煅烧铝矾土路用超薄磨耗层配合比设计及性能评价

Mix Proportion Design and Performance Evaluation of Ultra-thin Friction Course with Calcined Bauxite for Pavement

为提高超薄磨耗层路面的抗滑性能,采用煅烧铝矾土与石灰岩集料混掺的方法制备了沥青混合料,鉴于两种集料的吸水率存在差异,采用沥青浸渍试验对粗集料空隙填充法进行了改进,并将其应用于煅烧铝矾土超薄磨耗层(CB-UTFC)混合料的配合比设计。通过马歇尔、高温车辙、低温弯曲和冻融劈裂等试验对所设计的不同煅烧铝矾土掺量的沥青混合料进行了路用性能测试,并通过摆值和构造深度来测试混合料的抗滑性能。采用灰靶决策理论,针对混合料的高温稳定性、低温抗裂性、水稳定性以及抗滑性能各项指标,建立了基于多指标的煅烧铝矾土掺量优选模型,从而确定了煅烧铝矾土在CB-UTFC中的最佳掺量。结果表明:煅烧铝矾土的掺入对沥青混合料性能的影响较为明显,随着掺量的增加,沥青混合料的低温抗裂性和水稳定性整体呈现增强趋势,其高温稳定性和抗滑性能指标则呈现出先上升后下降的趋势,分别在煅烧铝矾土掺量为60%和40%时,动稳定度和抗滑性能达到峰值;掺煅烧铝矾土集料的沥青混合料整体各项路用性能均优于未掺状态下的混合料;当CB-UTFC沥青混合料的路用性能达到较优平衡时,煅烧铝矾土的最佳掺配比例范围为40%~60%。应用改进的粗集料空隙填充法所设计的煅烧铝矾土沥青混合料可广泛应用于超薄磨耗层的铺筑和建设中。

In order to improve the skid resistance of ultra-thin friction course pavement,the asphalt mixture is prepared by mixing calcined bauxite and limestone aggregate.Due to the difference in the water absorption of the 2 aggregates,the coarse aggregate voids filling method is improved by using asphalt immersion test,and it is applied to the mix proportion design of CB-UTFC mixture.Through Marshall test,high temperature rutting test,low temperature bending test and freeze-thaw splitting test,the road performances of the designed asphalt mixture with different calcined bauxite contents are tested,and the skid resistance of the mixture is tested by the swing value and structural depth.The optimization model of calcined bauxite content based on multiple indicators is established in view of the high temperature stability,low temperature crack resistance,water stability and skid resistance of the mixture by using the grey target decision-making theory,so as to determine the optimal content of calcined bauxite in CB-UTFC.The result shows that(1)The addition of calcined bauxite has an obvious influence on the performance of asphalt mixture.With the increase of the content,the low temperature crack resistance and water stability of asphalt mixture show an overall strengthening trend,while its indicators of high temperature stability and skid resistance show an upward and then downward trend.When the content of calcined bauxite is 60%and 40%respectively,the dynamic stability and skid resistance reach the peak values.(2)The overall road performance of asphalt mixture mixed with calcined bauxite aggregate is better than that of asphalt mixture without calcined bauxite aggregate.(3)When the road performance of CB-UTFC asphalt mixture reaches better balance,the optimal mix proportion range of calcined bauxite is 40%-60%.The calcined bauxite asphalt mixture designed by the improved coarse aggregate voids filling method can be widely used in the paving and construction of ultra-thin friction course.