Testing of cement composites during setting and hardening using ultrasonic waves

Research is made on correlation between properties of ultrasonic waves which travel through the cement composite and the processes of setting and hardening which occur as a consequence of hydration in cement materials. The aim of the research is to enable estimation of materials properties by monitoring changes of the ultrasonic waves. Ultrasonic measuring system was assembled at the Faculty of Civil Engineering in Zagreb at the Department of Materials which enables continuous measuring of ultrasonic wave properties during hydration. Basic principles of acousto-ultrasonic testing method are presented and the term stress wave factor (SW factor) is introduced. Experimental work is conducted where initial and final setting time, compressive strength tests and hydration heat liberation was monitored and concurrently ultrasonic testing was made. Research was made through testing of cement paste and concrete made with two types of cement (CEM I and CEM III/B) and with different water-to-cement ratios.