Action Mechanism of Sticky Rice-Paste-Modified Site Soil: A Traditional Chinese Cementitious Material

Sticky rice paste is a viscous material commonly used in traditional Chinese construction. It has the basic properties of high viscosity and viscoelasticity, good corrosion and weather resistance, and a small coefficient of expansion. Sticky rice paste is usually added to site soils to modify their basic physical and mechanical properties. This study found that gelatinized sticky rice-paste-modified site soils have clearly improved physical and mechanical properties compared to 20 and 100 degrees C water-modified soils when 1% (wt%) sticky rice paste is added as the soil modifier. The liquid and plastic limits, and the plastic index of the soil are improved upon modification, to 27.4, 17.7, and 9.7%, respectively. The unconfined compressive strength and hydraulic conductivity were significantly increased and reduced, respectively. In addition, there was a reduction in the rate of disintegration by water, while the water resistance of the soil was improved. X-ray diffraction, Fourier transform infrared, and thermogravimetry/differential scanning calorimetry studies reveal that the improved properties arise through physical processes between the sticky rice paste and the soil. Scanning electron microscopy reveals that dispersed branched-chain sticky rice-paste molecules extensively infiltrate the surfaces of the soil particles on the nanoscale and become attached to them to form a good adhesive colloid that solidifies the soil particles after water evaporation, resulting in a compact structure.