再生剂对高RAP掺量厂拌热再生沥青混合料性能影响研究

Study on Influence of Regenerant on Performance of High RAP Content Plant Mixed Hot-recycled Asphalt Mixture

摘要:

随着我国道路建设事业的蓬勃发展，旧沥青路面回收材料（reclaimed asphalt pavement，RAP）的资源化利用需求日益凸显。针对RAP掺量为50%的厂拌热再生沥青混合料，系统研究了0%、2%、5%、8%、11%不同再生剂掺量对其性能的影响。通过回收RAP中的老化沥青［针入度18.2（0.1 mm）、软化点68.5 ℃］，测试再生剂对沥青性能的恢复效果。结果表明：当再生剂掺量达到8%时，针入度提升至53.1（0.1 mm），软化点降至56.3 ℃，黏弹特性显著改善；当掺量超过8%后，沥青的高温稳定性明显衰减。在AC-20混合料设计中，新油石比优化至2.26%，级配满足规范要求。性能试验显示：8%再生剂掺量下，混合料空隙率降至4.21%，马歇尔稳定度达12.95 kN，提升了17.7%，动稳定度达4 165 次/mm，提升了31.2%；水稳定性方面，浸水残留稳定度（MS₀）和冻融劈裂强度比（TSR）分别达94.7%和86.6%，较未掺再生剂时分别提升了7.5%和6.66%。当再生剂掺量超过8%时，会稀释沥青黏度，导致混合料的高温稳定性和水稳定性下降。研究表明，在50% RAP掺量下再生剂的最佳掺量为8%，该方案实现了老化沥青性能恢复、混合料体积参数优化与力学性能提升的协同，为高掺量再生技术提供一些可参考的意见。

Abstract:

With the vigorous development of road construction industry in China, the demand for resource utilization of recycled asphalt pavement materials (reclaimed asphalt pavement, RAP) has become increasingly prominent. For the plant-mixed hot recycled asphalt mixtures with a RAP content of 50%, the effects of different regenerant dosages of 0%, 2%, 5%, 8% and 11% on its performance are systematically studied. By recycling the aged asphalt from RAP [with a penetration of 18.2 (0.1 mm) and a softening point of 68.5 ℃], the recovery effect of the regenerant on asphalt performance is tested. The results show that when the dosage of regenerant reachs 8%, the penetration degree increases to 53.1 (0.1 mm), the softening point decreases to 56.3 ℃, and the viscoelastic properties are significantly improved. After the dosage exceeds 8%, the high-temperature stability of asphalt significantly deteriorates. In the design of AC-20 mixture, the new asphalt-aggregate ratio is optimized to 2.26%, and the gradation meets the specification requirements. Performance tests show that at an 8% dosage of regenerant, the void fraction of the mixture decreases to 4.21%, and the Marshall stability reaches 12.95 kN, with an increase of 17.7%. And the dynamic stability reaches 4 165 times/mm, with an increase of 31.2%. In terms of water stability, the residual stability after immersion (MS₀) and the freeze-thaw splitting strength ratio (TSR) reach 94.7% and 86.6%, respectively, which are 7.5% and 6.66% higher than those without the addition of regenerant. When the dosage of regenerant exceeds 8%, the viscosity of asphalt will be diluted, resulting in a decrease in the high-temperature stability and water stability of the mixture. Research shows that the optimal dosage of regenerant with 50% RAP is 8%. This scheme achieves the synergy of restoring the performance of aged asphalt, optimizing the volume parameters of the mixture and enhancing its mechanical properties, providing some reference suggestions for high-dosage recycling technology.