Expansive Mineral Growth and Concrete Deterioration, HR-384, 1997

(1997) Expansive Mineral Growth and Concrete Deterioration, HR-384, 1997. Transportation, Department of

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Abstract

A significant question is: What role does newly-formed expansive mineral growth play in the premature deterioration of concrete? These minerals (ettringite and brucite) are formed in cement paste as a result of chemical reactions involving cement and coarse/fine aggregate. Petrographic observations and SEM/EDAX analysis were conducted in order to determine chemical and mineralogical changes in the aggregate and cement paste of samples taken from Iowa concrete highways that showed premature deterioration. Mechanisms involved in deterioration were investigated. A second objective was to investigate whether deicer solutions exacerbate the formation of expansive minerals and concrete deterioration. Magnesium in deicer solutions causes the most severe paste deterioration by forming non-cementitious magnesium silicate hydrate and brucite. Chloride in deicer solutions promotes decalcification of paste and alters ettringite to chloroaluminate. Calcium magnesium acetate (CMA) and magnesium acetate (Mg-acetate) produce the most deleterious effects on concrete, with calcium acetate (Ca-acetate) being much less severe.

Item Type: Departmental Report
Keywords: Acetates, Calcium, Calcium magnesium acetate, Chlorides, Concrete pavements, Deicing chemicals, Deterioration, Electron microscopy, Ettringite, Magnesium, Magnesium compounds, Petrography, Brucite, Scanning electron microscopy
Subjects: Transportation > Pavements
Transportation
Transportation > Railroads
Transportation > Roads and highways
Transportation > Research > Concrete
Transportation > Design and Construction
ID Code: 16269
Deposited By: Iowa DOT Library
Deposited On: 06 Mar 2014 19:24
Last Modified: 29 Oct 2014 12:06
URI: http://publications.iowa.gov/id/eprint/16269