Moisture Susceptibility of Open-Graded Friction Course Mixes with EAF Steel Slag and Modified Binders

Open-graded friction course (OGFC) mixtures are sensitive to the moisture damage because of their high air void content and longer exposure to water. In the present study, moisture susceptibility characteristics of OGFC mixes in terms of tensile strength characteristics, aggregate-binder bond strength, and the raveling potential of OGFC mixtures were studied. The experimental design for this study included OGFC mixes with two different types of aggregates (natural aggregates as a main source and electric arc furnace (EAF) steel slag as a secondary source), two different types of modified binders (polymer-modified bituminous binder and crumb rubber-modified bituminous binder), and one cellulose fiber as an additive. OGFC mixes were designed with five different percentages (0, 25, 50, 75, and 100 %) of secondary aggregates as a partial replacement of main aggregates. OGFC mixes were then evaluated for moisture susceptibility through four different test methods, viz. the indirect tensile strength (ITS) or tensile strength ratio (TSR) method, wet abrasion loss (WAL) method, static immersion test method, and modified boiling test method. OGFC mixes with EAF steel slag showed higher ITS values under both dry and wet conditions compared with the control mixes with natural aggregates alone. Steel slag content, binder type, and freeze-thaw cycles had statistically significant effects on the ITS, TSR, and WAL values. Modified boiling test results showed a good correlation with the modified Lottman and WAL test results.