USE OF UNCONVENTIONAL AGGREGATES IN HOT MIX ASPHALT CONCRETE

The study investigates use of dolomite sand waste as filler or/and sand material plus blast oxygen furnace steel slag as fine and coarse aggregate for design of high performance asphalt concrete. Both environmental and economic factors contribute to the growing need for the use of these materials in asphalt concrete pavements. This is particularly important for Latvia, where local crushed dolomite and sandstone do not fulfill the requirements for mineral aggregate in high and medium intensity asphalt pavements roads. Annually 100-200 thousand tons of steel slag aggregates are produced in Latvia. However, it has not been used extensively in asphalt pavement despite of its high performance characteristics. Dolomite sand waste, which is a byproduct of crushed dolomite production, is another widely available polydisperse by-product in Latvia. Its quantity has reached a million of tons and is rapidly increasing. This huge quantity of technological waste needs to be recycled with maximum efficiency. Various combinations of steel slag, dolomite sand waste and conventional aggregates were used to develop asphalt concrete AC 11 mixtures. The mix properties tests include resistance to permanent deformations (wheel tracking test, dynamic creep test) and fatigue resistance. Laboratory test results showed that asphalt concrete mixtures containing steel slag and local limestone in coarse portion and dolomite sand waste in sand and filler portions had high resistance to plastic deformations and good resistance to fatigue failure.