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Seeing Is Believing: New Tests Show Advantages of Cor-Tuf Ultra-High Performance Concrete

Seeing Is Believing: New Tests Show Advantages of Cor-Tuf Ultra-High Performance Concrete

By Tim Lysett


As the advantages of Ultra-High Performance Concrete (UHPC) become more well-known in the concrete and construction industries, it becomes even more important for builders and contractors to learn about the differences between the various UHPC products on the market. One may think that there are only slight nuances between one mix of UHPC versus another, but the truth is the differences are quite significant.

In fact, choosing the best UHPC for a given project can determine your success or failure when it comes to meeting project timelines, requirements, and budget. Here we take a closer look at what to consider when evaluating UHPC products and how a proprietary UHPC mix—Cor-Tuf UHPC—opens new doors when it comes to how this new concrete product can be used in all types of concrete construction projects. 

Qualities to consider when evaluating UHPC providers

Here are the top items to keep in mind when selecting a UHPC mix to use on your next project. 

  • Pourability—It is difficult to use UHPC for large products if it cannot be poured. The mix has to be flowable (and even pumpable) if you want to use it for large-scale projects. Make sure the mix you choose can be easily poured.
  • Batch size—Many conventional UHPC products can only be mixed in small quantities (think 50-pound bags). This requires constant measuring and mixing of many batches during a given project, resulting in downtime for machinery and laborers. Be sure to look for a UHPC product that can be mixed in larger batches that meets the demands of the job.
  • Consistency—Batch size is a big factor impacting consistency. Numerous small batches on a given project naturally have small margins of error that result in a lack of overall consistency in the final product. These variances negatively impact quality and durability. UHPC that can be made in large, mass-produced batches do not have this consistency issue and are a better choice.  
  • Machinery—New materials often require new equipment or processes. While this is true of some UHPC mixes, there are UHPC products available that can be mixed and poured with traditional machinery following the same process as you would for traditional concrete. This removes the cost of new equipment and keeps your current workforce moving smoothly with the tools and workflow they already know.
  • Mixing time—The mixing time for UHPC products can vary greatly, with many conventional mixes needing up to 20 minutes per batch. Be sure to consider the mixing time required when evaluating UHPC products, as there are options that are ready in just a few minutes.
  • Customization—While all UHPC mixes provide gains in strength when compared to traditional concrete, there are differences in strength across UHPC products and mixes themselves. It is the unique blend of integrated fibers in the mix that deliver gains in strength. Look for a provider that can create a custom mix to meet the specific strength needs of your project. Additional customization around working time and leveling can also be achieved by some UHPC providers, adding more benefit to your project timeline and success. 

See for yourself: Five game-changing advantages of Cor-Tuf Ultra-High Performance Concrete

Cor-Tuf Ultra-High Performance Concrete is a proprietary UHPC mix developed by the U.S. Army Corps of Engineers to meet the need for an incredibly strong (yet accessible) material to protect personnel and weapons facilities from blasts and intrusions. Cor-Tuf UHPC is the exclusive licensed producer of this proprietary UHPC mix, making it available for commercial and governmental projects through certified distributors.

The team at Cor-Tuf has been rigorously testing Cor-Tuf UHPC to demonstrate the unique benefits that this UHPC mix provides when compared to other commercial variations. Our most recent testing highlights five ways Cor-Tuf UHPC is a game-changer—not only in the larger concrete industry, but within the smaller UHPC community as well.

In these tests, the Cor-Tuf team produced two 30-foot pretensioned beams, one 63-foot pretensioned beam, and two 30-foot pretensioned H-pilings. You can watch these products being made and tested in the video below, but here is a sneak peek into what you will discover about this innovative UHPC concrete mix. 

Demonstration of Cor-Tuf UHPC’s ability to pour full-scale UHPC components with a ready mix truck. Here the team is producing the first of two 30’x30’x30” beams, which were created over a two-day span.

User-friendly

When you use Cor-Tuf UHPC, the dry mix is delivered on site. Conventional sand, cement, and the proprietary wet constituents are then added. In our most recent round of testing, ready mix trucks were used along with other industry-standard equipment to demonstrate how simple it is to start using Cor-Tuf UHPC on a construction project. 

