引言随着我国社会经济的持续发展，社会对于公路交通系统的需求也在持续增长，其一方面推动了公路交通网络建设的持续推进，另一方面也使得公路质量及要求不断提升。沥青路面作为我国公路常用路面，一般设计使用寿命为 15~20 年，我国很多区域公路在长久使用后均已经进入到大中修期，如何、、低成本地完成公路修复已经成为当前关注的问题。据此，本文以某农村公路为研究对象，对沥青路面就地冷再生技术的有效应用进行综合分析，旨在为后续其他农村公路的修复及改造提供相应的技术参考。1 工程概况某三级公路 2017 年竣工，经过多年运营后，公路路面已经出现较为明显横裂、纵裂、沉陷、坑槽、涌包等病害问题，相关病害不仅影响公路的正常通行，还会导致路面出现渗水、积水等问题，诱发其他公路病害，严重影响公路的使用寿命。通过对旧路的钻芯取样，确认路基破损较为严重，而传统公路修补工艺难以满足公路修复要求，综合分析后终采用沥青路面就地冷再生技术。在具体施工前，需先获取旧路的冷再生混合料级配。此过程中分别采用 150r/min和 100r/min两种刀头转速进行旧路现场取样，再依次选用 26.5~0.075mm套筛进行样本筛分，进而获取到旧路粗细集料含量，绘制出旧路筛分曲线如图 1 所示。

　　Introduction: With the continuous development of China's social economy, the demand for highway transportation system in society is also growing. On the one hand, it promotes the continuous promotion of highway transportation network construction, and on the other hand, it also leads to the continuous improvement of highway quality and requirements. Asphalt pavement, as a commonly used road surface in China, is generally designed to have a service life of 15-20 years. Many regional highways in China have entered the period of major and medium repairs after long-term use. How to efficiently, high-quality, and low-cost complete highway repairs has become a key issue of concern at present. Based on this, this article takes a rural road as the research object and comprehensively analyzes the effective application of in-situ cold recycling technology for asphalt pavement, aiming to provide corresponding technical references for the repair and renovation of other rural roads in the future. 1 Project overview A third-class highway was completed in 2017. After many years of operation, the road surface has appeared obvious transverse cracks, longitudinal cracks, subsidence, pits, bumps and other diseases. The related diseases not only affect the normal traffic of the road, but also lead to water seepage, ponding and other problems on the road surface, induce other road diseases, and seriously affect the service life of the road. Through core sampling of the old road, it was confirmed that the roadbed was severely damaged, and traditional highway repair techniques were unable to meet the requirements of highway repair. After comprehensive analysis, the asphalt pavement on-site cold recycling technology was ultimately adopted. Before specific construction, it is necessary to obtain the grading of the cold recycled mixture for the old road. During this process, two different blade speeds of 150r/min and 100r/min were used for on-site sampling of the old road. Then, 26.5-0.075mm sieve sets were selected for sample screening in sequence to obtain the coarse and fine aggregate content of the old road. The old road screening curve was plotted as shown in Figure 1.

　　如图 1 所示，当刀头转速为 150r/min时，旧路集料 5mm以下筛分通过率较小，接近标准规范下限，确认集料较粗。旧路集料 19mm筛分通过率超过标准规范上限，确认筛孔偏细；当刀头转速为 100r/min时，旧路集料 10mm以下筛分通过率超过标准规范下限，确认集料较粗。综合分析后确认两种集料均未完全满足标准级配范围区间，所以在具体沥青路面就地冷再生技术应用时还需要掺加中砂对集料进行合理调制。但考虑到中砂对路面强度的影响较小，应用后会增加施工成本，150r/min筛分曲线接近标准级配下限，并且该规范标准为水泥稳定土标准，而沥青路面就地冷再生技术与水泥稳定土工艺存在较大差异，所以综合考虑后确认可保留 150r/min级配结果。2 冷再生添加剂及配合比设计2.1 冷再生添加剂

