Every year, 30 billion tonnes of sand and gravel are extracted from the ground to produce new concrete. At the same time, raw materials are running out and concrete rubble is often downcycled into cheap fill or road sub-base. Cement production alone accounts for approximately 8% of global CO₂ emissions. That needs to change.
We do not see concrete rubble as waste, but as a source for up to 100% circular concrete. Using our own machine, the Smart Liberator, we liberate the original raw materials from existing concrete: sand, gravel, and cement. From these, we produce Liberated Concrete: new concrete of the same quality as traditional concrete, but without new extraction and with significantly lower CO₂ emissions. The new standard in construction.
Recycled materials
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CO2 reduction
Recycled materials
We are building the new standard in concrete together. Discover projects featuring circular concrete, sector updates, and knowledge from our lab.
Using the Smart Liberator, we liberate the original raw materials from concrete rubble. The result is Smart Liberated Materials: high-quality raw materials that we process directly into circular concrete. Demolition sites are our source of raw materials. That is why we begin quality testing before demolition starts, so we know exactly what we are taking in.
FREEMENT® → High-quality recovered cement (fine & coarse)
FREESAND® → Pure circular sand
FREEGRAVEL® → Clean, liberated gravel
Voor het oogsten beoordelen we de betonkwaliteit via boorkernen en een eigen techniek die het DNA van het beton vaststelt. Deze data garanderen de beste oogst.
Grote brokken betonpuin van verschillende kwaliteit worden direct van de oogstlocatie afgevoerd en overdekt opgeslagen.
Het betonpuin wordt verkleind tot hapklare brokken per oogststroom.
Door middel van een aantal scheidingstechnieken wordt al het betonvreemde materiaal uit het betonpuin verwijderd.
Door de techniek in de Smart Liberator worden zand, grind en cement van elkaar bevrijd. SL Materials maakt hier gebruik van de verschillende eigenschappen van materialen in beton. Het grind wordt direct gescheiden met behulp van een zeef. Het resultaat is schoon grind: Freegravel.
De mix van zand en cement wordt door de Smart Refiner verder geraffineerd. Eerst scheiden we de zandfractie van het cement, dit noemen we Freesand. De mix van cementfines scheiden we in twee typen cement: de fijne en de grove fractie. Beter bekend als Freement fine en Freement coarse.
De twee Freement-fracties (fine en coarse) verwerken we in onze eigen cementfabriek tot nieuw cement. Zo garanderen we de laagst mogelijke milieuimpact.
Van de losse grondstoffen maken we nieuw beton. Dit beton is van dezelfde technische kwaliteit en heeft dezelfde certificaten als traditioneel beton. De prijs voor deze duurzame keuze is marktconform.
Up to 100% circular — the new standard we are realising today. Compare the environmental costs (ECI – Environmental Cost Indicator) and CO₂ (GWP – Global Warming Potential) of our concrete with regular concrete mixes. Our average score is already groundbreaking, and certain mixes go even further.
Find the answers to frequently asked questions here.
SL Materials is a Dutch concrete company that processes concrete rubble into high-quality raw materials for new, up to 100% circular concrete. Using our own technology, the Smart Liberator, we liberate sand, gravel and cement from existing concrete and process them directly into Liberated Concrete. We are based in Zaandam and grew out of the Rutte Group, an Amsterdam family business with more than 60 years of experience in the concrete sector.
Traditional concrete suppliers build with primary raw materials: sand, gravel and cement extracted from the ground. SL Materials recovers those same raw materials from existing concrete. With the Smart Liberator, we liberate them to a level of purity and quality equivalent to primary materials. The result is Liberated Concrete: circular concrete with the same certifications and performance, without new extraction and with significantly lower CO₂ emissions.
Liberated Concrete is our circular concrete product, made up of three proprietary raw materials: Freesand (circular sand), Freegravel (circular gravel) and Freement (circular cement). It meets the same standards as traditional concrete and achieves an ECI and CO₂ reduction of 63% to 80% compared with reference concrete based on average cement use in the Netherlands.
For demolition companies and buyers. Demolition companies deliver concrete rubble, which we process into raw materials. Contractors, prefab companies and project developers order the result: Liberated Concrete. We also work with architects, scientists and knowledge institutions such as TU Delft.
Our factory is located in Zaandam. We are active across the Netherlands, with a focus on Amsterdam and the surrounding area as a source of raw materials.
Whether it's circular concrete, a tender, or a potential partnership — or you simply have a question for our team — we're ready to talk.
Kruisbaken 2
1505 HS Zaandam
PO Box 9587
1006 GB Amsterdam
The Netherlands
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