Electric-Pulse Fragmentation for Concrete Paste–Aggregate Separation
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Solution Overview
Problem
Existing concrete recycling technologies struggle to efficiently separate hydrated cement paste from aggregates, particularly the fine fraction, resulting in low-quality recycled materials that limit the application of recycled concrete in fresh concrete production and fail to effectively sequester carbon dioxide.
Innovation Solution
A method combining electric-pulse fragmentation with carbonation to separate waste concrete into clean aggregates and high-quality carbonated recycled concrete paste (cRCP) by applying high voltage pulses in the presence of carbon dioxide, followed by sieving to obtain a fine fraction suitable for supplementary cementitious materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard crushing and sieving circuits are used to recycle concrete, then coarse recycled aggregate and fine fraction can be recovered, but the recycled materials contain significant amounts of hydrated cement paste which impairs their quality and limits their application in fresh concrete production
Solution Approach 1:
The patent replaces conventional mechanical crushing and sieving with high-voltage electric pulse fragmentation. This substitution uses electrical energy to induce dielectric breakdown and mechanical stress within particles, achieving separation of hydrated cement paste from aggregate based on differences in dielectric properties and internal structure, rather than relying solely on mechanical force and particle size differentiation.
Solution Approach 2:
The patent applies high-voltage electric pulses (typically 10-100 kV) to change the physical state and mechanical properties of the concrete material during fragmentation. The electric field parameters (voltage, pulse duration, frequency) are optimized to selectively fracture hydrated cement paste while preserving aggregate integrity, fundamentally altering the separation mechanism from mechanical to electro-mechanical.
2Quantity of substance
If conventional recycling methods are used, then concrete waste can be processed, but a significant amount of recycled concrete paste cannot be recovered and the fine fraction quality is insufficient for use as supplementary cementitious material
Solution Approach 1:
The electric pulse fragmentation process uses electrical fields to selectively break down hydrated cement paste bonds while leaving aggregate particles largely intact. This electro-mechanical approach enables thorough liberation of fine paste particles from aggregate surfaces, maximizing recovery quantity while achieving sufficient fineness and purity for supplementary cementitious material applications.
Solution Approach 2:
The patent employs periodic high-voltage pulse sequences applied to the concrete material. Multiple pulses at controlled intervals progressively fragment the hydrated cement paste while allowing heat dissipation and preventing excessive agglomeration, thereby maximizing both the quantity recovered and the quality of fine particles produced.
3Manufacturing precision
If electric-pulse fragmentation with carbonation is applied, then high-quality carbonated recycled concrete paste can be obtained suitable for supplementary cementitious materials, but the process complexity increases
Solution Approach 1:
The patent combines electric pulse fragmentation with in-situ carbonation in a single integrated process step. Carbon dioxide is introduced into the fragmentation chamber where it reacts with freshly exposed calcium hydroxide and calcium silicate phases during and immediately after electric pulse treatment. This merging of separation and carbonation operations achieves high-quality carbonated recycled concrete paste while minimizing additional equipment complexity.
Solution Approach 2:
The patent maintains continuous carbon dioxide exposure throughout the electric pulse fragmentation process and subsequent drying phase. This continuous action ensures complete carbonation of liberated calcium-containing phases, transforming the recycled paste into a stable, high-quality supplementary cementitious material with improved durability and reduced shrinkage, while keeping the process flow simple and continuous.
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 approach achieves a high-quality carbonated RCP suitable for use as filler and SCM, enhancing the recyclability of concrete and effectively sequestering carbon dioxide while producing clean aggregates for new concrete production.
Implementation Method 1
applying high voltage pulses in the presence of carbon dioxide
Implementation Method 2
carbonation of the fine fraction in a CO2 atmosphere
Data Source
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AI summary
Method for separating hydrated concrete paste from aggregate comprising the steps of providing a feedstock comprising waste concrete with a D10 ≥ 0.1 mm and a D90 ≤ 100 mm, passing the feedstock, a water containing liquid and carbon dioxide into a fragmentation vessel, where the wet feedstock is subjected to electric-pulse fragmentation, withdrawing fragmented solid material from the fragmentation vessel, separating the fragmented solid material from admixed liquid phase, separating the fragmented solid material into a fine fraction with a maximum particle size of 250 µm to provide the carbonated recycled concrete paste and a coarse fraction, recycling the coarse fraction into the fragmentation vessel and/or discharging the coarse fraction as clean aggregate, use of the recycled concrete paste obtained thereby as supplementary cementitious material or filler.