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Urban mining of masonry

Denne idé er en del af The Circular Construction Challenge – Rethink Waste

Ebbe Naamansen
Ebbe Naamansen
3. oktober 2018

What makes the solution circular?

With this solution, we bridge the gap between waste from demolitions and the manufacture of new construction products. Today, the masonry waste is lost as a resource as it is crushed and used for low quality road purposes. The present solution turn masonry into a new heavy, inorganic building (HIB) material. By this, the masonry waste is retained as a resource in valuable construction products for the building industry.

— Which type of waste does the solution reduce?

Masonry from demolition and renovation of buildings.

By law, construction and demolition waste (C&DW) must be sorted out in ten fractions and one of these fractions is masonry including non-separable concrete e.g. mortar with cement.

— How large is the waste fraction that you reduce?

Masonry waste is estimated to be up to 10% of all C&DW in Denmark, resulting in a yearly tonnage of approx. 3-400.000 tons.

— How much can you reduce this fraction? How big is the upcycled part?

Approximately 25% of the masonry waste is lost during the preparation of aggregates due to necessary removal of non-acceptable surface products as e.g. paint containing metals or tar containing PAH and migrating contaminants as e.g. PCB; hence approx. 75% is recycled in the preparation of HIB products.

— Why is this type of waste fraction particularly important to reduce?

Masonry represents approx. 250 million tons of the in-use Danish building stock and contribute with up to 10% to the yearly Danish construction and demolition waste generation.

Today, a small, insignificant part of waste from masonry is re-used, but the major part of the waste is crushed and recovered for low quality road purposes.

Virgin materials for masonry are limited resources with an estimated capacity in Denmark for another 40 to maybe 70 years.

— How big is the CO2-reduction of your solution compared to a conventional approach?

By one to one replacement with HIB for concrete the CO2-reduction would be 25%, based on EPD’s for comparable existing materials. (Global Warming Potential is 216 kg CO2-eq./m3 for HIB and 290 kg CO2-eq./m3 for concrete).



What is the visionary aim of the solution?

The aim is to secure that the resources from masonry is no longer lost as a resource within the built environment, but is utilized in cost competitive products with a lower climate effect compared to competing products. By this approach, the anthropogenic stock of accumulated masonry materials in the built environment becomes a potential secondary resource in future urban mining.

— What makes the solution new or even radical?

Firstly, this solution is dealing with the construction and demolition waste originating from the existing building stock. The solution ensures, that a significant share of the present waste generation is returned to the construction industry, becoming available for the building industry and hence returned to the built environment.

Secondly, the solution is preparing for the future, where construction products must be designed for disassembly and take-back schemes. This is done in a way, that it can be re-use repeatedly and in a way, that is economically attractive.

Thirdly, solutions like this is a prerequisite for future urban mining. In addressing the challenges of primary resources supply, urban mining is a recognized strategy. In urban mining, the stock of materials in the built environment acts as secondary resources for future construction industry.

— How does the solution differentiate from other solutions on the market?

The solution differs in two ways. Firstly, the HIB material is a new construction material based on >90% recycled masonry and the product manufactured from this HIB material will be designed for re-use. 

Secondly, this new product is based on a production technique, which is well known and well established, as it is used to produce calcium silicate blocks for masonry in e.g. Germany, Poland and Holland. This means that large, appropriate production facilities already exist in Germany and other northern European countries, and that the construction details and building techniques including appropriate tools also exists, albeit not known in Denmark.

Thirdly, with an industrial production set-up, this solution will be supported by quality control and documentation.

With this approach - building on known technologies - many of the challenges connected with introduction of new products and techniques are already solved. 


Value creation

What value do you create for the user, the planet and society as a whole? 

The value proposition for the costumer is a product with characteristics comparable to similar products, but with lower climate effect.

For the planet and society, the solution ensures, that the resources embedded in the existing building stock is retained, reducing the demand for virgin raw materials.

— Who are the primary customers and users?

The HIB material is well suited for use as either loadbearing inner wall or slim cladding products for the façade. Target customer group is e.g. contractors with interest in building sustainable, tested and proven load bearing wall constructions.

