Estimation of Elastic Constants of Restoration Mortars, Used on Historic Masonries Restoration Interventions, VIA Ultras
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OO6.2.1
ESTIMATION OF ELASTIC CONSTANTS OF RESTORATION MORTARS, USED ON HISTORIC MASONRIES RESTORATION INTERVENTIONS, VIA ULTRASONIC TECHNIQUE AND CORRELATION TO THEIR MECHANICAL AND MICROSTRUCTURE PARAMETERS
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Antonia Moropoulou, 1Asterios Bakolas, 1Eleni Aggelakopoulou, 1Anastasia Odatzidou, 2 Christos Teas, 2Dimitris Papageorgiou
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National Technical University of Ath9ens, School of Chemical Engineering, Section of Materials Science and Engineering, 9 Iroon Polytechniou St., NTUA Campus, Zografou, Athens, Greece, 2TITAN Cement S.A., Department of R&D and Quality, Kamari Plant, Greece
ABSTRACT Eight syntheses of mortars used for restoration interventions in historic masonry were produced using the traditional materials of aerial lime and artificial pozzolanic additives. The mortars were aged over a 15-month period and then tested for properties related to chemical and mechanical stabilization using the following four analytical techniques: ultrasonic velocity propagation and the mortars' dynamic modulus of elasticity (Ed), mercury intrusion porosimetry for evaluation of microstructural characteristics (percentage open porosity, bulk density, average pore radius, total cumulative volume, and specific surface area), water capillary rise tests for the determination of total cumulative volume accessible to water and capillary rise coefficients of the mortars, and conventional mechanical tests for the determination of the mortars' flexural and compressive strength. Performance is correlated to the mortars' chemical composition, microstructural characteristics (as measure by average pore radius) and mechanical characteristics as measured by dynamic modulus of elasticity (Ed) and flexural and compressive strength (Fc). INTRODUCTION To evaluate the mortars conservation state as building materials in a historic or traditional structure, it is essential to determine their mechanical characteristics. This could be accomplished using either conventional destructive mechanical tests or non-destructive ones, like ultrasonic technique. Taking into account that in the case of historic structures the number of samples that could be taken and examined in lab is limited, there is a need to measure these characteristics indirectly, using the non-destructive ultrasonic technique. In the literature, there are several studies dealing with the determination of ultrasonic velocity and dynamic modulus of elasticity evaluation in concrete or cement mortars [1] or in stone [2, 3, 4] but very few studies dealing with lime or pozzolanic mortars [5]. Furthermore, there is a great interest in the possibility of correlation of the data obtained by ultrasonic technique to the microstructural characteristics of materials such as the average pore radius, the total porosity and the density. Analogous studies have been accomplished in the case of stone that correlate their elastic constants measured by ultrasonic technique to the ones measured by conventional mechanical tests and to the stones’ microstructural characteristics [2, 3, 4]. In this
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