Lightweight natural lime composites for rehabilitation of Historical Heritage Elisa Sala a , Cristina Zanotti b,⇑ , Chiara Passoni c , Alessandra Marini c a Department of Civil, Environmental, Architectural Engineering and Mathematics, University of Brescia, via Branze, 43, 25123 Brescia, Italy b Department of Civil Engineering, The University of British Columbia, 2016-6250 Applied Science Lane, Vancouver (BC) V6T 1Z4, Canada c Department of Engineering and Applied Science, University of Bergamo, viale Marconi 5, 24044 Dalmine (BG), Italy highlights  Lightweight natural lime mortar is developed for Historical Heritage rehabilitation.  Vault filling & floor overlay, usually made with Portland Cement (PC), are targeted.  The mortars proposed are chemically/ physically/mechanically more compatible than PC.  Mortar strength, density, stiffness, cost, and carbon footprint are compared.  Several factors are varied and optimum mortars are selected for each application. graphical abstract article info Article history: Received 20 November 2015 Received in revised form 9 August 2016 Accepted 10 August 2016 Keywords: Natural hydraulic lime Lightweight aggregate Rehabilitation Repair Historical Heritage Compressive strength Compatibility Masonry Vaults Floors abstract Failure and deterioration of structural interventions on masonry buildings demonstrated the need for compatible repairs. Mechanical, chemical, transport properties and density of Portland Cement concrete are poorly compatible with lime mortar masonry structures. Several natural lime composites are developed in this study for compatible Historical Heritage rehabil- itation. Two relevant interventions with different strength/density requirements are considered: masonry vault filling and wooden floor non-structural overlay. Density minimization is attained with various lightweight aggregate (LWA) types/contents; different LWAs in one same mortar are also employed. Composites’ density, strength, stiffness, cost, and carbon footprint are compared; the influence of different factors is discussed. Ó 2016 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.conbuildmat.2016.08.033 0950-0618/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: czanotti@civil.ubc.ca (C. Zanotti). Construction and Building Materials 125 (2016) 81–93 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat