In the USA concrete is shipped using cubic yards. A standard sized concrete truck will hold around 9-Yards of concrete.
This is sufficient to provide concrete for a slab of concrete that is 8 ft. x 10 ft. and 4-inches thick.
This figure can vary by yard either way. There are some trucks that will only carry 8 yards, and there are some trucks that carry 10 yards.
The model of the truck is often the deciding factor, as is the weight limit imposed to stop trucks from damaging roads. This can vary from jurisdiction to jurisdiction. Even the trucks that have a capacity of 10 yards will typically only deliver 9 yards.
According to a mixer truck driver in Indianapolis, his company say that there is a risk of damaging roadways if a truck is over 9.5 yards. This view is supported by many other sources.
How long can you keep concrete in the truck before it is no good?
Ensuring the truck arrives at the expected time is very important. If you are not ready when the truck arrives and it has to wait, it could be a problem.
The suggested maximum time that concrete should remain in the truck is 2 hours. After that, it may not be any good. That is based on temperatures of between 60F and 80F.
If it’s colder than that the time might be extended a little. After this time the concrete begins accelerated hardening.
The trucks will have received their load of concrete from a mixer plant This is where the concrete is originally mixed. The truck continues to agitate this mix during transit, keeping it from settling.
What kind of concrete mix do you need?
The mix of concrete will depend very much on scope of work if the project involve the use of an engineer design, the concrete mix will be listed on the approved plans. The standard mix usually between 2500 and 3000 PSI.
The concrete contractor should be able to read the approved plans, or advise you if it a basic flat work job such as driveway, patio slab , etc.
What happens if a load expires?
Concrete does not expire dead in 90 minutes and when it reaches 2 hours it may not be useless.
The concrete company will not want to waste the load and will try to use it for some low-level task depending on how long they have left. Some companies will pour the ageing mix into bunker block molds.
If they do not have time or the mix has gone past that point, the mix may be dumped.
When ordering concrete, it is essential to pay attention to ensuring that the moment the truck arrive staff can get into action and pour it.
Considering how much the truck can transport will have an impact on how many loads there will be. Trucks waiting at building sites are costing the trucking company money and they want the concrete poured as quickly as possible.