Experimental evaluation of sustainable ground improvement techniques

The effectiveness and durability of some ground improvement methods, such as cement stabilizer, lime stabilizer, microbial induced calcite precipitation (MICP), geopolymers, and recycled materials, are evaluated. The improvement in engineering properties of soil, including strength (UCS), permeability, and durability, is quantified experimentally. For the strength of waste glass/MB modified backfills, the maximum strength is achieved for cement stabilization (6.0 MPa), and the minimum strength is obtained in terms of lime stabilization (2.9 MPa). MICP and geopolymers UCS were observed at 0.8 mPa and 1.0 mPa, while the values of UCS were lowest in the case of recycled materials, which is 1.5 MPa. In terms of permeability, cement stabilization can lower it up to 1e-6 cm/s, whereas in comparison with MICP and geopolymers, both could withhold at 2e-4 cm/s, 3e-5 cm/s, and 4.5e-5 cm/s, respectively. The permeability test on the recycled products was approximately 1.8E-4 cm/s. The cement stabilization was better in addition to freeze-thaw cycles, allowing up to about 85% over geopolymers (75%) and lime stabilization (70%). The ratio of requests under MICP vs. recycled materials was 60% and 50%, respectively. CS was identified as the most environmentally impactful while having the highest carbon profile at 1500 kg/t, and RM as the process with the least CO? footprint, reaching a minimum of 100 kg/ton. The raw material cost for CS was $150/t, and for RM, raw materials were much cheaper, approximately around $50/ton. The results of the study report that recyclable materials with cement stabilization will make an alternative in terms of sustainability and low-cost options particularly in comparison with conventional materials based on strength and durability performance qualities. The focus of future work needs to be on field-scale applications, optimization of bio-based treatment, and specification of a combined solution that will be advantageous of both well-developed methods and green solutions.