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Physical, Mechanical, and Microstructure Characteristics of Ultra-High-Performance Concrete Containing Lightweight
1Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia.
Materials (Basel, Switzerland)
|July 14, 2023
Summary
This study shows that adding lightweight aggregates (LWAs) to ultra-high-performance concrete (UHPC) improves flowability and microstructure. While higher LWA content reduces strength, it enhances resistance to high temperatures and explosive spalling.
Area of Science:
- Materials Science
- Civil Engineering
- Concrete Technology
Background:
- Ultra-high-performance concrete (UHPC) is susceptible to explosive spalling at elevated temperatures.
- Lightweight aggregates (LWAs) offer potential for modifying concrete properties.
Purpose of the Study:
- To investigate the effect of incorporating varying percentages of LWAs (0-30%) on the mechanical properties, durability, and microstructure of UHPC.
- To assess the UHPC's resistance to explosive spalling under elevated temperatures.
Main Methods:
- UHPC specimens were prepared by partially replacing silica sand with LWAs.
- Evaluated properties included compressive and flexural strengths, density, mass loss, shrinkage, and porosity.
- Microstructural analysis was performed using scanning electron microscopy (SEM).
Main Results:
- LWA incorporation improved UHPC flowability and decreased density.
- 30% LWA resulted in 4.8% mass loss at 300 °C, with reduced strengths but enhanced high-temperature performance compared to ambient conditions.
- Microstructure analysis revealed increased density in 30% LWA specimens due to LWA-derived hydration.
Conclusions:
- LWAs influence UHPC's physical and strength characteristics, offering improved high-temperature resistance.
- Optimizing LWA content is crucial for balancing density, porosity, and mechanical performance.
- Findings support the development of advanced, lightweight concrete materials with enhanced durability.
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