Construction and Building Materials 18 (2004) 419–424 0950-0618/04/$ - see front matter  2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.conbuildmat.2004.03.012 Marble behaviour under monotonic and cyclic loading in tension Giuliana Cardani *, Alberto Meda a, b Department of Structural Engineering, Politecnico di Milano, Piazza L. Da Vinci, 32-20133 Milano, Italy a Department of Civil Engineering, Universita degli Studi di Brescia, Via Branze 38-25123 Brescia, Italy b ` Received 14 January 2003; received in revised form 8 March 2004; accepted 9 March 2004 Abstract The tensile behaviour of marble at failure is analysed. A series of monotonic and cyclic bending tests were carried out in the laboratory on geometrically similar specimens of different size. The strain distribution was monitored with strain gauges and laser interferometry techniques. Three and four point bending configuration was considered. It is shown that cyclic loads in a three point bending configuration induce permanent tensile deformation.  2004 Elsevier Ltd. All rights reserved. Keywords: Marble; Tensile strength; Cyclic load 1. Introduction Marble, an aggregate of calcite crystal granules, is a stone used in structural and non-structural elements both in ancient and modern building. It is the most frequently used metamorphic rock for thin wall panels. Interlocking grains of mostly calcite or dolomite give maximum density and strength with a minimum pore space w1x.A structural element or even a decorative element may be subjected to monotonic and cyclic state of stress. There- fore, for the correct use of a given material in a structural context it is appropriate to know what is the behaviour under different conditions. Cyclic stresses, both thermal and mechanical, applied to structures composed of natural building stone can produce several problems that may range from perma- nent deformations to premature collapse. In particular, if a strain gradient is present in a cyclically loaded element of stone, permanent deformations can produce residual strain (or residual stress) that alters the aesthetic and the functionality of the element, denoting a material misuse w2x. Classic examples of stones not properly used were the facade of the Finlandia Hall in Helsinki w3x, of the ¸ Amoco Building in Chicago and of the Grande Arche *Corresponding author. Tel.: q39-2-2399-4208; fax: q39-2-2399- 4220. E-mail address: cardani@stru.polimi.it (G. Cardani). de la Defense in Paris, where thinly cut marble panels ´ failed due to weathering. With certain marble, the weathering reveals itself as a progressive grain-bond loosening called decohesion, which produces increase in porosity and scaling. In addition, scanning electron micrographs have shown that thermal cycling, a typical type of weathering process, produced damage mechanisms similar to cyclic mechan- ical loading w4x. Therefore, the decohesion mechanism may be induced by either thermal or mechanical cyclic loading of sufficient magnitude. The failure of stone is associated with complex phenomena of microcracking that produce size effects on a structural level: the nominal strength is a decreasing function as the element size increases. Likewise, size is important in defining the global response of the structures that may be very brittle in large elements w5–7x. With this kind of material, carrying out cyclic tests is also helpful in achieving results on fatigue behaviour. These tests allow after every cycle the observation of residual strains, caused by the decohesion of the marble grains, which in turn causes the bowing phenomenon in thin marble plates. Monotonic and cyclic tests, performed on Carrara marble (Lorano quarry) specimens, are discussed. Spec- imens of different size under three and four point bending configuration were tested in a closed loop