Hi All,
We are looking at the value of UHPC facade systems vs pre cast and wondering if anyone else is seeing any progress on the embodied carbon side. We looked into this two years ago and found that UHPC had high cement content, therefor higher embodied carbon. Just doing some research recently I haven’t seen anything new on this, has anyone else found anything more sustainable about UHPC?
Thanks,
Kristen
Hi Kristen,
While you’re generally correct the UHPC has higher cement content compared to traditional precast, the volumes of concrete are typically significantly different, therefore looking at the comparison on a concrete basis alone is not an apples-to-apples comparison. You need to look at the installed facade area for comparison purposes.
What resources are you using for your comparison?
M@
Hi Kristen,
UHPC covers a fairly broad spectrum of possible mix designs that each may have different requirements for their binder recipe. One thing they all have in common is that they almost always use a higher SCM replacement percentage of OPC (Ordinary Portland Cement) than any of the other mix designs used in the construction of a building, bridge, street and so on. Matt is correct in that they must be compared to other UHPC, and over the last 10 years I believe the embodied carbon has probably gone down in terms of lbs pcy of OPC, but was offset by having to source and transport the SCM from further away, but that is only drawing from personal experience, and observation of the industry, not hard facts from a survey, etc. There are also many more companies producing UHPC now, so that in itself has forced everyone to get creative, and also manage their costs, which will drive down OPC in the mix design. Something else to consider is that 2 years in the construction and concrete industries is like the blink of an eye, because change has happened very slowly for as long as I remember. Consider broadening the time range you evaluate, and contact suppliers from opposite sides of the country and you will have a good idea whether the embodied carbon is up or down.
Respectfully,
Matt McCombs
We are wrapping up on development and testing of a novel geopolymer, Techcement, for use in precast applications. We’re gettting high-definition pours and rapid curing, on most pieces we can turn them out of the molds in 2 hours. The geopolymer has a very high (80%+) reduction in CO2, and as we continue to iterate on recycled materials will get even more carbon savings accomplishes. For large format precast (vaults, septic tanks, marine decks, etc.) we have a sulfur concrete that eliminates over 95% of the CO2 when compared to OPC. Both are stronger as well, with TechCement capable of getting over 20K PSI. All of our precast testing has been with a large precaster and we should be ready for production in the coming weeks.
Chris,
Can we set up a time to talk more about you new development? It sounds incredible!
Absolutely. Traveling most of this week, let’s set up a time for next week. My email is Chris*otbmaterials.com. Changed the ampersand so that robots don’t copy my address and start spamming me. Thanks! Chris