Abstract:
The expansive soil under investigation has caused damage to lightweight structures due to its swelling and
shrinkage characteristics in response to changing moisture content. The study aims to assess the impact of
municipal solid waste (MSW) fly ash on the engineering properties of subgrade expansive soils and its influence
on pavement structure deformation. The influence of municipal solid waste fly ash on expansive soils was
evaluated using laboratory tests and finite element methods. The Abaqus software was used to investigate the
effects of MSW fly ash on pavement structure deformation. The input parameters employed for this analysis were
elastic modulus, Poisson ratio, load, contact area dimension, and pavement layer thickness. To mitigate this
issue, MSW fly ash was used as a stabilizing agent at varying percentages (5 %, 10 %, 15 %, 20 %, 25 %, and 30 %
of the dry mass of the soil sample).According to the AASHTO soil classification, the soil is classified as A-7, has a
high free swell, a low soaked CBR value, and a high soaked CBR swell, and does not meet the ERA manual
standard for subgrade materials. The laboratory tests shown several improvements in the engineering properties
of expansive soil when MSW fly ash were mixed. These improvements included a reduction of soaked CBR
swelling, free swell index, plasticity index, specific gravity, optimum moisture content. Additionally, the
maximum dry density and soaked CBR values increased. Numerical analysis using Abaqus software focused on
vertical deformation of the pavement structure. The results showed that as the percentage of MSW fly ash in form
0 % to 25 % of soil dry weight, the vertical deformation of the pavement structure decreased from 0.84 mm to
0.67 mm. This demonstrates that the addition of MSW fly ash reduced the deformation of expansive sub-grade
soil and improved the engineering qualities of pavement structure. In conclusion, the study revealed that the use
of MSW fly ash as stabilizing agent effectively reduced the deformation of expansive subgrade soil and improved
the engineering qualities of pavement structure.
