On-site vs off-site precast manufacturing: which is better for large projects?
We set up precast plants at project sites for a living, so you might expect me to say on-site is always better. It isn't. Here is how I would think about it if I were sitting on your side of the table.
Let me start with the answer most people don't expect from us: for a lot of jobs, you should simply buy your blocks from a good factory nearby.
If you need a few thousand square metres of pavers for a warehouse apron and there is a reliable plant 40 km away, setting up production at your site makes no sense. You would be paying to mobilise machines, moulds and people for a job that a factory can finish from its regular stock. For a job like that, we would tell you to buy.
The picture changes when the job gets big, far away, or heavy. That is the territory we have worked in since we started in precast in 2001, and it is where the comparison gets interesting.
What the factory route gets right
A factory is already built. Its machines are commissioned, its curing yard is running, its people know the routine. You place an order and material arrives. For small and medium quantities, and when the factory is close, that is hard to beat.
The factory also carries the risk of its own plant. If a press breaks down, it is their problem, not yours (as long as they still deliver on time).
Where the factory route starts to hurt
On a large project the weak points are not in the block. They are in everything that happens after the block leaves the factory gate.
Freight. Concrete is heavy and cheap per kilo, which is a bad combination for trucking. Once the distance grows, freight becomes a serious share of the landed cost. With heavy units it gets worse: the kerb blocks we made at NTPC Sipat weighed around 110 kg each. You do not want to be paying to move tens of thousands of those across states.
Handling. Every time a block is lifted, stacked, loaded, unloaded and restacked, there is a chance of a chipped edge or a broken corner. A few percent does not sound like much until you multiply it across lakhs of units, and then argue with the supplier about who pays.
Dependence. Your laying gangs are now waiting on a factory's order book and a transporter's availability. If the factory has a bigger customer that month, or trucks are scarce during harvest season, your work front stops.
What changes when the plant sits at your site
When we install a plant at the project, the block travels from our curing yard to your work front, often within the same boundary wall. Production follows your programme instead of a factory's. If you need to speed up in one zone, we can shift output the same week.
Quality becomes something your engineers can see, not a certificate that arrives with the invoice. They can walk to the press, watch the cubes being cast, and check the curing. I think that visibility is underrated; it removes a lot of arguments before they start.
And scale becomes manageable. At Dhamra Port in Odisha, Adani Ports needed 2,50,000 square metres of 80 mm M-50 unipavers for internal roads, truck parking and a steel stackyard, at a very remote site. We set up production at the port and laid what we made. Trucking that quantity in from a distant factory would have meant a very different, and much more fragile, supply chain.
What on-site asks of you
It is not free, and I would rather you hear that from us than discover it later. An on-site unit needs space for production, curing and stacking. It needs water and power. It needs time to set up before the first block comes off the press. And it needs a project large enough, and long enough, to pay back the effort of getting there.
Four questions that usually settle it
- How much? Small quantities favour the factory. Large quantities favour on-site.
- How far? The further the nearest suitable factory, the stronger the case for on-site.
- How heavy per piece? Kerbs, RE blocks and thick heavy-duty pavers tilt the answer towards on-site much sooner than light tiles.
- How long? A plant that runs for many months spreads its setup cost thin. A two-week job does not.
If you answer "a lot, far, heavy, long" to most of those, it is worth a conversation about on-site production. If you answer "a little, close, light, short", buy from a factory, and we will happily tell you so.