Every year, the State of Qatar generates about 400,000 tons of steel slag and another 500,000 tons of gravel as a result of steel manufacturing and washing sand, respectively. The two materials (by-products) are not fully utilized to their best market values. At the same time, infrastructural renewal will take place in Qatar over the next ten years, and there will be a greater demand for aggregates and other construction materials as the country suffers from the availability of good aggregates. This paper presents results obtained on the use of steel slag, gravel and gabbro (control) in hot mix asphalt concrete (HMAC) paving mixtures and road bases and sub-bases. Tests were conducted in accordance with Qatar Construction Specifications (QCS-2010) and results were compared with QCS requirements for aggregates used in these applications. Based on the data obtained in this work, steel slag and gravel aggregates have a promising potential to be used in hot mix asphalt concrete paving mixtures on Qatar’s roads, whether in asphalt base and asphalt wearing courses or as unbound aggregates in the base and sub-base pavement structure.