A New Generation of Dense-Graded Asphalt Mixtures with Superior Performance against Stripping and Moisture Damage

The presence of moisture beneath the pavement surface is a matter of great concerns as it is responsible for significant distresses such as asphalt concrete (AC) stripping, fatigue cracking, rutting, and poor durability of asphalt mixes. The objective of this study was to evaluate and recommend an asphalt mixture design that would provide superior performance against AC stripping and cracking. To achieve this objective, a laboratory test factorial was developed to evaluate the use of nanomaterials, emerging anti-stripping agents, warm-mix asphalt technologies, and adhesion promotors. In the experimental program, the modified Lottman test (AASHTO T 283) and the Indirect Tensile Asphalt Cracking Test (IDEAL-CT) test were used as performance indicators of moisture damage resistance and cracking susceptibility. Results were analyzed statistically to identify and quantify the effects of the design variables and selected additives on the performance, moisture damage resistance, and durability of asphalt mixes. Based on the cracking test results, a superior cracking resistance performance was observed with Zycotherm^®, irrespective of the mix type. AD-here^® had the lowest average cracking indices for both mix types, which suggests that it would not function as good as the other additives in terms of cracking resistance. Overall, Stone Matrix Asphalt (SMA) mixes showed greater cracking resistance than the dense-graded mixture, which may have been a result of the RAP material used in the dense-graded mix and its lower asphalt binder content. In terms of moisture resistance, both nanomaterials (Graphene Nanoplatelet [GNP] and Nanoclay) did not perform well as they did not meet the minimum required tensile strength ratio (TSR) criterion. Overall, nanomaterials showed the lowest TSR values in both mix types suggesting that their effectiveness against moisture-induced damage may not be as good as warm-mix additives. In addition, warm-mix additives were expected to show enhanced performance in terms of moisture resistance as compared to the other additives evaluated in this study.路面表层下方的水分积聚问题备受关注，因其会引发诸多严重病害，诸如沥青混凝土（asphalt concrete, AC）剥落、疲劳开裂、车辙以及沥青混合料耐久性下降。本研究旨在评估并推荐一种沥青混合料配合比设计方案，使其在抵御AC剥落与开裂方面具备更优异的性能。为达成该目标，本研究构建了实验室析因试验方案，以评估纳米材料、新型抗剥落剂、温拌沥青技术以及黏附促进剂的应用效果。在试验方案中，采用改进的洛特曼试验（AASHTO T 283）与间接拉伸沥青开裂试验（IDEAL-CT）分别作为抗水损害性能与开裂敏感性的评价指标。通过对试验结果进行统计学分析，识别并量化了各设计变量与选定外加剂对沥青混合料路用性能、抗水损害性能及耐久性的影响。基于开裂试验结果，无论混合料类型如何，Zycotherm®均展现出更优异的抗开裂性能。AD-here®在两种混合料类型中的平均开裂指数均为最低，这表明其在抗开裂性能方面不及其他外加剂。总体而言，沥青玛蹄脂碎石混合料（Stone Matrix Asphalt, SMA）相较于密级配混合料展现出更优异的抗开裂性能，这可能是由于密级配混合料中掺入了再生沥青混合料（Recycled Asphalt Pavement, RAP）材料，且其沥青结合料含量更低。在抗水损害性能方面，两种纳米材料——纳米石墨烯片（Graphene Nanoplatelet, GNP）与纳米黏土——的表现均未达标，未能满足最低抗拉强度比（tensile strength ratio, TSR）要求。总体而言，两种混合料类型中纳米材料的TSR值均为最低，这表明其抵御水致损害的效果可能不如温拌外加剂。此外，相较于本研究评估的其他外加剂，温拌外加剂在抗水损害性能方面有望展现出更优的表现。