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| Strength and micropore characteristics of cement-solidified/stabilized zinc-contaminated red clay |
| Received:December 10, 2015 |
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| KeyWord:zinc contamination;red clay;solidification/stabilization;unconfined compressive strength;micropore |
| Author Name | Affiliation | E-mail | | FAN Hao-lun | College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China | | | SHEN Xiang-dong | College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China | ndsxd@163.com | | ZHOU Hai-long | College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China | | | DONG Wei | College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China | | | XUE Hui-jun | College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China | |
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| Abstract: |
| Contaminated soil excavated from contaminated sites may be used as building materials for shallow foundation or bank protection or other insensitive areas after solidification/stabilization(S/S) with cement, enabling reutilization of contaminated soil. In this study, air-dried red clay sample amended with zinc nitrate was stirred with cement and was then compressed into specimens. The specimens were cured for 7 d or 28 d under standard conditions. The effects of different zinc concentrations, cement rates, and curing times on the strength, micropore, and moisture content of cement-stabilized zinc-contaminated red clay product were examined by unconfined compression test, mercury injection experiment, moisture content measurement, and volume measurement. Results showed that the strength increased with the curing time if cement rates were less than 10% and zinc ion concentrations below 5000 mg·kg-1. However, the strength initially increased but then dropped with curing time if zinc concentrations was above 5000 mg·kg-1. At cement rates of 6% and 8%, the strength of the cemented products was negatively correlated with the zinc ion concentration. At 10% of cement rate, there was a 1000 mg·kg-1 threshold of zinc ion concentration that influenced the strength. Compared with zinc ion-free 28 d solidified/stabilized product, the products with zinc concentrations below 1000 mg·kg-1 had more pores smaller than 10 nm, fewer pores larger than 10 μm, and greater strength. At zinc concentrations higher than 1000 mg·kg-1, less C-S-H gel was produced, more pores larger than 10 μm were found, greater total porosity observed, and more amorphous substances with 0.1~10 μm pore size detected. High Zn additions increased hydrophilicity of the red clay, resulting in elevated water absorption during curing, and thus dropped strength. |
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