Metamorphic rocks from Córdoba (Argentina) and the alkali-silica reaction

The “Sierras Pampeanas de Córdoba” (Argentina) is an igneous-metamorphic complex affected by shear zones. The deformation varies from one sector to another producing microstructures that affect the internal order and the size of the crystals, generating sites susceptible to suffering the attack of alkaline solutions. This process, known as alkali-silica reaction (ASR), occurs between cryptocrystalline, strained and/or amorphous silica compounds and the alkalis in the concrete pore solution, and forms a gel that increases its volume producing cracks and concrete deterioration. To evaluate the potential reactivity of rocks from the Córdoba region, the petrographic method (ASTM C 295), the accelerated mortar bar test method (ASTM C 1260) and the determination of dissolved silica (ASTM C 289) were carried out. The preliminary results allow determining a positive linear correlation (R2 = 0.86) between the expansion in mortar bars and leached silica. These values grow with deformation intensity increment in quartz-bearing rocks