A bio-cementing technique for enhancing sandy soil resistance and durability against water

• Published in: Arabian journal of geosciences 2024, Vol.17 (1), Article 29
• Main Authors: Hatami Gigloo, Ayda, Negahdar, Alireza, Mehrishal, Seyedahmad, Tulaarud, Aliashraf Soltani
• Format: Article
• Language: English
• Subjects: Calcium; Calcium carbonate; Calcium carbonates; Calcium chloride; Carbonates; Cementation; Cementing; Compressive strength; Crystals; Curing; Curing (processing); Durability; Earth and Environmental Science; Earth science; Earth Sciences; Injection; Internal friction; Mechanical properties; Original Paper; Parameters; Sandy soils; Soil; Soil improvement; Soil mechanics; Soil properties; Soil resistance; Soil stabilization; Soil water; Stabilization; Toughness; Water; Water chemistry; Water resistance
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-023-11806-2

Bio-cementation is a novel technique for improving soil mechanical properties by forming calcium carbonate crystals within soil particles. This study examined the loose soil in the Firuzkooh region of Iran and aimed to enhance its resistance and durability. A series of experimental tests were performed to determine the influence of curing time, the number of injection stages, and the concentration of calcium chloride cement solution. The results showed that under a one-molar cementation solution concentration, stabilization improved all sample resistance parameters by more than 70%, including unconfined compressive strength, cohesion coefficient, and internal friction angle. However, these improved samples were still not durable against water. To enhance durability, samples treated with higher solution concentrations and different numbers of injection stages were investigated. The results showed that a single-stage injection of a 5-molar solution provided the best results in terms of sample resistance, durability against water, and optimal improvement procedure. Microscopic observations indicate that this is due to the formation of a specific type of calcium carbonate crystal that adheres to soil particles and bonds between grains, making it resistant to water molecules. As an overall result, it is possible to conclude that the improved soil will become more resistant by increasing the parameters of the curing times (28%), the number of injections (57%), and the concentration of the cementation solution (78%), and among of these, the concentration of cementation solution has a greater effect on increasing the strength and durability of the samples. This study offers valuable insights to enhance bio-cementation techniques for effective and sustainable soil stabilization, thereby introducing the methods for soil improvement in water-prone environments. Graphical Abstract