Durability Of Mortars For Restoration

Abstract

A series of mortars and grouts commonly used in structural restoration of old masonry as well as in building with new masonry (and especially reinforced one) were tested under in-lab and in-situ conditions at NTU of Athens, within the framework of an extended BRITE-EURAM research programm, financed by EU. Mechanical, physical and chemical testing was performed, with emphasis on problems of durability, and especially those associated with humidity in masonry walls. 1 SHORT INTRODUCTION It is almost common practice in interventions and structural restoration (repair/strengthening) of old masonry the use of techniques such as: • Incorporation of diffused reinforcement (in vertical and horizontal tieelements, made practically of mortar or grout), or • Lighty reinforced rendering/coating (of small thickness), applied in zones or even on the entire masonry faces. The attack of steel bars (usually of small diameter) occurs from the agressive agents penetrating into mortars and grouts through their porous system or through fine cracks and capillary action; the rate of reinforcement corrosion depends on mortar's or grout's properties as well as on the environment's agressivity, with emphasis on the role of moisture (with or without dissolved salts) and moisture movement. The composition of mortars and grouts affects their mechanical strength and porosity, as well as their ability to act as barriers against agressive agents. On the other hand, in-situ performance of rather thin additional layers or elements is conditioned by the curing contracTransactions on the Built Environment vol 15, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509