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BIA-Brukerstyrt innovasjonsarena

Dare2C - Durable Aluminium Reinforced Environmentally-friendly Concrete Construction

Alternative title: Dare2C - Durable Aluminium Reinforced Environmentally-friendly Concrete Construction

Awarded: NOK 6.6 mill.

Project Manager:

Project Number:

269767

Project Period:

2017 - 2021

Funding received from:

The main goal of the DARE2C project was to develop more environmentally friendly and durable types of concrete. The project is divided into two parts: 1) The target is to use bauxite residue (BR), one of the world's largest waste streams, as clinker replacement and/or as a supplementary cementitious material to reduce the CO2-footprint of the cement as well as avoiding bauxite residue deposition. 2) The target is to replace today's steel reinforcement with aluminum reinforcement. This to be done by developing new cement mixes that are compatible with aluminum, followed by development of aluminum reinforced concrete designs. The advantage is that aluminum, as opposed to steel, has a good corrosion resistance towards air and sea water, which makes the concrete more durable and allows slimmer concrete constructions. In addition, aluminum is recyclable and lightweight as well as an enabler for the use of low-CO2 cements. Part 1) The R&D project had one breakthrough in terms of reducing the alkali level in bauxite residue (BR) using acetic acid. Test results showed a reduction in the sodium oxide content of Hydro's BR from 9.6% to <1%. The process appears to be simple, and it can enable the use of BR as a partial cement replacement in concrete. This alkali reduced BR has promising properties as a pozzolanic material, and initial investigations also indicate that concrete based on alkali reduced BR is compatible with aluminium. Opportunities for continuing the research on BR will be considered, following up on the promising results from the pre-processing route developed. Part 2) DARE2C was based on the idea that using aluminium as reinforcement in concrete could enable the use of more environmentally friendly cements. Aluminium cannot be used as reinforcement in today's commercially available concretes because it corrodes in the highly alkaline environment. Likewise, the development of more environmentally friendly clay-substituted (>35%) cements is hindered by the resulting low alkalinity of these concretes, which is not compatible with regular steel reinforcement. Thus, DARE2C aimed at hitting two birds with one stone by combining aluminium reinforcement with low-CO2-cement-based concrete. In a standard concrete, the cement will produce calcium hydroxide and a mixture with high pH. The project has performed tests showing that by replacing approx. 55% of the cement with a cheap pozzolan as blue clay calcined at 800oC, reduces the alkalinity. This concrete mix can be reinforced with aluminum, and will provide a durable, maintenance-free construction with extraordinary service life. The system is more environmentally friendly than ordinary concrete, and the CO2 footprint is further reduced through the carbonation, which a higher porosity allows. During the project period, properties of various aluminum alloys, including scrap-based metal, have been studied. The properties are adhesion, thermal expansion, elasticity, formability, durability and compatibility with the concrete paste . The materials properties show that a composite construction seems favourable for various floor and bridge constructions. One composite concrete / aluminum element has been delivered to Sunndal Aluminium Plant's new RoRo quay to demonstrate that an aluminum-concrete construction can be a good solution in a heavily loaded quay floor in a corrosive environment. The construction has been validated through lab test. Furthermore, the project has delivered concrete slabs reinforced with aluminum to a universal designed entrance ramp at the Geitbåt-Museum in Valsøyfjord. Façade elements are prefabricated to highlight new architectural possibilities with aluminum reinforcement and have shown that design patterns can be made from used melted engine blocks. Demonstrators, examples of positive environmental impact and active presentation of the concept in various forums, have been met with a lot of enthusiasm, interest and have given the project positive coverage in magazines and various media. Part 2 of the project will be continued in a new IPN project; its goal is to commercialize aluminium reinforced concrete structures. The DARE2C project consortium had the following partners: Norsk Hydro, Norcem, Veidekke, Overhalla Betongbygg, SINTEF and NTNU.

The main outcome is the development of a calcined clay-based concrete with lower carbon footprint than currently commercially available cements. It is compatible with (scrap-based) aluminium and has been realized in several small-scale demonstrators. The concrete's main features are that it - requires far less energy and CO2 emissions to produce - enables slimmer concrete structures - is maintenance-free - can absorb and store CO2 during use phase The partners have built up competence, networks and a broader material and process understanding through the project. The collaboration will continue in a new IPN project with the goal to commercialize of aluminium reinforced concrete structures. Opportunities for continuing the research on red mud as a supplementary cementitious material (SCM) will also be considered, following up on promising results from the pre-processing route developed in the current project.

The DARE2C project's main goal is to develop a new type of reinforced concrete that is more durable and more environmentally friendly than existing qualities. The aim is to replace about 30% of the clinker with less CO2-intensive cement constituents. The new constituents shall be produced from waste materials. It is expected that the new concrete may be considerably lighter than today's concretes. The main challenge is to ensure that the new concrete constituents are compatible. The concrete strength must be sufficiently high and the strength must be maintained throughout the expected lifetime of the concrete constructions. The R&D work will focus on sourcing the right raw materials, making new concrete blends, producing concrete samples and testing their properties. If successful, the project will not only provide an attractive new lighter concrete with reduced CO2 footprint, but also lead to new large markets for what is today considered waste materials. Partners in the project are Hydro ASA, Norcem AS, Veidekke Entrprenør AS, Sintef Byggforsk and NTNU

Funding scheme:

BIA-Brukerstyrt innovasjonsarena