高掺量橡胶改性沥青性能研究及优选

Study and Optimization on Performance of High-dosage Rubber Modified Asphalt

摘要:

橡胶沥青的掺量大小对沥青的性能和使用成本都有显著的影响。为了提高橡胶改性沥青掺量的同时兼顾其性能,本研究选择20%、30%、40%、50%四种掺量的橡胶改性沥青,通过温度扫描试验和弯曲梁流变试验评价不同掺量的橡胶改性沥青的高温性能与低温性能,并根据规范要求确定PG分级。通过拟合半对数坐标下车辙因子-温度曲线,对比了老化前后各个沥青的感温性。结果表明：高温流变性能方面,老化前后车辙因子大小均表现为40%RA＞30%RA＞50%RA＞20%RA,当胶粉掺量超过40%以后,高温性能显著下降。随着胶粉掺量的提高,胶粉改性沥青的高温性能先上升后下降,考虑高温性能,则胶粉掺量不宜超过40%；从半对数坐标的拟合结果来看,掺量在20%-40%之间时,胶粉能提高沥青的温度稳定性。低温性能方面,随着胶粉掺量的提高,胶粉改性沥青的低温变形能力和应力松弛能力逐渐增强；综合温度扫描试验和BBR试验的结果,得到4种胶粉改性沥青的PG分级结果：20%RA为PG82-22,30%RA/40%RA为PG88-28,50%RA为PG82-34；综合考虑性能和经济性,在实际工程中较为推荐30%掺量和40%掺量的胶粉改性沥青。

Abstract:

The dosage of rubber asphalt has a significant impact on the performance and using cost of the asphalt. To increase the dosage of rubber modified asphalt while taking into account its performance, four rubber-modified asphalts with the dosages of 20%, 30%, 40%, and 50% are selected to evaluate the high-temperature performances and low-temperature performances of these rubber modified asphalts with the different dosages through the temperature sweep test and bent beam rheological test. The PG classification is determined according to the specification requirements. By fitting the rutting factor - temperature curve under the semi-logarithmic coordinate, the temperature sensitivity of each asphalt before and after aging is compared. The results show that in terms of high-temperature rheological properties, the rutting factors before and after aging are both 40%RA＞30%RA＞50%RA＞20%RA. When the dosage of rubber powder exceeds 40%, the high-temperature performance will decrease significantly. With the increase of rubber powder dosage, the high-temperature performance of rubber powder modified asphalt first increases and then decreases. Considering the high temperature performance, the rubber powder dosage should not exceed 40%. From the fitting result of semi-logarithmic coordinate, when the dosage is between 20%~40%, the rubber powder can improve the temperature stability of the asphalt. In terms of low temperature performance, with the increase of the dosage of rubber powder, the low-temperature deformation ability and stress relaxation ability of rubber powder modified asphalt gradually increase. By integrating the results of the temperature scanning test and the BBR test, the PG classification results of 4 kinds of rubber powder modified asphalt are obtained, that is 20%RA is PG82-22, 30%RA/40%RA is PG88-28 and 50%RA is PG82-34. By comprehensively considering the performance and economy, the 30% and 40% dosages of rubber powder modified asphalts are more recommended in the practical projects.