Swell and microstructural characteristics of high-plasticity clay blended with cement

• Published in: Bulletin of engineering geology and the environment Vol. 79; no. 4; pp. 2119 - 2130
• Main Authors: Abbey, S. J., Eyo, E. U., Ng’ambi, S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2020
• Subjects: Earth and Environmental Science; Earth Sciences; Foundations; Geoecology/Natural Processes; Geoengineering; Geotechnical Engineering & Applied Earth Sciences; Hydraulics; Nature Conservation; Original Paper; Plasticity index; Swelling clay; Swell potential; Kaolinite-bentonite mix; Microstructure; Swell pressure
• ISSN: 1435-9529; 1435-9537
• DOI: 10.1007/s10064-019-01621-z

This study presents the effect of high plasticity on swell potential, swelling pressure and micro-structural characteristics of kaolinite-bentonite mixed clays. Five different mix ratios of kaolinite bentonite mixture of 100:0, 90:10, 75:25, 50:50 and 25:75 in % by weight of dry kaolinite were used. All five synthesised soils were then mixed with 0%, 5% and 8% of cement by weight of dry soil, cured for 28 days and subjected to the Atterberg limit, one-dimensional oedometer and scanning electron microscope test. The inclusion of 5% and 8% cement reduces the plasticity index of the treated soils as the percentage of bentonite increases. The effects on plasticity of treatment with 5% and 8% cement after a 28-day curing period was evaluated, and the results show that reduction in plasticity index resulted in decreased swell potential and swelling pressure of the kaolinite-bentonite mixed clays. The results of microstructural analysis of 5% cement-treated soils show formation of flocculated fabric and cementation of soil particles, and filling with cementitious compounds of the voids of flocculated fabric in the soil. The reduction in swell can be attributed to the resulting compacted and dense mass of treated soils due to cementation of soil particles and cation exchange. The complex swell behaviour of high-plasticity kaolinite-bentonite mix is explained using the one-dimensional oedometer test, by further experimental study and examination of the microstructure of treated soils.