冷再生沥青混合料第二次压实过程分析

冷再生沥青混合料(Cold Recycled Mixture)凭借其保护环境、节约资源、降低工程造价等诸多优点,已经开始在我国得到推广应用,并且有着非常好的应用前景。冷再生沥青混合料在常温下摊铺和碾压,空隙率较大,性能方面不能达到热拌沥青混合料(HMA)的标准,一般被用在路面结构中的基层或下面层中,其上还须加铺一定厚度的HMA以满足道路使用的要求。在冷再生层上摊铺HMA时,HMA高达150℃~170℃的高温,会将冷再生层加热,加之施工机械和车辆荷载等作用,致使冷再生层会被进一步压实,称之为冷再生层的"第二次压实"过程。对现场冷再生层钻芯取样后发现,摊铺HMA前后的冷再生芯样的空隙率相差可达3%。现有冷再生混合料设计方法对这一现象并未考虑,导致冷再生层在实际施工过程中出现了严重的压密性车辙。该文对这一现象进行阐述,提出在进行冷再生混合料设计时必须考虑"第二次压实"过程的影响,并对改进现有设计方法提出一些建议,可供同行参考。

Analysis on Secondary Compaction Process of Cold Recycled Asphalt Mixture

The cold recycled asphalt mixture has been widely spread in China and has very good application foreground by depending on its many advantages of protecting the environment,saving the resource,reducing the engineering construction cost and etc.The cold recycled asphalt mixture is paved and rolled under the normal temperature,and its void ratio is larger.Its performance can not satisfy the standard of high mixed asphalt mixture(HMA).It is generally used in the base or the lower layer of the pavement structure,and a certain thickness of HMA must be paved on it so as to satisfy the application requirement of road.When HMA is paved on the cold recycled layer,the temperature of HMA is high to 150~1700C and heats the cold recycled layer,which will be further compacted plus the actions of construction mechanism and vehicle loading.It is named as the "secondary compaction" process of cold recycled layer.It is discovered that the void ratio difference of cold recycled core samples before and after paving HMA can be 3% by the field core sampling drill of cold recycled layer.The present cold recycled mixture design method does not consider this phenomenon so as to result in the serious compaction rut of cold recycled layer in the practical construction.The article sets forth this phenomenon,puts forward the influence of the "secondary compaction" process having to be considered in the design of the cold recycled asphalt mixture,and puts forward some suggestions for improving the existing design methods.