The construction sector is undergoing a fundamental transformation in light of accelerating climate change and increasing resource scarcity. Buildings and the materials used in them account for a significant share of global greenhouse gas emissions and raw material consumption. Against this background, the demand for innovative, sustainable, and circular building materials is rising—materials that reduce the ecological footprint while enabling high-quality and durable construction. In the field of floor systems in particular, the development of new, material-efficient solutions offers considerable potential to meet climate and resource protection goals.

Conventional floor assemblies today typically consist of multi-layer screed systems that include a separation layer on the structural slab, thermal and impact sound insulation made of plastics or wood fibers, a cement- or calcium-sulfate-based screed, and a final floor covering. Especially wet screeds based on cement or anhydrite present several technical and ecological drawbacks: they introduce substantial moisture into the building, require long drying times, and are therefore only partially compatible with modern timber construction. Moreover, their CO₂ footprint—as well as that of the commonly used polymer-based insulation, separation, and covering layers—is unfavorable, making floor assemblies one of the most environmentally burdensome components in building construction.

Dry screed systems offer a potential alternative but are often associated with limitations. They tend to be labor-intensive to install, exhibit lower mechanical load capacity, are sensitive to moisture, and are not compatible with all common underfloor heating systems. In addition, many dry screed elements are made from materials with low sustainability, significantly limiting their ease of disassembly and recycling potential.

Historically, a number of mineral binders were used in addition to today's ubiquitous cement, but they were largely pushed out of the market due to faulty formulations, improper execution, and the specialized expertise required. In light of the rapidly growing number of timber-construction projects—where cement-based screeds are not only unsustainable but also regarded as aesthetically incompatible—there is renewed potential for a revival of these materials. The advancement and modernization of non-cementitious screed systems therefore represents a promising approach to addressing the ecological and building-physics shortcomings of current floor constructions. The aim of the project was to develop a fully recyclable floor system, both as a loose-fill screed material and as an additively manufactured system element. The use of mineral low-carbon binders and biogenic residual materials enabled the creation of novel, ecological, and cost-effective products that can surpass conventional cement screeds in terms of environmental performance, resource efficiency, and economic viability. The solutions developed enable a significant reduction in material and energy consumption, make use of waste streams, and—through their circular design—contribute to minimizing the ecological footprint in construction. At the same time, the products were designed to be widely applicable, making sustainable construction accessible to a broader population. Natural materials, improved indoor environmental quality, and material-efficient manufacturing methods can further enhance the standard of living in urban buildings.

The methodological approach began with a systematic analysis and evaluation of industrial processability of the newly developed materials—from raw material procurement to storage, mixing, and large-scale processing. Subsequently, mechanical strength properties and material parameters were determined to characterize product performance and compare it with conventional cement screeds. In parallel, an ecological assessment was conducted using product footprint methodologies to quantify the advantages of low-carbon binders, biogenic residuals, and recyclability. A calculable cost basis was established through techno-economic analyses. For the system element, additive manufacturing technologies were adapted and optimized to achieve further material and resource savings through geometric design. Finally, circularity concepts were developed to ensure complete recyclability and reusability.

The project generated important insights into the development of a recyclable screed system and significantly enhanced the technical expertise of the project team. The investigations confirmed that the developed screed can be successfully produced and that the required normative tests were largely fulfilled. At the same time, it became evident that low processing temperatures negatively affect the strength development of the binder—an expected but now empirically verified behavior for which appropriate mitigation strategies were defined. Additive manufacturing, however, did not yet achieve the necessary strengths for a normative system element; nevertheless, the CNC-based alternative developed within the project demonstrates that practicable solutions are already feasible. The gained material insights, particularly regarding good machinability, pave the way for future product variants. Based on the project results, sales materials, a systematic quality management framework, and further technical evaluations can now be developed. In addition, the project provided important momentum for market introduction: the documented sustainability advantages constitute a key unique selling point relevant to end customers, planners, and potential licensees. At the same time, normative and regulatory challenges were identified, particularly concerning alternative biogenic fillers whose use will require further standardization developments and additional performance verification. Future work will therefore focus on the development of the final floor covering as well as on validating material performance for different applications in order to complete the product portfolio and further advance market readiness.

Project management

ParaStruct GmbH: Georg Breitenberger, Dr. Gregor Metzler

Parastruct GmbH
Speckbacherstraße 39
A-6020 Innsbruck
Tel.: +43 (664) 310 42 21
E-mail: info@parastruct.org
Web: www.parastruct.org