alkali-silica reaction


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alkali-silica reaction

In portland cement, the reaction between the alkalies and particular siliceous rocks and/or minerals which are present in some aggregates; may result in abnormal expansion and cracking of concrete under service conditions.
References in periodicals archive ?
Alkali-silica reaction, pessimum effects and pozzolanic effect, Cement and Concrete Research 39(8): 716-726.
This provides invaluable information for the development of predictive tools and standard tests to monitor and prevent the occurrence of alkali-silica reactions in concrete structures.
Although previous researchers identified alkali-silica reactions as a major problem, many questions remain.
This method enables to detect the potential of the deleterious alkali-silica reaction in mortar bars within 16 days.
The long-term test method included in the ASTM C 1293 [5] covers the determination of the aggregate capacity for the alkali-silica reaction which causes concrete expansion.
The tests of mortar and concrete microstructures after the alkali-silica reaction have been conducted by means of scanning microscopy combined with X-ray analysis within the microsurface.
Similarly, the expansion of mortar bars with quartzite sandstone, measured in compliance with the ASTM C 1293, clearly suggests the occurrence of the alkali-silica reaction in concrete (Fig 4).
This conclusion finds confirmation in the occurrence of the alkali-silica reaction in concrete structures after a long period of use [18].
In case of slow reactive alkali aggregates, even after 180 days, no expansion exceeding 0,1% is observed, and thus suggesting that the aggregate is alkali reactive, since in this case the alkali-silica reaction occurs very slowly, and its consequences can only become noticeable after several years [19].
When they are completed, the Consensus Framework document and reports from the alkali-silica reaction (ASR), cold in-place recycling (CIR), and accelerated aging projects will be available in hardcopy from FHWA and in electronic format (PDF) at the Recycled Materials Resource Center (RMRC) Web site (www.
Its focus is on the production of concrete containing recycled concrete aggregate (RCA), where the recycled concrete is suffering from alkali-silica reaction (ASR).