A large amount of waste clay is generated in shield tunnel engineering. Although the physical properties such as the unconfined compressive strength of the clay have been improved through lime modification, some still fail to meet the specifications for road embankment materials. In this study, a indoor carbonation device was used to carbonize lime-modified clay samples with different lime contents. The changes in water content (ω), plasticity index (IP), undrained compressive strength (qu), and softening coefficient (Kr) of the samples were analyzed. Microscopic mechanisms were investigated through tests such as Scanning electron microscope (SEM) and Diffraction of x-rays (XRD). The results showed that with increasing carbonation period, the ω and IP of soil samples with different lime contents gradually decreased and stabilized. After 2 hours of carbonation, the qu, elastic modulus (E50), and Kr of the soil samples significantly increased. After 1 hour of carbonation and 7 days of curing, the modified clay with lime content greater than 7% met the subgrade strength standards for secondary and lower-grade highways (IP ≤ 26; qu ≥ 500 kPa). The carbonation reaction resulted in the formation of CaCO3 crystals on the surface of soil particles and Ca(OH)2. With carbonation further developed, a CaCO3—Ca(OH)2—C-S-H hybrid material was generated, which filled the pore space in clay reinforcing the structure and improving the strength of lime-modified clay.
Study on the Effect of Carbonation on the Mechanical Properties of Lime Modified Waste Clay
KSCE J Civ Eng
KSCE Journal of Civil Engineering ; 28 , 10 ; 4668-4677
2024-10-01
10 pages
Article (Journal)
Electronic Resource
English
Study on the Effect of Carbonation on the Mechanical Properties of Lime Modified Waste Clay
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