Construction quality control of cold recycling of old pavement

　　近几年来，我国公路发展非常迅速，随着交通量的日益增加，大量公路已接近设计使用年限，需要进行大修或改造，现场冷再生技术是适宜的维修或改造方式。现场冷再生技术，不仅可以节约能源，降低施工成本，更有益于环境保护。结合改建工程，采用现场冷再生处理旧路面面层及基层，取得良好效果。冷再生基层是指把原路面的旧面层、基层用专用路面再生机，按照一定的厚度进行破碎处理，同时加入一定规格和数量的新集料、粘合剂（水泥等），按一定配合比拌和，之后进行整形、碾压，使其恢复达到路面基层或底基层技术要求的施工工艺。现场冷再生技术，不仅可以节约能源，降低施工成本，更有益于环境保护。下面就于改建工程现场冷再生技术分析如下：

　　In recent years, China's highway development is very rapid, with the increasing traffic volume, a large number of roads are close to the design service life, and need to be overhauled or transformed. The cold regeneration technology on site is the appropriate maintenance or transformation method. On site cold recycling technology can not only save energy, reduce construction cost, but also benefit environmental protection. Combined with the reconstruction project, cold recycling is used to treat the surface and base of old pavement, and good results are achieved. Cold recycled base course refers to the construction technology that the old surface course and base course of the original pavement are crushed with a special pavement regenerator according to a certain thickness, and a certain specification and quantity of new aggregate and binder (cement, etc.) are added, mixed according to a certain mix proportion, and then reshaped and rolled to make it recover to meet the technical requirements of pavement base or subbase. On site cold recycling technology can not only save energy, reduce construction cost, but also benefit environmental protection. The following cold regeneration machine rental on the reconstruction project site cold regeneration technology analysis is as follows:

　　1、再生老路概况

　　1. Overview of old road regeneration

　　改建工程全长29.374km，其中k0+000-k8+850段进行冷再生施工，宽7m。原路面面层为3cm沥青碎石，基层为15cm石灰稳定土，冷再生处理旧路18cm。

　　The total length of the reconstruction project is 29.374km, in which the K0 + 000-k8 + 850 section is constructed by cold recycling, with a width of 7m. The surface course of the original pavement is 3cm asphalt macadam, the base course is 15cm lime stabilized soil, and the cold recycling treatment of the old road is 18cm.
               

　　2、旧路面冷再生施工质量控制

　　2. Construction quality control of cold recycling of old pavement

　　鉴于目前冷再生试验无我国规定，本次试验参照《公路土工试验规程》（JTJ051-93）和《公路工程无机结合料稳定材料试验规程》（JTJ057-94）进行。

　　In view of the fact that there is no national regulation for cold recycling test at present, the test is carried out according to "highway geotechnical test specification" (jtj051-93) and "highway engineering inorganic binder stabilized material test specification" (JTJ057-94).

　　（1）改建工程冷再生技术为旧路面面层、基层再生为基层，设计强度1.5MPa。通过对现有材料进行分析，采用掺加粘合剂（水泥）的方法，保证基层强度。

　　(1) The cold recycling technology of the reconstruction project is that the old pavement surface layer and the base layer are recycled into the base course, and the design strength is 1.5MPa. Through the analysis of the existing materials, the method of adding binder (cement) is adopted to ensure the strength of the base course.

　　（2）选择水泥的掺配比例为百分之3、百分之4、百分之5、百分之6。通过击实试验、无侧限抗压强度试验确定水泥的掺入量。击实、无侧限抗压强度得出试验结果。

　　(2) The mixing proportion of cement is 3%, 4%, 5% and 6%. Through compaction test and unconfined compressive strength test, the amount of cement added is determined. The test results are obtained by compaction and unconfined compressive strength.

　　（3）经试验室确定冷再生掺加水泥用量百分之5，施工过程中按百分之6控制，进行200m试验路段施工，其压实度、强度等各项指标均达到设计要求。

　　(3) According to the laboratory determination, the amount of cement mixed with cold recycling is 5%, and the control rate is 6% in the construction process. The construction of 200m test section is carried out. The compactness, strength and other indicators meet the design requirements.