Investigation of Moisture and Salt-Erosion Resistance of Asphalt-Calcined Bauxite Systems

This study aims to investigate the moisture and salt-erosion resistance of asphalt-calcined bauxite systems (ACBSs). The effects of the type of asphalt, aged asphalt, polymer modifiers, and grade of calcined bauxite on the moisture and salt-erosion resistance are evaluated by the pull-off strength and flaking rate of ACBSs after water immersion and neutral salt spray. The results show that a lower grade of asphalt is beneficial for the moisture resistance of an ACBS. Styrene-butadiene-styrene (SBS), antistripping agents, and polyphosphoric acid (PPA) improve moisture resistance, whereas rubber powder reduces it. Although the short-term thermal oxygen aging process can improve moisture resistance, high temperatures can result in the failure of the ammonia antistripping agent. The crystallization erosion from salt increases the moisture damage caused by water. The addition of modifiers and nonammonia antistripping agents can improve salt-erosion resistance; however, PPA has a weaker effect on salt-erosion resistance. Because the higher strength of the interface prevents moisture and salt erosion, an ACBS with a higher grade of calcined bauxite has higher moisture and salt-erosion resistance.