Application of ultrasonic testing to describe the hydration of calcium aluminate cement at the early age

Nondestructive and in situ characterisation techniques, such as ultrasonic measurements, permit to follow cement hydration at the early age from a few minutes to a few hours after mixing. The technique reported in this paper is based on measurements in reflection modes. Results concerning an alumino us cement, Secar71, are presented (water-to-cement weight ratio (WIC): 0.3 and 0.4; temperature of measurement: 20 degreesC; duration: 0-24 h). Inform ation deduced from ultrasonic measurements (longitudinal wave velocity, ref lection coefficient) associated with other data obtained from X-ray diffrac tion (XRD), differential thermal analysis (DTA) and thermogravimetric (TG) measurements enable to propose a qualitative description of hydration's chr onology. The sensitivity of these ultrasonic parameters to hydrates formati on and structuring is underlined. (C) 2001 Elsevier Science Ltd. All rights reserved.