TNO develops new approach towards more sustainable concrete

The Netherlands faces a major task to drastically reduce CO2 emissions while coping with materials scarcity. Construction plays an important role in achieving the climate goals. In fact, the sector consumes half of all raw materials in our country, accounts for 40 percent of energy consumption and one-third of total CO2 emissions. Since half of all building material is concrete, there is much to be gained by making it more sustainable. TNO has developed a new approach and tool for this purpose, focusing in particular on using more sustainable types of concrete and reusing secondary raw materials. So far, these materials are not yet used on a large scale, mainly because application in concrete structures is complex: on the one hand, the concrete we have always known is changing, and on the other hand, there are more and more requirements; a structure must not only be safe and affordable, but also sustainable and circular.

Resource based engineering with MIMO

The new approach, in full Material Driven Multi-criteria Design Optimization (MIMO), is a design approach for more sustainable concrete that helps make optimal choices for multiple stakeholders: clients, construction companies, contractors, demolition contractors, recyclers. The MIMO approach forms a hub between data, models and smart optimization software. Information about locally available raw materials is central: "resource-based engineering. For example, the material properties of elements or granules from concrete rubble are determined, the data. At the same time, all requirements are specified, such as minimizing environmental impact and costs but also maximizing safety - after all, we want safe concrete structures. MIMO then uses calculation models to process the data into design scenarios that optimally and measurably meet the various requirements simultaneously. The user can now easily weigh what the best scenario is based on requirements and schedule.

Significant CO2 reduction through optimal use of secondary materials

Every year, some 22 million tons of stony waste is released from demolition. At present, only 2 million tons of this is reused, while we produce 33 million new concrete annually. TNO's assessment is that MIMO can support weighing up and optimally deploying reuse and recycling from construction and demolition waste. 'This stream accounts for more than half of current concrete production!' says Siska Valcke of TNO, an expert on circular concrete. 'In optimizing reuse, also for CO2 reduction, thanks to MIMO, two main strategies soon come into the picture: full reuse of elements from existing concrete structures and deployment of crushed masonry rubble would reduce an estimated 0.75 to as much as 1.25 million tons of CO2 per year,' Valcke explains.

Putting more information to best use for the industry

MIMO ties in with initiatives that the sector is already developing, such as new types of concrete with less cement, leaner construction and demountable construction. Parties can weigh different strategies for sustainability and circularity and combine them optimally. The new approach is now being tested as a tool on a limited scale. This shows the advantages the approach offers the parties involved if it is used at different stages in decision-making and design. Constructors can include the capabilities and data of suppliers, demolition companies and recyclers in their design at an early stage to arrive at an optimal solution. Clients gain insight into solutions that measurably meet their requirements and that they can transparently compare. Contractors and demolition companies gain measurable insight into the costs and benefits of smart dismantling and storage of materials.

Groundwork laid

MIMO is set up in such a way that new design questions, requirements, data and models can be added and linked so that it can be used more widely step by step. Siska Valcke: 'Our approach delivers the most value if cooperation in the concrete sector starts to grow: companies, governments and knowledge institutions. Then MIMO can be an enabler in the chain-wide transition to more sustainable concrete. The foundation has been laid and from here we can work together with the sector to make the transition to large-scale resource-based engineering towards more sustainable concrete.'

TNO will June 14, 2022 on Concrete Day presenting the approach.