Development of a new short-term concrete prism test method (SCPT) to improve predictability for potential alkali reactivity of aggregates

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2019

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Hafçı, Alkan

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Alkali-aggregate reaction (AAR) is a chemical deterioration process which happens in concrete due to the presence of reactive aggregate, sufficient alkalis and moisture. The analysis for the reactivity may be very difficult because AAR has sophisticated and slow progression behaviour. Analysing the aggregates’ structure in detail is primarily necessary before preparation of concrete mixture. Therefore, fast, simple, and reliable tests should be carried out. In the first step of the study, seven pilot new test methods taking 28 days were performed on 8 types of aggregates to develop a new method, which would a reliable accelerated performance for predicting potential alkali reactivity of aggregates. RILEM Accelerated Mortar-Bar Test (14 days) and Concrete Prism Test (20 weeks) were applied on these aggregates to analyse the degree of correlation between the developed new methods. Common specifications of these methods are usage of 50 mm x 50 mm x 200 mm concrete prisms, 16 mm maximum aggregate size, storage temperature at 60 oC and soak solution with different ingredients. These solutions were prepared by using variable chloride based de-icers with sodium hydroxide. After completion of the preliminary study, two new methods in addition to seven methods were performed on new 24 types of aggregates by modifying preliminary best methods to improve correlation. Data obtained from totally 32 types of aggregate shows that a new method entitled as short-term concrete prism (SCPT) test can be applicable due to good correlation with Concrete Prism Test Method and relative compliance with field performances of test aggregates.

Subject Keywords

Alkali-aggregate reactions., Alkali-aggregate Reaction, Short-term Concrete Prism Test, Chloride Based De-icers, Correlation.

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http://etd.lib.metu.edu.tr/upload/12623864/index.pdf
https://hdl.handle.net/11511/45184

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

A. Hafçı, “Development of a new short-term concrete prism test method (SCPT) to improve predictability for potential alkali reactivity of aggregates,” Thesis (Ph.D.) -- Graduate School of Natural and Applied Sciences. Civil Engineering., Middle East Technical University, 2019.