At present, the commonly used stabilizers for cold recycling of asphalt pavement are cement and emulsified asphalt, and foam asphalt has gradually become a research hotspot. The different characteristics of these three stabilizers determine their unique design methods, construction processes, and quality control standards during the cold regeneration process. Table 1 compares the advantages and disadvantages of the three different cold regeneration stabilizers mentioned above.

水泥作为稳定剂时,其添加方式有两种,一种是以固态粉状水泥与再生料混合,另一种是以水泥稀浆形式与再生料混合。

When cement is used as a stabilizer, there are two ways to add it: one is to mix solid powder cement with recycled materials, and the other is to mix it with recycled materials in the form of cement slurry.

以水泥为稳定剂时,再生结构层易产生收缩裂缝,应从下列方面考虑尽量减少收缩开裂程度

When using cement as a stabilizer, the recycled structural layer is prone to shrinkage cracks, and the following aspects should be considered to minimize the degree of shrinkage cracking

水泥含量。水泥用量多则收缩大。为控制收缩开裂,水泥稳定剂的用量为2%~4%。

Cement content. A large amount of cement results in a large shrinkage. To control shrinkage cracking, the dosage of cement stabilizer is 2% to 4%.

回收旧料的性质。某些材料以水泥进行处理时,收缩量特别大;有些材料在含水量变化时体积变化相当大,塑性指数较高。当材料的塑性指数大于10时,不应单独采用水泥作稳定处理,必须用石灰与水泥混合或单独使用石灰,以降低材料的塑性。

The nature of recycled materials. When certain materials are treated with cement, the shrinkage is particularly large; Some materials have significant volume changes and high plasticity indices when the water content changes. When the plasticity index of the material is greater than 10, cement should not be used alone for stabilization treatment. Lime must be mixed with cement or used alone to reduce the plasticity of the material.

施工碾压时的含水量。收缩开裂的程度与施工碾压再干燥而消失的水量成正比,但含水量太低易造成压不实。一般建议将施工碾压时的含水量控制在比佳含水量低1%~1.5%。

The water content during construction compaction. The degree of shrinkage cracking is directly proportional to the amount of water that disappears after construction compaction and drying, but too low water content can easily cause compaction failure. It is generally recommended to control the water content during construction compaction to be 1%~1.5% lower than the optimal water content.

干燥的速率。对经水泥处理后的结构层材料适当加以养护,以降低材料干燥速度,从而降低收缩开裂。一般水泥稳定结构层施工完后7 d内必须洒水养生,或铺筑临时封层和沥青层,以免结构层表面水分蒸发过快,导致结构层收缩开裂。如果没有铺筑临时封层,则一定期限内水泥稳定结构层不得开放交通。

The rate of drying. Properly curing the structural layer material treated with cement to reduce the drying rate of the material and thus reduce shrinkage cracking. Within 7 days after the construction of the cement stabilized structural layer, it is necessary to sprinkle water for curing, or lay a temporary sealing layer and asphalt layer to avoid rapid evaporation of water on the surface of the structural layer, which may cause shrinkage and cracking of the structural layer. If a temporary sealing layer is not laid, the cement stabilized structural layer shall not be open to traffic for a certain period of time.

以乳化沥青为稳定剂的沥青路面冷再生

Cold regeneration of asphalt pavement using emulsified asphalt as stabilizer

乳化沥青在常温下可与潮湿的粒料进行拌和提高材料的强度,因此,乳化沥青是常用的一种沥青类稳定剂。一般情况下,将乳化沥青和水泥混合使用,除了可提高再生混合料的水稳定性外,还可提高其早期强度,但水泥添加量必须控制在粒料重量的2%以下,以免削弱混合料的抗疲劳性能。

Emulsified asphalt can be mixed with moist particles at room temperature to improve the strength of the material. Therefore, emulsified asphalt is a commonly used asphalt stabilizer. In general, mixing emulsified asphalt and cement can not only improve the water stability of the recycled mixture, but also improve its early strength. However, the amount of cement added must be controlled below 2% of the weight of the aggregate to avoid weakening the fatigue resistance of the mixture.