Experimental study on improving the water storage capacity of sandy capillary barrier with bio‐based or biomass materials

Capillary barrier is an engineered structure composed of a fine‐grained layer overlying a coarse‐grained layer. However, traditional two‐layer configurations of fine and coarse grains exhibit suboptimal water storage performance in semi‐humid to humid regions. Thus, we investigated the enhancement of water storage capacity in the fine‐grained layer by incorporating diatomite, wheat straw ( Triticum aestivuml ), and peanut shells ( Arachis hypogaea L). The results demonstrate that (1) modified capillary barriers exhibit significantly enhanced water storage capacity (admixture ratio > 1:0.3 at least 10% increased), diatomite outperforms 20% better than peanut shells and wheat straw as a modifying material. (2) Both modified and unmodified capillary barriers show stable water storage capacity under continuous rainfall. (3) All modified fine‐grained layers show improved evaporation characteristics. The residual moisture content increases as the volume admixture ratio increases. (4) Modified fine‐grained layers exhibit pseudo‐cohesive force. The shear strength of the fine‐grained layer modified by diatomite increases as the volume admixture ratio increases.