IDENTIFICATION OF ALKALI-SILICA REACTIVE GRANITE AGGREGATES

摘要

In the province of Buenos Aires there has been early deterioration of many works, especially road works, which started 8 to 10 years after their construction. In search of the deterioration causes, many aspects were analyzed, such as the influence of the type and amount of vehicles, environmental factors, base structures, etc. No satisfactory answer, however, was obtained. Furthermore, the constituent materials and the initial properties of concrete were studied. In general, they all meet the requirements of the specified standards to fall into the category of good quality concrete. Before their use, the aggregates were tested for alkali reactivity (ASTM C 227 and C 1260). Mineralogical and petrographic studies showed that the aggregates used come from granitic rocks and contain deformed strained quartz, seen in thin sections by measuring the undulatory extinction angle. Further studies were then performed on the deleterious reactivity of the aggregates by applying the concrete prism test method, ASTM C 1293, and the Australian method, RTA T363. Concrete prototypes were then made to be assessed periodically up to the age of 8 years. This aper reports the results from petrographic and mineralogical studies, accelerated methods, the study of prototyper by NDT methods, and the application of a technological solution based on natural pozzolans to reduce the deleterious effects produced by the alkali-silica reaction (ASR).