When operating a concrete mixer (free-fall type), you can usually run a few batches and then clean it out, which is indeed important to do. But if you're going to mix many batches, perhaps working continuously for a half or whole day, should you make breaks for intermediate cleaning now and then, and how often in that case? Over half or a whole day, the initial batches would start to harden or at least stiffen quite a bit, but you could also imagine that the remnants from one batch are continuously mixed well with the next batch, so that the concrete to be washed away at the end remains almost fresh.
If you use most of a batch, the old mix becomes so low that it doesn't matter (unless you're building a highway bridge or a high-rise pillar).
Mix all day, but make sure you rinse the edge of the inside of the opening where you add water in the next batch. Otherwise, it usually sticks there permanently.
Mix all day, but make sure you rinse the edge of the inside of the opening where you add water in the next batch. Otherwise, it usually sticks there permanently.
When my little brother drove the concrete truck, they always filled it with gravel and water, letting it spin around a few times when they returned to the concrete station. Another option is to gently tap with a hammer or carefully use the machine so that it loosens occasionally.
However, I find it hard to say how often this should be done. Letting a shovel of gravel and water spin around can be done for a short while between each batch. Tapping with a sledgehammer can be done when it starts to build up too much.
However, I find it hard to say how often this should be done. Letting a shovel of gravel and water spin around can be done for a short while between each batch. Tapping with a sledgehammer can be done when it starts to build up too much.