Properties of Early-Age Portland Cement Mortar Monitored with Shear Wave Reflection Method

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Title: Properties of Early-Age Portland Cement Mortar Monitored with Shear Wave Reflection Method

Author(s): Thomas Voigt and Surendra P. Shah

Publication: Materials Journal

Volume: 101

Issue: 6

Appears on pages(s): 473-482

Keywords: dynamic modulus of elasticity; early ages; hydration; portland cement mortar; test; ultrasonic

Date: 11/1/2004

Abstract:
The presented investigations examine the ability of a shear wave reflection method to monitor the hydration kinetics of portland cement mortar. The wave reflection method measures the reflection loss of shear waves at an interface between a steel plate and the mortar. Mortars with water-cement ratios (w/c) of 0.35, 0.5, and 0.6 were tested at isothermal curing conditions of 25 °C. The hydration behavior of the mortars is characterized by setting time, heat of hydration, compressive strength, dynamic shear modulus, and degree of hydration. The results show that compressive strength has a bilinear relationship to the reflection loss. The comparison of the dynamic shear moduli determined by torsional resonant frequency, ultrasonic shear wave velocity and shear wave reflection loss suggests that the wave reflection measurements are qualitatively governed by the dynamic shear modulus of the mortar. Finally, the reflection loss data of all three tested mortars were found to be uniquely related to the gel-space ratio of the cement paste phase of the mortars.