RefGuide says in page 373 "In the case of supplementary cementitious materials (SCMs) used in concrete recycled from other operations, the recycled content value can be based on the mass of the cementitious materials only, rather than on the entire concrete mix".
I just want to make sure I'm getting this right. So we have a concrete mix made out of cement, crushed stone, water, sand, and additives. Only the cement has recycled content - recycled pre-consumer - and let's say it weights 1000kg. The cement represents 10% of the composition, so 100kg. 53% of the 100kg of cement is recycled, which leads to 5,3% x 1/2 (since is pre-consumer) of 100kg = 2,65kg of recycled content from the total concrete mix.
On the other hand, if I consider only the cementitious material instead of the entire concrete mix, I will have then 100kg of cement, from which 53% is pre-conumer recycled content, which leads to 26,5% x 100kg = 26,5kg. 10 times more! Is that what the RefGuide is saying?
Thanks
Nadav Malin
CEOBuildingGreen, Inc.
LEEDuser Expert
844 thumbs up
November 26, 2012 - 10:59 pm
Hi Marcio,No, you don't have it quite right. To use this option and calculate the SCMs separately, you must be able to get the cost of those ingredients from your supplier separately from the cost of the whole mix. While the cementitious materials might be 10% of the mix by weight, they typically represent a much larger share of the cost. If your total cost of concrete is $10,000, then in your first example the recycled content value is 53kg/1000kg = 5.3%, which leads to:5.3% x 0.5 x $10,000 = $265 recycled content valueBut if you can document that the cementitious materials represent 60% of the cost of the mix, or $6,000, then you can do it this way:53% x 0.5 x $6,000 = $1,590 recycled content value.
Marcio Alberto Casado Pereira
181 thumbs up
November 27, 2012 - 7:20 am
Got it! Thanks Nadav!
Our provider gave us the cost of all concrete componentes separetely, however, all in the same invoice though. Would that be a problem if I want to use the SCM option?
And should water be included in these calculations at all?
Nadav Malin
CEOBuildingGreen, Inc.
LEEDuser Expert
844 thumbs up
November 27, 2012 - 9:04 am
Glad I could help. No, it's not a problem that they're all on the same invoice. If you calculate the SCMs as a separate item, then it doesn't matter if you include the water or not. If you do the concrete as a whole--whether or not to include the water seems to fall into a gray area, which means that you can probably get away with doing it either way. I'd love to hear from others on that--any experiences to share?
Marcio Alberto Casado Pereira
181 thumbs up
November 27, 2012 - 11:18 am
Great! To close the subject, we would like to know if using the SCM option will have any impact in credit MRc5 Regional Materials. For instance, can I still consider the non-cementitious concrete components for MRc5 (assuming that they meet the requirements, of course) even if I exclude them from MRc4 calculations?
Also, I will simply ignore the cost of sand, crushed stone, etc, in the entire project or only for the SCM case (let's say I'm using sand for the masonry, should it be considered if it was excluded from the concrete)?
Thanks
Nadav Malin
CEOBuildingGreen, Inc.
LEEDuser Expert
844 thumbs up
November 29, 2012 - 6:29 am
Hi Marcio,Yes, you CAN still include other concrete ingredients in the Regional Materials credit (and even in the Recycled Content credit, if they have recycled content--but don't try to count "recycled water"). To make sure that your calculations are consistent, just treat the cement + SCMs part of the concrete as one "product" on the spreadsheet and the remaining ingredients as another "product." The $ cost of these two products should add up to your total cost for the concrete. And no, you should NOT ingore the cost of the other ingredients--those have to still be include in your total product cost. The method I just described above should work for that, whether or not any of those other ingredients help you earn any points.
Jennifer Preston
BKSK Architects64 thumbs up
January 8, 2013 - 3:44 pm
Hi Nadav,
This is a bit confusing because the reference guide says mass not cost, as you use in your example "the recycled content value can be based on the MASS of the cementitious materials only, rather than on the entire concrete mix". So in my 1000 kg of cementitious material I have required 40% be recycled content. Or in other words 40% by weight is SCM in the form of Slag. If the total cost of all CONCRETE (cement + aggregates) is $10,000 than I claim $2,000 (40%/2) in recycled value toward MRcr4. This means I do not have to ask the contractor for itemized costs, just itemized weights which is much easier to obtain as they have to provide it in the structural mix approval anyway. Is this acceptable?
Nadav Malin
CEOBuildingGreen, Inc.
LEEDuser Expert
844 thumbs up
January 8, 2013 - 4:04 pm
No, I'm afraid that won't work. If you read later in the same paragraph in the Reference Guide, it says that you have to obtain the value of the cementitious materials separately from the total cost of the concrete. So, you can base this calculation on the mass of the cementitious materials separately from the rest of the mix, but to do that you have to also isolate the cost of those materials separately.