热阻式SMA-13沥青混合料级配优化

为了研究热阻式SMA-13沥青混合料中耐火碎石最佳掺量, 设计了SMA-13沥青混合料配合比方案, 即在2.36~4.75 mm集料中, 耐火碎石体积掺量为100%, 在4.75~9.5 mm集料中, 耐火碎石体积掺量分别为20%、40%、60%、80%、100%, 在9.5~13.2 mm集料中, 耐火碎石体积掺量分别为10%、20%、30%;研究了耐火碎石掺量对SMA-13沥青混合料路用性能和阻热性能的影响规律, 提出了耐火碎石最佳掺量, 并分析了最佳掺量下热阻式SMA-13沥青混合料路用性能和阻热性能。试验结果表明: 与普通SMA-13沥青混合料相比, 将2.36~4.75 mm集料全部替换为耐火碎石时, 热阻式SMA-13沥青混合料路用性能降低约3%, 试件温度降低约1.4℃; 4.75~9.5 mm耐火碎石掺量占该粒径普通集料60%时, 热阻式SMA-13沥青混合料路用性能降低5%~10%, 试件温度降低约5.7℃, 阻热效果明显, 耐火碎石掺量超过60%时, 热阻式SMA-13沥青混合料路用性能急剧衰减, 阻热效果不明显, 掺量为60%~80%时, 热阻式SMA-13沥青混合料路用性能降低幅度达到10%~20%, 而试件温度降低幅度不超过0.7℃; 9.5~13.2 mm耐火碎石掺量占该粒径普通集料10%~20%时, 热阻式SMA-13沥青混合料路用性能基本不变, 而阻热效果明显, 掺量达到20%时, 路用性能降低约13%, 试件温度降低约7℃, 耐火碎石掺量超过20%时, 路用性能急剧下降, 无阻热效果, 试件温度增加0.1℃; 基于热阻式SMA-13沥青混合料降温效果最佳原则, 建议2.36~4.75、4.75~9.5与9.5~13.2 mm耐火碎石掺量分别占同粒径普通集料的100%、60%和20%。

Gradation optimization of thermal resistant SMA-13 asphalt mixture

In order to study the optimal dosage of refractory gravel in the thermal resistant SMA-13 asphalt mixture, the mixture proportion schemes were designed.In the schemes, the volume content of refractory gravel in the 2.36-4.75 mm ordinary aggregate was 100%, the volume content in the 4.75-9.5 mm ordinary aggregate was 20%, 40%, 60%, 80%, and 100%, respectively, and the volume content in the 9.5-13.2 mm ordinary aggregate was 10%, 20%, and 30%, respectively.The influence laws of refractory gravel content on the road property and heat resistant property of the SMA-13 asphalt mixture were studied, the optimum content ofrefractory gravel was put forward, and the road performance and thermal resistant performance of the SMA-13 asphalt mixture with this content were analyzed.Research result shows that compared with the ordinary SMA-13 asphalt mixture, when the 2.36-4.75 mm aggregate is entirely replaced by the refractory gravel, the road performance of the thermal resistant SMA-13 asphalt mixture reduces by about 3%, and the temperature of specimen decreases by about 1.4 ℃.When the 4.75-9.5 mm refractory gravel accounts for 60% of the same particle size of ordinary aggregates, the road performance of the thermal resistant SMA-13 asphalt mixture reduces by5%-10%, the temperature of the specimen decreases by about 5.7 ℃, and the heat resistance effect is obvious.When the content of the 4.75-9.5 mm refractory gravel is more than 60%, the road performance of the thermal resistant SMA-13 asphalt mixture decays rapidly, and the heat resistance effect is not obvious.When the content of the 4.75-9.5 mm refractory gravel is 60%-80%, the road performance of the thermal resistant SMA-13 asphalt mixture reduces by 10%-20%, and the temperature of the specimen decreases by less than 0.7 ℃.When the 9.5-13.2 mm refractory gravel accounts for 10%-20%of the same particle size of ordinary aggregates, the road performance of the thermal resistant SMA-13 asphalt mixture does not change basically, but the heat resistance effect is obvious.When the content reaches 20%, the road performance decreases by around 13%, and the temperature of the specimen decreases by about 7 ℃.When the content exceeds 20%, the road performance decreases sharply, the temperature of the specimen increases only by 0.1℃, and there is not heat resistance effect.Based on the best principle of cooling effect of the thermal resistant SMA-13 asphalt mixture, it is suggested that the contents of 2.36-4.75, 4.75-9.5and 9.5-13.2 mm refractory gravels account for 100%, 60%, and 20% of the same particle size of ordinary aggregates, respectively.