Page - 93 - in Intelligent Environments 2019 - Workshop Proceedings of the 15th International Conference on Intelligent Environments

soil and subsoil. Taking into account that lime cements are composed mostly by calcium or magnesium oxides, there are three candidates that could be selected as an additive to improve the heat insulating capability: SiO2, Al2O3 and Fe2O3. A comparison of the properties of these candidates shows that iron (III) oxide has the lowest thermal conductivity (λFe2O3 = 0.58 W/(m·K); λSiO2 = 1.1 W/(m·K); λAl2O3 = 25 W/(m·K) ), which is also lower than that of the limestone (λlimestone = 1.3 W/(m·K)) [14-15]. Moreover, iron (III) oxide is inexpensive mineral, the seventh most abundant compound in the Earth’s crust [16], which is an important factor for a mineral to be used as a construction material. From the point of view of environmental sustainability, iron (III) oxide (hematite) is a component present in farmlands, beneficial for plant species. For this reason, the rubbles generated after the stage in service of buildings would not have a detrimental effect on the environment [17]. 3.1. Materials and Methods Hidraulic lime NHL-3.5 Morcem Cal Base 434 CR CSII W0 (produced by Grupo Puma, Spain) was selected in accordance with the EN 459-1:2001 standard, to use as a base product of the mortar. Iron (III) oxide red (produced by Labkem, Spain) of chemical purity higher than 95% and solubility lower than 1%, was used as the additive. In order to analyse the effect of Fe2O3 on the thermal properties of a lime mortar, five samples with different iron (III) oxide content were prepared. The quantity of water added to the dry mixture was higher as the iron (III) oxide content increases in order to obtain a cement lime mortar of equal workability and elastic consistency according to ISO 12439 standard [18]. Cylindrical samples (12 cm height and 10 cm diameter) were produced using a plastic mould. Curing time was at least 60 days. The mass of water needed to obtain the optimal mixing increases linearly with iron (III) oxide content, since the addition of Fe2O3 small size particles increases the specific area, demanding an increasing addition of water to surround the surface of the particles. 3.2. Density and porosity The analysis of density of the set of samples provides information crucial for understanding the behaviour of thermal conductivity. Expected density of the mortars show a notable increase, linear in Fe2O3 content, due to the higher density of iron (III) oxide compared to the lime mortar. The experimental density of the studied samples, also linear with the iron (III) oxide content shows much weaker increase with Fe2O3 as compared with the expected values. Lower values of experimental density compared with expected values are the consequence of the increase of porosity due to the presence of iron (III) oxide particles. The pores in mortars are created during the process of curing due to evaporation of water. With the increase of the content of Fe2O3 submicronic particles, the amount water needed to prepare the mixture increases, thus the degree of the porosity generated by releasing of water becomes higher. B.Alordaetal. /OverheatingMitigationStrategiesAnalysis: AMediterraneanCaseStudy 93