Who cares about mix optimization?
In the concrete industry ”mix optimization” is an often abused term that vendors to the ready mix producers use when trying to justify their “value proposition” and sell their products. However, when used proactively, from the ready mix producer standpoint, mix optimization can be a powerful tool to save money in mix costs and provide the contractor with a better product. Mix optimization, however, isn’t easy. It takes days in the concrete lab weighing up, mixing, and testing a range of concrete mixtures, then more time to properly prepare and analyze the data.
With respect to Smart Concrete™, how can a ready mix producer, then, use maturity to help themselves proactively in mix optimization? First, a brief explanation of how the Smart Concrete system works. Smart Concrete is built off of the concept of maturity -- an idea that has been around for more than 60 years. Maturity says that if the time and temperature history of a concrete element is known, and that can be tied back to a calibration curve, then the properties of that concrete can be estimated. Maturity can be used to estimate the evolution of concrete properties that are dependent on the chemical reactions that occur in a cementitious mixture. These properties may include permeability, modulus of elasticity, and strength. By specification, maturity measurements are taken every 30 minutes or less. So, when using maturity for strength evaluation, rather than breaking cylinders at maybe 3 data points (say 3, 7, and 28 days) to evaluate a concrete mixture, with maturity, data points are automatically collected every half hour to create a very well defined history of the concrete strength from set through the first weeks of hardening. This allows one to look back and see what the performance of the concrete mixture was at an exact time (say 48 hours), with little effort.
Smart Concrete takes maturity, removes all of the friction points in the process, and makes data processing, handling, and sharing very easy. All of the data is moved automatically in the background and handled by online systems, so getting the data from the field to the office happens in a click. By generating field test results so easily, that data can be used for mix optimization of performance mixtures rather than going through a cumbersome lab process.
Two of our Smart Concrete producers have shared success stories of using maturity in their mix optimization efforts. Both producers have been able to provide their contractors with more workable, more finisher-friendly mixes at a lower mix cost, lower carbon footprint, and with reduced potential for long-term problems.
In the first application of maturity for mixture optimization, the project was a high-rise concrete structure. The contractor elected to buy value-added Smart™ concrete mixes instead of ordinary concrete mixes for the project. The producer provided the contractor several options of different mixtures to hit different early strength targets so that the contractor could select the optimal mix based on the weather and performance. The contractor found out early on in the project that the mix he had budgeted to use was significantly outperforming the construction schedule -- he was spending more money on a mix than he needed to be. So, the contractor was able to use a mixture with reduced cementitious material content that did not gain strength as fast, and did not cost as much, but still met the performance requirements for the construction schedule. While the contractor wisely made an upfront investment in Smart Concrete for the project, his savings were three times his investment in the Smart™ concrete mixes. Additionally, the contractor was able to save more money because he could use a smaller finishing crew to finish the concrete without having to worry about it getting away from him, while giving his customer a flatter, more level floor.
A second Smart Concrete producer reports significant cost savings in their “high-early” mixtures typically used for industrial work or pavement repairs. Demand in their market is most common for a 4,000 psi mix at 48 hours. Using cylinders to evaluate the performance of such a mix can be cumbersome as breaks need to be completed at exactly 48 hours. Generating sufficient performance data can be problematic for companies with lean QC departments or when 48 hour breaks fall at off times like in the middle of the night or on weekends. Due to these complexities of testing, they used a “bulletproof” mix -- a mix that they didn’t know exactly how well it performed at 48 hours, but knew it never came up short on early strength. As this producer started implementing Smart Concrete practices in their business, their “high-early” mix was one of the first to be evaluated. They quickly realized that the mix was over-performing their technical targets based on field data. Through additional mix optimization efforts they realized that they could save over $4 per cubic yard by reducing cementitious content and still meet their customer's expectations. For this producer, the cost savings found in optimizing just this one concrete mix more than paid for their annual investment in Smart Concrete.
These two examples show not only the power of Smart Concrete for concrete mixture optimization, but also the ease with which it allows cost saving decisions to be made that can quickly impact profitability for both the contractor and ready mix producer. If you are ready to start optimizing your mixes with Smart Concrete, visit us at www.smartconcrete.co.Photo credit: http://ssebe.engineering.asu.edu/research/labs/concrete-instructional.html