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Showing 3 results for Microbial Induced Carbonate Precipitation
Field Scale Application of Microbial Induced Carbonate Precipitation in Soil Improvement: Challenges and Opportunities
M. Maleki-Kakelar, M. Yavari,
Volume 24, Issue 1 (5-2020)
Abstract
Biocementation through microbial induced carbonate precipitation (MICP) is a recently developed new branch in geotechnical engineering that improves the mechanical properties of bio-treated soils. The potential application of MICP to handle problems such as liquefaction and erosion has been established; this technique offers an environmentally friendly, cost-effective and convenient alternative to traditional soil improvement approaches. Nevertheless, in spite of the widespread demonstration of the process at laboratory scale, few field and practical applications have been implemented to assess the efficiency of the biochemical process. Therefore, this paper presents a review of the utilization of MICP for soil improvement and discusses the treatment process including the key constituents involved and the main affecting factors, especially in field scale applications. The major contribution of this research is to identify the main parameters restricting the application of this method on site. Finally, technical and commercial progress in the industrial adoption of the technology and the main challenges that are ahead for the future research prior to real practical application are briefly discussed.
 
 

Investigating the Effect of Microbial Induced Carbonate Precipitation on Reducing Wind Erodibility of Soils in Segzi Desert Area, Isfahan
A.r Modares Nia, M. Mirmohamad Sadeghi, A. Jalalian,
Volume 25, Issue 4 (3-2022)
Abstract
Desertification has become one of the main problems of human societies living in the vicinity of desert areas in recent years. One of the methods that have been considered in recent years and are rapidly expanding in the field of soil mechanics is the Microbial Induced Carbonate Precipitation (MICP). In this method, urea-positive organisms that are naturally present in the soil can stabilize the soil and improve its engineering parameters by using urea and calcium chloride. Recently, attempts have been made to use this method to create a crustal layer on the soil to prevent wind erosion. In the present study, the effect of environmental conditions in deserts such as temperature and sand bombardment on microbial soil treatment has been investigated using this new method. The soil of the Segzi region as one of the main centers of dust in the Isfahan region was studied in this research. Therefore, the improved samples are subjected to regional temperatures which increased the surface layer resistance with increasing temperature. Also, the sandstorm conditions of the region were simulated using three different grain sizes of sand inside the wind tunnel. The results of these experiments showed that stabilized soil could withstand the conditions at wind speeds of 7 and 11 m/s. However, by increasing the wind speed to 14 m/s and the grain size, the crustal layer destroys and increases the wind erosion of the soil. Also, the resistance of the surface layer increased by increasing temperature in the tested samples. This increase in resistance continued up to 24 degrees with a high slope, but from 24 degrees onwards, this slope decreases. Based on the results of this research, it can be said that the microbial improvement method can be used as an alternative method in the future to stabilize desert soils.

Performance Evaluation of MICP Method for Sustainable Improvement of Expansive Soils
A.r. Eftekhari, M. Mirmohammad Sadeghi, A. Jalalian,
Volume 27, Issue 2 (9-2023)
Abstract
The use of biotechnology-based methods in the field of geotechnical engineering has led to the birth of new knowledge of biogeotechnology and several studies have been conducted using this new knowledge in various geotechnical issues including reducing permeability and increasing shear strength, especially in sandy soils and the desired results have been obtained. Nevertheless, little research has been done using biogeotechnology in the field of improving the mechanical properties of clay soils, especially in reducing the swelling of expansive soils, which is considered one of the types of problematic soils. The main cause of swelling of expansive soils is the presence of montmorillonite clays in these types of soils. Using chemical additives to stabilize expansive soils such as lime and cement is a common practice. However, environmental concerns related to greenhouse gas production caused by the production of chemical substances and the destructive effects of these substances on the environment and soils have encouraged researchers to use other sustainable stabilization alternatives. Microbial Induced Carbonate Precipitation (MICP) is a technique that can be a promising solution to solve this problem. The objective of the present study was to investigate the effect of the MICP method on the swelling of expansive clay soils and its effect on the mechanical strength of this type of soil. One-dimensional swelling tests, uniaxial compressive strength tests, and Atterberg limits tests were performed on clay soil with a liquid limit of 53 using Sporosarcina pasteurii bacteria, calcium chloride, and urea as nutrients. Taguchi's method was used for the design of the experiments and the statistical analysis of the results. This method designs experiments through partial factorial and reduces their number without a significant effect on the results. Bacterial concentration, nutrient molarity ratio, treatment time, and soil moisture were selected as four factors with Four levels of variation. The results showed that the (MICP) method was effective in reducing the swelling potential of expansive soils and also caused a significant increase in the unconfined compressive strength of the soil and its undrained shear strength.

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