Study On Electrical Resistivity Characteristics Of Heavy Metal Contaminated Soil Solidified By Cement

To explore the applications of AC resistivity method in the field of environmental geotechnical engineering detection, through the indoor experiment, ordinary portland cement would be used to solidify the degree of pollution and the types of the contaminated soil which includes typical ingredients as common heavy metals zinc, cadmium. Then resistivity and unconfined compressive strength test have been systematically condusted. First study result of testing cement solidified contamination soil is its reasonable alternating current frequency, and secondly based on the above frequency of the alternating current, the effection of different heavy metals ion content and age respectively on the electrical resistivity of soil cement and the strength has been explored. Finally, we concluded that the quantitative relationship of the resistivity and unconfined compressive strength.The results are summarized as follows:(1) The frequency of alternating current has a significant effect on the resistivity of the samples of zinc and cadmium contaminated soil after cement solidification. With the increase of the frequency of the alternating current, theresistivity of the cement soil is decreasing. In the process of this change, there are two areas, namely the sharp change and the slow change area in resistivity,and the junction of the AC frequency value is 50 kHz.(2) Zinc ions have obvious retarding effect on cement. With the increase of the content of zinc ion, the retarding effect of cement becomes more and more obvious, and the time of the playing a complete role of the cement soil strength increases gradually, but C=500 mg/kg, the retarding effect is abnormal.(3) when the zinc ion content of C=50mg/kg, the resistivity reached a minimum value, when the zinc ion content of C=100mg/kg, the strength reached a minimum value, and the resistivity and strength reached a maximum value at500 mg/kg. When C=500 mg/kg, the zinc ion increases the strength of the cement soil, and when the zinc ion content continues to increase, the deterioration of the strength of the cement soil is more and more obvious.(4) No matter whether the soil is polluted by cadmium, the strength and resistivity increase with the increase of curing age.(5) Under the condition of constant curing age, when the cadmium content is 50 mg/kg, the strength and the resistivity of the cement soil reach maximum,and with cadmium ion content increases gradually, strength and resistivity remained unchanged, and slightly higher than the cadmium ion pollution of cement soil strength and resistivity.(6) The unconfined compressive strength and resistivity of cement solidified Zn and Cd contaminated soils increased with age. The unconfinedcompressive strength of cement soil increases linearly with the increase of resistivity, and the correlation is better.(7) When the water content is constant, the resistivity of Cd contaminated sand increases with the increase of void ratio, when the water content is increasing, the resistivity increases gradually; The resistivity decreased with the increase of water content and cadmium ion content. The resistivity of solidified cadmium polluted sand remained unchanged under the content of each cadmium ion, which reflected the solidification of the Cd Polluted sand by the cement.(8) Leaching cadmium ion concentration of cadmium ion in solidified sand was increased with the increase of the concentration of cadmium ion,and close to the leaching of cadmium ion concentration in two range of 100~500 mg/kg and 1000~2500 mg/kg; With the increase of the age and electrical resistivity of cement solidified Cd contaminated sand, the concentration of cadmium ion decreased; When the content of cadmium ion was constant, the concentration of cadmium ion was decreased with the increase of the resistivity of solidified Cd contaminated sand.