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Basic oxygen furnace (BOF) slag is a by-product of steel plants and is different from conventional natural aggregates. Studies have shown that BOF slag asphalt concrete is able to store heat. However, no quantitative research results have been presented. In this study, conventional natural aggregates and reclaimed asphalt pavement (RAP) are replaced by BOF slag in an asphalt concrete mixture. To observe the temperature variations in BOF slag asphalt concrete pavement during construction and after being opened to traffic, test roads with different levels of BOF slag and RAP were constructed in Kaohsiung City, Taiwan. The goal of this study was to provide information about the temperature differences between asphalt concrete pavement containing natural aggregates and those containing BOF slag aggregates. The results of this research indicate that for the same transportation time and distance, the temperature of asphalt concrete pavement with 40% BOF slag was approximately 7°C higher than that with 0% BOF slag. Because the internal heat energy of pavement with a large amount of BOF slag is not easily released, a longer curing time is needed after rolling compaction of the pavement, and thus, a longer time is needed before the BOF slag pavement can be opened to traffic. The temperature required to open the pavement to traffic was approximately 65°C. Furthermore, after opening the road to traffic, temperatures at depths of 3 and 5 cm in pavement with 40% BOF slag were 2 to 4°C lower than at the same depths in pavement with 0% BOF slag. [ABSTRACT FROM AUTHOR]

A comprehensive laboratory testing program, including rotary loaded wheel rutting, four-point bending fatigue, and low-temperature bending tests, was carried out in this study to evaluate a newer type of asphalt concrete mixture modifier, termed as Interface Modifier. Unlike many of the traditional asphalt binder modifiers, such as Styrene-butadiene-styrene (SBS), Styrene-butadiene Rubber Latex (SBR), Polyethylene (PE), etc., the Interface Modifier was fed directly into the mixing chamber and mixed with heated aggregate. The electron microscope scanning combined with rheology testing was also used to analyze the mechanism of interface modifier/aggregate interactions. With the use of the Interface Modifier, improved bonding between the asphalt binder and the aggregates were observed. Test results show that the use of the Interface Modifier in the asphalt concrete mix could improve its resistance to rutting at high temperature and water stability, as well as increase its fatigue life significantly. [ABSTRACT FROM AUTHOR]