Research On Cement Cold-recycled Base

Cement cold-recycled technology is very important practical significance to use fully the original pavement materials, decrease the exploitation of resources and reduce the cost of maintenance. But after years of practice, it is found that compressive strength of cement cold-recycled mixture designed in accordance with specifications is lower than usual, the long road performance is not ideal. Therefore it is necessary to study deeply cement cold-recycled technology for solving problems.First, this paper presents the research status of cement cold-recycled technology at home and abroad. Then the various factors of influence on pavement performances of cement cold-recycled mixture are summarized. The problems and reasons of the current research for cement cold-recycled technology are discussed in detail. At the basis of the research for cement cold-recycled technology at home and abroad, through systematic research on the gradation analysis, strength test, shrinkage test and failure mode of cement cold-recycled base material, Theoretical foundation is provided for the application of cement cold-recycled technology on highways in china.Secondly, the compaction property of recycled materials is tested by heavy compaction and gyratory compaction combined with the results of water content on strength and shrinkage properties of recycled materials. The results show that the compaction property of recycled materials is different widely from new aggregate. The water content at the maximum dry density is not as the optimum water content, and the optimum water content is finalized by balance the strength and shrinkage properties of recycled materials.The optimum cement content is determined to achieve the expected road performance by the research of compressive strength and failure modes.Thirdly, expansive agent, superplasticizer and fly ash are studied to improve the shrinkage performance for the problem of insufficient shrinkage performance of recycled materials. The results show that expansive agent and fly ash can reduce shrinkage strain and improve the shrinkage performance of recycled materials. Althongh the superplasticzer can reduce the maximum shringage strain, it increases the early shringage strain and the risk of early cracking of recycled materials. So the use of superplasticizer should be careful and adequate early conservation must be guaranteed.Finally, the research results are summarized. And further research direction of cement cold-recycled base technology is provided using the above empirical findings.