REPAIRING A GRAIN SILO (CONCRETE GOES FARMING PART II)

It’s difficult to understand the person you’re talking to because the echo inside one of these giant hollow cylinders is like being inside of a massive cave. It takes a minute for your eyes to adjust to the darkness as you climb inside. In this blog we’re going to discuss:

• Applying epoxy and water-stopping cement to the silo floor
• Dowelling in pegs to fasten wire mesh reinforcement
• Spraying shotcrete and finishing the new silo floor
  • Preparation
  • Application
  • Finishing

Last time we were here, we took a look inside of the grain silos for the first time and assessed the problem. Water was seeping in through cracks in the concrete floor and there was six feet of standing water at the bottom of the silo pits. We mapped out a plan for how we would fix the problem and today we are here to execute the final stages of that plan. As usual, we’re going to address these topics in real time as we show up on the job.

• Applying epoxy and water-stopping cement to the silo floor

JC is pulling buckets of water out from one of the silo pits. “We’ve got water coming in,” he says. “There’s a water table, and we’re trying to keep all the water out of the concrete. We’re filling all the cracks in, but right now it’s beating us! But I think we’re gonna have it handled here soon.“

In the adjacent silo, the water problem is under control. Epoxy has been put in all of the cracks and Tim is now putting another layer of water-stopping cement down on the surface of the silo pit. “[This stuff] does a pretty good job of filling in the cracks, and it dries immediately,” he says as he touches up a few remaining spots. It’s difficult to understand because of the echo.

• Dowelling in pegs to fasten wire mesh reinforcement

2 Inch long pieces of rebar are cut to dowel 1 inch into the silo floor. They’ll be shallow enough to not bust through the other side but still hold strong with epoxy. A big orange circle is painted on the cylindrical floor at the point the work will commence, six feet up from the bottom. The rebar pegs are doweled in approximately two feet apart, all the way around and down.

Wire mesh reinforcement is cut out in sections to place all the way around the bottom six feet of the pit and tied to the rebar.

• Spraying shotcrete and finishing the new silo floor:
  • Preparation

They’re using planks that span across the bottom of the pit as scaffolding because the floor of the silo pit itself is too steep to stand on. One plank spans in one direction, another plank spans in the other direction. Directly beneath those two planks are two more, also spanned across but cut shorter and at a lower level.

A strong rope has been stretched out across the top of the pit. It’s tied to rebar that’s embedded in the concrete in a handle-like fashion, all the way around the top of the pit. The pump hose is fastened to the rope and let’s down in the center, directly above the area Tim will be spraying. “We would’ve used a cable or something to stop it from sagging down so much with the weight,” Tim said later. The rope was tight at first, but by the end of the pour it sagged down about four feet from where it originally was. “It got in the way,” Tim explained.

• Application

Tim has the pump hose hoisted up and Abraham is standing behind him, ready to pick up any slack in the hose. It’s very heavy. Tom stands at the top of the Silo pit with the pump control in his hand and starts to count down. “Three,” He yells. He’s just a silhouette against the backlight of the small silo entranceway, but his voice echoes loud in the giant empty space, “two.” Tim widens his stance and braces himself like a football player. “One!” Tom yells at the same time the hose begins to blast concrete. The force of the hose pushes Tim back, and he signals up for Tom to turn the pressure down.

Once Tim has a quarter or so of the area sprayed, Abraham begins to trough. Tim sprays more and then helps trough as well. After the upper portion has been sprayed and troughed, they pull out the two planks they had been standing on and descend to the lower two planks. They continue spraying, moving the hose around and troughing as they work their way down and around. Soon they are removing the lower two planks as well, and soon after that Abraham is climbing out of the pit.

• Finishing

Tim finishes up at the very bottom, but it’s tricky. He is standing in a pit of wet concrete and has to wait for it to dry enough to get on top of, and then work his way out. JC comes down the ladder to help support the rope that Tim is hanging on as he finishes. He can finally get on top of the concrete and slowly finish behind himself as JC inches him up and out of the pit. Like watching The Cliffhanger with Sylvester Stallone, I am fascinated as if by a unique work of art. And at that exact moment, my camera battery dies!

Thanks for reading, everyone! See the full video below.