Effect of diatomite on soil evaporation characteristics

Abstract

The soil evaporation property which can cause dry–wet cycle has an important impact on soil cracking and salinization. This study focuses on the effect of diatomite, which has an inner porosity structures, on soil evaporation. The results show that the whole process of evaporation can be divided to three stages by two turning points for both homogeneous soil and the mixed soil. However, the durations of constant evaporation rate stage and falling rate stage become longer with the increasing of incorporation mass ratio of diatomite. The volumetric water contents are same and about 0.1 when the evaporation process enters the residual stage for the diatomite, the calcined diatomite and the loess even though the initial saturated volumetric water contents of these soils are different. When the mixing proportion of diatomite is less than 30%, the higher the mixing ratio, the more water that the mixture can maintain. On the contrary, the increase of the mixing ratio has no obvious effect on the volumetric water content during evaporation. For the calcined diatomite, when the mixing proportion is about 3–10%, the increase of the mixing ratio has no obvious influence on the results. The volumetric water content range of the mixture of calcined diatomite at turning point I is 0.124–0.164, the value is about 10% larger than that of the mixture of diatomite. At the turning point II, the volumetric water content range of the mixture of calcined diatomite is 0.004–0.04, and it is smaller than that of the mixture of diatomite. The layered soil results show that the first stage of mixed soil becomes longer as the thickness of cover layer increases, and the layer sequence has increasing effect on evaporation which the duration of the overall evaporation of mixed soil becomes longer when the diatomite lays underneath.