基于MMLS3设备的OLSM抗反射裂缝性能研究

为评价开级配大粒径沥青碎石（OLSM）抗反射裂缝性能及其影响因素，采用MMLS3设备对1/2路面结构进行弯拉-剪切作用下反射裂缝模拟试验，测定不同集料粒径、分形维数、胶浆膜厚度和粉胶比等影响因素下OLSM面层的瞬时应变幅值，分析不同影响因素下OLSM面层裂缝扩展规律。结果表明：OLSM面层随加载的累积应变、瞬时应变幅值和裂缝扩展速率均显著低于AC面层，终裂时其加载次数比AC面层提高了64.9%；随着公称最大集料粒径的增大，OLSM面层随加载的瞬时应变幅值和裂缝扩展速率显著降低，终裂时OLSM-30和OLSM-40面层加载次数比OLSM-25面层分别提高了20.2%和41.5%；随着分形维数的减小，OLSM面层随加载的瞬时应变幅值和裂缝扩展速率先提高后降低，终裂时加载次数先提高后降低；随着胶浆膜厚度和粉胶比的增大，OLSM面层随加载的瞬时应变幅值、裂缝扩展速率先提高后降低，终裂时加载次数先提高后降低。OLSM对裂缝扩展起到较好的抑制作用，具有良好的抗反射裂缝性能；大粒径集料对裂缝扩展起到较好的抑制作用，选用较大集料粒径的OLSM可有效提高其抗反射裂缝性能；随着分形维数、胶浆膜厚度和粉胶比的增大，OLSM抗反射裂缝性能先提高后降低；采用分形维数2.39~2.43、胶浆膜厚度50~56 μm和粉胶比1.2~1.4设计OLSM，可有效提高其抗反射裂缝性能。

Research on Anti-reflective Cracking Performance of Open-graded Large Stone Asphalt Mixes Based on MMLS3

To evaluate the anti-reflective cracking performance and influencing factors of open-graded large stone asphalt mixes (OLSM), the MMLS3 equipment was used to simulate reflection cracks under the action of bending and shearing on half of the pavement structure. The instantaneous strain amplitudes of the OLSM surface layer under different influencing factors, such as aggregate size, fractal dimension, mortar film thickness, and powder-to-binder ratio, were measured and the crack propagation law of it under different influencing factors was analyzed. It was found that during the loading process, the cumulative strain, instantaneous strain amplitude, and crack propagation rate of the OLSM surface layer are significantly lower than those of the AC surface layer, and the number of loading times is 64.9% higher than that of the AC surface layer during the final cracking. With the increase in nominal maximum aggregate size, the instantaneous strain amplitude and crack growth rate of the OLSM surface layer during the loading process reduce significantly. The loading times of the OLSM-30 and OLSM-40 surface layer increase by 20.2% and 41.5%, respectively, compared to the OLSM-25 surface layer during the final cracking. With the decrease in fractal dimension, the instantaneous strain amplitude and crack growth rate of the OLSM surface layer increase first and then decrease during the loading process, and the loading times during the final crack increases first and then decreases. With the increase in mortar thickness and powder-to-binder ratio, the instantaneous strain amplitude and crack growth rate of the OLSM surface layer increase first and then decrease, and their loading times during final cracking increase first and then decrease. The results show that OLSM has a good inhibitory effect on crack growth and anti-reflection crack performance. The large particle size aggregates have a good inhibitory effect on crack growth, and using a large aggregate size in OLSM can effectively improve its anti-reflection crack performance. With the increase in fractal dimension, mortar thickness, and powder-to-binder ratio, the anti-reflective cracking performance of OLSM increases first and then decreases. It is recommended to design OLSM with a fractal dimension of 2.39-2.43, mortar film thickness of 50-56 μm, and powder-to-binder ratio of 1.2-1.4 to effectively improve its anti-reflective crack performance.