A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
A 25-Year Evaluation of Concrete Containing Reactive Kansas-Nebraska Aggregates
Durable concretes made with reactive aggregates require compatible ingredients, properly blended and cured. Initially, accelerated tests were used to evaluate materials; however, seldom is the opportunity available, as it is here, to reassess the original concretes after many years of weathering. The concrete slabs, exposed out-of-doors for 25 years, which were inspected for soundness and measured initially, have now been inspected to determine dimensional stability. Concretes contained aggregates which had varying potential for reacting with alkalis in the cements. Methods tried for alleviating effects of reactive expansion included use of various additive aggregates, pozzolans, and portland cements, both with and without entrained air. Fundamental conclusions from initial accelerated tests were confirmed. These require the use of cements having very low alkali content or 45 percent crushed limestone additive with the reactive aggregate. However, use of palliatives such as pozzolan and granite or crushed quartzite aggregate additives delay, but do not prevent, reactive expansion and cracking.
A 25-Year Evaluation of Concrete Containing Reactive Kansas-Nebraska Aggregates
Durable concretes made with reactive aggregates require compatible ingredients, properly blended and cured. Initially, accelerated tests were used to evaluate materials; however, seldom is the opportunity available, as it is here, to reassess the original concretes after many years of weathering. The concrete slabs, exposed out-of-doors for 25 years, which were inspected for soundness and measured initially, have now been inspected to determine dimensional stability. Concretes contained aggregates which had varying potential for reacting with alkalis in the cements. Methods tried for alleviating effects of reactive expansion included use of various additive aggregates, pozzolans, and portland cements, both with and without entrained air. Fundamental conclusions from initial accelerated tests were confirmed. These require the use of cements having very low alkali content or 45 percent crushed limestone additive with the reactive aggregate. However, use of palliatives such as pozzolan and granite or crushed quartzite aggregate additives delay, but do not prevent, reactive expansion and cracking.
A 25-Year Evaluation of Concrete Containing Reactive Kansas-Nebraska Aggregates
L. C. Porter (author)
1978
89 pages
Report
No indication
English
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