Microstructural analysis of marl stabilized with municipal solid waste and nano-MgO

Abstract

Municipal solid waste (MSW) is accumulating over elapsed time across the world, and it is observed in many projects associated with weak soils, such as marl. Therefore, effective solutions to the environmental problem are essential. Conventional techniques for stabilizing marl generally use substances such as lime and cement, which could exacerbate pollution. For this, some new stabilizers, e.g. nano-MgO, are used. There are large quantities of marls and MSW in Shiraz City, Iran. The present study aims to evaluate the feasibility of using nano-MgO as a green low-carbon binder to remove MSW from the environment and make construction projects more cost-effective. Consolidated drained shear tests were conducted to evaluate the mechanical behaviors of the nano-MgO treated marl specimens at high normal stresses. The marl specimens containing MSW percentages of 15%, 25%, 35%, and 45% and nano-MgO percentages of 0.25%, 0.5%, 0.75%, and 1%, were used. It is found that the marl containing 15% and 25% MSW and 0.5% nano-MgO at 28-d curing can perform cation exchange and form new cementitious products. The soils with merely MSW show good performance due to the removal of the kaolinite and the formation of brucite. However, the soil with 25% MSW and 0.5% nano-MgO shows the same strength enhancement as the specimen with the optimal nano-MgO (0.75%) through the formation of dolomite, with a 20.59% increase in strain energy (SE).

Keywords

• Marl
• Shear strength
• Microstructure
• Nano-MgO
• Municipal solid waste (MSW)