Sustainable Mortars with Slag for Green Facades

The energy crisis in the world is intensifying again in the last years. Since buildings consume about 42% of total energy, much more than industry and transport, it is logical that research in the world should be directed towards energy-efficient buildings and materials. They reduce the workload of heating and cooling systems, thereby contributing to saving energy and money. At the same time, a comfortable and pleasant temperature and the necessary thermal comfort are provided in the buildings and facilities. In this context, research in recent years has been reduced to new light composite materials, which replace part of the aggregate or cement with vegetable or polymer materials. Also, various waste materials from the industry, such as slag or ash, as well as natural materials such as perlite, vermiculite, etc. can be used. All of them contribute to obtain lighter composites, with a lower density, and a much more favorable thermal conductivity, which makes them suitable for use in new sustainable energy efficient buildings. For the purposes of this research, different types of thermal mortar samples with slag were examined, in order to prove the physical-mechanical and thermal properties of the mortar. The actual Macedonian standards were used for the tests. Compressive strength of the thermal mortar is 1.45 N/mm2, which includes it in the CS I class of mortars, whose compressive strength ranges from 0.4 – 2.5 N/ mm2. The absorption of water leads to the conclusion that the thermal-mortar can be favorably used in external atmospheric conditions, i.e. for facades. The thermal conductivity of the tested samples is λ = 0.16 W/m·K. This makes it a better thermal insulator than classic cement mortar by almost 11 times, and by 3.6 times than gypsum mortar. By increasing the volume mass (density) of the thermal mortar, the thermal conductivity increases. Tests showed that with an increase in density by 5.56%, the thermal conductivity increased by 9.5%. Similarly, for an increase of 9.26% in the density of the thermal mortar, its thermal conductivity increased by 20.1%. Furthermore, based on the obtained results, the paper points out the possibilities of applying this type of innovative thermal insulation material, as well as the method, details and technique in construction of new and reconstruction of existing buildings.