Research On The Design And Road Performance Of High Modulus Steel Slag Asphalt Mixes

As China’s infrastructure construction continues to advance,quality stone resources are becoming more and more scarce and suitable stone substitutes are urgently needed.Steel slag,as a bulk industrial waste with excellent mechanical properties,can be used as engineering aggregate in asphalt mixes to alleviate stone scarcity and improve the utilization rate of industrial solid waste.But due to the poor volumetric stability of steel slag in contact with water,it will cause damage to the mix volume when used directly in the mixes without treatment.In this thesis,steel slag is applied to asphalt mixes to reduce the contact between steel slag and water by using high modulus asphalt and reducing the void ratio of the mix design to achieve the purpose of improving the performance and service life of steel slag asphalt mixes.In this thesis,the physical and chemical properties of the selected steel slag were studied and the structural characteristics of the slag itself were analyzed.The unstable particles contained in the steel slag were also investigated: the unstable particles were analyzed by XRD,and their content and source were detected,so that the treatment of the unstable particles could be proposed.In addition,the asphalt absorption coefficient of steel slag with different particle sizes was measured by asphalt impregnation method,the adsorption law of steel slag and asphalt was analyzed,and the effective relative density of synthetic gradation was measured,and finally the theoretical maximum relative density was obtained by calculation.Besides,the road properties of five asphalt mixtures were studied: all steel slag,all coarse steel slag,50% all coarse steel slag,all fine steel slag and all limestone.Research shows that the addition of steel slag can significantly improve the rutting resistance of asphalt mixes,its dynamic stability is three times that of limestone mixes,lowtemperature crack resistance and fatigue life are improved;at the same time,the addition of high-modulus asphalt can improve the volume stability of steel slag aggregates and extend the service life of steel slag asphalt mixes.The performance of high-modulus all-steel slag in hightemperature stability,low-temperature cracking resistance,water stability and fatigue resistance is more balanced,and the rutting resistance is about three times that of ordinary high-modulus asphalt mixes;the 3 and 21-day water immersion swelling rates are 0.718% and 5.976%,respectively,which can maintain excellent volumetric stability;through dynamic modulus tests,the hysteresis of high-modulus all-steel slag asphalt mixes is small and the mechanical response is excellent;the actual production process is excellent.The cost analysis of the actual production process found that the production cost of high modulus all-steel slag is 6.5% higher than that of ordinary SBS limestone mix,but the road performance can be improved by 2 to 3 times,which can obtain good social and economic benefits.