scholarly journals Improving the Erosion Resistance Performance of Pisha Sandstone Weathered Soil Using MICP Technology

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1112
Author(s):  
Yanxing Wang ◽  
Chi Li ◽  
Cuiyan Wang ◽  
Yu Gao
Keyword(s):  
Calcium Carbonate ◽  
Wind Erosion ◽  
Erosion Resistance ◽  
Carbonate Content ◽  
Calcium Carbonate Precipitation ◽  
Undisturbed Soil ◽  
Soil Particles ◽  
Weathered Soil ◽  
Before And After ◽  
Internal Mechanism

In this study, we applied microbial induced calcium carbonate precipitation (MICP) technology to improve the undesirable characteristics of Pisha sandstone weathered soil that collapses easily upon environmental erosion. Through disintegration tests and wind erosion tests, the anti-water scour and anti-sand erosion performance of the weathered soil was tested before and after the improvement. Combined with an analysis of the physical properties and pore structure of the samples, this paper analyzes the internal mechanism by which MICP technology improves the poor characteristics of the soil. The results show that after improvement with the use of MICP technology, effective cementation is formed between the soil particles to form a solidified material with a strength of up to 1 MPa with a precipitated carbonate content of up to 15%, which effectively improves the water erosion resistance and wind erosion resistance. The disintegration rate of the improved soil sample was only 1.95% at the 30th minute, the remolded soil completely disintegrated, and the undisturbed soil reached 39.64%. The wind erosion resistance of the improved sample is improved, and its coefficient at a 30° erosion angle is increased roughly 20-fold on average when the wind speed is 31 m/s. The internal mechanism of the improved soil when it comes into contact with water and wind is that the induced calcium carbonate crystals fill the pores of the soil particles and adhere to and bridge between soil particles for effective cementation. When the soil expands after water invasion or the soil is destroyed after external erosion, the cementation of mineral crystals on the particles can resist the expansion force and punching force so as to improve the soil’s overall anti-erosion performance.

Increasing wind erosion resistance of aeolian sandy soil by microbially induced calcium carbonate precipitation

2018 ◽  
Vol 29 (12) ◽  
pp. 4271-4281 ◽  
Author(s):  
Kanliang Tian ◽  
Yuyao Wu ◽  
Huili Zhang ◽  
Duo Li ◽  
Kangyi Nie ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Sandy Soil ◽  
Wind Erosion ◽  
Erosion Resistance ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation

scholarly journals Experimental Study on Wind Erosion Resistance and Strength of Sands Treated with Microbial-Induced Calcium Carbonate Precipitation

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Zhaoyu Wang ◽  
Nan Zhang ◽  
Jinhua Ding ◽  
Chen Lu ◽  
Yong Jin
Keyword(s):  
Calcium Carbonate ◽  
Wind Erosion ◽  
Erosion Resistance ◽  
Small Scale ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation ◽  
Bonding Effect ◽  
Strength Tests ◽  
Desert Areas ◽  
Number Of Treatment

Wind erosion phenomenon is commonly encountered in desert areas, which is harmful to engineering constructions and environment. This study proposed an innovative microbial-induced calcium carbonate precipitation (MICP) technique to reinforce sands for mitigating natural hazards caused by the wind erosion. A series of small-scale laboratory experiments were performed to evaluate wind erosion resistance of MICP-treated sands with different treatment cycles. The spraying method was used to treat sand specimens, and unconfined compression (UCC) strength tests were also conducted to assess the performance of the MICP technique. Experimental results revealed that the bulk density of treated sand was slightly increased with the number of MICP treatment cycles. Additionally, the wind erosion rate of treated sands was significantly decreased, and the UCC strength was increased (maximum to 4 MPa) with the number of treatment cycles, which was mainly attributed to the bonding effect from the microbial-induced CaCO3 crystals among sand particles based on the scanning electron microscopy (SEM) analyses. Such effect also facilitated to form a hard protection layer on top of the sand specimen in order to improve the wind erosion resistance of MICP-treated sands. This technique provides an alternative method to mitigate and prevent the aggravation of desertification.

scholarly journals Study on Micro-Characteristics of Microbe-Induced Calcium Carbonate Solidified Loess

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1492
Author(s):  
Xiaojun Liu ◽  
Chaofan Pan ◽  
Jing Yu ◽  
Jinyue Fan
Keyword(s):  
Calcium Carbonate ◽  
Contact Area ◽  
Structural Characteristics ◽  
Point Contact ◽  
Silty Clay ◽  
Indirect Contact ◽  
Soil Particles ◽  
Pore Area ◽  
Surface Contact ◽  
Before And After

