عنوان مقاله [English]
Strength determination of some soil stabilizer mulches
Background and objectives:
Mulching is one of the most common ways to soil stabilization, prevent wind erosion and control dusts. Some types of mulches is not economically practical choices, thus use of inexpensive and safe industrial wastes in the mulch compositions have both economically and environmentally importance(waste recycling). Therefore, a key objective of this research is use two types of industrial waste for preparation of mulch. Since Proctor method has been considered to test and compare the strength of mulches, so another purpose of this research is simplification of Proctor method to estimate the strength of soil stabilizer mulches under the influence of wind erosion.
Materials and methods:
Based on the results of previous studies and pre-treatments, some mulches were tested. These mulches were non-living composed of different percentages of stone powder, converter sludge, clay soil, and sandy soil. Instron device was used to measure the compressive strength of the mulch. Considering applying of the Proctor method for working with Instron device, simplification of the procedure was also performed. These two methods were called as “Proctor” and “simplified Proctor” methods, whose results were compared as the criterion for utilizing the simplified method. The treatments included five types of mulch in three replications, where their compressive strength was measured by the two methods of “Proctor” and “simplified Proctor” and were compared by the random factorial designs.
Reducing the clay percentage from 80 to 50 and increasing the percentage of sand from 20 to 50 in the treatments containing clay and sand in both methods resulted in compressive strength reduction of mulches. Increasing the percentage of the stone powder from 5 to 25 and simultaneous reduction of clay percentage from 85 to 65 together with constant percentage of converter sludge led to decreased compressive strength through the simplified Proctor method. The differences between the results of the two Proctor and simplified Proctor methods were not significant, but the simplified Proctor method had specific order in the results.
Compressive strength reduction with reduced clay percentage and increased stone powder percentage was showed in the comparison of the treatments containing clay and stone powder through the simplified Proctor method. However, the results of the Proctor method lacked a logical order. The comparison of the treatments containing clay and sand indicated that in both methods, as the clay decreases and the sand increases, compressive strength reduced. Compressive strength test results using Instron device was compared in both simplified Proctor and Proctor methods, therefore it was showed that these two methods do not have a significant statistic difference, although orderly changes of the simplified Proctor method results was found. Considering the simplicity and time reduction in the simplified Proctor method, this method is recommended for mulch comparisons in wind erosion.