Volume 24, Issue 4 (2024)
MCEJ 2024, 24(4): 21-34 |
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Ghasemi S, HOMAMI P, Keyvani J. Investigation of the Microstructural Impact of Heavy Metal Lead on Cement Setting Time. MCEJ 2024; 24 (4) :21-34
URL: http://mcej.modares.ac.ir/article-16-72001-en.html
URL: http://mcej.modares.ac.ir/article-16-72001-en.html
1- Department of Civil Engineering, Faculty of Engineering, Kharazmi University, Tehran. Iran.
2- Department of Civil Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran ,homami@khu.ac.ir
3- Department of Civil Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran
2- Department of Civil Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran ,
3- Department of Civil Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran
Abstract: (496 Views)
Heavy metal pollutants containing lead have consistently been major sources of environmental contamination over the past decades. Human and industrial activities have directly or indirectly led to the introduction of substantial amounts of lead-based pollutants into soil and groundwater. The Solidification/Stabilization (S/S) technique using cement, by significantly reducing the mobility and solubility of lead in soil, serves as an effective tool for remediating lead-contaminated soils. Conversely, the heavy metal pollutant lead significantly affects the setting time of cement, and the setting time directly impacts the efficiency of cementitious compounds. Consequently, understanding the interaction between lead and cement is of paramount importance. In this regard, the present study aims to investigate the influence of the heavy metal lead on the setting time and microstructural interaction of lead and cement. To achieve this, lead nitrate solution with concentrations of 0, 10,25,50, 100, 250 and 500 kg/cmol-solid, was added to cement. The effect of lead on the hydration process and setting time of cement was examined through setting time tests, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) images, and leachability analysis (TCLP). According to the research results, the precipitation and chemical complexation of the heavy metal lead in the form of Pb(OH)2 and Pb-C-S-H delayed the cement hydration process, extended the initial and final setting times of cement paste, and immobilized and solidified lead pollution effectively. By adding 25 kg/cmol-solid lead nitrate, the initial setting time of cement increased from 65 minutes to 155 minutes. Microstructural results demonstrated that cement effectively interacted with heavy metal lead up to a concentration of 100 cmol/kg-solid during the Solidification/Stabilization (S/S) process, keeping pollutant levels within permissible limits for soil.
Article Type: Original Research |
Subject:
Civil and Structural Engineering
Received: 2023/10/15 | Accepted: 2024/03/3 | Published: 2024/10/1
Received: 2023/10/15 | Accepted: 2024/03/3 | Published: 2024/10/1
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