　　As shown in Figure 1, when the blade speed is 150r/min, the screening pass rate of the old road aggregate below 5mm is relatively small, approaching the lower limit of the standard specification, confirming that the aggregate is coarse. The pass rate of the old road aggregate 19mm sieve exceeds the upper limit of the standard specification, confirming that the sieve holes are too fine; When the blade speed is 100r/min, the screening pass rate of the old road aggregate below 10mm exceeds the lower limit of the standard specification, confirming that the aggregate is coarse. After comprehensive analysis, it was confirmed that both types of aggregates did not fully meet the standard grading range. Therefore, in the specific application of on-site cold recycling technology for asphalt pavement, it is necessary to add medium sand to mix the aggregates reasonably. However, considering that the impact of medium sand on pavement strength is relatively small, its application will increase construction costs. The 150r/min screening curve is close to the lower limit of the standard grading, and this standard is for cement stabilized soil. However, there are significant differences between the in-situ cold recycling technology for asphalt pavement and the cement stabilized soil process. Therefore, after comprehensive consideration, it is confirmed that the 150r/min grading result can be retained. 2 Cold regeneration additives and mix design 2.1 Cold regeneration additives

　　沥青路面就地冷再生技术常用的添加剂包括水泥、石灰、粉煤灰、乳化 /泡沫沥青等，必要时还可以根据工程实际情况添加一定量的集料。具体添加剂选用需要结合工程路面结构、区域土质、沥青含量、含水量、再生沥青混合料级配等多种因素综合确定，各类添加剂可单独使用，也可以多种添加剂复合应用。根据国内现有沥青路面就地冷再生技术应用经验，添加剂与再生沥青混合料之间的质量比一般为水泥 3%~6%、乳化沥青 3%~4%、泡沫沥青3%~5%［1-2］。根据本工程实际情况，终选择水泥作为冷再生添加剂。采用水泥作为再生沥青混合料的稳定材料，主要是利用水泥水化产物以及水泥沥青混合物形成的凝聚力与沥青混合料所具备的粘聚力共同组成复合力，使处理后的材料可满足公路使用性能要求。

　　The additives commonly used in the cold in place recycling technology of asphalt pavement include cement, lime, fly ash, emulsified/foam asphalt, etc. When necessary, a certain amount of aggregate can be added according to the actual situation of the project. The specific selection of additives needs to be determined comprehensively based on various factors such as the engineering pavement structure, regional soil, asphalt content, moisture content, and gradation of recycled asphalt mixture. Various additives can be used separately or in combination with multiple additives. According to the domestic experience in the application of cold in-situ recycling technology for asphalt pavement, the mass ratio between additives and recycled asphalt mixture is generally 3%~6% for cement, 3%~4% for emulsified asphalt, and 3%~5% for foam asphalt [1-2]. Based on the actual situation of this project, cement is ultimately chosen as the cold recycling additive. The use of cement as a stabilizing material for recycled asphalt mixture mainly utilizes the cement hydration products and the cohesive force formed by the cement asphalt mixture, as well as the cohesive force possessed by the asphalt mixture, to form a composite force, so that the treated material can meet the performance requirements for highway use.

　　2.2 冷再生配合比设计

　　2.2 Cold regeneration mix design

　　通过路面再生机在选定路面区域进行破碎干拌处理，获取充足的试验样品。所获取的样品通过 80℃ 的烘箱进行烘干处理，然后置于铁板上进行平摊晾晒，风干后使用四分法获取较具有代表性的样品进行筛分试验，以此获取混合料级配。针对不符合要求的级配应合理掺入集料，促使处理后级配可满足使用要求。同时，针对旧路再生沥青混合料进行土质分析，以此合理选取添加剂种类。采用击实试验，以水泥为添加剂，在水泥含量为 5.5%时，再生混合料的击实曲线如图 2 所示。

　　Use a road surface regeneration machine to crush and dry mix the selected road surface area to obtain sufficient test samples. The obtained samples are dried in an 80 ℃ oven and then placed on an iron plate for flat drying. After air drying, representative samples are obtained using the quartering method for screening tests to obtain the gradation of the mixture. For gradation that does not meet the requirements, aggregates should be reasonably added to ensure that the treated gradation meets the usage requirements. At the same time, soil analysis is conducted on the recycled asphalt mixture for old roads to select appropriate types of additives. Using a compaction test with cement as an additive, the compaction curve of the recycled mixture is shown in Figure 2 when the cement content is 5.5%.

