The use of composites in architectural restoration: some critical considerations on the theoretical implications COÏSSON Eva 1, a * and OTTONI Federica 2,b 1 DICATeA, Parco Area delle Scienze 181/A, 43124 Parma, Italy 2 DICATeA, Parco Area delle Scienze 181/A, 43124 Parma, Italy a eva.coisson@unipr.it, b federica.ottoni@unipr.it Keywords: historical buildings, principles of restoration, durability, reversibility Abstract. The use of composites in the field of architectural restoration is becoming more and more widespread, because of the great technical advantages they convey in many cases. But applying these materials to the Cultural Heritage poses not only technical issues, common to all the applications on the same materials, but also artistic, historical and, more generally, cultural ones. The present paper faces these issues, starting with some considerations on how they were dealt with in history, when the “new” materials were iron, steel and reinforced concrete. Then, the specific problems posed by the composite materials are discussed and some examples are shown in order to identify the correct approach to the many different cases that can arouse in the field of architectural restoration. There isn’t a single right solution for each problem, but there is a right approach that starts from the comprehension of the building’s behavior, passes through a comparison of all the possible solutions and aims at finding the best equilibrium among the technical and theoretical issues for the single case study. Introduction In the centuries-long debate on restoration, the use of modern materials in strict contact with the ancient ones for their conservation or strengthening has been subjected to many quarrels. Already in the XIXth century, the separation between stylistic and conservative restoration theorists brought its consequences on the approach towards new materials: while on one side Viollet-le-Duc studied thoroughly the ancient materials and building techniques in order to apply them as similar as possible in his restorations, on the other side Ruskin stated that a restorer should “bind it [an old building] together with iron where it loosens; stay it with timber where it declines; do not care about the unsightliness of the aid: better a crutch than a lost limb” [1]. The 1931 Athens Charter concluded that modern techniques and materials (reinforced concrete, in particular) may be used in restoration work, but should be concealed whenever possible [2]. The 1964 Venice Charter dedicates an entire article (n. 10) to this issue: “Where traditional techniques prove inadequate, the consolidation of a monument can be achieved by the use of any modern technique for conservation and construction, the efficacy of which has been shown by scientific data and proved by experience” [3]. Of course, these statements concerned mainly the use of steel and concrete, but the approach is the same we should now use for the composites: learning from the past and particularly from the errors made at the beginning of the use of these “once new” materials can help to avoid new errors, now that the composites represent the “presently new” materials. Learning from the past: the “once new” materials In the course of time, man has always used all the available materials to restore and strengthen his objects, from the most simple (fig. 1) to the most complex ones. When dealing with buildings, the most widespread “new” materials used in the last centuries are iron (or steel) and reinforced concrete. The theoretical approach towards these materials varied from diffidence to blind trust. Key Engineering Materials Vol. 624 (2015) pp 11-18 Online available since 2014/Sep/12 at www.scientific.net © (2015) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/KEM.624.11 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 160.78.30.113, Parma University, Parma, Italy-26/01/15,18:28:21)