Despite the innovative UHPC mix design, new machinery or processes are not required. Cor-Tuf UHPC can be mixed and poured the same as you would traditional concrete. In our current tests, the mixing process was complete in as little as four minutes, keeping downtime on the site to a minimum.

The ready mix truck under the batch plant, ready to receive the first mix of the day. Here the Cor-Tuf team is loading one yard of pre-mixed material complete with steel fiber onto the conveyor belt leading to the mixer.

Scalable 

In these particular tests, the Cor-Tuf team used one-yard, pre-mixed Super Sacs of dry Cor-Tuf constituents to deliver the product to the site. In addition to using Super Sacks, we are also designing our batch plants to accommodate silo-style mixing and distribution to more efficiently and cost effectively pour larger batches. 

This makes Cor-Tuf UHPC extremely easy to scale for any project, large or small. The product can be delivered in a number of increments, ranging from 50-pound bags all the way up to full tankers, making it easy to use on even the largest infrastructure projects.

Pourable 

Unlike other UHPC products, Cor-Tuf UHPC has a long working time (more than an hour) and is very flowable. This high flowability allows workers to use standard equipment such as a ready mix truck with its slower dispensing rate without any problems. 

In our recent tests, ready mix trucks easily poured Cor-Tuf UHPC into even the tightest of forms. Cor-Tuf UHPC can even be engineered during the mix to increase or decrease the working time to add even more benefits to the on-site process.

A close-up view of Dura-Stress Inc. and Cor-Tuf crew members guiding Cor-Tuf UHPC into the top of the form for one of two 30’’x30’’x30’ H-Pilings. Cor-Tuf UHPC is being poured from a standard ready mix truck, demonstrating its ability to be used with industry-standard equipment.

Quality

The quality and consistency of UHPC can make or break a project. Our most recent tests further confirmed the quality and dependability of Cor-Tuf pretensioned products. The H-pilings were outfitted with strain gauges to monitor potential movement of the pretensioned cables in the pilings. As expected, the pilings displayed no relevant movement of the cables embedded inside them during the de-tensioning. 

After de-tensioning, a crane extracted the pilings. This was done with no complications, resulting in a nearly perfect product. The extracted pilings had a nearly ideal finish, matching their steel forms to the finest details. As part of our rigorous quality control standards, they were completely free of any major voids, bug holes, or other defects. 

During our quality control procedure, we take extensive samples of each batch of Cor-Tuf UHPC after it is mixed. The samples are tested before the material is poured, ensuring the batch conforms to our strict standards.

The finish of both H pilings matches that of their steel forms exactly, down to the smallest detail. Because of the extremely small particle size of its primary constituents, Cor-Tuf can be fit into very small and complex areas retaining every detail of whatever it was cast against. This results in nearly limitless finishing possibilities.

Strength 

One of the major benefits of UHPC versus traditional concrete is its strength, and our testing clearly shows just how strong Cor-Tuf UHPC is. Samples were tested for compressive strength at the 24, 48, and 72-hour marks, with results in excess of 8,000 pounds per square inch (psi), 13,500 psi, and 16,500 psi respectively. A final 28-day cure compressive strength of 28,200 was achieved.

UHPC is revolutionizing the concrete industry, bringing unheard-of strength, durability, and more to the table. But the specific UHPC mix selected does matter. Cor-Tuf UHPC not only delivers when it comes to strength, but it has been proven to be able to do things other UHPC mixes simply cannot.

Cor-Tuf UHPC makes it possible for this new concrete technology to break through to mainstream use. The ability to use standard equipment and processes along with the long working time, pourability, and scalability make the transition from traditional concrete to UHPC a simple one for any construction or infrastructure job. Proven consistency coupled with the strictest of quality control procedures removes any worry about what you’re getting. Ultra-High Performance Concrete truly is the future of concrete, thanks to Cor-Tuf UHPC.  

Take a look at the video below to see our most recent testing event and watch Cor-Tuf in use for two 30-foot pretensioned beams, one 63-foot pretensioned beam, and two 30-foot pretensioned H-pilings. Stay tuned for more updates as we continue to create new concrete solutions and innovation with Cor-Tuf UHPC.  

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