Our primary product will be a building block for inner wall constructions in the construction industry. In Denmark, this market is at present supplied with building materials from primarily concrete and aerated concrete. In periods with delivery problems, the marked is asking for bricks. In Germany, comparable calcium-silicate building elements are used for inner walls.

A second product envisioned is a new design for façade cladding. This market is today supplied with many types of materials e.g. glass, metal, concrete, bricks, etc. HIB is a durable material with the potential of a novel, attractive appearance, reflecting its origin in masonry products.

— What is the target market for the solution, for example geographically?

The initial market for the solution would be Denmark with possible expansion to other countries with masonry in the building stock and waste stream. This would include the northern part of Europe.

In Denmark, the market driver would be the introduction of a new building material for inner walls based on waste but with characteristics similar to calcium silicate blocks and with a reduced carbon footprint.

Germany and other northern European countries are short in supply of sand, and this would be the marked driver for the use of aggregates from masonry in the calcium-silicate industry.

— What is the business model for the solution, and what makes it circular?

Produce and sell load bearing walls from the current flow of masonry waste at competitive prices to construction companies.

The linear value chain originates with the production of conventional construction products (masonry) based on virgin resources. The masonry is used in the design and construction of new buildings, and thus demanded for by the building owners/developers. After use of the building, the construction is demolished, the masonry waste fraction is crushed and used for low quality road construction purposes. Hence, the resource is lost for the construction industry.

In the circular value chain, the HIB approach is bridging the gap between the waste handling company and the construction product manufacturer, thus turning the waste handler into a resource supplier providing raw material for the manufacturer. Hence, the resources embedded in masonry waste re-enter the production line and becomes available for building constructions again.

In the circular value chain, the HIB products after use are disassemble for re-use. If the product must be discarded, it may be recycled in the production of new HIB products.

— What social, economic and environmental gains does the solution achieve?

The solution result in a significant reduced CO2 emission from construction industry and contribute to the necessary effort towards global warming. Transforming the entire 250 million tons of masonry in the Danish building stock into HIB products (over many years) and substituting concrete would reduce the emission of CO2 with a total of more than 10 million tons.

The limited availability of virgin resources is becoming more and more evident. With the construction industry as a major consumer of virgin raw materials, it is important to retain the resources within the industry. With the present solution, it is possible to return a significant part of yearly flow of masonry waste to the production line and to reduce the demand for virgin materials.

Manufacture of construction products based on masonry waste will introduce a cost competitive product on the market compared to products based on virgin raw materials. Deficiency of virgin materials will reinforce this difference.

The waste handling facilities as well as the manufacture facilities could be established within the vicinity of larger cities like Copenhagen. By this, the city become able to handle its own masonry waste, making it self-sufficient with raw materials for manufacture of HIB construction products and thus transforming the built environment in the city to a pool of resources for coming production of HIB products.

By gathering the waste handling and the manufacturing within the metropolitan area, transport distances are also reduced as need for distant transport of virgin materials is avoided.

— Which of the UN Sustainable Development Goals does the solution address?

This solution addresses several UN SDG’s.

The SDG #11 contribution from this solution is related to the reduction of waste production.

The SDG #12 contribution from this solution is due to the increased value in the recycling of construction waste as opposed to the traditional material recovery. This results on the long term in a more sustainable management and efficient use of virgin resources.

The SDG #17 is addressed by the fact that this solution includes the whole value chain and thus promote partnership based on common strategic approach to resource management.



What is the market potential of the solution? 

The present Danish market of approx. 300.000 m3 of load bearing construction products is significant and expected to increase.

Based on the accessible sources of masonry waste, a total of 300.000 tons of building material can be manufactured, equaling approximately 167.000 m3 of blocks or at least 830.000 m2 loadbearing wall.

The supply of raw material for the solution i.e. waste flow of masonry is a reliable and huge resource. The annual flow of approx. 3-400.000 tons is significant and expected to increase in the future. In addition, the in-use stock masonry in the present built environment is with approx. 250 million tons a huge hibernating resource.

— How big a market does the new solution appeal to?

