How Central Iowa Ready Mix is Reducing Cement in Concrete Paving

Jeffrey Goss is the ready mix Quality Control Manager at Central Iowa Ready Mix. Working with them since 2016, Jeffrey has been in the concrete industry for 17 years, 15 of which have been in ready mix. Central Iowa Ready Mix is part of the Rasmussen group, a family-run business with over a century of heavy construction experience working with multi-faceted design-build construction companies. The specializations include bridge construction, marine contracts, concrete asphalt, paving, and crane operations; “you name it, we do it,” said Jeffrey. This well-regarded employer takes pride in delivering the highest quality sustainable concrete, located primarily out of Des Moines, where they have over 20 plants throughout the Southwest corner of Iowa and Southeast of Nebraska. 

In a recent webinar, Jeffrey Goss and Ashley Underwood, Technical Services Representative at CarbonCure Technologies, discussed how Central Iowa implemented CarbonCure to supply the Iowa Department of Transportation with sustainable concrete for public projects. 

An Integrated Approach to Sustainability

When CarbonCure came up on Jeffrey Goss's radar, he committed to research the technology of CO₂ sequestering. He saw immediately that this was the direction this industry had to go. In his mind, what the concrete industry was able to do in so far as sequestering the amount of CO₂ was significant and not only that, it brought down the cement content — a win-win for everyone. The Rasmussen Group takes pride in providing a positive impact on the communities they work in, striving to reduce the environmental impact and meet the responsibility of social progress. "With 70% of our production in the metro area, Central Iowa Ready Mix puts out around 1.7 million cubic yards (1.3 million cubic meters) of concrete a year. That’s an average of 25 lbs of CO₂ per cubic yard (15 kg per cubic meter) that is no longer available to escape into the atmosphere. The Rasmussen group believes in promoting sustainability where there is a better future for our kids, grandkids and great-grandkids," said Jeffrey.

Central Iowa Ready Mix's First Process with CarbonCure

In the beginning, Jeffrey Goss and his team did a lot of testing to make sure CarbonCure Ready Mix was going to do what it was expected to do. When it came to test batches, they typically made 100 cylinders a day, sometimes three days a week. Then, they would do comparison testing of the same mix design on the same job, some trucks running CarbonCure, others not. The ones that got CarbonCure had up to a 3% reduction in cement. Air void analysis, surface resistivity, and permeability tests showed that all the numbers were almost identical, with the exception of some variations.

"One thing that was found in the concrete with CarbonCure, it actually was less permeable. But for an area like Iowa with very hard freeze and thaw cycles, this is a good thing because it makes the concrete more durable," said Jeffrey. 

Attaining the Iowa Department of Transportation Goals

The Iowa Department of Transportation (DOT) represents 25% of work for Central Iowa Ready Mix. "They're not like commercial mixers where we're given a specification: 6% air, plus/minus 1, and 4,500 psi (31 MPa) with 0.45 water-cement ratio," said Jeffrey. The Iowa DOT typically runs cycles and new specifications at least once to twice a year. When it came to working with CarbonCure, knowing that they were going to have a cement reduction and use a Type 1L cement (also known as Portland Limestone Cement) replacement percentage, Jeffrey was unsure how things would go. After many discussions with the Iowa DOT, Central Iowa Ready Mix had specific test parameters and performed certain tests. Within four weeks of completing the testing, they had the approval to run CarbonCure Ready Mix in all their projects.

“When the approval came at the end of 2021, I was floored but very excited. I believe they understand we're all out for the same thing; we can make reductions, make a greener product, and provide that to communities- then the taxpayers are winning," said Jeffrey. 

Watch the On-Demand Webinar

Going into the Future

Central Iowa Ready Mix has confidence in CarbonCure, seeing the results repeatedly. But, according to Jeffrey, there is an odd pushback because people don't understand the technology.

"They don't understand the difference between the initial carbonization of concrete, CO₂ sequestering, and CO₂ assault on concrete, which takes years as CO₂ seeps into the concrete and deteriorates rebar," said Jeffrey.

In his opinion, the atmospheric CO₂ has less chance to permeate CarbonCure concrete and get to that rebar because it includes its path through the decreased permeability. When it comes to explaining the new technology to people to build confidence, Jeffrey knows he can lean on CarbonCure's Technical Services & Support team. They help him build and nurture these working relationships.  

Watch the on-demand webinar to learn more about Central Iowa Ready Mix's experience reducing cement in their concrete paving with the Iowa DOT and adopting CarbonCure in their operations.