Investigation on swelling-shrinkage behavior of compacted expansive soils during wetting-drying cycles

Author(s):  
N Zhao ◽  
W Ye ◽  
B Chen ◽  
Y Chen
2011 ◽  
Vol 243-249 ◽  
pp. 3050-3055
Author(s):  
Cheng Yu ◽  
Jin Cheng Wei

The swelling behaviour of compacted expansive soils have been studied with variation in initial state. For comparison, a series of swell and shrinkage capacity laboratory tests with different initial dry densities,moisture contents and pressures have also been made with three different consistency state. Both percent swell and shrinkage are significantly influenced by the consistency state index. There is an unique relationship between percent swell and consistency state index of the soil. The percent swell-load relationship could be identified as a logarithmic relationship facilitating the prediction of ultimate percent swell under different load with a few initial results.


Author(s):  
Shi He ◽  
Xinbao Yu ◽  
Aritra Banerjee ◽  
Anand J. Puppala

Calcium-based stabilizers such as lime and cement control swell and shrinkage behavior and enhance strength properties for expansive soils through the formation of pozzolanic components. However, sulfate-bearing subgrade soils stabilized with calcium-based stabilizers might cause excessive swelling and shrinkage due to the formation of highly expansive minerals like ettringite and thaumasite. In this paper, one liquid ionic soil stabilizer (LISS) was evaluated as an alternative stabilizer used to control swelling and shrinkage behavior of expansive soils. A comprehensive laboratory experiment program including a linear shrinkage test, a one-dimensional swell test, and an unconfined compressive strength test, was designed and carried out on soils from Dallas, Texas before and after treatment. Three dosage levels of stabilizer and four different curing periods were investigated. Test results indicate that LISS is an effective stabilizing agent, which not only reduces swelling and soil plasticity but also increases soil strength. Furthermore, a similar type of LISS is utilized to treat the soil in Dallas via deep injection using a hydraulic pump. Field emission scanning electron microscopy results on the test soil showed that the stabilizing program is likely to work through clay flocculation and morphological variations in the clay particles.


Author(s):  
Masoud H. Bonab ◽  
Fariba Behrooz Sarand ◽  
Majid Farrin

Author(s):  
Rinu Samuel ◽  
Anand J. Puppala ◽  
Aritra Banerjee ◽  
Oscar Huang ◽  
Miladin Radovic ◽  
...  

Expansive soils are conventionally treated with chemical stabilizers manufactured by energy-intensive processes that significantly contribute to carbon dioxide emissions globally. Geopolymers, which are synthesized from industrial byproducts rich in aluminosilicates, are a viable alternative to conventional treatments, as they are eco-friendly and sustainable. In this study, a metakaolin-based geopolymer was synthesized, and its effects on the strength and volume-change behavior of two native expansive soils from Texas, with a plasticity index over 20 were investigated. This paper elaborates on the geopolymerization process, synthesis of the metakaolin-based geopolymer, specimen preparation, and geopolymer treatment of soils. Comprehensive material testing revealed two clays with a plasticity index over 20. They were each treated with three dosages of the metakaolin-based geopolymer and cured in 100% relative humidity for three different curing periods. The efficiency of geopolymer treatment was determined by testing the control and geopolymer-treated soils for unconfined compressive strength (UCS), one-dimensional swell, and linear shrinkage. Field emission scanning electron microscope (FESEM) imaging was performed on the synthesized geopolymer, as well as on the control and geopolymer-treated soils, to detect microstructural changes caused by geopolymerization. A significant increase in UCS and reduction in swelling and shrinkage were observed for both geopolymer-treated soils, within a curing period of only 7 days. The FESEM imaging provided new insights on the structure of geopolymers and evidence of geopolymer formation in treated soils. In conclusion, the metakaolin-based geopolymer has strong potential as a lower-carbon-footprint alternative to conventional stabilizers for expansive soils.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bendadi Hanumantha Rao ◽  
Peddireddy Sreekanth Reddy ◽  
Bijayananda Mohanty ◽  
Krishna R. Reddy

AbstractMicrolevel properties such as mineralogical and chemical compositions greatly control the macro behaviour of expansive soils. In this paper, the combined effect of mineral (i.e. montmorillonite, MMC) and chemical contents (i.e. Ca and Na in their total (T), leachable (L) and exchangeable form (CEC)) on swelling behaviour is investigated in a comprehensive way. Several 3-dimensional (3D) graphs correlating MMC and Ca/Na ratio, together, with swelling property (swelling potential, Sa, and swelling pressure, Sp) are developed. 3D plots, in general, portrayed a non-linear relationship of Sa and Sp with MMC and Ca/Na ratio, together. It is hypothesized that swelling initially is triggered by chemical parameters due to their quick and rapid ionization capability, but the overall swelling phenomenon is largely controlled by MMC. It is importantly found that expansive soils are dominant with divalent Ca++ ions up to MMC of 67% and beyond this percentage, monovalent Na+ ions are prevalent. From the interpretation of results, the maximum Sa of 18% and Sp of 93 kPa is measured at MMC of 43%, (Ca/Na)T of 10–14 and (Ca/Na)L of 2–7. It is concluded from study that total CEC + MMC for determining Sa and (Ca/Na)T + MMC for determining Sp are superior parameters to be considered. The findings of the study also excellently endorsed the results of Foster32, who stated that ionization of Na or Ca depends on the constituent mineral contents. The findings presented herein are unique, interesting and bear very practical significance, as no earlier research work reported such findings by accounting for chemical and mineralogical parameters impact, in tandem, on swelling properties.


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