IN-PERSON Barcelona. Section A

Abstract

One approach to decarbonizing cities is the appropriate choice of building materials. Renewable resources could reduce and bind CO2 in the long term. However, increasing shortages of raw materials and extreme price increases, even for renewable resources such as wood, underline the urgency of exploring new affordable, regional and renewable resources. The “StrohGold” research project, funded by a German federal ministry, therefore aims to develop straw – a by-product of agriculture – into a load-bearing building material. The straw is being processed, provided with additives, thermally treated and pressed in such a way that biodegradable bricks can be produced. The investigations focus on two approaches: the addition of starch and the activation of the straw’s own lignin combined with the addition of further lignin. Load tests demonstrate a fivefold increase in compressive strength compared to large straw bales (density: 200 kg/m3), which are used for building constructions. With the comparatively high load-bearing capacity and rigidity, not only new buildings but also urban redensification projects, e.g. building extensions, can be realized with standard wall thicknesses of approx. 40 to 50 cm. The simple monolithic exterior walls, which can be erected in a traditional manner, can provide both load transfer and thermal insulation thanks to the insulating properties of the straw. As – compared to conventional straw-bale masonry – only minor further deformations are to be expected after completion, windows and doors can be installed shortly afterwards and a protective layer of plaster can be applied without the risk of significant cracking.