Study On Cold Recycle Central Plant Aggregate Metering System

The asphalt pavement built in the early stage of China has reached or exceeded the design life,and faced with the problems of how to carry out road maintenance and reconstruction.The cold recycle central plant technology has been gradually promoted in the field of road recycling with its unique advantages.Due to the large measurement error of the aggregate metering system of some plants mixed with cold regeneration equipment,it is difficult to meet the needs of emulsified asphalt cold regeneration and foamed asphalt cold regeneration technology,and at present,there is a lack of research on high-precision aggregate metering system for cold regenerative mixing station.The paper has carried out the following research work on this issue.From the research on the cold recycle central plant technology,especially a large amount of literature combined with,the effects of the aggregate-level paired regeneration mixture in the cold regeneration of emulsified asphalt and the cold regeneration technology of foamed asphalt were analyzed in detail.The results show that compared with the cold recycle central plant technology with cement(hydraulic material)as the regenerant,the cold recycle central plant technology with emulsified asphalt or foamed asphalt as the regenerant has higher requirements for the grading of the aggregate.Then,the traditional aggregate metering system that affects the grading composition is studied.By using the mathematical model of the weighing error of the belt batching scale and combined with the change law of the pressure at the bottom of the hopper during the bulk material conveying process,the relationship between the height change of the material in the hopper and the change of the belt tension is analyzed,and the variation law of the weighing error of the belt scale caused by the change of the belt tension is calculated.At the same time,the relationship between the weight error and the cumulative amount error is explored.Further,the measurement accuracy test of the aggregate metering system was carried out,and the results of aggregate grading were analyzed.The results show that during the process of gradually reducing the material in the hopper from the full warehouse state,the measurement error of the traditional aggregate metering system fluctuates greatly,and the precision of the batching is low,so that the grading of the aggregate is difficult to stabilize within the specified grading range.Finally,by analyzing the cause of weighing error,the high-precision aggregate metering system suitable for cold reclaimed mixing station was developed.The high-precision batching unit with conveyor belt scale as the main metering device was designed.The new ingredients were determined.The working mode of the unit was selected,and the suitable sensor components were selected.The system error and error compensation method of the designed new aggregate batching unit were analyzed.The research work and research results of the aggregate metering system can provide theoretical reference and technical support for the design,upgrade and transformation of the cold recycle central plant aggregate metering system.