Volume 3 · Issue 6 (2026)
DOI number:
10.66521/2938-9933-2026062201
Analysis of the Physical and Mechanical Properties of Expansive Soil Enhanced by Rubber-Microbial Synergy
Peng Fei1, Liu Baohua1, Cai Yu1,*, Liu Xiaohu2
1 Hunan Agricultural University, School of Water Resources and Civil Engineering, Changsha 410128, China
2 China Construction Fifth Engineering, Division Third Construction Co., Ltd., Changsha 410007 China
Corresponding Author: Cai Yu (caiyu_826@163.com)
Funding: Fund of Hunan Provincial Natural Science Foundation and Universities (No. 2026JJ90017); Key Scientific Research Project of Hunan Provincial Department of Education (No. 25A0225); Outstanding Young Scholars Project of Hunan Provincial Department of Education (No. 21B0179).
Abstract: Expansive soil is known as "cancer soil" due to its prominent swelling and shrinkage characteristics. Traditional chemical and physical improvement methods have deficiencies in environmental protection and long-term performance. This paper proposes a novel synergistic improvement method using waste tire rubber particles combined with Microbially Induced Calcium Carbonate Precipitation (MICP). Rubber particles of 50-mesh, 20-mesh and 10-mesh with mixing ratios ranging from 5% to 15% were adopted, together with *Sporosarcina pasteurii* and cementation solution (1 mol/L urea + 1 mol/L CaCl₂). Compaction tests, swelling rate tests and consolidated-undrained (CU) triaxial tests were conducted to systematically investigate the physical and mechanical properties of rubber-microbe improved soil. The results show that the optimal mixing ratio for single rubber modification is 5%, and 50-mesh fine rubber particles deliver the best anti-swelling effect. When MICP is applied with the optimal rubber content, the peak deviator stress increases by approximately 30%. Calcium carbonate crystals fill pores and bridge the interfaces between soil and rubber particles, forming a rigid-flexible composite structure and achieving a synergistic reinforcement effect beyond simple superposition. This study provides a new approach for the eco-friendly improvement of expansive soil and the resource utilization of waste rubber.
Keywords: Modified expansive soil; Rubber particles; MICP technology; Triaxial test; Microstructure
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