High-Performance Compressed Straw Board (HPCSB): A New Generation of Building Materials

According to the Global Footprint Network, we need the resources of 1.6 planet Earths to support the current lifestyle. Generations to come will suffer; therefore, the UN's Sustainable Development Goals provides a chance to promote a sustainable growth for all. This project is in line with the 17 goals to transform our world (i.e. goal 11 - Sustainable cities and communities). If agricultural waste can be 'upcycled' via a cutting edge, state of the art manufacturing process, they can be re-introduced on a large scale as modern and worthy of ample adoption for their qualities of performance and sustainability by the construction industry. Straw biomass use with an industrially feasible approach for manufacturing of construction products is an important element of the transition to low-carbon economy.
This project aims to introduce a greatly improved, lightweight variant of compressed straw board (CSB) for the construction industry, strong enough to accommodate structural loads both in tension and under compression. It will exploit a novel concept of industrially efficient and highly selective removal of defects in straw feedstock, using scalable methods and tools. The optimising of the straw feedstock, i.e. removing its defects and improving its surface, will substantially enhance the performance of CSBs by 50%. This project is focussed on use of wheat straw (Triticum aestivum). However, the protocol should be applicable to other species in the family Poaceae, such as other cereal straw and, in particular, Norfolk reed (Phragmites australis). The residue left after separation of the grain from the stem of wheat straw is 16-20 million tonnes annually. Not all of this can be sent to livestock farms. Up to 10 million tonnes of wheat straw every year is either ploughed back into the land or put to very low-grade use. Our research can bring an end to the waste of this potentially valuable resource.
The motivation for this research is derived from our developed and demonstrated pilot results, where an environmentally friendly pre-treatment was employed, which led to an improved interface between resins and the micro porous surface of straw. The results showed that chemical functionalities of various surface profiles (i.e. when cut longitudinally in half, inner and outer) altered the bonding performance, i.e. extractive, waxes, and silica concentrated on the outer surface, inhibited the bonding quality which translates into an inefficient stress transfer under load. The pre-treatment however, could significantly: (i) modify the surface of straw with the partial removal of extractives, waxes, and silica which made it more compatible with water based resins, (ii) cause the microcellular structure of straw to expand and hence induce the mechanical entanglement on a micro level upon resin solidification. Therefore, these pilot results have given us the motivation to upscale the pre-treatment.

The aim is to generate impact through strategic links between stakeholders to confront the challenges posed by: 1) Climate change (i.e. global warming); 2) Growing awareness (i.e. conservation of natural resources); 3) Better societies and inclusive lifestyle (healthy living); 4) Circular economy (i.e. materials and energy pathways).
Environmental impacts: Approximately 1 kg of straw sequesters 1.35 kg of carbon dioxide. It is reasonably anticipated that use of agricultural by-products (straw) will cause a reduction in CO2 emissions from industrial activity in the UK, because of the low energy requirements of the proposed manufacturing process by comparison with those caused by the manufacture of conventional building products, i.e. aluminium, cement and steel. In the next five to 10 years renewable materials will play a crucial role in the construction industry.
Economic impacts: The research can lead to patents of great economic value, to be licensed to other countries of the world. The construction sector considered in this project is strategic to maximise the impact, as it accounts for 30% of industrial employment in the EU, with 3 million enterprises, 95% of which being SMEs. For 17% of EU SMEs, green products or services represent more than 75% of their annual turnover, whereas for large companies this figure is 6-10%.
Impacts on the construction sector: Increased project sustainability credential, intensifying the profile of bio-based construction materials and reduced project cost all are significant impacts on construction. A responsive strategy with a set of communication and dissemination activities (e.g. workshops, project website, mailing list and social media tools) will be used to achieve this impact. Vibrant messages will be conveyed to professionals and the broader public, about the benefits and the methods to use bio-based materials in construction.
Impacts on SMEs/technical consultancies: The outcomes from this project can inform decisions on potential investment priorities for these companies. The availability of reliable work to inform business priorities and provide insights that inform development and targeting of products can be of particular value to SMEs since in-house resources are typically limited. The establishment of production capacity to manufacture the new generation of CSB proposed in this project can equip UK SME's with the possibility of offering the construction market a high performance bio-based building product.
Impact on other academics: The result of fundamental research from this project will be wanted by academic groups in construction and sustainable materials. Conferences organised in Grow2Build at BUL will aim to create opportunities to make plans for further collaborative projects, assembling related cross disciplinary researchers and potential beneficiaries. The tangible results of the scientific research will be disseminated in the scientific peer-reviewed journals of composites, materials science and civil engineering sectors as well as the professional specialised forums. It is in the interrelationship between these sectors that the results will have value.
Impact on early career researchers: The PDRA along with other students that become engaged in the project will acquire valuable experience of the material science experimental and analytical techniques. In addition, they will gain experience in analysing/interpreting experimental data and writing technical reports or scientific publications. The skills obtained as a PDRA researcher working on this project will also be valuable to industry.