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I'm working on an EPD about concrete and I don't understand the modelisation of the end of life of concrete. 25% of the concrete is buried in the ground and 75% is recycled, let's say 25kg of concrete is buried and 75kg of concrete is recycled.

I used the flow "market for inert material landfill" to modelise the 25kg of concrete buried but in the results, I can't find for the indicator "waste - non-hazardous" the mass of concrete that is buried. Instead, I have a small value that is obviously not correct. Do I really have to link the mass of concrete to a flow, or can I just add in my EPD in the box "C4 waste non hazardous" : 25 kg and suppose that the market for inert material landfill is relative to the construction of the structure where concrete will be buried ?

For the recycled concrete, I have the same question but with a different flow. I used the flow "treatment of waste concrete, not reinforced, recycling" but I also have a very small value that is not corresponding to the recycling of 75kg of concrete. Is it the same reflexion ? Do I just have to add in the box "C4 output flows - materials for recycling" : 75kg and suppose that the flow "treatment of waste concrete, not reinforced, recycling" is for the action of recycling concrete ?

I'm sorry ,I'm a bit confused and I hope you'll understand my questions !

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Dear Marie,

The inventory indicator that you mean is non-hazardous waste disposed. So it tracks the waste mass that is disposed and it does not track waste mass in between to avoid double counting. The process "market for inert material landfill" is delivering a product flow that has not yet reached the last stage (disposal), because the process itself is not a waste treatment or disposal process. When you calculate it, it will be only the cradle-to-gate. You can use in your foreground model for example the "treatment of inert waste, inert material landfill | inert waste, for final disposal". This process will have "inert material landfill" in the input and it will have "process-specific burdens, inert material landfill | process-specific burdens, inert material landfil" in the supply chain which contains the elementary flow "Transformation, to dump site, inert material landfill" and this elementary flow contributes to the impact category for "Non-hazardous waste disposed" (about 1kg for 1kg of inert material landfill).

Best wishes,

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As far as I know (have not double checked it), there is no concrete modelled as a recyclable (flow connected to recycled content cut-off processes) in the background data from ecoinvent cutoff system model or the EN15804 add-on.

I don't know the technical details of potential concrete recycling. But in Cutoff/EN15804 you could model the recyclable as a negative input product or a positive output waste being connected to an empty provider or, depending on your system boundaries / compliance, being connected to a provider that "makes the recyclable concrete market ready" if needed.

In any case, for your own foreground models you can always track inventory indicators like "Materials for recycling" by adding the corresponding elementary flow to your foreground process with the correct amount that you want to track. It will simply appear (being added) in the calculation results for the inventory indicators.