Effect of Water Absorption and Loss Characteristics of Fine Aggregates on Aggregate-Asphalt Adhesion

This study aims to investigate the effect of aggregate water absorption and loss characteristics on aggregate-asphalt adhesion. Lab tests were designed to analyze the water absorption and loss characteristics of limestone, basalt. and steel slag fine aggregates with different particle sizes under various temperatures and humidity conditions. Meanwhile, the low temperature nitrogen adsorption test, combined with the Brunauer, Emmett and Teller (BET) theory and Barret, Joyner and Halend (BJH) model, were used to calculate the specific surface area and pore size distribution of aggregate. Moreover, the asphalt-aggregate adhesion was evaluated by the net adsorption test. The results indicated that the change trends of water absorption and loss for the aggregates exhibited two stages. In the first stage, the amounts of water absorption and loss of aggregates were large and their change rates were high, while in the second stage, an opposite trend was observed. Humidity had the greatest influence on the water absorption and loss of aggregates, followed by aggregate particle size, contact time, temperature, and aggregate type. The smaller-sized aggregates had greater specific surface area, which led to a higher sensitivity to temperature and humidity changes. In comparison, the 0.3 mm-sized aggregate had a large capillary energy inside the pores, and it was the most sensitive to moisture. The steel slag aggregate had the strongest adhesion with asphalt, followed by the limestone aggregate, and the worst was basalt aggregate