NTPC Sipat — heavy kerb blocks made at site
The problem with big kerbs
A kerb block 500 mm long, 300 mm wide and 250 mm high weighs around 110 kg. The traditional way to make something that size is by hand, in shuttering moulds. It works, but it is slow, the shapes vary from block to block, and the water-cement ratio is hard to control, which shows up as honeycombing and weak corners.
Then there is moving them. Every 110 kg block trucked in from a distant yard is a freight cost, a loading risk and an unloading risk.
What we did differently
We installed our fully automatic block plant at the site and made the kerbs on the vibro press instead of in shutters. The press gives every block the same fixed shape, and because the mix is compacted by vibration and pressure, we could control the water-cement ratio and still get a smooth finish, full density and no honeycomb.
Making them at site also meant the kerbs travelled a short distance from our yard to the fixing points, not hundreds of kilometres. With blocks this heavy, we planned the handling carefully so that each one moved safely to where it was fixed. The safety of our people on a job like this is not a line in a brochure; a 110 kg block dropped once is enough.
Why it matters beyond this job
Sipat is a good example of a situation where on-site production is simply the obvious answer: large, heavy units, in project quantities, needed at a site far from a suitable factory. If your project has kerbs, RE blocks or anything else that is heavy per piece, the transport arithmetic tends to point the same way.
From the site
