Production of eco-efﬁcient earth-based plasters: Inﬂuence of composition on physical performance and bio-susceptibility T ^ ania Santos a , Lina Nunes b , Paulina Faria a, * a CERIS e Civil Engineering Research and Innovation for Sustainability, Universidade NOVA de Lisboa, Department of Civil Engineering, 2829-516, Caparica, Portugal b LNEC, Structures Department, Av. do Brasil, 101, 1700-066 Lisbon, cE3c - Centre for Ecology, Evolution and Environmental Changes, Azorean Biodiversity Group, Universidade dos Açores, 9700-042, Angra do Heroísmo, Açores, Portugal article info Article history: Received 23 February 2017 Received in revised form 3 August 2017 Accepted 15 August 2017 Available online 16 August 2017 Keywords: Earth plastering mortar Air lime Natural ﬁbre Phase change material Physical property Bio-susceptibility abstract An experimental campaign was developed to evaluate the properties of earth plastering mortars, not only at the level of workability and physic-mechanical performance but also their susceptibility for biological colonization. A ready-mixed earth mortar and several other mortars formulated with a raw clayish earth were produced. The inﬂuence of partial replacement of ﬁne sand by a phase change ma- terial (PCM) and the addition of low amounts of oat ﬁbres and hydrated air lime were assessed. The experimental campaign shows that the PCM completely changes the mortar workability, with a decrease on wet density. The addition of PCM and ﬁbres decreases the bulk density and, consequently, increases the porosity of the mortars. The presence of PCM, ﬁbres and air lime decreases the thermal conductivity. Earth mortars are susceptible to mould development, and the ﬁbres or PCM seem to intensify their bio- susceptibility. A low addition of air lime increases pH and inhibits fungal growth though decreasing the mechanical properties. Mortars with PCM, ﬁbres and air lime present a higher surface roughness in comparison to other mortars, including the ready-mixed earth mortar with ﬁbres. Surface roughness was found to be an important factor inﬂuencing the level of colonization. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction Earth is, together with wood, one of the oldest building mate- rials known to man. After decades of neglect, the use of earth is regaining importance as a building material and an example are earth-based plasters that are now recognized, produced and applied as highly eco-efﬁcient (Darling et al., 2012; Emiro glu et al., 2015; Liuzzi and Stefanizzi, 2016; Maddison et al., 2009). Never- theless, research is needed to improve and optimize these plasters. Currently, these plasters are made of clayish mortars without any or, at least, without high amounts of binders, like lime or cement (Eires et al., 2017; Gomes et al., 2016; Niroumand et al., 2017). Thus, in comparison to common plasters, the stone mining, transport and energy consumption for the production of earth- based plasters is very low. When comparing, by life cycle assess- ment (LCA) methodology, environmental impacts of earthen plasters with plasters based on conventional binders, M elia et al. (2014) showed that the ﬁrst outperform all the others. Earth plastering mortars, as other building products based on raw clay, have a high capacity to adsorb and desorb water vapour (Lima et al., 2016). Therefore, they can strongly contribute to regulate the relative humidity of the indoor air (Cagnon et al., 2014; Emiro glu et al., 2015; Liuzzi and Stefanizzi, 2016; Randazzo et al., 2016), improving indoor air quality and inhabitants comfort and health (Lima et al., 2016), but also improving energy performance of the whole building (McGregor et al., 2014). Aesthetic, like natural colouring from the clay and texture, are also recognized as impor- tant aspects that can be explored. The technical characteristics and efﬁciency of these mortars only recently gain the interest of the scientiﬁc community and begin to be methodically tested (Delini ere et al., 2014; Hamard et al., 2013; Stazi et al., 2016). However, there are few earth building standards that can be applied and, therefore, even testing needs to be studied and deﬁned. Limiting the development of un- wanted biological growth is one important aspect to study. Generally, an earth mortar is composed by a clayish earth and, depending on the earth composition, additional sand is frequently * Corresponding author. E-mail addresses: tr.santos@campus.fct.unl.pt (T. Santos), linanunes@lnec.pt (L. Nunes), paulina.faria@fct.unl.pt (P. Faria). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro http://dx.doi.org/10.1016/j.jclepro.2017.08.131 0959-6526/© 2017 Elsevier Ltd. All rights reserved. Journal of Cleaner Production 167 (2017) 55e67