Research On The Application Of Semi-rigid Base Performance And Design Parameters Based On The Durability Of The Recycled Aggregate Of The Old Cement Concrete

Focusing on the problems of large amounts of waste of old cement concrete materialsand land pollution to the environment due to the disposal of old concrete slabs, the recyclingissues of concrete slabs in the process of rehabilitation of old concrete pavement, acomprehensive and in-depth study of using recycled concrete aggregate (RCA) as semi-rigidbase for asphalt pavement was performed in this study. It evaluated breaking process of oldconcrete slabs, physical and mechanical properties of RCA. Through experimental road testand numerical performance prediction, a structural design methodology for using RCA assemi-rigid base for asphalt pavement was developed based on multiple pavement performanceindexes and three stage design method. The main work and innovation are summarized asfollows:1. For the first time ever, a comprehensive coMParison analysis was conducted betweenoriginal concrete pavement material and the existing specifications of cement stabilized gravelin terms of physical and mechanical performance of raw materials, gradation and mixtureproperties. Typical old concrete slabs were selected for indoor breaking test to evaluate theperformance (gradation and shape) of recycled concrete aggregate (RCA). A CoMParisonbetween in-situ RCA and manufactured RCA was performed to evaluate the performance,feasibility and economy of using RCA as semi-rigid base. The difference between differentRCA due to the different source of virgin aggregate was also evaluated. In addition, it alsothoroughly studied the effect of breaking process on the performance of RCA2. Through comprehensive study on the design parameters and pavement performance ofthe cement stabilized recycled aggregate base, the mathematical relationship between thedesign parameters and pavement performance was developed. The dry-wet cycle test anddry-wet strength coefficient was first used to study the moisture stability and durability of thecement stabilized aggregate and a design criteria against cracking was developed. Design parameters for durable cement stabilized recycled aggregate were proposed based on multiplepavement performance indexes in terms of thermal cracking, fatigue, moisture stability anddurability.3. According to the performance characteristics of asphalt pavement based on recycledconcrete aggregate (RCA) as semi-rigid base, a structural design methodology is proposedusing three stage design methods.4. Through experimental road test, the quality control for crushing old concretepavement and stabilizing recycled concrete aggregate is developed. With the support of in-situpavement performance testing data and design parameters, a15-year performance curve ispredicted for asphalt concrete pavement using RCA as semi-rigid base based on AASHTOM-E PDG program using the principle of incremental superposition.5. For the first time ever, a systemic and comprehensive study is carried on thesemi-rigid base asphalt pavement using RCA in terms of the material constructability,crushing process, mix design, the comprehensive properties of the design parameters andpavement performance, aggregate index of durability of cement stabilized recycled concreteaggregate, the design of semi-rigid base asphalt pavement structure, field recycling of oldconcrete pavement in large scale, quality control of cement stabilized recycled aggregate, andperformance prediction of semi-rigi base asphalt pavement based on RCA. The results of thestudy will provide a strong technical support for promoting renewable resources,environmental protection, sustainable development and the large-scale industrializedproduction of recycling old concrete as aggregate used in the semi rigid base asphaltpavement.