This document summarizes an analysis of sulfates in concrete at Rawal Dam in Islamabad. Preliminary diagnoses found cracking, surface scaling, and exposed reinforcement due to spalling concrete. Experimental techniques measured the pH of concrete and water samples, and found carbonation through phenolphthalein testing. X-ray diffraction detected thaumasite in the concrete. The final diagnosis determined the concrete was attacked by sulfates, with thaumasite formation occurring through the reaction of calcium silicate hydrate with calcite and sulfate ions in the presence of moisture. Influencing factors included the presence of sulfates, carbonates, moisture, cement composition and quality. Proposed remedies included proper curing, placement, cover and