Donovan Mujah

State-of-the-Art Review of Biocementation by Microbially Induced Calcite Precipitation (MICP) for Soil Stabilization

ABSTRACT Biocementation is a recently developed new branch in geotechnical engineering that deals with the application of microbiological activity to improve the engineering properties of soils. One of the most commonly adopted processes to achieve soil biocementation is through microbially induced calcite precipitation (MICP). This technique utilizes the metabolic pathways of bacteria to form calcite (CaCO3) that binds the soil particles together, leading to increased soil strength and stiffness. This paper presents a review of the use of MICP for soil improvement and discusses the treatment process including the primary components involved and major affecting factors. Envisioned applications, potential advantages and limitations of MICP for soil improvement are also presented and discussed. Finally, the primary challenges that lay ahead for the future research (i.e. treatment optimization, upscaling for in situ implementation and self-healing of biotreated soils) are briefly discussed.

Influence of Key Environmental Conditions on Microbially Induced Cementation for Soil Stabilization

AbstractMicrobially induced calcite precipitation (MICP) is a sustainable biological ground improvement technique that is capable of altering and improving soil mechanical and geotechnical engineering properties. In this paper, laboratory column studies were used to examine the effects of some key environmental parameters on ureolytic MICP mediated soils, including the impact of urease concentrations, temperature, rainwater flushing, oil contamination, and freeze–thaw cycling. The results indicate that an effective crystal precipitation pattern can be obtained at low urease activity and ambient temperature, resulting in high improvement in soil unconfined compressive strength (UCS). The microstructural images of such crystals showed agglomerated large clusters filling the gaps between the soil grains, leading to effective crystals formation. The rainwater flushing was detrimental to the biocementation process. The results also indicate that traditional MICP treatment by the two-phase injection method did ...

Soil Arching Effect in Sand Reinforced with Micropiles Under Lateral Load

The mechanics of the mobilization of resistance from passive pile groups subjected to lateral soil movement is discussed from the standpoint of the arching effect. An innovative approach has been attempted to study the effect of introducing multiple rows arrangement of micropiles in sand at varying ground densities (30% and 80%). Similarly, parametric study focusing on the effect of the reinforcing rods cross sections (10 × 10 mm square and 3 mm in diameter piles) was also considered in terms of their pressure resistance. The results reveal that the formation and shape of the arching zone are functions of pile arrangement and pile shape. Group effects in multiple rows of piles are significant, but no significant effect under lateral soil movement (passive loading) for single row of piles was observed in sand.

Multirow arrangement of laterally loaded passive piles in sand

Donovan Mujah1,a, Hemanta Hazarika2, Naoto Watanabe3 and Fauziah Ahmad1,b 1School of Civil Engineering, Universiti Sains Malaysia, Malaysia. E-mail: adonovanmujah@gmail.com, bcefahmad@eng.usm.my 2Department of Civil and Structural Engineering, Kyushu University, Japan. E-mail: hazarika@civil.kyushu-u.ac.jp 3Technical Development Department, KFC Ltd., Tokyo, Japan. E-mail: watanabe.naoto@kfc-net.co.jp