Hot loads: what to do when concrete starts going off in the line

A hot load is concrete on a countdown. Whether it's a summer pour, a mix heavy on the early-strength gear, or an agi that sat in traffic for an hour, hot loads punish concrete pumpers who stop paying attention. The concrete doesn't care about your program. It's setting whether you pump it or not.

And once it starts going off inside your line, every option you've got left is a bad one. The job is to never get there.

Read the docket before it reads you

The batch time on the docket is the most important number on the truck. Concrete that was batched two hours ago on a 35-degree day is not the same product that left the plant. Check it every load. If the times are stretching, get on the phone to the plant before the problem is in your hopper — because once you've taken it, it's yours. Nobody from the batch plant is coming to dig it out of your pipeline. That's Module 01 thinking: no one is coming to save you, so sort it before it's in the system.

The tells

Pump pressure creeping up on the same mix. Strokes getting harder. Slump collapsing at the chute. Concrete balling in the hopper instead of folding. The line getting warm in patches. None of these mean stop the job — all of them mean stop assuming everything's fine.

Keep it moving

Concrete going off in a moving line is a problem. Concrete going off in a stopped line is a disaster. During delays — waiting on agis, waiting on the finishing crew, waiting on the builder — keep the load turning and stroke the pump every few minutes to keep the column alive. A long boom full of dying concrete is a pipeline you may end up clearing with a hammer, one clamp at a time, in the dark.

Talk to your hoseman, talk to the batcher, and slow the round trips before the gap between loads becomes the thing that kills the pour.

In the heat, plan the pour like the clock is against you, because it is. Closer load spacing, a word with the plant about retarder, a full waterline before the first agi backs in, and a washout plan that doesn't depend on everything going right. The pours that end badly are almost always the ones that started casual.

Know when to sacrifice the load

There's a point where a load is more dangerous than it is valuable. Pushing setting concrete through a line spikes pressures against every clamp, rubber and worn deck pipe you own — and a blowout under that kind of pressure doesn't send a warning first. Dumping a dying load feels expensive right up until you price a burst line at head height with the boys standing around it.

Wash out early, wash out properly, and treat a hot afternoon load with the suspicion it deserves. The gear can be replaced. The load can be replaced. The bloke on the hose can't.