Research on Agricultural By‐Products Wheat Straw as a Water Retention Agent for Construction Gypsum

ABSTRACT This work proposes an innovative method to use wheat straw, an agricultural by‐product, as a water retention agent for gypsum. The research shows that wheat straw can significantly improve the water retention performance of gypsum slurry. When the wheat straw content is 3.6% more than the control group without wheat straw addition, the water retention rate increases significantly by 7.9%, while the water‐to‐cement ratio only increases slightly by 0.04%. In addition, wheat straw exhibits a retarding effect on the setting of gypsum. Although this additive slightly reduces the strength of hardened gypsum, these properties still meet the requirements of standard specifications when the wheat straw content is below 3.6%. Thermogravimetric analysis indicates that the hydrophilic components in wheat straw can form hydrogen bonds with water molecules, delaying the temperature corresponding to the maximum weight loss rate of free water in gypsum meanwhile, the porous structure of wheat straw can store a large amount of water, leading to an increase in the proportion of free water weight loss. This work provides a cost‐effective and environmentally friendly alternative to synthetic water retention agents in the field of gypsum, and also offers an innovative idea for the resource utilization of agricultural by‐products.