High Strength Concrete

In the fall of 2020, I was working in Fort McMurrary, Alberta on a project for Cummins Canada. It was a big yard that was being rehabbed. The yard before wasn’t very good; it had ruts and people would get stuck a lot. They have an oversized forklift that is 25 000 kg and the need for a well-built yard was important. The year prior the old asphalt and gravel base was removed. They redid the subgrade and gravel base and paved asphalt on it. In 2020 they milled a layer off the asphalt to aggravate the surface to overlay the concrete on top of it. The concrete was an interesting process as they paved it with a huge concrete paving machine like you would with asphalt. It is a typical way to do airports and concrete highways. The minimum specification was 100mm thickness, but the majority was at least 125 mm thick.

The concrete mix used a fiber to increase the flexural strength without using rebar. This was an interesting way to do the reinforcement as its main purpose was to pave the concrete with the machine. If using rebar, the entire area would need to be done by hand. Rebar was used in some of the more vulnerable spots. The approaches to the shop were done with rebar for example. This is a high traffic and high load area so it’s important to have extra protection. With the fiber and the rebar, it created a very strong combination.

In one load of concrete the fibers were really clumped together in the mix. They were these big fur balls of the fiber it was a weird situation. It wasn’t too big of a deal, can just pick them out when they were spotted; but made for an interesting outcome. There was still enough of the fibers in the rest of the mix so it didn’t compromise the rest of the batch.

Since the machine needs a clearance on each side, every other row could be done by the machine. The inner rows were done by hand though. It was still a fairly quick process since the outer strips were already done. The contractors could use a smaller sit-in machine to smooth out the concrete since it could be supported on the concrete already poured by the machine.

There were complications with the project coordinating with the client and the contractor because the concrete needed to sit for 7–10 days before too much weight could go on it. The client wanted to be able to use their shop and have access since they were still in full production. We had to orchestrate the timing of the concrete pours with the days they needed them. And it was my job to make sure everything was done properly, and the client could keep access to the shop and ensure the contractor was able to keep the schedule going.

Liaison between the contractor and client was the majority of my role on site in order to make sure the contractor was doing a quality job and help them if they need anything from the client.

There were relief cuts in the concrete every 1.2-meter square to allow for flexing of the product. This was used to allow for flexing in the yard. And also, if the concrete is going to crack it will crack in the relief cuts. The end product was amazing and looked great. In the end The client was quite impressed with it.