Premix Concrete

The advantages of using premix concrete over site mixed

Banging the drum in favour of readymix concrete

Premix concrete is much more widely used in the UK than in Italy or so it seems. My experience of telling our esteemed workforce that they would have to 'handmix' something is not a pleasant memory nor is the verbal abuse that followed my mandate. Here, it is very different and a premix concrete plant is a last resort for buying concrete.

The average readymix lorry will hold 6 cubic metres although there is absolutely no way of knowing that the volume you have ordered is actually being delivered unless you set up a test area and empty the lorry into it to check. I've seen this done and it unsurprisingly creates a phenomenal amount of bad blood irrespective of the outcome. With the high cost of concrete, it is very tempting for a plant to short-deliver half a cubic metre on each load; something which would be almost impossible to detect. Given the Italian desire to avoid confrontation or even make a complaint, my guess is that this is what is behind the aversion to using premix concrete.

The main advantage of buying readmix is that it should make for a more controllable pour with the water content of the ballast being a known fact and not just guessed at by a site labourer. Deliveries can also be staggered so that the workforce are able to cope with the volume. Finally with the introduction of Tremi tubes and concrete pumps, it is much less effort to get the concrete to where it is wanted. The less time in a wheelbarrow the better for all parties.

We needed just under 18 cubic metres which conveniently works out at 3 lorry loads. Smaller loads are possible (down to 1 cubic metre) but you will be asked to pay a charge per cubic metre 'not carried'. For example if you want 1 cubic metre, the concrete may cost €75 but the lorry carries 6 and that means 5 cubic metres not carried - probably another €75 just for that meaning your 1 cubic metre will likely cost you about €150. Please note that concrete representatives prefer to use the term 'not carried' - don't ask them 'how much do you charge for air?' like I used to as this annoys them!

Another advantage of a premix concrete company is that they should be able to guarantee the quality of the mix load by load.

When it came to placing the order and given that our local plant was about 30 minutes away, I would have asked for one lorry on 'turnaround'. You get 30 minutes to unload the lorry, an hour travelling there and back plus another 30 minutes to load and this would have meant that the three loads would have been 2 hours apart - just about ideal to spread, level, vibrate and tamp before the next load arrived. No, our contractor knew better and had to do different - didn't he?

I don't exactly know what he said to the plant but I was shocked to see two lorries arrive together. 12 cubic metres and only 2 men to lay the concrete! It was also a warm day and I was concerned about the concrete going off in the lorry or, worse (from our point of view) being unworkable when it was poured.

The readymix driver backed up and set up his chutes - this seemed to take ages but eventually the concrete appeared. It took half an hour or more to unload the first lorry and, all this time, the second one was sitting there. It was immediately obvious, though, that the quality of the concrete was a world apart from the slurry our contractor had tried to palm us off with a few weeks earlier.

The second load started its pour but it was getting lumpy and I had to authorise the use of water to help maintain its workability. I could imagine the chaos that would occur if our contractor was left in charge of this so I did some quick mental arithmetic and told the driver the exact volume in litres that he could add.

Despite that and the effect of the third load of the readymix pour, the surface of this part of the slab was far from smooth and I asked for a screed to be laid over the top (at the contractor's expense) rather than risk putting the delicate swimming pool liner directly onto rough concrete. This met with some grumbles but it was done and it is better for it.

Read our article on reinforced concrete and see why I prefer premix concrete.