Microbial-induced carbonate precipitation (MICP) has outstanding characteristics in solidifying soil, such as good fluidity, ecological environmental protection, adjustable reaction, etc., making it have a good application prospect. As a typical silty clay, the composition of loess is fine, and the microstructure is quite different from that of sand. Previous research has found that the unconfined compressive strength of loess cured by MICP can be increased by nearly four times. In this paper, by comparing the changes of structural characteristics of undisturbed loess before and after MICP solidification, the mechanism of strength improvement of loess after MICP solidification is revealed from the microscopic level. Firstly, the microstructure of loess before and after solidification is tested by scanning electron microscope, and it is found that the skeleton particles of undisturbed loess are granular, and the soil particles coexist in direct contact and indirect contact, and the pores in soil are mainly overhead pores compared with the microstructure of solidified loess, it is found that the surface contact between aggregates increases obviously, and calcium carbonate generated by MICP is adsorbed around the point contact between aggregates, which makes the contact between soil particles change from point contact to surface contact. Then, Pores (Particles) and Cracks Analysis System (PCAS) is used to quantitatively analyze the pores of loess before and after solidification. The results show that the total pore area, the maximum total pore area and porosity of soil samples decrease, and the total number of pores decreases by 13.2% compared with that before MICP solidification, indicating that a part of calcium carbonate produced by MICP reaction accumulates in tiny pores, thus reducing the number of pores. One part is cemented between soil particles, which increases the contact area of particles. Therefore, some pores of loess solidified by MICP are filled and densified, the contact area between soil particles is increased, and the strength of loess under load is obviously improved.

scholarly journals Solidifying dust suppressant based on modified chitosan and experimental study on its dust suppression performance

2017 ◽  
Vol 36 (1-2) ◽  
pp. 640-654 ◽  
Author(s):  
Yanghao Liu ◽  
Wen Nie ◽  
Hu Jin ◽  
He Ma ◽  
Yun Hua ◽  
...  
Keyword(s):  
Erosion Rate ◽  
Wind Erosion ◽  
Material Handling ◽  
Erosion Resistance ◽  
Raw Material ◽  
Wind Disturbance ◽  
Wind Speeds ◽  
Modified Chitosan ◽  
Coal Particles ◽  
Before And After

In view of the fugitive dusts caused by wind disturbance and material handling in coal bunkers, surface plants, and open-air coal stocking yards of coal businesses, the solidifying dust suppressant based on modified chitosan is synthesized and prepared through the chemical modification of –NH2 with chitosan as a raw material and –NH2 was replaced by –CH2CH(OH)CH2N+(CH3)CI− through the technique of Fourier transform infrared spectroscopy. According to viscosity experiment results, the viscosity of the modified solidifying dust suppressant increased significantly. The coal particles suppressed by the dust suppressant as observed with a 50,000X scanning electron microscope were coagulated together, which indicated very good cohesion effect. In addition, wind erosion resistance experiment was conducted to analyze the wind erosion rate of coal powders before and after sprayed with the suppressant at different wind speeds, which indicated that the dust suppressant can effectively prevent fugitive dusts at a wind speed of 17 m/s.

scholarly journals Effect of Incorporating Polyvinyl Alcohol Fiber on the Mechanical Properties of EICP-Treated Sand

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2765
Author(s):  
Hua Yuan ◽  
Guanzhou Ren ◽  
Kang Liu ◽  
Zhiliang Zhao
Keyword(s):  
Mechanical Properties ◽  
Calcium Carbonate ◽  
Polyvinyl Alcohol ◽  
Carbonate Content ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation ◽  
Fiber Bridging ◽  
Ucs Test ◽  
Strength And Stiffness ◽  
Pva Fiber

Enzyme-induced calcium carbonate precipitation (EICP) technology can improve the strength of treated soil. But it also leads to remarkable brittleness of the soil. This study used polyvinyl alcohol (PVA) fiber combined with EICP to solidify sand. Through the unconfined compressive strength (UCS) test, the effect of PVA fiber incorporation on the mechanical properties of EICP-solidified sand was investigated; the distribution of CaCO3 in the sample and the microstructure of fiber-reinforced EICP-treated sand were explored through the calcium carbonate content (CCC) test and microscopic experiment. Compared with the sand treated by EICP, the strength and stiffness of the sand reinforced by the fiber combined with EICP were greatly improved, and the ductility was also improved to a certain extent. However, the increase of CCC was extremely weak, and the inhomogeneity of CaCO3 distribution was enlarged; the influence of fiber length on the UCS and CCC of the treated sand was greater than that of the fiber content. The improvement of EICP-solidified sand by PVA fiber was mainly due to the formation of a “fiber–CaCO3–sand” spatial structure system through fiber bridging, not the increase of CCC.

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