The effect of using waste from stone-cutting workshops in improving the mechanical properties of forest road bed soil

Fine-grained soils often have problems such as low load ability and shear resistance, difficulty in compaction and settlement. Therefore, the stabilization of fine-grained soils with additives has always been the focus of road construction engineers. On the other hand, today, the use of waste materials in soil stabilization has become common due to its economic nature. In this study, stone powder, which is the waste of stone-cutting workshops, was used to stabilize fine-grained soils.

Clay samples with low pastiness (CL) were mixed with different amounts of 0, 3, 5, 10, 15, and 20 percent of stone-cut soil compared to dry soil. 7, 28 and 90 days were taken into account for the processing time of soil and stone. In the next step, geotechnical characteristics including grain size, Atterberg limits and compressive strength or CBR were investigated. The characteristics of granulation were investigated using the sieve method, Atterberg limits using the Cassagrande and paste wick method, and compressive strength using the California loading test.

The results showed that with the addition of stone powder, the contribution of coarse soil fraction increased. So that by adding 20% of stone powder and after 28 days, more than 60% of the weight of each sample belonged to particles with a diameter greater than 0.1 mm. There was no significant difference between the processing times of 28 days and 90 days in terms of mental limit, mental index and loading capacity. However, the values of the mentioned variables were significantly different from the figures recorded in the processing time of 7 days. Adding rock powder to the soil samples decreased the flow limit and the paste index. By adding 20% of stone powder, the soil samples were transformed from pasty state (pasty index = 25) to medium pasty state (pasty index = 8). In addition, the highest amount of CBR or soil loading capacity (19%) was obtained by adding 20% of rock powder.

After 28 days, the soil samples showed the results of all the positive or negative interactions caused by the addition of stone powder, and the passage of more time has no tangible effect on the mechanical properties of the soil. Besides, in the present research, the desired changes in the mechanical properties of the soil were obtained by adding 20% of stone powder.