Concrete quality assurance - what do you do?

[Adam2]

My SE has recommended I get test cubes (7 day, 28 day and a spare) for 1 in 2 of my concrete pours. This is going to get expensive!!!! We're using fairly standard mixes from Cemex who of course have their own QC processes etc. Cemex will of course charge for each set of cubes and I'm looking at maybe 20 deliveries so this will be adding up to a cost I need to understand the value of.

 

The batch plant for Cemex is 2 miles away so very low chance of traffic delays causing big issues so I'm just not sure if this is really necessary, we can easily of course do a slump test on site so have that basic level of reassurance.

 

 

Would appreciate thoughts from the more experienced out there if this testing is usually done like this. For context, the project will have 3 separate floor slabs (300+ thick), ICF walls (200mm core), in-situ poured concrete terraces (200mm thick) and hollow-core concrete planks for intermediate floors. 2 of the wall sections would be classed as retaining as the floors are semi-basements.

   

[Russell griffiths]

I thought about this and worried for a few days, I then changed my foundation mix to the same mix as the walls to see how it pumped

C35 10mm aggregate, it pumped well with no added water and set up absolutely solid, I thought back to how many times I have had a truck of ready mix and how many times it hasn’t set correctly, and suddenly dismissed the test cubes as just another thing not needed. 

 

If it was coming out of a batch mixer on site I would be less confident, but never had a problem with a plant mix.