Bi Yufeng, Mu Minghao, Zeng Lujun, Ding Tingting, Qian Chengduo, Yu Deshui, Jiang Yingjun
Innovation Research Institute of Shandong Expressway Group Co., Ltd., Ji'nan 250000, China.
Key Laboratory for Special Area Highway Engineering of Ministry of Education, Chang'an University, Xi'an 710064, China.
Materials (Basel). 2024 Nov 22;17(23):5712. doi: 10.3390/ma17235712.
The pavement base and subbase are the main load-bearing structures of asphalt pavement, and their materials need to have sufficient bearing capacity. Therefore, in the development of LSAM-50 mixtures with higher bearing capacity, after significant research and engineering practice, conventional particle size asphalt mixtures have formed their own excellent mineral gradation and have been incorporated into relevant specifications, while LSAM-50 mixtures, including mineral gradation, have not been involved in related research and engineering applications. According to the strength composition mechanism of asphalt mixtures, under the same circumstances of asphalt, due to the large nominal maximum particle size of LSAM-50 and the small amount of asphalt used, the strength of mineral grading is more important than that of asphalt, which is one of the key issues to be solved in the research of LSAM-50 mixtures. This study aims to enhance the road performance of asphalt mixtures with a maximum nominal particle size of 50 mm (LSAM-50). The variation of void ratios in coarse aggregate skeletons was investigated when aggregates of 37.5-53 mm (designated as D1), 19-37.5 mm (designated as D2), and 9.5-19 mm (designated as D3) were mixed in different proportions. Meanwhile, the effects of fine aggregate gradation on the strength of asphalt mortar and the influence of the ratio of coarse to fine aggregates on the mechanical strength of LSAM-50 were examined. A densely graded structure with strong interlocking for LSAM-50 was proposed, and its road performance was verified. The results indicate that when the ratio of D1, D2, and D3 is 5:2:3, the void ratio of the mixed coarse aggregate is minimized. When the decrement factor i is 0.75, the compressive strength and splitting strength of asphalt mortar reach their maxima. Compared with the densely graded asphalt-stabilized aggregate mixture (ATB-30) with a maximum nominal particle size of 37.5 mm, the dynamic stability of LSAM-50 with the proposed gradation is increased by 400%, the low-temperature bending strain by 3%, the SCB bending strength by 47%, and the residual SCB strength by 90%.
路面基层和底基层是沥青路面的主要承重结构，其材料需要具备足够的承载能力。因此，在研发具有更高承载能力的大粒径沥青稳定碎石混合料（LSAM-50）时，经过大量研究和工程实践，常规粒径沥青混合料已形成自身优良的矿料级配并被纳入相关规范，而包括矿料级配在内的LSAM-50混合料尚未涉及相关研究及工程应用。根据沥青混合料的强度组成机理，在沥青相同的情况下，由于LSAM-50的公称最大粒径较大且沥青用量较少，矿料级配的强度比沥青的强度更为重要，这是LSAM-50混合料研究中需要解决的关键问题之一。本研究旨在提高最大公称粒径为50mm的沥青混合料（LSAM-50）的路用性能。研究了37.5 - 53mm（记为D1）、19 - 37.5mm（记为D2）和9.5 - 19mm（记为D3）的集料按不同比例混合时粗集料骨架中空隙率的变化情况。同时，考察了细集料级配对沥青胶浆强度的影响以及粗细集料比例对LSAM-50力学强度的影响。提出了一种具有强嵌锁作用的LSAM-50密级配结构，并对其路用性能进行了验证。结果表明，当D1、D2和D3的比例为5:2:3时，混合粗集料的空隙率最小。当递减系数i为0.75时，沥青胶浆的抗压强度和劈裂强度达到最大值。与最大公称粒径为37.5mm的密级配沥青稳定碎石混合料（ATB-30）相比，所提出级配的LSAM-50的动稳定度提高了400%，低温弯曲应变提高了3%，半圆弯曲（SCB）强度提高了47%，SCB残留强度提高了90%。
