Acoustic emission monitoring of fresh cementitious material

This study examines the use of acoustic emission (AE) as a means for non-intrusive monitoring of cementitious material. AE sensors enable a continuous measurement of the kinetics of the fresh material. The monitoring was accompanied by simultaneous measurement of ultrasound as as well as capillary pressure. Experiments with compacted and non-compacted cement paste were performed to characterize the ongoing process at an early age. It was observed that immediately after moulding, considerable activity of AE is recorded. Compacted samples registered higher AE than noncompacted samples. Furthermore, capillary pressure indicated a significant increase at an early age. However, a delay in capillary pressure behavior was noticeable for compacted samples. The objective of the study is to combine different techniques in order to explain and possibly quantify the sources of AE in fresh cement paste which include bleeding, bubble and water migration, settlement of cement particles as well as early age cracking