1、 Principle of full depth cement in situ cold regeneration technology
In situ cold recycling refers to the operation process of making full use of the old paving materials (surface course and base course) of the existing asphalt road, adding some new aggregate according to the requirements of the mixture performance, and adding a certain amount of cement according to the design, and continuously completing the milling, crushing, mixing, paving and compaction of the materials at the natural ambient temperature, so as to build a new base course with the required performance quality.
2、 Construction technology
Taking the cold recycled base course applied in the maintenance of k2634 section of G312 line as an example, this paper expounds the full depth cement in-situ cold recycled construction technology, using the existing asphalt road old paving materials (surface course and base course), according to the requirements of mixture performance, and according to the design requirements, adding no less than 5% of cement, the material can be milled, crushed, mixed, paved, compacted and shaped continuously under the natural ambient temperature, So as to build a new base with the required performance and quality.
1. Working width of wittgen local cold regenerator: 2500mm
Working depth: 500mm engine power: 315kw/500kw working weight: ca 23t/32t
2. Tank car is the supporting equipment of regeneration machine, which is used for water supply or liquid stabilizer. The capacity of the tank car should match the daily work quantity and the current situation of the road. The scheme is as follows: a fixed water tanker is connected to the regenerator, and another one or more water tankers are equipped with water pumps to make up water for the fixed water tanker. The number of water tankers to make up water depends on the water consumption speed and the distance of the water source, so as to achieve work efficiency.
3. Compaction equipment
In the construction process of applying wr2000 local cold recycling machine, a 22 ton single steel wheel roller is used for compaction.
As wr2000 is a tire type local cold regenerator, a grader is equipped to meet the requirements of flatness and elevation control during construction.
The curing method adopts watering for curing, and a sprinkler is equipped.
6. Rubber tyred roller
The rubber tyred roller mainly rubs the surface of the regenerative layer to make the surface as dense as possible and reduce the adverse impact of water on the regenerative layer. It is equipped with a rubber tyred roller with good water spraying function, with a self weight of 31 tons.
7. Preparatory work
The cold regeneration rental machine and supporting equipment are ready for construction. Before the formal construction, the cold regeneration unit must be prepared as follows:
(1) Conduct a comprehensive functional inspection of all mechanical equipment required in the cold regeneration construction;
(2) Connect all pipelines connected to the cold regenerator, discharge the air in the spraying system and ensure that all valves are in working condition;
(3) Check whether the operator of the cold regeneration rental machine inputs the data related to the amount of stabilizer into the computer.
8. Raw material test
Before the construction of cement stabilized cold recycling layer, the mix proportion of the original pavement is designed. Use wr2000 local cold regeneration machine to mill representative samples on the original road.
9. Construction of test section
(1) According to the experience and the characteristics of the cold recycling machinery used, the old road is milled according to the combination scheme of 6m/min recycling machine travel speed and rotor speed. After milling, the representative materials are sent to the laboratory for screening, and the grading is close to the ideal grading.
(2) According to the indoor test results, pave the newly added materials or fillers on the old road without adding stabilizers, milling according to the scheme determined in (1), take representative material samples after milling and send them to the laboratory for screening. If the screened gradation and indoor design gradation exceed the allowable fluctuation range, adjust the speed of the regenerator and the rotor speed, Make the grading after milling fluctuate within the allowable range compared with the indoor design grading.
(3) According to the type of stabilizer, 1 ~ 3 compaction schemes are adopted for construction (including roller tonnage, rolling sequence, times, etc.) to determine a reasonable rolling scheme.
(4) Take the mixture milled and mixed by the cold recycling machine and send it to the laboratory. For the cold recycling with cement as stabilizer, measure the water content and cement content of the cold recycled mixture, and form the test piece according to the requirements of the test procedures for inorganic binder stabilized materials in highway engineering, and measure its 7d unconfined compressive strength.
(5) The deflection, compactness, flatness, thickness, width and other indicators of the test section shall be tested.
According to the results of the test section, the gradation of the cold recycled mixture, the traveling speed of the regenerator, the rotor speed and the compaction process of the recycled structure used in the construction are finally determined.
Process flow of cement stabilized in situ cold regeneration
10. Pre shaping the original road
The local uplift or depression of the original road shall be treated according to the design to meet the design requirements.
11. Calculate material consumption:
(1) According to the average density within the regeneration depth of the original road, calculate the amount of new material added per square meter.
(2) Calculate the stacking distance of each truck according to the mass or volume of each truck.
(3) For manual placement and paving of cement, the cement consumption of 17.4kg per square meter of cement stabilized layer shall be calculated according to the cement consumption of 3.9%, and the vertical and horizontal spacing of cement placement shall be determined.
12. The travel speed of the cold recycling machine should be adjusted according to the damage condition of the pavement and the depth of cold recycling, which is generally 5m/min ~ 7m/min, so that the grading fluctuation range of the milled material is small. According to the horizontal control piles set on both sides of the road, regularly check whether the regeneration depth is correct. If the cold regeneration depth exceeds the design depth by ± 1cm, the reason should be found out before continuing the construction. After the cold regenerator, special personnel shall be assigned to carry out quality control, check the regeneration depth, cement content and water content at any time, and cooperate with the regenerator operator to adjust.
13. Rolling and shaping
(1) According to the road width, the wheel width and wheel spacing of the roller, the rolling scheme shall be formulated, and the rolling times of each part shall be the same as far as possible, and the two sides of the pavement shall be rolled for 2 ~ 3 times.
(2) After the cold regeneration, a large tonnage single drum vibratory roller shall be equipped for initial compaction. During initial compaction, let the roller closely follow the regenerator for one time of static pressure, and then use strong vibration (high amplitude and low frequency) for compaction. The number of compaction times should be enough to ensure that the compactness within the thickness range of 2/3 at the bottom of the regeneration layer meets the specified requirements.
(3) After completing the cold regeneration and initial pressure of an operation section, it should be reshaped with a grader immediately. In the straight section, the grader scrapes from both sides to the center of the road; In the flat curve section, the grader scrapes from the inside to the outside.
(4) Before reshaping, if the water loss on the surface of the cold recycled material is relatively serious, it can be watered first and then reshaped with a grader.
(5) After reshaping, the single drum vibratory roller shall be immediately used for re compaction with weak vibration (low amplitude and high frequency). When the straight line and the flat curve section without superelevation are rolled from the shoulder to the center of the road, 1/2 of the wheel width shall be overlapped each time, and it is one time when the full width of the road surface is pressed. Generally, it needs to be rolled for 4 ~ 6 times. The rolling speed of the roller should be 1.5 ~ 1.7km/h for the first two passes, and 2.0 ~ 2.5km/h for the future.
(6) The rubber tyred roller shall be used for final compaction, and watering and rolling can be carried out when necessary.
The above is a detailed introduction about the rental of cold regenerator, which I hope will help you. If you have any questions, please contact us. We will provide services for you with a professional attitude https://www.sddhfjx.com