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carbon-negative from rock to city block

Brimstone's carbon-negative process is a breakthrough in cement production, making ordinary portland cement with carbon-free calcium silicate rock instead of limestone.

Cement made with The Brimstone Process™ is chemically and physically identical to conventional portland cement, with the same quality and performance builders have trusted for over 150 years. Simply put, our process will turn cement, one of the most intractable climate problems, into a climate solution. It all starts with a new kind of rock.

 01   one rock

Cement is conventionally made from carbon-heavy limestone, which releases CO2 when processed. These process emissions are responsible for up to 60% of cement's overall emissions.


We make cement from carbon-free calcium silicate rock, eliminating these process emissions from the start. Calcium silicate rocks are abundant and voluminous at the surface of every continent in the world.


 02   one process

Our process produces two core products used in concrete: ordinary portland cement and supplementary cementitious materials (SCM). Today, cement and SCM are made from different processes and sourced from different locations. Our rock contains all the minerals necessary to make both cement and SCM from one process in one location.

 03   one big impact for the planet

Our process removes CO2 from the air, resulting in truly carbon-negative cement. How? In addition to the calcium, silicon, iron and aluminum used to make cement, our rock also contains magnesium. We use this magnesium to permanently remove atmospheric CO2.


let's build


We are working with industry leaders and other key partners to scale and maximize our impact on climate change. Interested in joining the fight? We’d love to talk.

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