Performance characteristics of asphalt mixture with basic oxygen furnace slag

Abstract

Lack of superior natural crushed stone and negative dumping effects on environment promote the recycling of basic oxygen furnace slag (BOF). Since BOF based asphalt pavements have been utilized for a certain history, their in-service performances necessitate comprehensive investigation imperatively, with respect to moisture sensitivity and permanent deformation behavior in particular. In this study the surface of BOF was firstly characterized by electron probe micro-analysis (EPMA) coupled with X-ray wavelength Energy Disperse Spectroscopy (EDS). Then the surface energies of asphalt and BOF were measured by determination of contact angles and they are further used to determine the work of adhesion. The asphalt mixtures incorporating BOF as coarse aggregate were prepared and subsequently subjected to modified Lottman test, immersion rutting test and fatigue life test to determine the moisture resistance. Also dynamic creep test was carried out to characterize the permanent deformation behavior at different high temperatures and various stress levels. Results show that the CaO–FeO–MnO–MgO solid solution and inert CaO are the major compositions on the surface of BOF. Large contents of Al and Ca elements may be beneficial for the bond energy between BOF and asphalt. The results of contact angle demonstrate that BOF possesses superior wettability with asphalt to basalt. The results combined with modified Lottman test show the superior moisture sensitivity of BOF based asphalt mixture to basalt based mixtures. And at higher temperature (above 45°C), mastic performs a prominent role in the resistance of BOF based mixture to permanent deformation. Additionally the permanent deformation behavior of BOF based asphalt mixture can be perfectly modeled and the results provide possibility to the establishment of predicting model for the permanent deformation of asphalt pavement with BOF.