Comparison Study of Dynamic Elastic Moduli of Cement Mortar and No-cement Slag Based Cementitious Mortar Activated with Calcined Dolomite with Impulse Excitation Technique

¹ Department of Civil and Construction Engineering, National Taiwan University of Science and Technology (NTUST) (Taiwan Tech), Taipei 106, Taiwan, ROC.
² Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan, ROC.
³ Department of Civil Engineering, Parahyangan Catholic University, Bandung 40141, Indonesia.

Abstract

This paper presents the comparison of an experimental investigation on compressive strength and dynamic elastic moduli of mortars made of Ordinary Portland Cement (OPC) and ground granulated blast furnace slag (GGBFS) incorporating with calcined dolomite. Dolomite powder calcined at temperature 900°C emerged as a GGBFS activator for producing cementitious mortar binder. In this study, no-cement mortar is made by activating GGBFS with calcined dolomite by a fixed amount of 20 wt%. The compressive strengths and dynamic elastic moduli were measured at 7 and 28 days. Comparing with cement mortar, the compressive strength of no-cement mortar was found about 54.4 and 46.9% lower at ages of 7 and 28 days, respectively. Non-destructive evaluation of the dynamic elastic moduli was investigated by impulse excitation technique (IET). It measures the resonant frequencies of induced vibration signal in the flexural and torsional mode for determining the dynamic Young's modulus and the dynamic shear modulus. The Poisson's ratio was calculated by the dynamic Young's modulus and the dynamic shear modulus relationship. The results showed that the 28-day dynamic Young's and shear moduli of cement mortar were 31.91 and 14.43 GPa, respectively. The dynamic Young's and shear moduli of no-cement mortar were lower by 23.3 and 15.2% than that of cement mortar at the age of 28 days. The obtained results showed that the 28-day Poisson's ratio of no-cement mortar had a wider range between 0.177 and 0.209 than that of cement mortar which ranged from 0.180 to 0.185.