| Air void structure in hardened concrete is critical to its durability. This project mainly focuses on investigating the air void system in hardened concrete with the microscopic analysis Linear Traverse Method specified by ASTM Specification C457-08 (Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete).;To understand the stability of the air void system in concrete, the same concrete mixes were examined with two other methods, pressure meter measurement and Air-Void Analyzer, under fresh state. The comparison of the results from the three methods for fresh and hardened concrete shows that properties of concrete vary in samples within the same batch with the same mix design, samples in different batches of the same mix design and samples with different mix designs. The measured air content from Linear Traverse Method and pressure meter are fairly close to each other, while Air-Void Analyzer measured air content is observed to be lower than that from Linear Traverse Method. The measured spacing factor from Air-Void Analyzer is observed to be higher than that from Linear Traverse Method, while the measured specific surface from Air-Void Analyzer is observed to be lower than that from Linear Traverse Method. However, no strong correlation in the measured air content and measured specific surface between Linear Traverse and Air-Void Analyzer is observed. |
