a School of Civil and Hydraulic Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
b Zijin School of Geology and Mining, Fuzhou University, Fuzhou, 350108, China
c School of Civil Engineering, Wuhan University, Wuhan, 430072, China
d College of Civil Engineering, Fuzhou University, Fuzhou, 350116, China
e School of Civil and Architecture Engineering, Henan University, Kaifeng, 475004, China
f School of Civil Engineering, Guilin University of Technology, Guilin, 541006, China
2024, 16(12): 5135-5146. doi:10.1016/j.jrmge.2024.09.017
Received: 2024-05-15 / Revised: 2024-08-09 / Accepted: 2024-09-13 / Available online: 2024-09-26
2024, 16(12): 5135-5146.
doi:10.1016/j.jrmge.2024.09.017
Received: 2024-05-15
Revised: 2024-08-09
Accepted: 2024-09-13
Available online: 2024-09-26
The one-phase-low-pH method is a simple, efficient, and user-friendly biogrouting technique that can effectively improve the biomineralization of enzyme-induced carbonate precipitation (EICP) using free urease enzyme. One of the most significant advantages of this method is its capacity to effectively delay calcium carbonate (CaCO3) precipitation by reducing the pH of the solution through the addition of acid. This prevents bioclogging during the biogrouting process and improves the biomineralization effect. However, the biomineralization of the one-phase-low-pH based EICP method may be influenced by the specific acid used. To investigate the impact of acid type on the one-phase-low-pH EICP method using crude soybean urease solution (CSUS), four types of acids, including hydrochloric acid (HCl), nitric acid (HNO3), acetic acid (CH3COOH), and lactic acid (C3H6O3), were used to adjust the pH of CSUS. A series of macroscopic and microscopic experiments were conducted to evaluate the effect of acid type on the one-phase-low-pH EICP method. The results indicate that the acid has an inhibition on the urease activity (UA) of CSUS. Among the acids tested, HNO3 exhibits the most pronounced inhibitory effect on the UA of CSUS, followed by HCl, and the least pronounced inhibitory effect for CH3COOH and C3H6O3 under the same pH conditions. Meanwhile, CH3COOH and C3H6O3 could provide a longer delay duration of CaCO3 precipitation than HNO3 and HCl. Therefore, the one-phase-low-pH EICP method based on CH3COOH and C3H6O3 can significantly improve the effective biocementation depth compared to that based on HNO3 and HCl. Nevertheless, the different types of acids appear to have no obvious effect on the polymorph and crystalline of the precipitated CaCO3 crystals.
Keywords: Enzyme-induced carbonate precipitation (EICP), One-phase-low-pH method, Acid type, Crude soybean urease solution (CSUS), Biomineralization
Junjie Zheng
Prof. Junjie Zheng obtained his BSc, MSc and PhD degrees from Zhejiang University, China, in 1988, 1990 and 2001, respectively. In 2012, he was appointed as a Changjiang Distinguished Professor by the Ministry of Education. He currently serves as an executive committee member of the Foundation Branch of the Chinese Society of Architecture and the Soil Mechanics and Geotechnical Engineering Branch of the Chinese Society of Civil Engineering. His research interests include: (1) new foundation treatment technology; (2) tunnel structure analysis and design calculation theory; and (3) mechanism and design calculation theory of reinforced piled embankments, and so on. He has presided over a number of National Natural Science Foundation of China (NSFC) projects.