基于贯入强度的水基聚合物稳定碎石材料组成设计

Composition Design of Water-based Polymer Stabilized Macadam Material Based on Penetration Strength

为了在实际工程中规范应用水基聚合物稳定碎石材料,建立了符合其柔性基层材料特性的组成设计方法,即确定水基聚合物稳定碎石材料的设计级配、养生条件以及最佳聚合物掺量。首先根据水基聚合物稳定碎石材料强度特性,从现有道路规范中选取符合要求的级配,由击实试验结果筛选出设计级配。再通过CBR试验确定水基聚合物稳定碎石材料的养生条件与养生目标含水率。最后采用单轴贯入强度试验确定了水基聚合物最佳掺量。试验结果表明:设计级配为水泥稳定碎石级配(C-B-1),其最大干密度2.27 g/cm^(3),最佳含水率为4.4%;试验养生温度为60℃,养生时间为2 d,养生目标含水率为1.4%,当含水率低于目标值时材料CBR值达到250%以上,满足相关规范要求;水基聚合物最佳掺量为0.5%时,材料的单轴贯入强度为0.91 MPa,超过普通沥青混合料单轴贯入强度的一般值(0.7 MPa),水基聚合物的单位掺量变化率达到峰值,对每吨碎石材料强度提升的性价比达到0.00264 MPa/元,在满足路用性能的同时材料工程性价比也为最佳;基于贯入强度的水基聚合物稳定碎石材料组成设计方法相较于传统CBR值设计方法更具有时效性,且单轴贯入强度能直观反映水基聚合物稳定碎石基层在荷载作用下材料的承载能力,更符合水基聚合物稳定碎石基层柔性材料特性。

In order to standardize the application of water-based polymer stabilized materials in practical engineering,the composition design method conforming to the characteristics of flexible base material is established,i.e.,to determine the design gradation,curing conditions and the optimum polymer content of the water-based polymer stabilized macadam material.First,according to the intensity characteristics of water-based polymer stabilized macadam material,the required gradation is selected from the existing road specifications,and the design gradation is screened from the compaction test result.Then,the curing conditions and the curing target moisture content of water-based polymer stabilized macadam material are determined through CBR test.Finally,the optimum content of water-based polymer is determined by uniaxial penetration strength test.The test result shows that(1)The design gradation is cement stabilized macadam gradation(C-B-1),with the maximum dry density of 2.27 g/cm^(3)and the optimum moisture content of 4.4%.(2)The test curing temperature is 60℃,the curing time is 2 d,and the curing target moisture content is 1.4%.(3)When the moisture content is smaller than the target value,the CBR value of the material reaches more than 250%,meeting the requirements of relevant specification.(4)When the optimum content of water-based polymer is 0.5%,the uniaxial penetration strength of the material is 0.91 MPa,which is higher than the general value of the uniaxial penetration strength of ordinary asphalt mixture(0.7 MPa).The change rate of the unit content of water-based polymer reaches the peak value,and the cost-performance ratio for the strength improvement of each ton of macadam material reaches 0.00264 MPa/yuan.The engineering cost-performance of the material is also the best while meeting the road performance.(4)The composition design method of water-based polymer stabilized macadam based on penetration strength is more timely than the traditional CBR value design method,and the uniaxial penetration strength can directly reflect the bearing capacity of water-based polymer stabilized macadam base under load,which is more consistent with the flexible material characteristics of water-based polymer stabilized macadam base.