Pore Structure Influence on Properties of Air-Entrained Concrete

Area of Science:

• Civil Engineering
• Materials Science
• Concrete Technology

Background:

• Air-entraining admixtures are crucial for enhancing concrete durability, particularly in freeze-thaw environments.
• Understanding the relationship between admixture dosage, pore structure, and concrete performance is essential for optimizing mix designs.

Purpose of the Study:

• To investigate the impact of air-entraining admixture content on the mechanical properties and pore structure of ordinary concrete.
• To correlate changes in pore characteristics with concrete performance metrics like compressive strength, ultrasonic pulse velocity, and freeze-thaw resistance.

Main Methods:

• Concrete samples with varying admixture dosages (0.00-1.50%) were prepared and tested.
• Mechanical properties (compressive strength) and physical properties (ultrasonic pulse velocity) were evaluated.
• Freeze-thaw resistance was assessed using direct and indirect methods, and pore structure was analyzed via computer-aided image analysis.

Main Results:

• Increased admixture dosage improved freeze-thaw resistance by increasing micropore content (<0.3 mm).
• Higher admixture content led to reduced compressive strength and ultrasonic pulse velocity.
• Statistical analysis confirmed significant correlations between pore parameters (air content, specific surface area, spacing factor) and concrete performance.

Conclusions:

• Optimizing air-entraining admixture dosage is key to balancing concrete's durability and mechanical performance.
• Quantitative stereological parameters derived from pore structure analysis effectively predict the behavior of air-entrained concrete.
• The study provides valuable insights for designing durable concrete structures exposed to harsh environmental conditions.