Effects of soil additive on soil-water characteristic curve and soil shrinkage

To explore the effects of additives on water retention and soil shrinkage characteristics, the experimental soil was mixed with the three types of additives(wheat strew, wheat husk and plant dreg), respectively. The soil water characteristic curves were measured by a centrifuge method, with water retention and soil shrinkage characteristic quantitatively evaluated. The results indicated there were few differences in the types of soil water characteristic curves of all treatments, and van Genuchten model was suitable for the curve fitting. Besides to increasing soil density and soil moisture, the three additives could strengthen water-retaining capacity, ranking in the order that plant dreg >wheat straw >wheat husk >pure soil. Furthermore, axial shrinkage occurred during dehydration, with the three-line model suitable for soil shrinkage curve fitting. A logarithmic function and a Logistic function were found in the relationship between suction and soil moisture, and soil linear ratio, respectively. Finally, the soil shrinkage was ranked in the order that wheat husk