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Updated: May 11, 2026
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Determination of Aggregate Surface Morphology at the Interfacial Transition Zone (ITZ)
Published on: December 16, 2019
Microstructural characterization of concrete prepared with recycled aggregates
Mafalda Guedes1, Luís Evangelista, Jorge de Brito
1Department of Mechanical Engineering, Escola Superior de Tecnologia de Setúbal, Instituto Politécnico de Setúbal, 2910-761 Setúbal, Portugal.
Summary
Recycled aggregates in concrete show typical microstructures, with a 10% addition strengthening the interfacial bond and reducing porosity. This indicates potential for developing stronger Portland cement concretes using construction waste.
Area of Science:
- Materials Science
- Civil Engineering
- Construction Technology
Background:
- Previous studies focused on workability, mechanical properties, and durability of concrete with recycled aggregates.
- A systematic microstructural characterization of recycled aggregate concrete is lacking.
Purpose of the Study:
- To investigate the microstructural characteristics of concrete using fine recycled aggregate to replace natural aggregate.
- To analyze the effect of recycled aggregate incorporation on the cement/aggregate interfacial transition zone and hydration products.
Main Methods:
- Microstructural analysis using microscopy.
- Controlled replacement of fine natural aggregate with fine recycled aggregate (0, 10, 50, 100 vol%).
- Hydration analysis at various time points (9 h, 24 h, 96 h, 28 days).
Main Results:
- Concretes with recycled aggregates display typical interfacial transition zone microstructures.
- Overall porosity increases with higher recycled aggregate content.
- An interfacial bond strength increase and porosity decrease were observed at 10% recycled aggregate replacement, enhancing material hardness.
Conclusions:
- Recycled aggregate concrete exhibits comparable microstructural features to normal strength concrete.
- Controlled addition of recycled aggregate (around 10%) can enhance interfacial bond strength and material hardness.
- This research suggests a viable pathway for developing high-strength Portland cement concretes utilizing construction waste.
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