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.

水泥作為穩(wěn)定劑時,其添加方式有兩種,一種是以固態(tài)粉狀水泥與再生料混合,另一種是以水泥稀漿形式與再生料混合。

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.

以水泥為穩(wěn)定劑時,再生結(jié)構(gòu)層易產(chǎn)生收縮裂縫,應(yīng)從下列方面考慮盡量減少收縮開裂程度

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。水泥用量多則收縮大。為控制收縮開裂,水泥穩(wěn)定劑的用量為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%.

回收舊料的性質(zhì)。某些材料以水泥進(jìn)行處理時,收縮量特別大;有些材料在含水量變化時體積變化相當(dāng)大,塑性指數(shù)較高。當(dāng)材料的塑性指數(shù)大于10時,不應(yīng)單獨(dú)采用水泥作穩(wěn)定處理,必須用石灰與水泥混合或單獨(dú)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.

施工碾壓時的含水量。收縮開裂的程度與施工碾壓再干燥而消失的水量成正比,但含水量太低易造成壓不實(shí)。一般建議將施工碾壓時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。對經(jīng)水泥處理后的結(jié)構(gòu)層材料適當(dāng)加以養(yǎng)護(hù),以降低材料干燥速度,從而降低收縮開裂。一般水泥穩(wěn)定結(jié)構(gòu)層施工完后7 d內(nèi)必須灑水養(yǎng)生,或鋪筑臨時封層和瀝青層,以免結(jié)構(gòu)層表面水分蒸發(fā)過快,導(dǎo)致結(jié)構(gòu)層收縮開裂。如果沒有鋪筑臨時封層,則一定期限內(nèi)水泥穩(wěn)定結(jié)構(gòu)層不得開放交通。

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.

以乳化瀝青為穩(wěn)定劑的瀝青路面冷再生

Cold regeneration of asphalt pavement using emulsified asphalt as stabilizer

乳化瀝青在常溫下可與潮濕的粒料進(jìn)行拌和提高材料的強(qiáng)度,因此,乳化瀝青是常用的一種瀝青類穩(wěn)定劑。一般情況下,將乳化瀝青和水泥混合使用,除了可提高再生混合料的水穩(wěn)定性外,還可提高其早期強(qiáng)度,但水泥添加量必須控制在粒料重量的2%以下,以免削弱混合料的抗疲勞性能。

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.