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Geomechanics and Engineering
  Volume 27, Number 6, December25 2021 , pages 573-582
DOI: https://doi.org/10.12989/gae.2021.27.6.573
 


Effect of bound water on mechanical properties of typical subgrade soils in southern China
Le Ding, Junhui Zhang and Zonghuang Den

 
Abstract
    From the effect of bound water, this study aims to seek the potential reasons for difference of mechanical experiment results of subgrades soils. To attain the comparatively test condition of bound water, dry forming (DF) and wet forming (WF) were used in the specimen forming process before testing, series of laboratory tests, i.e., CBR tests, direct shear tests and compaction tests. The measured optimal moisture contents, maximum dry densities, CBR, cohesion c, and internal friction angle o were given contrastive analysis. Then to detect the adsorptive bound water in the subgrade soils, the thermal gravimetric and differential scanning calorimetry (TG-DSC) test were employed under different heating rates. The free water, loosely bound water and tightly bound water in soils were qualitatively and quantitatively analyzed. It was found that due to the different dehydration mechanics, the lost bound water in DF and WF process show their own characteristics. This may lead to the different mechanical properties of tested soils. The clayey particles have a great influence on the bound water adsorbed ability of subgrade soils. The more the clay content, the greater the difference of mechanical properties tested between the two forming methods. Moreover, in highway construction of southern China, the wet forming method is recommended for its higher authenticity in simulating the subgrade filed humidity.
 
Key Words
    bound water; clayey content; differential scanning calorimetry; specimen forming; subgrade soil
 
Address
Le Ding and Junhui Zhang: National Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology,
Section 2, No.960, Wanjiali South Road, Changsha, China
Zonghuang Den: Jiangxi Tianchi Expressway High-Tech Development Co., Ltd., Jiangxi Provincial Expressway Investment Group, Co., Ltd, No.367, Chaoyangzhou Mid-road, Nanchang, China
 

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