Abstract:
Although considerable efforts have been made worldwide regarding alkali-silica reaction (ASR)
prevention and mitigation, including the approval of new national and international regulations,
several concrete structures are still being diagnosed with ASR. In Portugal, the new cases of ASR
pertain to concrete produced mainly with igneous aggregates, whose potential reactivity is difficult to
assess, notably on granitic and basaltic rocks.
The most effective way to prevent ASR is an adequate knowledge of the alkali reactivity of the
aggregate, which requires the application of appropriate tests and criteria to enable a correct
classification.
In the last 4 years a research program conducted in Portugal has evaluated more than 90
aggregates of different mineralogy and/or texture. The test campaign included petrography, ASTM
C1260, RILEM AAR-3 and RILEM AAR-4.1 test methods. In this paper the results of ASR reactivity
evaluation obtained in a group of granitic and basaltic aggregates are presented and discussed. From
the results obtained, proposals to improve the reliability of existing test-methods are presented.