I’ve appreciated the opportunity to share educational information and insights on the concrete pavement industry with the readers of the Colorado Public Works Journal over the last 10 years.  From concrete pavement construction best practices to concrete overlay performance and low carbon concrete, we have explored a wide variety of different topics.

University Boulevard in Denver – constructed in 1984 and still performing with the original concrete surface over 40 years later

Concrete pavement continues to serve the taxpayers of Colorado as roads are stretched well beyond their design lives and carry levels of traffic that weren’t anticipated 30 to 50 years ago.  I expect that our current focus on materials and construction practices that make concrete more durable will also result in today’s concrete pavements carrying the load well beyond our expectations.

While budgets continue to be a challenge for agencies of all sizes, investing in long term solutions like concrete pavement must be part of the strategy for managing assets and maintaining transportation infrastructure.  We can’t build ourselves out of the current poor conditions on Colorado’s highways with the band aid approach that has been used in recent years.  This cycle of rehabilitation and maintenance is not sustainable and is unnecessarily draining material and financial resources.  Concrete overlays are the permanent and proven solution to many of these challenges.

6” concrete overlay on SH 13 north of Craig – constructed in 2016 as an alternate bid at an initial cost less than the asphalt alternate

This will be my last column as the Executive Director of the Colorado/Wyoming Chapter of ACPA, and I’d like to thank you all for the great interactions we’ve had over the years.  Stay tuned to future columns to hear more from the concrete pavement industry and the next leader of ACPA.

Article published in the Spring 2025 issue of the Colorado Public Works Journal.

Concrete can be placed in the winter without issue, and it’s done regularly for both pavements and flatwork.  There are a few keys to creating deicer resistant concrete that need to be followed:

• Require 20% Class F fly ash. This is the most important component since using Supplementary Cementitious Materials (SCMs) greatly decreases the permeability of the pavement. Minimizing deicer penetration into the pavement reduces the potential for calcium oxychloride reactions.  SCMs are also important for increasing sulfate resistance.
• Reduce cementitious paste content. Utilizing a Performance Engineered Mixture (PEM) approach to concrete mixture development includes optimizing aggregate gradations and reducing paste content. It provides another avenue to reduce permeability and increase concrete durability, all while lowering the environmental impact.  Guidance on PEM strategies can be found at https://www.cptechcenter.org/performance-engineered-mixtures-pem/
• Maximum w/cm ratio of 0.42. Ideally, flatwork should be held to a maximum water-cementitious ratio (w/cm) of 0.42 for durability in our climate.  Many specs allow up to 0.45, including any water added onsite, and that limit should never be exceeded.  Permeability increases and strength decreases with high w/cm ratios.  ACPA recommends not exceeding in the field the w/cm ratio used in the lab to develop the mix design.
• Follow best practices for finishing. Working water into the surface and overfinishing are usually contributors when scaling happens. Working water in raises the w/cm ratio of the surface, which weakens it.  Overfinishing works the air out of the concrete surface, decreasing the ability for the concrete to resist the damage caused by freeze-thaw cycles.
• Consider a cure-seal product when deicers will be applied within 30 days. This is a type of curing compound that has a penetrating surface sealer built in.  Even with low permeability mixes it takes several weeks for the concrete to develop deicer resistance. These products are applied like any other cure but keep water and chemicals out while the mix is developing strength.  Cure-seal products should meet ASTM C1315, Type I or II, Class A.

The Municipal Government Pavement Engineers Council (MGPEC) has developed concrete specifications that include most of these approaches.  Check out Items 30-33 on their website at https://mgpec.org/mgpec-specifications.html.

For additional assistance with any of your concrete pavement questions, please contact Angela Folkestad at afolkestad@pavement.com.

Article published in the Fall/Winter 2024 edition of the Colorado Public Works Journal.