In Denmark, the market would primarily be loadbearing inner walls in the construction of buildings. This market is at present of a size of 300.000 m3 per year. Other uses could be supplemented e.g. the use as façade cladding. This market is of a comparable size. Hence, the potential market matches the present flow of masonry waste. The total market is estimated to be 20-30 million EURO in Denmark.

A significant worldwide trend is the development of high rise buildings, especially in the larger cities. This is a rather new development in Denmark. Because of this trend, there is a rising demand for lightweight, durable cladding materials for the façade. In markets, where facades made of bricks have been dominating, this trend will underpin the market for a new durable cladding material for the façade.

The relevant market is the northern part of Europe. Due to the use of bricks in the construction of buildings a huge stock of masonry exists, generating a significant amount of masonry waste. This could serve as the basis for expansion of the concept.

— What does it take for the solution to reach the market and scale?

We have upfront with success tested the applicability of the technical approach to produce this new heavy inorganic building material based on raw materials from masonry.

Reaching market and scale is achieved in three steps securing proof of idea, concept and business.

STEP 1: Proof of idea - Initial proof of idea is tested on prototype level, involving a simple production and construction of a load bearing wall with HIB blocks. In order to confirm the value propositions of the solutions and price towards targeted customers.

  1. Investigate the robustness of the HIB material resulting from fluctuation in the composition by fluctuations in masonry waste supply, and the use of other waste fractions.
  2. Design one proper building block to meet the expectations of one customer.
  3. Prepare a prototype of the one new HIB product (lab scale).

STEP 2: Proof of concept – Thorough demonstration of the feasibility of the solution to meet the market expectations on a production like scale. 

  1. Demonstrate that we can provide sufficient amounts of specified aggregate materials for an industrial scale production
  2. Demonstrate the expected characteristics by a Material Passport, Life Cycle Assessment (LCA) and an Environmental Product Declaration (EPD).
  3. Prepare for CE-marking of new constructions products or -system, documenting essential characteristics according to the Construction Product Regulation.
  4. Demonstrate that the market prize would be within an acceptable range with a reasonable margin.
  5. Test manufacture of products in larger scale

STEP 3: Proof of business – Measures to upscale and industrialize the concept for a full market entry.

  1. Market analysis
  2. Establish production costs
  3. Calculate Business case
  4. Describe investment case
  5. Financing
  6. Establish production facilities in an industrial scale.


Ad 1) As the resource for aggregates are the actual waste fraction from demolitions, this is exposed to some fluctuation in the composition of components (clay/sand) and the effect of this fluctuation on the resulting characteristics of the HIB material must be investigated. Other waste fractions as e.g. fine fraction concrete (<4 mm) is of interest due to the fact that the process of recycling of concrete into new concrete surplus a fine fraction of concrete. Likewise, aerated concrete could be a relevant resource. In addition, reinforcement of the HIB material by introduction of e.g. fiberglass could be tested.

Ad 2) With HIB specifications in place, we need to design the proper construction products, which take the specifications of the HIB material into account. This may be bearing structures (e.g. back wall elements or blocks) or products for protecting the exterior of building (e.g. bricks, shells). To demonstrate the characteristics of the final product(-s), a mock-up of these possible HIB construction products should be prepared.

Ad 3) Based on the design of new inner wall elements a lab scale production of the new HIB construction product must be carried out. This is possible in Denmark or neighboring countries.

Ad 4) The masonry in existing building may be contaminated with chemicals from e.g. paint, tar and sealing foam. To ensure high quality aggregates of masonry from demolitions, the process must ensure that chemicals in the existing building are screened and removed efficiently before demolition or removed during the preparation of the aggregates. Likewise, the masonry from the demolitions may contain impurities as e.g. wood, plastic, metals, glass and stone wool. The content of these impurities must be reduced to an acceptable level in the processing of the aggregates. Aggregate delivery must comply with specifications on as well chemicals as impurities according to a declaration, which is acceptable for the production facility and the manufacture of products.

Ad 5) LCA and EPD is needed to verify the expected reduction in CO2 emission and document the environmental effects of the product for benchmarking with competing products. In addition, the product may be evaluated according to DGNB or other schemes for sustainability of buildings.

