Strength development of bottom ash based geopolymer and their application in columns to improve soft soil underneath embankment: Achieving sustainability in ground improvement

• Published in: Transportation Geotechnics
• Main Author: Ullah A.; Kassim A.; Rashid A.S.A.; Huang Y.; Mohd Yunus N.Z.; Zhu C.; Khan I.; Apandi N.M.
• Format: Article
• Language: English
• Published: Elsevier Ltd 2025
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85211584296&doi=10.1016%2fj.trgeo.2024.101463&partnerID=40&md5=34e31e01421e906a312bec05e5516b31

In this study, bottom ash (BA) was used in ground improvement to conserve natural resources and promote sustainability. The effect of the fineness of BA on the properties of a geopolymer and the bearing capacity (qu) performance of embankment resting on the BA-based geopolymer columns (BAGC) was evaluated. The unconfined compressive strength (UCS) test and mineralogical, microstructural, and elemental analysis were carried out for the BA-based geopolymer (BAG) prepared with a different fineness of BA. Laboratory scale experiments and numerical analysis were performed on the soft soil reinforced with two column length to diameter ratios (L/d) of 6 and 8 and three column spacing to diameter ratios (s/d) of 1.8, 2.4, and 3.6. The UCS test results depict that UCS values significantly increased with the increase in the fineness of BA and satisfy the minimum strength requirement (1034 kPa) for the ground improvement project. The mineralogical analysis, microstructure, and elemental characterization showed that increasing BA fineness resulted in more BA decomposition and a denser geopolymer matrix. The results achieved from the laboratory scale experiments and numerical simulations showed that ultimate bearing capacity (qult) is enhanced by decreasing the s/d and enlarging the L/d values. Moreover, a mathematical expression with R2 of 0.999 was developed to predict qult. This study shows that BA-based geopolymer can be used to improve soft ground with substantial environmental benefits. © 2024