1.武昌工学院土木工程学院,武汉 430065
基金项目: 武昌工学院教学研究项目(2015KYZ03)
Effect of wetting-drying cycles on mechanical and leaching properties of solidified lead-contaminated soils
ZHAO Sanqing1,1.College of Civil Engineering, Wuchang Institute of Technology, Wuhan 430065,China
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摘要:为研究干湿循环作用对Pb污染土固化体力学和浸出特性的影响规律,采用普通硅酸盐水泥(OPC)和磷酸镁水泥(MPC)2种固化剂对Pb污染土进行固化/稳定化处理。基于无侧限抗压强度实验、渗透实验和浸出实验,探讨干湿循环作用对Pb污染土固化体力学和浸出特性的影响规律,并结合压汞实验分析干湿循环作用对Pb污染土固化体力学和浸出特性影响的微观机制。结果表明:干湿循环作用均会降低OPC和MPC固化体的力学特性,MPC固化体耐久性要优于OPC固化体；通过浸出实验发现,OPC和MPC固化体浸出浓度均随干湿循环次数的增加而增加,当干湿循环次数大于5次时,OPC固化体浸出浓度高于浸出安全标准,而MPC固化体的浸出浓度均低于浸出安全标准；通过压汞实验发现,干湿循环作用破坏了固化土的结构完整性,增大了固化体中大孔隙(孔径＞1 μm)体积。这是导致Pb污染土力学特性降低的根本原因,而固稳机制的不同是干湿循环作用下OPC和MPC固化体浸出浓度差异的本质原因。
关键词: 干湿循环/
Pb污染土/
力学特性/
浸出特性
Abstract:Portland cement (OPC) and magnesium phosphate cement (MPC) were used to stabilize/solidify lead-contaminated soils. Unconfined compressive strength test, permeability test, leaching test and MIP test were conducted to investigate the variation of mechanical properties and leaching properties of OPC and MPC treated lead-contaminated soils along with wetting-drying cycle tests. Results showed that wetting-drying cycles could reduced mechanical property of OPC and MPC solidified soil, while wetting-drying cycles durability of OPC solidified soil is worse than MPC solidified soil. Lead concentration of OPC and MPC solidified soil were increased with the times of wetting-drying cycle, the lead concentration of OPC solidified soil was above the regulations, when the times of wetting-drying cycle exceed 5, while the lead concentration of MPC solidified soil was conformed with the regulations in the whole wetting-drying cycle test. MIP test results showed that the pore volume of diameter larger than 1 μm for OPC and MPC solidified soil were increased significantly with the times of wetting-drying cycle. The changing in mechanical properties of OPC and MPC can be attributed to the increases of the pore volume of diameter larger than 1 μm, and the difference of lead concentration of OPC and MPC solidified soil can be attributed to the difference of solidified/stabilized mechanism.
Key words:wetting-drying cycle/
lead-contaminated soils/
mechanical properties/
leaching properties.
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刊出日期:2018-01-14
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干湿循环对Pb污染土固化体力学和浸出特性的影响
赵三青1,1.武昌工学院土木工程学院,武汉 430065
基金项目: 武昌工学院教学研究项目(2015KYZ03)
关键词: 干湿循环/
Pb污染土/
力学特性/
浸出特性
摘要:为研究干湿循环作用对Pb污染土固化体力学和浸出特性的影响规律,采用普通硅酸盐水泥(OPC)和磷酸镁水泥(MPC)2种固化剂对Pb污染土进行固化/稳定化处理。基于无侧限抗压强度实验、渗透实验和浸出实验,探讨干湿循环作用对Pb污染土固化体力学和浸出特性的影响规律,并结合压汞实验分析干湿循环作用对Pb污染土固化体力学和浸出特性影响的微观机制。结果表明:干湿循环作用均会降低OPC和MPC固化体的力学特性,MPC固化体耐久性要优于OPC固化体；通过浸出实验发现,OPC和MPC固化体浸出浓度均随干湿循环次数的增加而增加,当干湿循环次数大于5次时,OPC固化体浸出浓度高于浸出安全标准,而MPC固化体的浸出浓度均低于浸出安全标准；通过压汞实验发现,干湿循环作用破坏了固化土的结构完整性,增大了固化体中大孔隙(孔径＞1 μm)体积。这是导致Pb污染土力学特性降低的根本原因,而固稳机制的不同是干湿循环作用下OPC和MPC固化体浸出浓度差异的本质原因。
English Abstract
Effect of wetting-drying cycles on mechanical and leaching properties of solidified lead-contaminated soils
ZHAO Sanqing1,1.College of Civil Engineering, Wuchang Institute of Technology, Wuhan 430065,China
Keywords: wetting-drying cycle/
lead-contaminated soils/
mechanical properties/
leaching properties
Abstract:Portland cement (OPC) and magnesium phosphate cement (MPC) were used to stabilize/solidify lead-contaminated soils. Unconfined compressive strength test, permeability test, leaching test and MIP test were conducted to investigate the variation of mechanical properties and leaching properties of OPC and MPC treated lead-contaminated soils along with wetting-drying cycle tests. Results showed that wetting-drying cycles could reduced mechanical property of OPC and MPC solidified soil, while wetting-drying cycles durability of OPC solidified soil is worse than MPC solidified soil. Lead concentration of OPC and MPC solidified soil were increased with the times of wetting-drying cycle, the lead concentration of OPC solidified soil was above the regulations, when the times of wetting-drying cycle exceed 5, while the lead concentration of MPC solidified soil was conformed with the regulations in the whole wetting-drying cycle test. MIP test results showed that the pore volume of diameter larger than 1 μm for OPC and MPC solidified soil were increased significantly with the times of wetting-drying cycle. The changing in mechanical properties of OPC and MPC can be attributed to the increases of the pore volume of diameter larger than 1 μm, and the difference of lead concentration of OPC and MPC solidified soil can be attributed to the difference of solidified/stabilized mechanism.
