| The use of construction and demolition wastes(C&D wastes)recycled aggregates to partially replace or even completely replace natural aggregates for the construction of granular pavement base/subbase can provide a way to reduce costs and have great development potential for the further application of granular pavement base/subbase.At the same time,the pavement granular base and the subbase as the main bearing layer of the road should have good bearing capacity,fatigue crack resistance,and permanent deformation resistance.Their cyclic degradation characteristics under long-term traffic load have an significant impact on the service performance and service life of the road.Therefore,in order to conduct a more comprehensive and in-depth study and evaluation of the service performance of granular pavement base/subbase C&D waste recycled aggregates,it is necessary to conduct the long-term cycle dynamic characteristics and service performance of granular base/subbase C&D waste recycled aggregates study.In this paper,a large number of basic physical and mechanical properties,triaxial shear and cyclic dynamic tests have been carried out for C&D waste recycling blends(waste concrete recycled aggregate and waste clay masonry recycled aggregate blends)through large-scale dynamic triaxial apparatus and other equipment.The focus is on the influence of mix ratio,gradation,mixing method,effective confining pressure,amplitude of cyclic deviator stress,etc.on the cyclic dynamic characteristics of recycled blends such as cumulative deformation and resilient modulus.The specific research contents and results are as follows:(1)Tested the performance index test of waste concrete recycled aggregate and waste clay masonry recycled aggregate.For recycled blends,the compaction performance and particle crushing characteristics of recycled aggregate were studied.And found the water absorption rate of C&D waste recycled aggregate was and other performance basically meet the specification requirements.waste clay masonry recycled aggregate content has a significant impact on the compaction performance of the blends.The increase of waste clay masonry recycled aggregate content aggravates particle breakage.(2)Through the triaxial shear test under saturated drainage conditions,the static characteristics of the C&D waste recycled blends is studied,and it is found that the increase of waste clay masonry recycled aggregate content aggravated the volume expansion of the material.The peak triaxial strength of recycled blends one is generally higher than that of recycled blends two.(3)For the recycled blends under the two mixing methods,a multi-stage resilient modulus test was carried out through an large dynamic triaxial.And waste clay masonry recycled aggregate content,amplitude of the cyclic deviator stress,effective confining pressure,mixing method,etc.have a great impact on the resilient modulus is found.The increase of waste clay masonry recycled aggregate content reduces the resilient modulus for the recycled blends.The percentage changes in the resilient modulus for the recycled blends one and recycled blends two are respectively-20% and-34%.Based on the modified K-0 model,the modulus of resilience of C&D waste recycled aggregate was predicted,and the reference range of the model regression parameters was obtained.(4)Based on a large-scale dynamic triaxial instrument,a long-term cyclic dynamic test of recycled blends under saturated drainage conditions was carried out.And waste clay masonry recycled aggregate content,mixing method and amplitude cyclic deviator stress have an impact on shakedown characteristics and cumulative axial deformation are found.The increase of waste clay masonry recycled aggregate content increases the cumulative axial deformation and shakedown threshold of the recycled blends.At the same time,a cumulative deformation prediction model suitable for C&D waste recycled aggregate subgrade is proposed.(5)The test results of the recycled blends under two different mixing methods is compared comprehensively.And found that as waste clay masonry recycled aggregate content is low(e.g.,30%),the recycled blends one is used as the pavement base layer and the subbase granular material in shear strength,resilient modulus and cumulative axial deformation is better than recycled blends two.but its particle breakage is more serious than that recycled blends two.With the increase of waste clay masonry recycled aggregate content,the performance of recycled blends two is better than that of recycled mixture one. |
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