AUTHOR=Yan Jinkai , Liu Lei , Ma Yan , Wang Zhihui , Ren Tianxiang 

TITLE=Strength properties of soils treated with calcium-based flocculants and their impact on vacuum preloading

JOURNAL=Frontiers in Earth Science

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2023.1276159

DOI=10.3389/feart.2023.1276159

ISSN=2296-6463

ABSTRACT=<p>In this study, a series of unconfined compressive strength tests were conducted to investigate the effect of calcium-based flocculants on the strength and deformation properties of slurry. The test results indicated that the presence of calcium-based flocculants [Ca(OH)<sub>2</sub> or CaCl<sub>2</sub>] significantly enhanced the unconfined compressive strength (q<sub>u</sub>) of soil. A non-linear relationship was observed between q<sub>u</sub> and CaCl<sub>2</sub> content, revealing that the maximum value of q<sub>u</sub> is obtained at a CaCl<sub>2</sub> concentration of 24.8%. q<sub>u</sub> exhibited a high increase rate at early curing time in the presence of Ca(OH)<sub>2</sub>, with a lower increase rate after a longer curing time and high Ca(OH)<sub>2</sub> content. The deformation modulus <italic>E</italic><sub><italic>50</italic></sub> showed an increasing trend with increasing CaCl<sub>2</sub> content at 3 and 7 d, followed by a decreasing trend with increasing CaCl<sub>2</sub> content at 14 and 28 d. However, the failure strain ε<sub>f</sub> for CaCl<sub>2</sub>-treated soil ranges from 2.4% to 4.8%, showing no relation with q<sub>u</sub>. A significant increase in <italic>E</italic><sub><italic>50</italic></sub> for Ca(OH)<sub>2</sub>-treated soil in the early curing stages (3 and 7 d) was observed because of the increase in <italic>q</italic><sub>u</sub>. After 14 d of curing, <italic>E</italic><sub><italic>50</italic></sub> tended to decrease with increasing Ca(OH)<sub>2</sub> content. A positive relationship between the degree of vacuum and <italic>q</italic><sub>u</sub> in the presence of calcium-based flocculants was proposed, indicating that a higher <italic>q</italic><sub>u</sub> of treated soil leads to a lower water content after vacuum treatment for the same preloading period, emphasizing that the vacuum treatment efficiency increases with an increase in the <italic>q</italic><sub>u</sub> of calcium-based flocculant-treated soil.</p>