Ad 6) The quality of the aggregates, and the final construction element will be confirmed by an CE marking of both materials and products. When large scale production is established, the process and the resulting aggregates will be certified according to a Factory Production Control (FPC) manual and declaration.

Ad 7) As the present market prize for the masonry waste fraction is considerably below 0 EURO (varying from -15 to -10 EURO) and the market price of comparable virgin raw materials is approx. 10 EURO, this is a very reasonable starting point for a positive business case. The full business case must be calculated.

Ad 8) As no production facility of a proper size is present in Denmark, production could be tested in large scale in e.g. Germany.

— How can new technologies help speed up the production or scale the solution?

Production will be initiated with conventional autoclave technology based on petrochemical energy. However, we expect that shift in energy source to be at least partly microwave based, is a possible promising development, and this opens for energy based on renewable resources as e.g. wind or water. However, this is not a proven technology and must be developed further, before it is applicable for this purpose. This is a future development potential, which would further improve the positive climate effect of this solution.



Who is contributing to the solution?

— How does the solution involve the different parts of the value chain? And how does the solution include the value chain in order to optimize its own potential?

The solution involves the whole value chain. To make the solution work in an industrial scale, it is regarded as a prerequisite, that all relevant parts of the value chain somehow is involved, as their role is of importance for success.

Environmental consultants. At present, they perform the environmental screening. This work is of high importance as this is the base for an efficient recovery of the materials and sorting of the resources during demolition. In addition, the consultants will fulfill a new role in screening the resources of the existing building stock before demolition.

Demolition companies. At present, they perform the pre-demolition recovery of the construction waste. For the masonry to be used as resource for the preparation of aggregates, this surface cleaning and sorting must be quality assured and documented. In future, the demolition company will act as a disassembler for the re-use of building elements.

Waste handler. At present, RGS Nordic, as a waste handler, turn masonry into aggregates for road building purposes. In the future, we will prepare high quality raw material for the production of HIB products. The techniques to remove impurities and chemicals as well as the proper preparation of aggregates must be applicable to large scale operation.

Manufacturer. As this solution must be elevated to an industrial scale, the set-up of production facilities must be able to take into consideration the characteristics of the aggregates, the HIB material and the design of the product.

Entrepreneurs. The resulting building element is intended to be used in construction of future buildings. In this respect, it is very important that the operational issues around this use is optimized to make use practical for the construction workers.

— What partnerships are built around the solution, if any yet?

The road map for this solution to be marketed on the primary market in Denmark has three major steps. First step is proof of idea for the product(-s) and second step is proof of concept with test of industrial scale production facilities.

The Circular Construction Challenge would help facilitate step one and part of step two on this road map from idea to full market entry. We include a process plan with work packages for the completion of these two steps. For this to be completed we focus on resources, technology and design. To do this we need a consortium of four major partners:

Resource provider: This role is facilitated by RGS Nordic and lead on the project. During the project, we will demonstrate, that we can provide aggregates with a documented specification applicable to produce HIB based products.

Technology provider. This role is facilitated by Teknologisk Institut (TI) (en: The Danish Technological Institute): TI is technical advisor on the production of building elements from HIB and responsible for production set-up and design. During the project, TI will investigate and document the characteristics of the HIB material and set-up the prerequisite for waste fractions to be used in preparation of HIB aggregates. TI will document the LCA and EPD of HIB. TI will prepare the prototype(-s) of new HIB products for inner wall.

Design provider. We are looking for a partner, who can be the driver of the design process to develop the features of products. The designer contributes with knowledge on design for disassembly, construction industry and production processes to ensure, that these aspects are included in the design of products.

Customer. We expect, this partner to be an experienced entrepreneur, who design and build in Denmark. This partner contributes with knowledge of operational aspects of the building process and secure that these aspects are included in the design of new construction products.

We expect, that this work is done with a minimum viable product approach to ensure the operational features of the resulting products. In addition, we expect to involve a test facility for preparation of prototypes and a demolition company to ensure traceable waste material.