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Multi Expression Programming Model for Strength Prediction of Fly-Ash-Treated Alkali-Contaminated Soils
Kaffayatullah Khan1, Mohammed Ashfaq2,3, Mudassir Iqbal4,5
1Department of Civil and Environmental Engineering, College of Engineering, King Faisal University (KFU), Al-Ahsa 31982, Saudi Arabia.
Materials (Basel, Switzerland)
|June 10, 2022
Summary
Fly ash effectively stabilizes alkali-contaminated soil, significantly improving unconfined compressive strength (UCS). Optimal results were achieved with 20% fly ash addition, mitigating alkali-induced strength loss in kaolin and black cotton soils.
Area of Science:
- Geotechnical Engineering
- Environmental Engineering
- Materials Science
Background:
- Industrialization causes alkali contamination in natural soils, negatively impacting expansive soils.
- Alkali contamination reduces the unconfined compressive strength (UCS) of soils like kaolin and black cotton (BC).
Purpose of the Study:
- To investigate the efficacy of fly ash (FA) in stabilizing alkali-contaminated kaolin and BC soils.
- To determine the optimal FA dosage and the influence of alkali concentration and curing period on UCS.
- To develop predictive models for UCS using multi-expression programming (MEP).
Main Methods:
- Laboratory testing of alkali-contaminated kaolin and BC soils treated with varying FA dosages (10%, 15%, 20%).
- Assessment of UCS under different alkali concentrations (2 N, 4 N) and curing periods (up to 28 days).
- Development and validation of MEP-based predictive models for UCS using 384 data points.
Main Results:
- Alkali contamination reduced UCS by 36% (kaolin) and 46% (BC soil).
- FA addition linearly increased UCS, with the optimal dosage identified as 20%.
- MEP models demonstrated reliable performance in predicting UCS, validated by parametric and sensitivity analyses.
Conclusions:
- Fly ash is an effective stabilizer for alkali-contaminated soils, enhancing UCS through alkali-induced pozzolanic reactions.
- The developed MEP models provide accurate predictions for UCS of FA-treated soils.
- Findings offer valuable insights for managing and remediating alkali-contaminated problematic soils.
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