Study on the Erodibility and Mechanical Resistance of Mulches Prepared from Micro Silica–Cement Mixtures

Abstract

Mulching is fastest strategy to control sand dune movement in arid and semiarid areas. In the present study the effect of micro silica- cement mixture was evaluated as mulch. For this purpose, an experiment was carried out as a factorial arrangement and a completely randomized design with 3 replicates. Three studied factors included 6 micro silica rates (0 as control, 0.5, 2.5, 5, 7.5 and 12.5 percent), 2 rates of mulch thickness (one and two mm layers) and 2 time series (7 and 60 days). Prepared mulches based on different mixtures of micro silica + sand (400 g) and cement were sprayed on sand trays. Then 4 parameters including shear strength, penetration resistance, threshold friction velocity and soil losses at a wind speed of 15 ms−1 were measured on the studied treatments. Results obtained from the analysis of variances revealed that the effect of micro silica rates, thickness of mulch and time on the studied properties were significant. Mean comparisons also showed that shear strength, penetration resistance and threshold friction velocity increased and soil losses of treatments significantly decreased when the micro silica rates increased. The addition of micro silica to sand- cement mixture increased shear strength and penetration resistance by 76% and 82.5% respectively and decreased soil losses by 100%. The erodibility and mechanical properties of the treatments improved by increasing the thickness of the mulch. Moreover, in all studied treatments more improvements occurred in the mentioned properties of mulches during time. The application 7.5% of micro silica after 60 days was the optimal mulch to improve the soil erodibility and to increase the mechanical resistance against wind erosion.