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.

scholarly journals Evaluation of the Effectiveness of a Soil Treatment Using Calcium Carbonate Precipitation from Cultivated and Lyophilized Bacteria in Soil’s Compaction Water

Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 545
Author(s):  
Miguel Valencia-Galindo ◽  
Esteban Sáez ◽  
Carlos Ovalle ◽  
Francisco Ruz
Keyword(s):  
Calcium Carbonate ◽  
Laboratory Scale ◽  
Carbonate Precipitation ◽  
Swelling Potential ◽  
Calcium Carbonate Precipitation ◽  
Compaction Process ◽  
Expansive Clays ◽  
Soil Deposits ◽  
Calcium Sources ◽  
Strength And Stiffness

Microbial-induced carbonate precipitation (MICP) is a bio-inspired solution where bacteria metabolize urea to precipitate. This carbonate acts as a bio-cement that bonds soil particles. The existing framework has focused mainly on applying MICP through infiltration of liquid bacterial solutions in existing soil deposits. However, this technique is inefficient in soils with high fines content and low hydraulic conductivity, and thus few studies have focused on the use of MICP in fine soils. The main objective of this study was to evaluate the effect of MICP applied to compaction water in soils containing expansive clays and sandy silts. This approach searches for a better distribution of bacteria, nutrients, and calcium sources and is easy to apply if associated with a compaction process. In soils with expansive minerals, the effect of MICP in swelling potential was explored at laboratory and field scales. In sandy silts, the evolution of the stiffness and strength were studied at the laboratory scale. The treatment at the laboratory scale reduced the swelling potential; nevertheless, no significant effect of MICP was found in the field test. In sandy silts, the strength and stiffness increased under unsaturated conditions; however, subsequent saturation dissolved the cementation and the improvement vanished.

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