Cementations bind sand/soil particles via physical and chemical interactions to form composite solids with macroscopic mechanical properties. While conventional cementation processes (e.g., silicate cement production, phosphate adhesive synthesis, and lime calcination) remain energy-intensive, bio-cementation based on ureolytic microbially induced carbonate precipitation (UMICP) has emerged as an environmentally sustainable alternative. This microbial-mediated approach demonstrates comparable engineering performance to traditional methods while significantly reducing carbon footprint, positioning it as a promising green technology for construction applications. Nevertheless, three critical challenges hinder its practical implementation: (1) suboptimal cementation efficiency, (2) uneven particle consolidation, and (3) ammonia byproduct emissions during ureolysis. To address these limitations, strategic intervention in the UMICP process through polymer integration has shown particular promise. This review systematically examines polymer-assisted UMICP (P-UMICP) technology, focusing on three key enhancement mechanisms: First, functional polymers boost microbial mineralization efficacy through multifunctional roles, namely microbial encapsulation for improved survivability, calcium carbonate nucleation site provision, and intercrystalline bonding via nanoscale mortar effects. Second, polymeric matrices enable homogeneous microbial distribution within cementitious media, facilitating uniform bio-consolidation throughout treated specimens. Third, selected polymer architectures demonstrate ammonium adsorption capabilities through ion-exchange mechanisms, effectively mitigating ammonia volatilization during urea hydrolysis. Current applications of P-UMICP span diverse engineering domains, including but not limited to crack repair, bio-brick fabrication, recycled brick aggregates utilization, soil stabilization, and coastal erosion protection. The synergistic combination of microbial cementation with polymeric materials overcomes the inherent limitations of pure UMICP systems and opens new possibilities for developing next-generation sustainable construction materials.

Researchers have explored various materials and methods to improve the strength and stabilization of peat soil for construction. Deep peat soil's significant compressibility, low bearing capacity, and high creep potential present major challenges in geotechnical engineering. In this paper, the unconfined compression strength (UCS) and oedometer testing were conducted to determine peat strength and compressibility behavior after being stabilized with a bio-cement called vege-grout, derived from fermented vegetable waste. Soil stabilized with 5 %, 10 %, 15%, 20%, and 25% vege grout was cured for up to 8 weeks before undergoing UCS testing. The finding showed that, in between 4 and 6 weeks of the curing period, the UCS of the peat stabilized with vege-grout exhibiting substantial mechanical strength at all vege-grout inclusion levels. The results showed optimum strength improvements, with a 449 % increase in UCS at 15 % vege-grout after 8 weeks. At the optimal percentage, vege grout's cementitious properties bind peat particles, densify the matrix, and enhance soil strength and load-bearing capacity. The coefficient of consolidation (Cv) also improved, reducing settlement from 23.34 +/- 7.8 m2/year to 7.13 +/- 3.5 m2 per year over increasing effective stress. The significant improvement in strength and compressibility of peat after treatment with 15 % vege grout demonstrates the effectiveness of vege grout as a peat stabilizer and highlights its potential as an alternative to chemical stabilizers for foundation applications.

In the present study, the undrained cyclic behaviour of biotreated sands using microbial and enzyme-induced carbonate precipitation was investigated for a wide range of initial void ratio after consolidation (e0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e_{0}$$\end{document}), initial effective normal stress (sigma N0 '\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma{\prime }_{{{\text{N}}_{0} }}$$\end{document}) and calcium carbonate content (CC) under direct simple shear (DSS) testing conditions. The critical state soil mechanics framework for untreated sand was first established using a series of drained and undrained (constant volume) tests, which served as a benchmark for evaluating the undrained cyclic liquefaction behaviour of untreated and biotreated sands. The results indicated that the modified initial state parameter (psi m0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi_{{{\text{m}}_{{0}} }}$$\end{document}) in DSS condition showed a good correlation with instability states and phase transformation under monotonic shearing. In undrained cyclic DSS loading condition, samples displayed cyclic mobility indicated by an abrupt accumulation of large strain or sigma N0 '\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma{\prime }_{{N_{0} }}$$\end{document} transiently reaching zero or a sudden build-up of excess pore water pressure. The linkage between static and cyclic liquefaction was established for untreated and biotreated sand specimens based on the equivalence of characteristic soil states. The number of cycles before liquefaction (NL) for the biotreated sand specimens was mainly controlled by the cyclic stress ratio, e0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e_{0}$$\end{document}, sigma N0 '\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma{\prime }_{{{\text{N}}_{{0}} }}$$\end{document} and CC. For a similar initial state prior to undrained cyclic loading, the biotreated specimens required a larger NL compared to the untreated sand. The cyclic resistance ratio at NL = 15 (CRR15) increased with decreasing psi m0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi_{{{\text{m}}_{{0}} }}$$\end{document} for the untreated sand, while the CRR15 for biotreated sand increased with increasing CC and decreasing sigma N0 '\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma{\prime }_{{N_{0} }}$$\end{document}.

Landslides are one of the most catastrophic natural disasters. These calamities that are often caused by heavy rainfall, rapid snowmelt, and human activities may cause significant damage to people and property in the affected regions. The risk of landslides can be eliminated by investigating the probable cause of failure in the specific slopes and then mitigating them with an appropriate stabilization technique. Even though the available methods of mitigating landslides are highly effective, they may need to be more sustainable in nature. In recent years, microbially induced calcite precipitation (MICP) has proved to be a sustainable measure for improving the stability of slopes and preventing landslides. However, the efficacy of this method, considering various circumstances, such as soil type, slope geometry, the effective area of cementation, the effect of long-term exposure to climatic conditions, is a matter of debate among various researchers. In the present study, the potential of MICP to stabilize a homogeneous slope has been investigated numerically. Various parametric studies depending on the slope geometry and the effective areas of cementation were carried out to assess the efficacy of MICP in mitigating landslides in the chosen homogeneous slope. Preliminary analysis results indicate that MICP can effectively reduce landslides even with significant variations in soil type and slope geometry. However, certain constraints must be appropriately identified and addressed while designing such slopes. Based on these extensive numerical investigations, design charts can also be provided to determine the suitable range of parameters for slope geometry and effective area of cementation for designing an adequate bio-cemented slope in mitigating landslides.