Circular Economy

Circularity and sustainable building

In a world where resources are precious, we need to use them carefully. This approach is at the centre of our efforts to make our products recyclable. As concrete can be fully recycled, our industry is in a good position to do so.

Our circular economy strategy is clear: we want to save raw materials and contribute to significant CO₂ savings. From improving recycling technologies that enable the reuse of concrete in new buildings to formulating cements with reduced clinker content, we are setting new standards for innovation. By looking at the entire life cycle of concrete, we are creating a sustainable future that respects the limits of our planet's resources.

What is a Circular Economy?
A circular economy is a model of production and consumption designed to preserve and regenerate. It is based on three principles:
- Prevention of waste and pollution
- Recycling of products and materials
- Regeneration of natural resources
Read also the definition by the Ellen Macarthur Foundation

Leading the way in the circular economy

Heidelberg Materials is strengthening circularity along the entire value chain. We also see the increasing importance of resource efficiency and closed material cycles as an opportunity to develop new business models and drive sales of sustainable products. Through our subsidiaries, we are already active in the recycling business in several countries and are working on the targeted processing of concrete components, as well as their recarbonation and reuse in concrete as a building material.

As part of this, we are investigating the use and reuse of all rock fractions that are produced in the recycling process. By 2030, we want to offer circular alternatives for 50% of our concrete products. This will allow us to conserve virgin resources and meet our customers’ increasing demand for sustainable building materials in the future. Building material recovery and concrete recycling will make a significant contribution here and are crucial to us achieving our sustainability targets.

evoBuild: unified product line for sustainable construction

Using recycled materials to conserve resources

Demolition concrete is still partly disposed of at landfill sites today or is often used in road construction for compaction or as a frost protection layer. This does not do justice to the building material’s value-adding potential or its complex, energy-intensive production process. More can be achieved through recycling.

On the one hand, this saves primary raw materials such as sand and gravel, which are used as aggregates in the production of concrete. And on the other hand, the fine materials obtained when breaking up and sorting waste concrete can be separated off as so-called cement paste (recycled concrete paste, RCP), carbonated, and then returned to cement production as an alternative cementitious raw or filler material.

Recovery of all concrete components

Heidelberg Materials is working intensively on innovative methods for processing, reprocessing, and returning demolition concrete to the construction cycle as a valuable material. The opportunities afforded by innovation in this area are great. In line with the European Union’s circular economy targets, Heidelberg Materials is also involved in projects researching the reuse and recarbonation of recycled building materials. One such example is the K4 project (Carbon dioxide reduction through low-lime clinker and carbonation hardening), funded by the German Federal Ministry of Education and Research (BMBF), in which, over four years, six partners are investigating the permanent sequestration of CO₂ in cements and concretes. For example, paving stones can be produced that absorb an increased amount of CO₂ from the environment. As part of the innovative ReConcrete-360° process concept, waste concrete is crushed and sorted almost homogeneously into its components to obtain not only sand and gravel but also hardened cement paste. The latter can be reused as a valuable low-carbon raw material in clinker and cement production, replacing natural limestone as a raw material – in support of circularity. In addition, the hardened cement paste can absorb and permanently bind CO₂, thus acting as a carbon sink.

With ReConcrete-360°, we have been able to show on a pilot scale that concrete can be fully recycled without loss of quality through selective processing of its individual components. This innovative concept, which received the German Innovation Award for Climate and Environment in 2022, is now being used on a large scale at our plant in Poland.

Concrete recycling

Red truck on a road, several people in high-visibility waistcoats standing next to it

A twofold contribution to the circular economy

With a clear focus on our commitment to a circular economy, Heidelberg Materials has accelerated its recycling activities in the greater Seattle area: The opening of a new recycling site in Redmond and the acquisition of a recycling company in Woodinville in 2022 enabled us to expand our range of circular products and sell products made from 100% recycled materials.

The Heidelberg Materials team in North America works closely with our customer Rainier Asphalt in Redmond, Washington. Rainier is one of only a few companies in the region that favour concrete deliveries in volumetric vehicles. Volumetric trucks allow concrete to be mixed and poured directly at the construction site in the quantities actually required, which means that no concrete waste is produced.

