Abstract
The carbonation behavior of lime-stabilized expansive soil is important for assessing the stabilization efficiency from the perspective of durability. In this study, the accelerated carbonation tests, measurement of pH value distribution, and the free swell ratio tests were conducted to investigate the evolutions of carbonation depth, carbonation extent, and expansive potential of lime-stabilized expansive soil. XRD, MIP, and SEM techniques were adopted as supplements to reveal the carbonation mechanism. Results demonstrated that the carbonation depth of lime-stabilized expansive soil increased significantly as time elapsed; however, the rate of increase reduced when the carbonation time increased. Higher carbonation depth was obtained at higher temperature and CO2 concentration and lower relative humidity, which was described by an empirical model. Fully, partly, and noncarbonated zones were subsequently presented with an increase in the depth of the soil. The expansive potential of lime-stabilized expansive soil was partially recovered during carbonation. The obtained linear relationships between the free swell ratio and pH value were adopted to describe the evolution of expansive behavior with carbonation time and depth. In microstructural analysis, the conversion of portlandite into calcium carbonate was significant, which resulted in changes in microstructure and controlled the carbonation behavior.
Highlights
Expansive soil is found in tropical semiarid and moderate climatic regions and can trigger serious engineering hazards, such as foundation failure and slope instability, due to its swelling-shrinkage behavior and well-developed fissures during the water uptake/loss process [1,2,3,4]
For investigating the carbonation behavior of lime-stabilized expansive soil, the accelerated carbonation test, pH value distribution measurement, free swell ratio, and microstructural analysis were conducted. e conclusions drawn from the study are as follows: (1) Carbonation depth of lime-stabilized expansive soil increased significantly with time; the increasing rate became stable over a long period of time
Higher temperature and CO2 concentration along with lower relative humidity in the environment resulted in deep carbonation depths
Summary
Expansive soil is found in tropical semiarid and moderate climatic regions and can trigger serious engineering hazards, such as foundation failure and slope instability, due to its swelling-shrinkage behavior and well-developed fissures during the water uptake/loss process [1,2,3,4]. Investigations on carbonation mechanism showed that the formation of an insoluble salt of CaCO3 resulted in clogged pores with reduced pore size, which changed the carbonation front and propagation rate [17, 23, 28], and improved the strength and leaching characteristics of the stabilized material [6, 27, 28]. Carbonation behavior investigations into concrete and cement-treated soil have progressed since the 1980s, which include describing the carbonation process, assessing the carbonation effect, and displaying the carbonated mechanism. The carbonation behavior in lime-stabilized expansive soil is described, the carbonation effect on the expansive potential is investigated, and the carbonation mechanism is revealed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
