Construction of Cold Recycled Lime Fly-ash Crushed Stone Bas

Discussion on Construction Method of Cold Recycled Lime Fly-ash Crushed Stone Base Course


Abstract: Combined with engineering examples, this paper discusses and studies the Road cold recycler construction method, discusses the quality control in Road cold recycler construction, and puts forward its own opinions and suggestions for construction reference.


Keywords: Road cold recycler, construction technology, quality control


0 Preface


With the development of science and technology, the continuous innovation of construction equipment and construction technology for highway construction, the use of special construction equipment to recycle pavement structures has been maturely applied abroad, and China has also applied and researched on many projects. However, the application of this technology in our province has just begun, so the practical significance of the use of this construction technology is far greater than that of the project itself. Cold regeneration includes plant mixed cold regeneration, in-situ cold regeneration, and full-depth cold regeneration. In combination with actual engineering conditions, this project uses full-depth cold regeneration technology, which uses special regeneration equipment, using cement, lime, and pulverized coal. Inorganic binder such as ash or emulsified asphalt, foamed asphalt, etc. are used as a recycled binder, which is a technique for cold-recycling the asphalt layer and part of the base layer material in situ at the same time to form a pavement structure layer.


1 Project Overview


The World Bank loaned the Suzhou S303 project at the beginning of the junction with Sihong, Jiangsu, and finally, Huancheng Road, Suzhou, with a total length of 102 kilometers. The section is K0 + 000 ~ K13 + 825. The original pavement structure is limestone (thickness 13 ~ 20cm). + Asphalt crushed stone (thickness 3.5 ~ 6cm), this section is an important channel connecting Jiangsu, with heavy traffic and heavy vehicles, and the original road surface is quite damaged. Based on road deflection detection, structural layer drilling and coring detection and the actual situation of the old road, combined with the owner's opinions, this section carries out cold regeneration treatment at the grassroots level. The original design is to excavate the old asphalt surface layer and the old fly ash crushed stone, after crushing, add new materials and appropriate amount of regenerant, regenerate the fly ash crushed stone at 15 cm, and prepare the new fly ash crushed stone at 5 cm. The regeneration equipment is paved, mixed, shaped, and rolled together into a new recycled fly ash base.


Preparations before construction


Since all parties involved have no similar construction experience, under the guidance of relevant consulting units, a lot of test work has been performed, including original pavement coring investigation, original pavement material grading analysis, liquid plastic test, and relevant compaction test. , Mix ratio test, etc., and adopted the following test sections to verify:


Core description


This construction is 160m, 10 core samples are taken, the average thickness is 18㎝, the core samples are complete, and the structure is compact. 3 of the core samples have 1-2㎝ loose at the bottom, mainly due to the problem of combining with the original lime ash.


After careful organization and careful construction management, it should be said that the Road cold recycler construction has been successful. Through summary analysis and research, it can fully guide the next normal construction.




This article analyzes and studies the actual situation of the pavement Road cold recycler machine construction, and summarizes the construction technology, construction method and quality control of Road cold recycler. But in the next implementation process, based on my understanding and analysis, I put forward the following opinions and suggestions for reference during construction.




1) Due to the differences between the original pavement structural materials and the status quo, in the actual construction process, it is necessary to strengthen the preliminary test work and the investigation of the old road conditions, do a material grading analysis, and determine the specifications of the added crushed stone.




2) Because the original structure is lime ash gravel + bituminous gravel, after adding binder cement during regeneration, the rapid increase in the strength of the grassroots structure is delayed to a certain extent. Therefore, it is recommended to extend the health time to 14 days or more. Coring for a long time to ensure that the test data can better evaluate the quality of the grassroots. At the same time, if the test conditions allow, conduct relevant research to obtain more valuable data.




3) Fully consider the effect of the original structure of lime limestone + asphalt crushed stone on the cement dosage. Before construction, samples without cement can be taken for EDTA test, and compared with the samples with cement added, to ensure the accuracy and mixing of cement dosage. Of uniform.




4) Choose a suitable combination of roller compaction machinery, the vibration roller should not be too large, it should be 18 ~ 22T, to avoid damage to the underlying bearing layer due to excessive vibration, which will affect the overall quality of the base layer.




5) Using flow operation, each process must be closely combined in an orderly manner, and the rolling must be completed within a specified time. The delay time from mixing to the completion of rolling should be minimized.








[1] JTG F41-2007, Technical Specification for Asphalt Pavement Regeneration (Draft for Approval). Beijing: People's Communications Press.




[2] JTJ 034-2000, Technical specifications for highway pavement base construction. Beijing: People's Communications Press.


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