One of the problematic soil types that is found in wide areas in the world is marl soils. This soil type is more sensitive to erosion and requires modifications in pavement construction processes. In this research, mixed soil-Nano-CaCo3 was considered. For this purpose, 0.3 to 2.7% Nano-CaCo3, by specific dry weight, was combined with marl soils in 0.3% increments. To analyse the geotechnical properties of marl soil, optimum water content for soil compaction, maximum dry density, uniaxial compressive strength, California Bearing Ratio (CBR) and the consolidation test were investigated. The results showed dry unit weight increases with increasing Nano-CaCo3 content up to 2.2%. Furthermore, the CBR of modified marl soil with 2% Nano-CaCo3 is 2.7 times greater than the initial CBR; it increased from 6 to 15.5 by adding up to 2% Nano-CaCo3. Moreover, adding Nano-CaCo3 to marl soil increased the uniaxial compressive stress. The optimum percentage of Nano-CaCo3 was 2%, which increased the compression strength about 1.4 times. Besides, with increasing Nano-CaCo3 up to 2.2%, the amount of void ratio decreases from 0.46 to 0.35. Additionally, the compression index Cc and swelling Index Cs are almost constant and equal to 0.09 and 0.03, respectively. تفاصيل المقالة

This study provides a practical solution to manage non-hazardous waste and aid the environment. The largest group of non-hazardous waste is called municipal solid waste (MSW) which can be effectively used as an alternative material in civil projects. In this research, as an alternative to traditional modification methods of soil which causes global warming, the soft clay (Clay) was chemically modified by four different percentages of MSW in soil dimensions (15%, 25%, 35%, 45%) in 28 and 120 days. The optimum percentage of MSW addition (15%) to the Clay at the curing age of 28 days increased the unconfined compressive strength (UCS) and California bearing ratio (CBR) by 1.28 and 3.34 times, respectively. Given that higher percentages of MSW reduce the UCS and CBR in the specimens, four percentages of Nano-MgO, i.e., 0.25, 0.5, 0.75, and 1% were used for stabilization. The specimens containing optimum percentages of MSW (15%, 25%) and stabilized with 1% Nano-MgO could improve UCS and CBR 2.34 and 5.59 times, respectively that results had better durability over 120-days which can be attributed to the CBR testing condition. The cause of the increase in UCS and CBR was investigated using microstructural analysis for 120 days of curing. The specimen with high durability approved the cement bond formation with Anorthite & Dolomite minerals. In conclusion, using optimum MSW and Nano-MgO effectively solved the Clay problems in suitable conditions and allowed higher percentages of MSW to be removed from the environment. تفاصيل المقالة