Acoustic signatures of hydration and microcracking in early-age concrete

Processes occurring during concrete curing such as settlement, hydration, and early-age shrinkage cracking define its long-term performance. These processes result in the emission of elastic waves which contain characteristic information about them. In this study, concrete is monitored from its fresh state up to its early hardening state, using Acoustic Emission (AE), a technique that records waves released by irreversible processes within the material. The purpose of this paper is to contribute to the characterization of the different processes in early-age normal concrete and concrete containing superabsorbent polymers (SAPs). Emphasis is given to the AE activity of hydration and micro-cracking since they are positively and negatively, respectively, related to the final mechanical properties. Identifying the parameters with higher characterization potential enhances pattern recognition clustering with encouraging results. Parameters such as the amplitude and absolute energy of cracking AE signals are also correlated to the 28-day compressive strength.