portland cement, it undergoes a reaction to form calcium saccharate, a compound that compromises the mechanical strength of cement. As a result, the application of corn stover in building materials is limited. In this work, polyvinyl alcohol (PVA), urea-formaldehyde (UF) resin and γ-aminopropyltriethoxysilane (APS) were respectively compounded with a siliceous solution. The hydrophobicity of the treated corn stover was analyzed, and the influence of cellulose sugar on the performance of cement after hydration was studied. The results showed that after co-modification with APS and a siliceous solution, the contact angle of the corn stover reached 142° and then dropped to 102° within 60 min. At the corn stover content of 20 wt%, the compressive strength was 2.26 MPa, and the thermal conductivity was 0.098 W/(m·K), meeting the application standards for frame-filled walls. Thus, the issue of cement non-setting caused by the high content of corn stover was improved, providing certain reference value for the use of corn stover in the development of cementitious materials. • Composite siliceous solution boosts corn stover's wetting timeliness. • The modified corn stover improves thermal insulation performance of cement walls. • The use of corn stover is increased and the building energy consumption is reduced.