Improvement of Compressibility and Thaw-Settlement Properties of Warm and Ice-Rich Frozen Soil with Cement and Additives

• Published in: Materials
• Main Authors: Mingtang Chai, Jianming Zhang
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2019
• Subjects: permafrost; compression coefficient; scanning electron microscope (SEM); thaw strain; calcium silicate hydrate; Technology; T; Electrical engineering. Electronics. Nuclear engineering; TK1-9971; Engineering (General). Civil engineering (General); TA1-2040; Microscopy; QH201-278.5; Descriptive and experimental mechanics; QC120-168.85; Ice
• Online Access: https://doi.org/10.3390/ma12071068; https://doaj.org/article/5dd15391f37c439894a59597419963ce

The warm and ice-rich frozen soil (WIRFS) that underlies roadway embankments in permafrost regions exhibit large compression and thaw deformation, which can trigger a series of distresses. Cement and additives were used in this study to improve the compressibility and thaw-settlement properties of WIRFS. We, therefore, selected optimum additives and studied the improvement effect on the frozen soil with 30% water content based on our previous research. Given constant load and variable temperatures, compression coefficients, thaw strains, and water content changes were obtained at temperatures of −1.0 °C, −0.5 °C, and 2.0 °C to evaluate the effect of improvements. A scanning electron microscope (SEM) was then used to observe the microstructure of improved soils and analyze causal mechanisms. Data show that hydration reactions, physical absorptions, cement, and additives formed new structures and changed the phase of water in frozen soil after curing at −1.0 °C for 28 days. This new structure, cemented with soil particles, unfrozen water, and ice, filled in the voids of frozen soil and effectively decreased the WIRFS compression coefficient and thaw strain.