Erosion resistance test of soil cement application for surface erosion protection

抄録

In this study, soil cement, as a method to enhance soil strength, was used as surface erosion protection. A series of erosion resistance tests were conducted to evaluate the resistance of soil cement to erosion due to rainfalls. In the experiments, two materials: DL clay (artificial silt) and normal Portland cement were used. The erosion model tests consisted of two layers of soils: 10 cm thick top layers treated with cement and 20 cm thick DL foundation layers. Three cases with different cement contents: Cc = 0, 3 and 5% in dry weight ratio were conducted under rainfall intensity 50 mm/h. The slope models were compacted in dry density:ρd = 1.3 g/cm3, the water content: w = 17 % and degree of compaction: D = 86%. The soil cement layers were cured for 7 days. The results of experiments show that in the case with Cc = 0%, the erosion developed from the lower to the middle part of the slope, and it was recognized as rill erosion. In the case with Cc = 3%, little erosion occurred and several spot splits, whose diameters were approximately 5 cm, were found on the surface. In the case with Cc = 5%, some small holes were only seen on the surface after the test. The bond due to cement hydration was sufficiently so strong that it prevented the surface layer treated with cement from strong detachment. The hydration of cement, DL clay and water formed the intra-aggregate pores inside the treated soil, which lead to increase the permeability and enhanced the infiltration of water into the soil. It reduced amounts of runoffs and soil loss. The overall results suggest clearly that the cemented DL clay layer effectively protects soil surface from erosion.