Long-term leaching mechanisms of Portland cement-stabilized municipal solid waste fly ash in carbonated water

Journal Article · Mon Feb 01 04:00:00 EST 1999 · Cement and Concrete Research

OSTI ID:345089

Andac, M; Glasser, F P ^[1]

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1. Univ. of Aberdeen (United Kingdom). Dept. of Chemistry

A leach test is described and applied to municipal incinerator fly ash (10%) stabilized in Portland cement. The test differs from previous tests mainly by bubbling CO{sub 2} through the leachant, which itself is periodically renewed. An advantage of the test is that pH remains nearly constant at 6.5 to 6.8 throughout the test duration. The results of leach tests are correlated with microstructural studies of the leached layer, which reaches a depth of {approximately} 800 {micro}m in 214 days. Development of a complex zonal structure gives a semiprotective surface layer. If the initial slope of the leaching curve as a function of time {sup 1/2} is prolonged, experimental results fall well below this extrapolated curve as leaching times increase beyond > 100 to 200 h. Important changes occur in leach mechanisms at about this time, and the predictive accuracy of short-term accelerated tests, particularly when pH is not stabilized, is questioned.

• OSTI ID: 345089
• Report Number(s): CONF-971201--
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Journal Issue: 2 Vol. 29; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
54 ENVIRONMENTAL SCIENCES
CARBON DIOXIDE
CORRELATIONS
FLY ASH
LEACHING
MICROSTRUCTURE
MUNICIPAL WASTES
PH VALUE
PORTLAND CEMENT
SURFACES