　　2.3 添加剂及骨料选择

　　2.3 Selection of Additives and Aggregates

　　就地冷再生技术添加剂及骨料选择流程如图 3 所示。

　　The selection process of additives and aggregates for on-site cold recycling technology is shown in Figure 3.

　　3 沥青路面就地冷再生技术在公路施工中的应用3.1 工艺流程

　　Application of in-situ cold recycling technology for asphalt pavement in highway construction 3.1 Process flow

　　沥青路面就地冷再生主要工艺流程如图 4 所示。

　　The main process flow of on-site cold recycling of asphalt pavement is shown in Figure 4.

　　3.2 沥青路面就地冷再生基层施工

　　3.2 On site cold recycling base construction of asphalt pavement

　　3.2.1 施工方案

　　3.2.1 Construction Plan

　　（1）试验阶段。选取 100~300m道路作为试验路段，主用于检验施工设计是否可满足工程施工的实际要求，并根据试验结果对施工设计进行针对性调整，以保证后续施工质量。

　　(1) Experimental phase. Select a road section of 100-300m as the test section, mainly used to verify whether the construction design can meet the actual requirements of the project construction, and make targeted adjustments to the construction design based on the test results to ensure the quality of subsequent construction.

　　（2）摊铺水泥。根据工程设计中再生层厚度、密度以及水泥使用量，计算单位面积内水泥需求量，并确定水泥施工间距，按照要求以人工施工或者机械施工进行水泥均匀摊铺。本工程施工中采用水泥浆车进行水泥摊铺，具体施工工艺流程为：制作水泥浆→水泥浆运抵现场采集→软管连接再生机→微机控制喷洒→铣刨施工→级配与水泥混合→布料绞龙进一步混合→振动熨平板熨平。

　　(2) Spread cement. Calculate the cement demand per unit area based on the thickness, density, and cement usage of the regeneration layer in the engineering design, determine the cement construction spacing, and evenly spread the cement according to the requirements through manual or mechanical construction. In the construction of this project, cement slurry trucks are used for cement paving. The specific construction process is as follows: making cement slurry → transporting the cement slurry to the site for collection → connecting the hose to the recycling machine → computer-controlled spraying → milling and planing construction → grading and cement mixing → further mixing with fabric winches → vibrating and ironing plates for leveling.

　　（3）再生层破碎拌和。为方便施工路段正常通行，具体施工过程采用半幅封闭式施工工艺，但考虑到半幅施工后的搭接问题，在前半幅施工时应加宽 20~30cm的施工范围，以此方便后半幅施工的搭接问题。实际施工冷拌再生机再生层破碎拌和过程需要配有 2~3 辆洒水车提供拌和用水，具体拌和过程应严格根据工程设计进行水量添加［3-4］。考虑到水泥初凝时间以及工序衔接，单幅每次施工的长度为 100m，冷拌再生机的行走速度应控制在 8m/min，在拌和施工后，质检人员应立刻实施质检工作，确保发现问题及时处理。

　　(3) Crushed and mixed regeneration layer. For the convenience of normal traffic on the construction section, the specific construction process adopts a half width enclosed construction technology. However, considering the overlapping problem after half width construction, the construction range should be widened by 20-30 cm during the first half of the construction to facilitate the overlapping problem of the second half of the construction. The actual construction of the cold mixing and regeneration machine requires 2-3 sprinkler trucks to provide mixing water for the crushing and mixing process of the regeneration layer. The specific mixing process should strictly follow the engineering design for water addition [3-4]. Considering the initial setting time of cement and the connection of processes, the optimal length for each single construction is 100m. The walking speed of the cold mixing and recycling machine should be controlled at 8m/min. After the mixing construction, the quality inspection personnel should immediately carry out quality inspection work to ensure timely handling of problems found.

