Dear all,
On my project, the

Caroline - First you need to get the cost of the aggregate separately so that you can calculate its recycled content value. Without the cost you can't count it as recycled. Please review this post below - http://www.leeduser.com/credit/NC-2009/MRc4?page=0#comment-51689 - and let me know if you have any remaining questions about how to enter information into the BDC Materials and Resources calculator as well as how to calculate the value of the supplementary cementitious materials (fly ash).

Caroline - I like to have solid backup for all material attributes even if it is not required to be provided as LEED documentation. I don't think you can calculate the fly ash contribution accurately without having the cement cost separate from the aggregate. Hopefully your concrete supplier can work with you on this. Good luck!

Caroline: Your post says that your concrete contains 6% fly ash and 5% recycled aggregates. How did you determine these percentages? Here in the US, structural engineers usually require concrete suppliers to submit “mix design” reports for each type of concrete used on the project. These “recipes” show the proportions of each component in each mix, usually in pounds per cubic yard (or in kg/m3). I usually calculate material percentages using these reports. Your original post also says, “it’s impossible to get the cement price and aggregate price separately.” Have you been able to obtain combined cost figures that include all concrete components (cement, SCMs, aggregates, and water)? If your suppliers will not report cementitious material costs separately, you cannot use the SCM calculation. However, if they will attest to the composite cost for each concrete “recipe,” you may still be able to calculate recycled content using the standard calculation. Finally, does your project have only one type of concrete? A single project typically uses many different types of concrete, each one with a different “recipe” comprising different proportions of ingredients. I would expect suppliers to submit a different “mix design” and cost for each type used. I hope that this helps. Bon courage!

Exactly! If I understand correctly, you have 10 “recipes” corresponding to 10 values for composite cost, but you do not know the costs of cementitious materials. All of the recipes use some recycled aggregate and five of them include fly ash (pre-consumer). You plan to enter information for each “recipe” on 10 separate lines of the MR spreadsheet. Was your recycled aggregate recovered from post-consumer sources, or did it come from pre-consumer sources, just like the fly ash? If it is pre-consumer, calculate the percentage by summing the kg/m3 of recycled aggregate to the kg/m3 of fly ash, and divide the sum by the total kg/m3 for the recipe. If it is post-consumer, calculate the percentages of aggregate and ash separately, and enter the percentages into the appropriate spreadsheet columns. If you knew the costs of cementitious materials, you could use the SCM Method. The SCM Method would require two lines for each recipe—one line for cementitious materials, and one line for aggregates and water.