Alkali Activated Fly Ash-Based Concrete: Evaluation of Curing Process Using Non-Linear Ultrasonic Approach

This paper investigates the applicability of the nondestructive testing and evaluation (NDT&E) method using ultrasonic signals to monitor the curing of alkali-activated fly ash-based concrete (AAFC). The evaluation was carried out on AAFC specimens with two different water/binder (W/B) ratios of 0.3 and 0.5 and after curing at 60 degrees C for 7, 14, and 28 days, respectively. The signals are recorded and analyzed using linear and non-linear ultrasonic techniques. The results show that the non-linear ultrasonic technique has a clear advantage over the linear ultrasonic technique when monitoring the curing of AAFC specimens with a lower W/B ratio. However, the specimens with the higher W/B ratio do not undergo proper curing and therefore do not show clear distinctions between the curing times measured from the two ultrasonic techniques. The unconfined compressive strength (UCS) of the AAFC specimens at different W/B ratios and curing times is also measured. The UCS results showed a good correlation with the ultrasonic results.

Automated summary

This paper investigates the applicability of nondestructive testing and evaluation method using ultrasonic signals to monitor the curing of alkali-activated fly ash-based concrete. The results show that non-linear ultrasonic technique has an advantage in monitoring the curing process of specimens with a lower water/binder ratio, while specimens with a higher water/binder ratio do not show clear distinctions between the curing times measured from the two ultrasonic techniques. In addition, the unconfined compressive strength results show a good correlation with the ultrasonic results.