Type IL Concrete Challenges

This article is an excerpt from an internal correspondence with my team about Type IL cement and how the shift to this concrete mix design is creating challenges for the concrete polishing and coating industry. These are my experiences with the product and may vary from others. I am sharing this in hopes of bringing awareness of these issues to the concrete polishing community and to collaborate with industry experts on "best practices" for dealing with Type IL cement going forward. Also, for my followers in construction, design, architecture, etc., please know that this has an effect on your projects as well.

I want to make you aware of something new in our industry that is affecting us from an operation standpoint and is having a financial impact on our company and the industry as a whole. Thanks to “the green new deal” and the desire for America to lead the way in saving the world from Global Warming aka Climate Change, there has been a push in the construction industry to reduce the amount of Portland cement in concrete as an effort to offset carbon emissions and reduce the overall carbon footprint of concrete.

For those of you interested in nurding out and furthering your education on concrete and the differences in standard Type I/II cement and Type IL you can follow this link https://www.ctlgroup.com/portland-limestone-cement/ to an article written by CTL (Construction Technology Laboratories), the leading authority on concrete design, testing and innovation in America.

Issues With IL Cement

Porosity

• Extremely porous product Requiring substantially more densifier than standard concrete
• Requiring multiple applications of densifier
• Hydrate the slab
• Application to refusal
• Allowing to gel Scrub and rinse
• Requires special formulations of densifier designed to react with the excessive amounts of limestone in the mix design

Surface and Matrix

• Very gritty and rough surface
• Requires different tooling than traditional Portland Cement/Type I/II
• Tooling manufacturers are not prepared for this challenge and are working on new formulations of resins and metal bond diamond tooling that will last longer on this concrete
• Currently we are getting 25% life out of traditional tooling
• Requires running more tooling to decrease head pressure or point load being applied to the diamond surface
• Double the tooling on the bottom of the grinder or trowel to decrease point load per tool, increase speed of machine, wet cut where possible
• This process will increase the life of the tooling by 50% (this is still a 50% decrease in tool life)
• Tooling cost needs to be considered when pricing these projects. It is double traditional cost
• While this may not hold true on every project with this IL cement this is the current data we have
• Due to its gritty nature IL cement tends to lose aggregate from its matrix during the grinding process
• This is causing particles of material to be lodged in tooling and in general causing scratching of the surface during the polishing process

Additional steps of polishing and refining are being required to remove these scratches and to refine the surface to meet specifications

Inability to achieve DOI readings with traditionally accepted steps

Our experience currently is that in order to hit a DOI reading of 40-60 we are required to polish up to 1500

Another option to increase the DOI to acceptable levels is to apply a grout coat over the floors surface at an appropriate level to help close up the pours in the surface and allow for additional reflectivity and gloss.

This is our first experience with IL cement and this project is 285,000 feet. It has been an expensive learning experience that we should all take value from.

I will continue to experiment and learn everything available about this new cement mix design and provide additional information and updates at they become available. Please, be cautious when pricing future projects and make sure to protect yourself from economic loss by qualifying your project pricing around Type IL cement due to the anomalies and unknown nature of this product.

Grind on,

Dwayne Lewis

President/CEO GPS