Basaltic rocks from Argentina used in concrete structures

Basaltic rocks have been widely used in several countries of South America for major engineering projects, such as the hydroelectric dam “Yacyretá”, built on the Paraná River, between Argentina and Paraguay. Moreover, basalts are very abundant in the Patagonia and participate in important amounts in most coarse and fine aggregates (gravel and sand). However, there are engineering works where important damage has been detected as result of the alkali-silica reaction. The aim of this work is to study basalt quarries located in the NE of Argentina to identify deleterious species, mainly fresh and devitrified volcanic glass, expansive clays and residual cryptocrystalline silica. Petrographical studies on thin sections and X-ray diffraction were made and the results obtained were compared with the behavior of these aggregates in structures in service and with standard test methods (accelerated mortar bar method, ASTM 1260 and dissolved silica determined according to chemical method, ASTM C289) studied in previous works