TCA’s research efforts for 2020 saw the continuation of some earlier research projects undertaken with Tennessee universities (see below) and the initiation of what we like to call Practical Research. With the addition of John Pearson, PE as TCA’s Director of Technical Services our goal is to utilize Mr. Pearson’s expertise and TCA’s new campus to perform research with immediate, practical utilization for ready mix producers.
In addition to our in-house research efforts, TCA has submitted a research proposal to the RMC Foundation to measure how quickly concrete carbonates when exposed to atmospheric CO2. TCA is proposing to take measurements of actual concrete placements utilized in the construction on our new office building that will take place in 2021, with these measurements continuing over the next decade. Carbonation of existing concrete in the built environment is a “hot button” issue in sustainable construction and could give concrete another significant advantage over competing construction products.
Our first Practical Research project focused on the proper storage of acceptance cylinders under field conditions. The required conditions for storage of acceptance cylinders is well known but rarely achieved in the real world. Responsibility for achieving and maintaining those conditions in the field is slippery in spite of being well-defined in the testing standards, much to the frustration of ready mix producers everywhere. The goal of our research was to document whether or not some common field practices could actually maintain compliance with the testing standards during the heat of Tennessee summer weather.
Mr. Pearson explains how we conducted the research in the video below and the chart summarizes the findings of our initial tests. Click here to see the full report. We plan to further validate our data by working with undergraduate engineering programs across Tennessee to have them conduct similar testing protocols and then collect that data. In addition to gathering more data, we feel this will be a powerful lesson about what works (and what doesn’t!) when it comes to meeting specification requirements for acceptance cylinders.
For engineers and specifiers who are currently practicing, Mr. Pearson has put together a presentation using this data to reinforce the importance of meeting the specification requirements. The presentation was presented at two virtual conferences in 2020.
Cylinder Curing Study
The final results in this three year project were compiled and released in 2020 with their publication in our Tennessee Concrete magazine - click here to see the paper.
And click here to see how TCA's research in this area anticipated changes to concrete durability requirements released by ACI in the latest version of ACI 332-20, Residential Code for Concrete.
CRED 2020 Final Paper
TCA Ready Mix Operator Survey Results
While most of TCA's research is product-focused, we know that people - especially mixer operators - are what truly drive our operations. TCA conducted a mixer operator survey in early 2019 to collect data on how mixer operator's viewed their jobs - you can see the survey HERE.
Commercial & Residential Enhanced Durability (CRED) Research:
Phase Two of this study was undertaken in 2019 to determine effective methods of protecting exterior concrete from chemical attack (specificially Magnesium Chloride). This project will have final testing in early 2020 (here is the final report released in 2020). Our research demonstrates that protection can be achieved through advanced mix designs or through the application of penetrating sealers such as silane.
Beneficiated Fly Ash Research Project:
Because a reliable, consistent source of fly ash is so critical to the concrete’s industry ability to produce durable, high performance concrete TCA has been active in lobbying the Tennessee Valley Authority to switch from landfilling fly ash at several coal-fired power plants in Tennessee to investing in one of several beneficiation processes that could turn TVA’s disposal problem into a profit opportunity while preserving and extending a vital resource for the concrete industry in Tennessee and surrounding states. (See more information on this effort in our Public Policy section)
To support our work to bring more beneficiated fly ash to the market in Tennessee, TCA worked with long-time research partner Dr. L.K. Crouch at Tennessee Technological University to do a study on the impact of using beneficiated fly ash in concrete mixtures utilizing common Tennessee materials. The research was performed by students at TTU in the summer of 2018. An abstract of the research project can be seen HERE. This research will be presented by TTU at the 2019 World of Coal Ash.
ACI 332 Mix Design Research:
The TCA Technical Committee came together to test both the fresh and hardened properties of mixes typically supplied for residential concrete driveways. Different mixes were run in the lab to simulate what happens to concrete when a producer’s mixes are subject to the addition of water (often significant amounts of water) at the jobsite. Tests were run to determine properties both before and after the addition of water, including the collection of calometric data above to show the impact of water addition on set times. While there were no surprises in the data, it was very useful to show not only the reduction in the strength that comes from water addition, but also the increase in set time. Data can be found HERE and the "one-pager" summarizing ACI 332 requirements can be found HERE.
Portland Limestone Cement (PLC) Research:
PLC is not widely used in Tennessee as of 2018, with only one cement supplier marketing PLC in Tennessee (at only one terminal in Memphis, TN). However, it appears that PLC may increase in both availability and use going forward so TCA responded to a research request from students at TTU interested in comparing concrete mixtures utilizing PLC to those using conventional Type 1 cement. TCA helped in getting a sample of PLC to the TTU campus and students were able to begin their research. A plan of the research can be seen HERE.
Commercial & Residential Enhanced Durability (CRED) Research:
This study was undertaken to support the work of the TCA Technical Committee with regard to ACI 332 and exterior concrete durability. Because of the increasing prevalence of magnesium chloride in commercially available de-icing products, this research was designed to focus on potential impacts from the use of these products on common concrete mixtures being used in Tennessee. Phase One of the study was completed in 2018 and results can be seen HERE. As expected, impacts of the use of de-icers can be measured and the research demonstrated these impacts.
TCA Research Archive
Beneficiated Fly Ash
Controlled Low Strength Material (Flowable Fill)
HVFA and LGM
Low Perm PCC
2004 TN Conc Maturity Lesson 1