Microwave Radiation as a Pre-Treatment for Standard and Innovative Fragmentation Techniques in Concrete Recycling

Area of Science:

• Materials Science
• Civil Engineering
• Sustainable Construction

Background:

• Concrete recycling is crucial for sustainable construction.
• Reducing cement matrix content in recycled aggregates is a key challenge.
• Novel fragmentation techniques are needed for efficient concrete recycling.

Purpose of the Study:

• To assess the effectiveness of different concrete fragmentation techniques.
• To evaluate aggregate liberation and cement matrix content reduction.
• To compare standard mechanical crushing (SMT) with electrodynamic fragmentation (EDF), including microwave weakening pre-treatment (MWT).

Main Methods:

• Lab-made concrete samples subjected to SMT and EDF.
• Investigation of microwave weakening pre-treatment (MWT) influence.
• Analysis of particle size distribution, aggregate selective liberation, and cement matrix content (thermogravimetric measurements).

Main Results:

• Electrodynamic fragmentation (EDF) significantly outperforms SMT in selective aggregate liberation (up to 37 wt.% vs. 14-16 wt.%).
• EDF effectively reduces cement matrix content in the >5.6 mm aggregate fraction.
• Microwave weakening pre-treatment (MWT) enhances SMT but shows no significant benefit with EDF.

Conclusions:

• EDF is a superior technique for liberating aggregates and minimizing cement matrix content in concrete recycling.
• MWT can be beneficial as a pre-treatment for SMT, improving recycled aggregate quality.
• Findings offer insights for implementing advanced technologies in concrete recycling plants.