　　（4）整平及碾压。整幅路段拌和施工完成后，使用平地机进行路段整平，若局部区域存在麻面等质量问题，应及时进行修补处理。整平完成后，使用 22t振动压路机进行碾压处理，此过程中应保障压路机前进时静压，返回时振动碾压，碾压后再采用 26t振动压路机进行碾压处理，通常需要碾压 2~3 遍，之后再使用胶轮压路机进行终压处理。碾压过程应严格控制路面平整度。

　　(4) Leveling and rolling. After the mixing construction of the entire road section is completed, a grader should be used to level the road section. If there are quality problems such as rough surface in some areas, timely repair and treatment should be carried out. After leveling is completed, a 22t vibratory roller is used for rolling treatment. During this process, static pressure should be ensured when the roller moves forward, and vibratory rolling should be carried out when it returns. After rolling, a 26t vibratory roller is used for rolling treatment, usually requiring 2-3 passes of rolling, and then a rubber tired roller is used for final rolling treatment. The compaction process should strictly control the smoothness of the road surface.

　　（5）养护。碾压完成后，应及时在路面覆盖塑料薄膜养护。养护过程应严禁车辆通行，并保证再生层表面的湿润程度，实际养护周期应控制在 7d以上［5］。养护完成后，使用空压机吹净表面浮灰，洒涂透层油后，再撒一层石屑，处理完成后道路可恢复正常使用。

　　(5) Maintenance. After compaction is completed, plastic film should be promptly covered on the road surface for maintenance. The maintenance process should strictly prohibit the passage of vehicles and ensure the moisture level of the regeneration layer surface. The actual maintenance period should be controlled at 7 days or more [5]. After the maintenance is completed, use an air compressor to blow off the surface dust, sprinkle a layer of oil, and then sprinkle another layer of stone chips. After the treatment is completed, the road can be restored to normal use.

　　3.2 就地冷再生基层施工质量控制

　　3.2 Quality control of on-site cold recycling base construction

　　3.2.1 旧路预处置

　　3.2.1 Pre disposal of old roads

　　农村公路运营多年后存在着各种各样的病害问题，仅采用冷再生技术进行处理，将可能会影响施工后道路整体质量及使用寿命。对此，应根据旧路的不同病害进行提前预处理［6］。针对坑槽病害，可将坑槽区域挖出，回填水稳碎石到旧路标高，然后再实施冷再生处理；针对沉陷病害，可先实施冷再生处理，再刮除部分再生料后，回填水稳碎石；针对涌包病害，应增加冷再生过程中拌和深度及水泥量，若是涌包较大，应提前刨除涌包后再实施冷再生施工。

　　After many years of operation, rural roads have various disease problems, and using only cold recycling technology for treatment may affect the overall quality and service life of the roads after construction. In this regard, pre-treatment should be carried out in advance according to the different diseases of the old road [6]. For pit and groove diseases, the pit and groove area can be excavated, backfilled with water stabilized crushed stones to the elevation of the old road, and then subjected to cold recycling treatment; For subsidence diseases, cold regeneration treatment can be implemented first, and then some regenerated materials can be scraped off before backfilling with water stabilized crushed stones; To address the issue of bulging, the mixing depth and cement content during the cold recycling process should be increased. If the bulging is significant, it should be removed in advance before implementing cold recycling construction.

　　3.2.2 再生深度

　　3.2.2 Regeneration depth

　　再生深度直接影响再生层厚度，若是再生深度较浅，则会导致再生层厚度小于设计要求；反之则增加施工成本。具体施工前应通过随机钻样检查来确定冷再生铣刨深度，根据国内冷再生施工经验［7-9］，确认水泥再生层 7d时冷再生基层强度应控制在 1.8MPa以上，底基层应控制在 1.5MPa以上，基层与底基层厚度应控制在 18~20cm和 15~20cm。

　　The depth of regeneration directly affects the thickness of the regeneration layer. If the depth of regeneration is shallow, it will result in the thickness of the regeneration layer being less than the design requirements; Otherwise, it will increase the construction cost. Before specific construction, the depth of cold recycling milling should be determined through random drilling inspection. According to domestic cold recycling construction experience [7-9], it is confirmed that the strength of the cold recycling base layer should be controlled above 1.8 MPa when the cement recycling layer is 7 days old, and the bottom layer should be controlled above 1.5 MPa. The thickness of the base layer and bottom layer should be controlled between 18-20 cm and 15-20 cm.

