Impact of air pollutants on some building materials in Cairo atmosphere

Abstract

Damage of materials is one of the most important adverse effects of air pollutants. The present investigation was undertaken to identify the extent of damage caused to some building materials by air pollutants in Cairo atmosphere and to what extent the pollutants accelerate the "natural" corrosion of materials. Samples of six different types of building materials (limestone, sand-lime brick, neat cement samples, cement blocks, industrial gypsum samples and LECA samples) were exposed to the ambient atmosphere for a period of three successive years at five locations, having different loads of air pollution represent residential and industrial areas through Cairo City. The changes in physical and chemical properties of the exposed materials were determined. It was found that the deterioration of building materials, exposed to Cairo city, was high related to the atmospheric pollution load with reference to sulfate, chloride and nitrate concentrations. Higher correlation coefficients between the compressive strength losses and the atmospheric SO 2 and NO 2 doses were found for cement block and limestone samples. The mineralogical composition (X-ray diffraction) of the product films of the exposed building materials showed the formation of gypsum and hydrated calcium silicate components in the building materials and cement content.