Recycled Aggregate Milling via Self-Media Rubbing
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Solution Overview
Problem
There is a lack of an established method for collecting high-quality recycled aggregate corresponding to the 'recycled aggregate H' standard from concrete debris, which is essential for reuse in construction projects, due to inefficient processing techniques.
Innovation Solution
A method involving a series of crushing, classification, and milling steps, where large diameter components are used as milling media to remove cement paste from small diameter components, with multiple reprocessing steps to ensure the quality meets JIS A 5021 standards, including a specific volume ratio of lime-based raw material to ensure alkali silica reactivity is harmless.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional crushing and milling methods are used on concrete debris, then processing can be performed with simple equipment, but the quality of recycled aggregate cannot meet the 'recycled aggregate H' standard
Solution Approach 1:
The patent divides the processing into distinct stages: crushing step, first classification step, milling step, second classification step, and reprocessing step. Each stage uses specific equipment and achieves particular quality objectives, allowing the system to meet high quality standards through systematic segmentation of the overall process.
Solution Approach 2:
The patent performs preliminary classification before milling to separate large and small diameter components. This preliminary action ensures that only appropriately sized materials enter the milling step, preventing over-processing and ensuring that the final product meets quality specifications for 'recycled aggregate H'.
2Manufacturing precision
If multiple reprocessing steps are performed to ensure quality, then recycled aggregate meets JIS A 5021 standards, but processing time and production cost increase
Solution Approach 1:
The patent implements a reprocessing step where classified components are fed back into the milling process. This feedback mechanism allows quality control through iterative processing, ensuring that recycled aggregate meets the required standards while providing a clear criterion for when processing can be terminated.
Solution Approach 2:
The patent changes processing parameters by adjusting the number of reprocessing cycles and the classification thresholds. By optimizing these parameters, the system achieves compliance with JIS A 5021 standards while minimizing unnecessary processing time through data-driven decision making.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively produces recycled aggregate with an absolute dry density of 2.5 g/cm3 or greater and water absorption of 3.0% or less, meeting the quality criteria for 'recycled aggregate H' as per JIS A 5021, ensuring it can be used similarly to ordinary aggregate.
Implementation Method 1
a milling step for supplying the large diameter components and the small diameter components classified in the first classification step to a mill with a volume ratio of the large diameter components relative to the small diameter components equal or greater and rubbing the large diameter components and the small diameter components with each other at the mill
Data Source
AI summary
Provided is a method for manufacturing high quality recycled aggregate by using concrete debris as raw material including: crushing a raw material including concrete debris; classifying the crushed raw material into small diameter components and large diameter components; supplying the components to a mill with a volume ratio of the large diameter components relative to the small diameter components equal or greater and rubbing the components with each other at the mill, the mill not including a milling medium; reprocessing the components in the mill at least once or more; and collecting the reprocessed components as recycled aggregate.