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Title:

Leaching Controlling Mechanisms of Metals from Soil-Fly Ash-Lime Kiln Dust Mixtures

Accession Number:

01551514

Record Type:

Component

Availability:

Transportation Research Board Business Office

500 Fifth Street, NW
Washington, DC 20001 United States

Abstract:

Fly ash is one of the industrial byproducts that is used in geotechnical and transportation infrastructure as a soil stabilizing agent or soil amendment. It has been well established that fly ash improves the strength and stiffness of highway base/subbase/subgrades when it is used as a stabilizing agent. However, there are concerns regarding the leaching of trace elements at concentrations above groundwater standards. This article discusses the speciation and leaching controlling mechanisms of leached metals from highway base layers stabilized with fly ash and lime kiln dust (LKD). Metals that were studied in particular were aluminum (Al), chromium (Cr), iron (Fe), and manganese (Mn). Column leach laboratory test (CLT) data, collected from the previous data, were used to conduct geochemical modeling analyses. Effluent pH, electrical conductivity, oxidation-reduction potential (Eh), and metals concentrations measured from CLTs were used as input data in a geochemical model. Geochemical modeling results indicated that the dominant oxidation states of Al, Cr, Fe and Mn were Al³+, Cr⁶+, Fe³+, and Mn²+, respectively. It was determined that leaching of Al, Fe, and Mn were solubility controlled suggesting that dissolution and precipitation of (hydr)oxides of these metals controlled the leaching behaviors. On the other hand, geochemical model results showed that the solubility of Cr(VI) was not controlled by its (hydr)oxides and it was speculated that Ba(S,Cr)O4 solid phases may control the leaching of Cr.

Supplemental Notes:

This paper was sponsored by TRB committee AFP40 Physicochemical and Biological Processes in Soils.

Monograph Accession #:

01550057

Report/Paper Numbers:

15-2976

Language:

English

Corporate Authors:

Transportation Research Board

500 Fifth Street, NW
Washington, DC 20001 United States

Authors:

Cetin, Bora
Aydilek, Ahmet H

Pagination:

13p

Publication Date:

2015

Conference:

Transportation Research Board 94th Annual Meeting

Location: Washington DC, United States
Date: 2015-1-11 to 2015-1-15
Sponsors: Transportation Research Board

Media Type:

Digital/other

Features:

Figures; References; Tables

Uncontrolled Terms:

Speciation

Subject Areas:

Environment; Geotechnology; Highways; Materials; I15: Environment; I30: Materials; I34: Steels and Metals; I40: Soils and Rocks

Source Data:

Transportation Research Board Annual Meeting 2015 Paper #15-2976

Files:

TRIS, TRB, ATRI

Created Date:

Dec 30 2014 1:00PM