Assesment of sulfur containing air pollutants in utilizing the sulfur extended asphalt concrete mixes in Saudi Arabia

The rapid economic growth witnessed in the Kingdom of Saudi Arabia has brought about an increasing demand for fossil fuels, leading to the substantial release of major airborne pollutants. Acquiring a better knowledge of their distribution and behavior is a prerequisite to further development. In the Gulf region, particularly in Saudi Arabia, because of the increase in number of oil and gas refineries, the production of sulfur as a by-product has increased tremendously from 400 to 6000 tons/day. This alarming situation has developed the urgent need of finding an environmentally risk free ways to utilize sulfur. A study has been conducted at KFUPM on the feasibility of using sulfur as an additive for local asphalt concrete mixtures. The research work covered many aspects of utilizing sulfur modified asphalt in road construction. One of the aspects covered was to evaluate the concerns related to air pollution due to sulfur containing gases. Gaseous emmision at the asphalt plant and field construction site released from sulfur modified asphalt mixes was studied. The results show that, under controlled conditions, hydrogen sulfide concentration generated during mix production and placement was well below the allowable ambient air quality standards. With regard to sulfur dioxide concentration, an exceedance above the standard was observed at mixing temperature of 145C, which can be safely abated by taking appropriate precautions. An overall assesment of the environmental impact of sulfur-asphalt technology shows that there is no long-term hazard as indicated by the acceptable values of emission of hazardous gases (<1 ppm) even at the high in-service pavement temperature of 76C.