Reconstituted stone engineered to form sustainable cladding

Abstract

The use of stone throughout the years has developed from structural load-bearing blockwork to thin skin cladding. This development has shifted the use of stone to an exterior decorative feature which over the past years has helped to maintain the traditional aesthetic homogeneity due to the increased use of concrete brickwork. However, natural stone is a limited resource so alternative construction material must be identified to pave the way for a more sustainable construction industry. This research paper focuses on the use of reconstituted stone panels for cladding. Firstly, the investigation of the quality and performance of reconstituted stone as cladding material, and the effect of using polyurethane as backing. Secondly, the design of the fixing systems proposed. To verify the mentioned properties and performance criteria, the latest design mix was used to produce reconstituted stone panels of 800x800x30mm. These panels were manufactured and supplied by Halmann Vella Ltd. and were used to conduct a number of tests to establish numerical values to characterise material properties. Specifically, flexural strength tests were carried out to address material variability and to also check the flexural stress at midspan under uniformly distributed design load, such as wind load. In addition, rupture resistance tests were also carried out to analyse impact performance of a panel. Each of the previously mentioned tests were also conducted for specimens with polyurethane foam backing. A comparison of the results between the coated and uncoated specimens was obtained to understand the effect and use of a cladding backing material. In order to investigate the different fixing systems proposed, the adhesion and bond strength between the substrate, adhesive and the fixing connection were analysed using the Pull-out testing method. From the experiments it was concluded that polyurethane strengthened the reconstituted stone cladding panels, however its pull-out strength to the mechanical fixings was considerably low when compared to the estimated design loads it is required to withstand.