The air void size distribution has significant impacts on mechanical, thermal and transport properties of concrete and long-term durability such as freeze-thaw resistance. Measuring the characteristics of air voids in concrete (especially at early-ages) is thus very important in assessing its long-term durability. Nondestructive ultrasonic technique will be developed for potential concrete mixture quality control both in lab and field applications.
1. Develop ultrasonic air void size distribution measurement techniques for hardened air-entrained concrete and evaluate the accuracy with ASTM C 457 measurements
2. Develop ultrasonic air void size distribution measurement techniques for early-age air-entrained concrete and evaluate the accuracy with the ASTM C 457 measurements
3. Develop the testing procedures and data processing tools for potential field applications
1. Prepare air-entrained concrete samples with/without internal curing reservoirs (using light-weight fine aggregates) for air void distribution measurements
2. Design the ultrasonic measurement system for both hardened and early-age concrete sample measurements and develop the signal processing programs for the air void distribution evaluation of both types of samples
3. Evaluate the measurement accuracy by comparing with RapidAir ASTM C 457 and propose the testing procedures for potential field mixture quality control