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Strength and microstructural characteristics of cement solidified lead-contaminated kaolin exposed to leaching circumstances

Liu, ZP and Du, YJ and Liu, SY and Jiang, NJ and Zhu, JJ (2014) Strength and microstructural characteristics of cement solidified lead-contaminated kaolin exposed to leaching circumstances. Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering, 36. pp. 547-554. ISSN 1000-4548

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Abstract

The strength and microstructural characteristics of cement stabilized/solidified lead-contaminated kaolin clay are investigated. The leaching of calcium (Ca) is studied under the targeted leachant pH of 2, 4, and 7 via a series of semi-dynamic leaching tests. The results reveal that the unconfined compressive strength (qu) of the stabilized/solidified soils experiencing the semi-dynamic leaching tests is 1% to 42% lower than that of the soils cured for 39 days under standard conditions (SC). The cumulative leaching fraction of Ca (CFRCa) at the leachant pH of 2 is 2 to 7 times greater than that at the leachant pH of 4 or 7. The difference in qu or CFRCa of the soils experiencing the semi-dynamic leaching tests at the lechant pH of 4 and 7 is marginal. When the cement content increases from 12% to 18%, qu increases by 35% to 98%; whereas CFRCa decreases by 40% to 58%. Furthermore, qu of the stabilized/solidified lead-contaminated soils is 50% to 68% lower, and CFRCa is 29% to 175% higher than that of the stabilized/solidified clean soils. An empirical equation is proposed for predicting the loss of unconfined compressive strength (i.e., ratio of qu obtained after leaching tests to that obtained at curing time of 39 days under standard conditions) using CFRCa. It is shown that the proposed method has high accuracy. The results of X-ray diffraction, scanning electron microscope, and mercury intrusion porosimetry analysis show that the relatively high concentration of Pb has remarkably retarded hydration/pozzolanic reactions in the stabilized/solidified lead-contaminated soils. Therefore, the strength development, leaching of Ca, and microstructural characteristics of the stabilized/solidified lead-contaminated soils differ from those of the stabilized/solidified clean soils in a notable manner.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div D > Geotechnical and Environmental
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:28
Last Modified: 17 Mar 2020 12:01
DOI: doi:10.11779/CJGE201403018