Vertua: Net-Zero CO2 Concrete / Comments on Reduction Claims?

Hello - Anyone have a critical review of Cemex’s ‘Vertua’ “Net-Zero CO2 Concrete”? Their literature suggests that this product “… reduces the carbon footprint by up to 70%. The remaining 30% footprint is neutralized through offsetting efforts.” Vertua Net-Zero CO2 Concrete - CEMEX

Thanks,
Aaron

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Cemex has an alkali activated alumina silicate net zero mix. They say that they get the thermodynamics down to 30% and use offsets, not RECs, for the rest of the way. There is definitely some concern about the alumina and silicate carbon from the NGO side. Sorry, I don’t have better specifics. Also, for cement kilns across the board, air toxics are as big of a concern as carbon. A sizable variety of hazardous waste without much legitimate fuel value gets dumped into unregulated cement kilns. This generates some big tipping fees. Perhaps some of the newer CO2 injection processes at kilns will work better without a lot of different toxic contaminants. Also, as the rest of the EPD or LCA is ignored besides GHGs, kilns are also big ozone and smog generators.

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Generally, CEMEX have been pretty obscure with their low carbon claims. In Europe they have launch 3 ‘green’ concretes, out f which just one is a cement-free geopolymer (AACM) mix, the Vertua Ultra Zero.
That one is indeed much lower in carbon compared to standard cement (CEM I OPC).
If the remaining emissions are covered by credible offsets, it could classify as a net-zero product.
Nevertheless, the construction industry needs to bear in mind that the main cement substitute it is currently relying on (GGBS) is a by-product of primary steelmaking and hence finite and definitely not sufficient to cover the ever increasing global demand for low carbon cementitious materials.
Exploring new sources of robust supplementary cementitious materials is key.

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