Feasibility Study on Utilization of Incinerated Solid Waste Ash for Mitigating Swell–Shrink and Consolidation Characteristics of Expansive Soil

The disposal of municipal solid waste is a critical issue in urban environments. In recent times, waste-to-energy plants have been installed and operated across the globe to reduce the volume of trash. In Hyderabad, India, there are currently five such waste-to-energy plants operating in Dundigal, Jawaharnagar, Bibinagar, Pyaranagar, and Yacharam. These energy production units produce incinerated ash as a by-product. In the current study, an attempt was made to determine the feasibility of using incinerated ash from domestic waste to mitigate the swell-shrink behavior of locally available expansive soil. Domestic waste was collected from a municipal solid waste dump yard, and ash was made by burning it. Tests such as shrinkage limit test, free swell index test, and oedometer tests were performed as per IS 2720 to study the swell–shrink and consolidation characteristics of locally available soil and the soil treated with incinerated ash. The shrinkage limit of virgin soil, which was initially 15%, increased to 38%, 52%, and 55% by the inclusion of 20%, 30%, and 50% of incinerated ash by weight of soil, respectively. By incorporating 25% of burned ash into the soil mass, the free swell index of virgin soil was dropped by 23%, which was 30% initially. Consolidation characteristics were found for virgin soil, incinerated ash, and soil mixed with the optimum quantity of ash. An increase of 75% in the rate of consolidation was observed for the soil mixed with the optimum quantity of ash. Based on the test results, the ideal amount of incinerated ash required to mitigate swell-shrink and settlement characteristics of expansive soil can be determined.