Development of enclosure masonry walls made with improved thermal performance blocks

Abstract

Energy savings/efficiency and environmental sustainability in building construction are motivating the development of new masonry products with these concerns in the last decade. This paper describes the development of a new masonry wall with improved thermal and mechanical behavior, made under the scope of a national/Portuguese research project. One of the main challenges of this project was to conciliate/maximize the thermal resistance of the wall without significantly impairing its mechanical strength. Since the blocks have the most important/influential role in the behavior of the masonry walls, the work performed was focused on the development of a new block with limited width (250 mm), however with improved thermal insulation and enough mechanical strength. An experimental campaign, involving factory productions, lab tests and numerical/optimization simulations, was made to support/validate the thermal/mechanical characteristics of the new block, including masonry assemblies made with these blocks. Several mixtures of lightweight concrete, with dry densities between 700 to 1100 kg/m3, and different proposals for the internal geometry of the block were developed in order to achieve the best possible thermal/mechanical behavior for the block. The final solution obtained was a vertical perforated block with an optimized internal geometry, made with an open structure lightweight concrete with dry density (near 800 kg/m3) and low thermal conductivity. The results obtained from lab tests and numerical simulations demonstrated that this new block has a high potential to constitute masonry walls with improved thermal behavior and enough mechanical strength. However, some adjustments are still needed, highlighting a better stabilization of the concrete thermal/mechanical properties after being submitted to the manufacturing/casting process of the blocks (vibration/compression).