Recycled Aggregate Treatment via Microbial Degradation and Carbonate Deposition
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Solution Overview
Problem
The rapid consumption of concrete in urban infrastructure development leads to significant waste production, causing environmental degradation and resource shortages, with recycled concrete performance being compromised by varying waste compositions and residual substances like sugar residues.
Innovation Solution
A method involving the use of composite microbial powders, such as saccharomycetes and acetobacters, to degrade carbohydrates in recycled concrete, combined with Bacillus mucilaginosus to fill cracks and a calcium source solution to reduce water absorption and enhance performance, specifically by peeling off mortar layers and depositing carbonate minerals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If recycled aggregates are used directly without treatment, then resource recycling is achieved, but water absorption is high and performance is compromised
Solution Approach 1:
The patent applies preliminary treatment actions before using recycled aggregates in concrete. Step (1) performs preliminary microbial degradation of carbohydrates in the aggregate surface. Step (2) fills cracks with microbial powder under vacuum. Step (3) sprays calcium source solution to deposit carbonate minerals. These preliminary actions remove harmful substances and fill defects before the aggregates are used, thereby improving reliability while maintaining recycling benefits.
Solution Approach 2:
The patent converts harmful carbohydrate substances (sugar residues) that compromise aggregate performance into beneficial treatments. Microbial powders (saccharomycetes and acetobacters) degrade these harmful carbohydrates through biological decomposition, transforming them into harmless or beneficial substances. This converts the harmful effect of residue contamination into a beneficial purification process.
2Reliability
If microbial degradation is applied to remove carbohydrates, then water absorption is reduced, but treatment time and process complexity increase
Solution Approach 1:
The patent uses composite microbial powder containing multiple species (saccharomycetes and acetobacters in specific ratios) to accelerate the degradation process. This composite approach enhances the biological decomposition efficiency compared to single-species treatments, reducing the time required to remove carbohydrates while maintaining effective water absorption reduction.
Solution Approach 2:
The patent optimizes treatment parameters including temperature (20-30°C), stirring speed (10-50 r/min), stirring time (24-72 hours), and microbial powder ratios. By carefully controlling these parameters, the process achieves effective carbohydrate degradation within reasonable time frames, balancing performance improvement with treatment duration.
3Strength
If crack filling and carbonate deposition are performed, then strength is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent employs self-service mechanisms where microbial powders automatically fill cracks through vacuum suction, and calcium source solution spontaneously deposits carbonate minerals on crack surfaces. The vacuum device passively draws microbial powder into cracks without complex injection systems, and the calcium solution naturally precipitates carbonate minerals through chemical reaction, reducing the need for complex mechanical crack-filling equipment.
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
This method significantly reduces water absorption of recycled aggregates by over 50%, improving their strength and addressing environmental concerns while being cost-effective and environmentally friendly.
Implementation Method 1
polysaccharides are degraded into small molecular substances through micro-biological degradation and converted into acidic substances
Implementation Method 2
the acid substances can peel off the mortar layer adhering to the surface of the recycled aggregates to reduce the water absorption of the recycled aggregate
Implementation Method 3
filling the cracks of the recycled aggregate with a microbial powder in a vacuum environment
Implementation Method 4
carbonate minerals are deposited at the cracks by spraying the calcium source solution to block the cracks of the recycled aggregates
Data Source
AI summary
The present disclosure discloses a method for improving the performance of concrete aggregates, comprising the following steps: (1) adding composite microbial powders, recycled aggregates and water into a stirring pot in a certain ratio to be continuously and uniformly stirred; (2) placing the recycled aggregate obtained in step (1) and another microbial powder in a vacuum device so as to fill the microbial powder into the cracks of the recycled aggregate in a negative-pressure environment; and (3) spraying a calcium source solution to the surface of the recycled aggregate obtained in step (2) at an interval of 5-6 hours for repeating 3-5 times to maintain the wet surface of the recycled aggregate.