The urban pavement at 600 Catamarca street in the city of Bahía Blanca (Argentina) burst lifting the concrete slabs at the contraction joint. The aim of this study was to investigate the causes that lead to the concrete deterioration. Aggregate constituent materials, their mineralogy, textures, condition of the paste and the aggregate-mortar interface were determined by a petrographic analysis of the concrete. A petrographic optical microscope, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) was used. Abundant ettringite development was noted both inside cavities and on the concrete surface. Its occurrence was confirmed by XRD and EDX analyzes. The aggregate deleterious constituents were mainly glassy vulcanites and volcanic glass, generally altered to argillaceous minerals of the montmorillonite group and strained quartz, with undulatory extinction. It was concluded that pavement deterioration was due to the alkali-silica reaction (ASR).