As a pioneer in the local market, Rainier also carries out concrete work and deliveries using 100% recycled aggregates – produced by Heidelberg Materials. Initial trials have shown that the concrete produced using recycled concrete aggregates (RCA) precisely fulfils the performance requirements and specifications demanded by the work in question. The cooperation between the two partners is therefore making a twofold contribution to the circular economy.

EcoBlock+

Large stackable concrete blocks form a wall

Efficient use of leftover concrete

On delivery to construction sites, ready-mixed concrete must be used within a very short time – or else it hardens. A key concern for concrete manufacturers is therefore how to efficiently use concrete residues that arise when customers do not consume all of the concrete supplied or from a surplus during production.

Our Lithuanian subsidiary Heidelberg Materials Lietuva Betonas UAB has found a sustainable solution for the excess material and created a new product in the process: under the EcoBlock+ label, standardised, stackable blocks are cast from leftover concrete. These blocks are suitable for a wide range of building projects and for use on construction sites. They can be combined flexibly and without binders to form durable constructions but can also be disassembled again afterwards and used elsewhere. The recycled concrete thus saves material and time.

Alternative fuels

Many by-products from other industries serve as valuable raw materials for Heidelberg Materials. We use these resources as alternatives to finite natural raw materials and fossil fuels in the production of cement. In this way, we are helping to conserve resources and solve the problems associated with waste disposal faced by municipalities and industrial companies near our plants. At the same time, these efforts are also reducing our CO₂ emissions. We want to increase the proportion of alternative fuels in our fuel mix to 45% by 2030. In 2023, the figure was 29.9%. The waste-based biomass used, which accounted for around 13% of the fuel mix in 2023, makes a special contribution here, as it is considered climate-neutral under European legislation. By 2030, we intend to raise this figure to 20%.

Alternative fuels are generally waste that either cannot be recycled in full and would therefore be uneconomical to recycle or can only be incinerated for energy recovery to ensure safe disposal. In this scenario, co-processing in clinker kilns for thermal energy recovery offers a practical alternative, as it not only uses the waste’s calorific value but also embeds its mineral components into the clinker as raw material. The waste is co-processed without any residue in a burning process that meets the same strict emission standards as those set for waste incineration plants. About 90% of our cement plants have environmental management systems. As such, they are subject to regular internal and external audits, which cover toxic emissions and hazardous substances as well as waste.

Reuse in cement plants has proved to be a safe means of recovery, particularly for various types of hazardous waste. The high temperatures of over 1,450 °C and the long incineration period in the kilns ensure that all harmful components are completely destroyed. This has been confirmed by measurements taken by independent state-certified institutes.

Waste

Active waste management and the associated reduction of environmental pollution are two core objectives of a circular economy. Our main focus in waste management is on minimising production waste and reusing by-products from the production process in expedient ways. For example, kiln dust that is a by-product of clinker production is generally reused as an alternative raw material in the production of certain types of cement. This dust has to be removed from the kiln systems at several facilities in order to prevent disruptions to proper kiln operations. In some exceptional cases, the locally produced cement type portfolio prevents us from fully recycling the dust. A second possibility for us is to use the kiln dust as a raw material for the production of special concretes. If no other option is available, it can be deposited in underground landfill sites in a controlled process. The local operating permit at each plant specifies the allowable amount of process-related waste products and how they are to be used. Our R & D department regularly checks the by-products arising from production for their suitability for various applications, either in our own operations – as cementitious material, for example – or in the processes of industry partners.

Excess concrete is also generally reused in our plants: either as fresh concrete or cured in the form of building elements, which are then used, for example, to secure construction sites. If concrete cannot be reused fresh, it is still possible to crush the completely recyclable concrete and return it to the production cycle. With digital solutions such as our OnSite app, we also support our customers in demand planning and ordering to avoid overproduction in the first place.

Water recycling

In addition, we place a significant emphasis on water recycling – a key aspect of our environmental sustainability efforts. At our ready-mix concrete (RMC) plants, we capture the water from truck washouts and combine it with solid residues to be reused in concrete production. Water from our quarries is also collected for use. Our cement manufacturing process operates with a near-zero wastewater footprint, substantially reducing our environmental impact. For a deeper understanding of our water sustainability practices, please visit our Environmental Sustainability page.