Slab and Foundation Pours: Planning the Day, Not Just the Concrete

A large pour is a logistics problem

The concrete is the easy part. What decides whether a slab goes well is whether the trucks arrive at the rate the crew can place and compact, over several hours, on a Nairobi road network that does not cooperate.

Too slow and you get cold joints. Too fast and trucks queue on the access road, waiting time is charged, and the concrete in the last drum is not the concrete that was batched.

We plan the schedule with you

Before a large pour we agree the placing rate, which is a function of your crew, your access and your method, and then schedule deliveries to match it. That schedule accounts for the plant-to-site run at the actual time of day, which on Mombasa Road or Thika Road in the morning is a completely different journey from the same run at ten o’clock.

Pours on the Athi River and Syokimau corridor are usually scheduled early for this reason alone.

Cold joints, and why they matter

If concrete already placed has begun to set before the next load arrives, the two do not become one material. You get a plane of weakness through the slab, invisible once the formwork is struck, and in a water-retaining structure or a suspended slab it is a genuine structural defect rather than a cosmetic one.

This is the thing continuity buys, and it is why we would rather turn down a pour we cannot supply continuously than start one and leave you with a joint.

Before the trucks are called

Formwork checked and propped, reinforcement fixed and inspected, cover confirmed, vibrators on site and working with a spare, enough people to place at the agreed rate, and a plan for wash-out. Every one of these has stopped a pour we have attended, and every one is cheaper to fix the day before.

Curing starts the moment you finish

In Nairobi sun a slab left uncured loses surface water fast, and the surface it leaves behind is weak, dusty and prone to crazing. Cover it, keep it wet, and keep it that way for the first week. The concrete you paid for is the concrete you cure.