　　3.2.3 级配

　　3.2.3 Grading

　　具体施工应根据工程设计的不同路段划分，针对性开展冷再生料检测及级配调整，确保调整后的级配可满足施工设计要求。若是在施工中出现实际级配与设计级配偏差情况，应深入分析问题成因，并及时调整冷拌再生机的转子速度及行走速度。

　　The specific construction should be carried out according to the different road sections of the engineering design, and targeted cold recycled material testing and grading adjustment should be carried out to ensure that the adjusted grading can meet the requirements of the construction design. If there is a deviation between the actual grading and the design grading during construction, the cause of the problem should be analyzed in depth, and the rotor speed and walking speed of the cold mix recycling machine should be adjusted in a timely manner.

　　3.2.4 路面标高

　　3.2.4 Road surface elevation

　　采用沥青路面就地冷再生技术对农村公路处理后，通常会出现路面标高高于旧路情况，进而导致旧路原有建构物与旧路接头区域不匹配的情况。对此，可在施工中通过架设高台帽、重做桥面、更换支座等方式保障路面与桥面的接顺效果；建构物则可通过提高道牙、分隔带等方式提高道路纵横向舒适性；处理后道路的起点和终点可设置渐变段保证与旧路的接顺效果。

　　After using the in-situ cold recycling technology of asphalt pavement to treat rural roads, it is common for the pavement elevation to be higher than the old road, resulting in a mismatch between the original structures of the old road and the joint area of the old road. In this regard, the smooth connection between the road surface and the bridge deck can be ensured during construction by installing high platform caps, redoing the bridge deck, and replacing supports; Constructions can improve the longitudinal and transverse comfort of roads by raising curbs, dividers, and other means; The starting and ending points of the processed road can be set with gradient segments to ensure smooth connection with the old road.

　　4 效果分析传统方法多采用挖除旧路、路基整平、重做稳定土底层等方式进行旧路处理，相较于传统工艺，沥青路面就地冷再生技术在旧路面刨除及外运、基层原材料摊铺、原材料运输、缩短施工周期等方面均具有更大优势。根据理论计算确认，传统施工方案工程造价约为 35 元 /m2，而沥青路面就地冷再生技术施工造价约为 28 元 /m2，此公路整个工程线路长 22.45km，路面宽度为 9m，预计可节约工程费用约 100 多万元，由此可以确定，沥青路面就地冷再生技术具有更强的应用价值，建议在旧路改造工程中优先采用该技术。5 结语综上所述，本文以某农村公路为研究案例，对沥青路面就地冷再生技术的有效应用进行了综合分析。沥青路面就地冷再生技术具有操作简单、无需原材料运输和基层材料外运、缩短施工工期等优势，相较于传统施工工艺，可有效降低工程成本，效益明显，建议在后续施工中进行推广应用。

　　Traditional methods often use methods such as excavating old roads, leveling roadbeds, and redoing stable soil layers to treat old roads. Compared with traditional processes, on-site cold recycling technology for asphalt pavement has greater advantages in the removal and transportation of old road surfaces, paving of base raw materials, transportation of raw materials, and shortening of construction cycles. According to theoretical calculations, the construction cost of traditional construction methods is about 35 yuan/m2, while the construction cost of on-site cold recycling technology for asphalt pavement is about 28 yuan/m2. The entire project route of this highway is 22.45km long and the pavement width is 9m, which is expected to save more than 1 million yuan in engineering costs. Therefore, it can be determined that on-site cold recycling technology for asphalt pavement has stronger application value, and it is recommended to prioritize the use of this technology in old road reconstruction projects. In summary, this article takes a rural road as a research case and conducts a comprehensive analysis of the effective application of in-situ cold recycling technology for asphalt pavement. The on-site cold recycling technology for asphalt pavement has the advantages of simple operation, no need for raw material transportation and external transportation of base materials, and shortened construction period. Compared with traditional construction processes, it can effectively reduce project costs and has significant benefits. It is recommended to promote and apply it in subsequent construction.

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