At a recent concrete conference a representative from FHWA made a statement that really hit home on why we should be using Performance Engineered Mixtures (PEM). He stated PEMs are the most significant field-level advancement in 40 years in the concrete pavement industry. That’s an entire career for many. That’s my entire lifetime. The South Dakota Department of Transportation and the South Dakota Chapter of the ACPA have provided funding to be one of the champion states for PEM. We recognize need for a more durable, long-life concrete pavement is necessary in South Dakota as stresses from the freeze-thaw environment and the de-icers that come along with the environment have created the need for the concrete pavement industry to deter these harsh chemicals. As a champion state of PEM, the SDDOT has been using PEM for several years now on many concrete pavement projects with much success. Contractors using the mixes have found them to be a more workable concrete, especially in slip-form paving applications.
Some of the highlights of the SDDOT “Special Provision for Contractor Furnished Mix Design for PCC Pavement” include:
- A Quality Control approach allowing the Contractors to be responsible for the performance, production, and composition of their concrete mix designs.
- A well graded aggregate gradation in the mix design allowing the mix to be more workable with less paste.
- The inclusion of 20% to 25% fly ash in the minimum 575 lb/cy cementitious content in the mix. Fly ash is proven to mitigate alkali silica reaction (ASR) and deter reactions to deicing chemicals.
- Establishing a maximum water/cementitious ratio in the mix. Lower w/c ratios provide a less permeable concrete providing another mitigation against deicers.
Our concrete pavement specifications have not been keeping pace with advancements in science and innovation within the concrete pavement industry. These mixes bring us into the 21st century in the industry. The link below more thoroughly summarizes PEM and their benefits. If you have any questions regarding implementing these into your concrete pavement project, please contact your local ACPA chapter or the CP Tech Center.