Chromium 6 (Cr6) is an important factor when recycling concrete. Elisabeth Helsing at Rise concludes in a recent article in Bygg & Teknik that the chromium 6 varies depending on:

• lower pH = leaching risk of Cr6 is tenfold when pH decrease from 12.5 to between 8-11

• higher carbonatization (due to porosity/smaller fraction size/aging etc) = increased leaching risk

Ways of decreasing leaching risk could be:

• to use ground granulated blast-furnace slag GGBS in the concrete.
• remove other conatminated materials from the concrete before recycling
• wash the concrete using a wet process
• covering the concrete aggregates under crushed rocks, asphalt or other types of isolation

Further reading:

• Article 2020-11-26 Bygg & Teknik Vad händer med sexvärt krom i återvunnen betong? (print version)

• Report 2019 RISE Krom i krossad återvunnen betong

What other methods do we have to decrease the risk of chromium 6 leaching?

Excess materials and other biproducts from construction and demolition projects are transported, sold, recycled and reused by numerous different companies.

1. Construction companies, contractors and haulages
   The largest part of the secodary market is managed by the companies involved in the generation of excess materials. The reuse of materials is usually limited to "clean" materials (mindre än ringa risk). Examples of companies: Peab, NCC, Svevia, Veidekke, Skanska, Sveab, NKR Demolition, Destroy, Märsta Förenade, Bellmans, ABT-bolagen etc.

2. Recycling companies, quarries and terminals
   Another large actors are specialised of different types of fairly clean materials. These companies usually crush or sort part of the materials. Examples of companies: Swerock, ABT-bolagen, Märsta Förenade, Veidekke, Skanska, DA Mattsson, Hans Andersson, Hummeltorp, RGS etc.

3. Landfills
   Landfills usually do not ever resell the material received. They receive all types of materials including completely clean material to hazardous waste. Examples of companies: Ragn-Sells,

4. Brokers
   Brokers of materials are primaily focused of matching excess supply and demand for "clean" materials (mindre än ringa risk) between different construction companies. The brokers usually add different types of quality tests in addition to brokering the deal. Companies includes: Massbalans, Massoptimering, Avfallspartner etc.

5. Market places
   Markets places are trying to match supply and demand by some sort of open or semi-open market place. The largest one in Sweden was previously Loop Rocks with over 18 000 registrered users, that site is no longer active. Companies today include: Massabyte, CCBuild, Pinpointer, Fleety etc.

Please suggest other companies and categories.

The first report from a project to create scientifically based environmetal risk assessment tools was just published. The goal of the project is to create an easy to use tool for risk assessment when you apply for a registration to use recycled materias with slighty higher pollution levels (ringa risk according to the Swedish regulation). Today, each local municipally have the ability create their own local risk assessment models which is highly detrimental for the use of recycled material in Sweden.

The project was financed by SBUF and more about the project can be found on their website. The report can be downloaded here. The report is written in Swedish.

Other similar reports in Sweden includes a risk assessment model for soil material from road ditches from Trafikverket (the Swedish Transportation Agency) and a similar report about bottom ash recycling in road construction from Avfall Sverige (the municpal waste management and heating companies).

The next step in the project to create a scientific risk assessment tool is to gather knowledge about the correlation between total content and leaching values for different materials. If suceessful we will be able to approximate the envrionmental risk for certain materials based only on total content levels.

Do you have any input and suggestions for the upcoming new projects?

The world's first fall-friendly and shock-absorbing bicycle lane is built in Lund in southern Sweden by Massbalans and Peab. The first test lane was constructed on the 13th of July 2020. It is a 300 m long test lane along Dalbyvägen, between Östervångsvägen and Pedellgatan. Lund is already one of the premier ebicycle cities in Sweden and this lane one small step towrdas improving that. The lane will be upgarded during the upcoming weeks in October and replaced with a new version in the spring that is further improved.

​The number of serious injuries among cyclists and people walking exceed the number of serious injuries among motorists. The fall-friendly and shock absorbing asphalt will be approxiamately 4-5 times softer compared to normal asphalt. The cirtical fall height (when serious injuries are likely) will increase from 20 cm (normal asphalt) to 85-100 cm for rubber asphalt. Accroing to previous studies the rolling friction will not increase and most cyclists prefer the rubber asphalt feeling when biking. Here is a report from a previous study financed by Vinnova.

​The research project is led by RISE and is partially financed by Resource/Energimyndigheten. The parties involved in the project is addition to Lund also Peab Asfalt, Massbalans and Genan, the worlds largest producer of rubber granulate.
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The rubber asphalt contains 11-17 weight percentage (20-30 volume %) rubber granulate of the asphalt mix. Here is a material specification from Genan of the rubber granulate describing the leaching values from rubber granulate (drinking water quality). By reusing rubber in the asphalt we can create a new innovative product and at the same time save some rubber from being incinerated.

Read more about the project here. Do you know any other similar projects around the world made by rubber asphalt or similar products/solutions.

The expert group for the circular construction industry presented its first report last week. The expert group consists of 40+ construction companies, environmental consultants, environmental inspectors and large procurers and is part of the Swedish government's Delegation for Circular Economy. A condensed presentation was given to the members of the delegation.

Some of the top suggestions that the Swedish government should do include:

1. Involve of the construction industry and a broad group of experts when designing the laws and regulations to make sure that the goal of the Swedish government's strategy for Circular Economy is enforced as efficiently as possible.
2. Create a new handbook for recycling and a nationally approved guideline (allmänna regler) for recycling of soil, rocks, rubber, concrete, bottom ash and other aggregates to facilitate a circular flow of resources.
3. Create a guideline or directive that clearly defines that bi-products from tunnel drilling is considered a bi-product and that this valuable and usable exceess material is not waste.
4. Create a national guideline for end-of-waste-criterias, when waste becomes a product,
5. Implement the EU exemption for non-polluted soil to be reused without being considered waste.
6. Use digitalization and tarceability to create effective tools for environmental supervision.
7. Encourage regional planning of stone material supply and demand.
8. Consider the ethical foundation for the environmental decision making. Align the design of the rules and legislation to serve the intention and purpose of the environmental goals in Sweden.

Topics that are considered to be subjects for upcoming meetings:

• Organized crimes and environmental supervision.
• Excess material logistics when building houses.
• Review of drafted parts of the new handbook for recycling
• Recycling of sulfidic rocks in Sweden, Norway and Finland
• The government investigation about how environmental supervision should be organized.
• Digital traceability and standards using BEAst.

What do you think should be the focus if we are to elimiate the institutional bariers against recycling?