Hello!
I've poured a slab and calculated the exact amount that should have been used, namely 18.73 m3.
(I've also laid underfloor heating and reinforced it, which should use 200-300 liters less concrete, but I haven't accounted for that to be on the safe side.)
It should be exact since the form has been built in foam.
I ordered 20.5 m3 and when I received it, there was 1 m3 missing! The last cubic meter cost 5000:-!
How accurate is the concrete station's calculation? Perhaps I didn't receive the ordered amount?
The drivers of the concrete trucks claim that the foam settles, hence the increased amount, but can the foam settle by over 2 cm? I find that hard to believe!
The slab is 133 m3, and if the foam settled by 2.25 cm, it would correspond to 3 m3.
What do you think? Is it common practice to receive less than ordered, or are they right that the foam sinks that much?
Regards/T
I've poured a slab and calculated the exact amount that should have been used, namely 18.73 m3.
(I've also laid underfloor heating and reinforced it, which should use 200-300 liters less concrete, but I haven't accounted for that to be on the safe side.)
It should be exact since the form has been built in foam.
I ordered 20.5 m3 and when I received it, there was 1 m3 missing! The last cubic meter cost 5000:-!
How accurate is the concrete station's calculation? Perhaps I didn't receive the ordered amount?
The drivers of the concrete trucks claim that the foam settles, hence the increased amount, but can the foam settle by over 2 cm? I find that hard to believe!
The slab is 133 m3, and if the foam settled by 2.25 cm, it would correspond to 3 m3.
What do you think? Is it common practice to receive less than ordered, or are they right that the foam sinks that much?
Regards/T
It should be possible to calculate that, right? There should be data on how much the foam compresses under a certain weight. Or you can call and check with the reseller/manufacturer of the foam. They should know.
When I poured the floor in the basement, the guys doing the job said that they always brought a little more than what the customer ordered just in case (which was lucky because we needed a little extra)... and they didn't charge any extra for it. But what is standard practice, I don't know...
When I poured the floor in the basement, the guys doing the job said that they always brought a little more than what the customer ordered just in case (which was lucky because we needed a little extra)... and they didn't charge any extra for it. But what is standard practice, I don't know...
It's normally not possible to get all the concrete out of the trucks either, so the practice is to order a little extra just to avoid having to send an extra truck. I don't think the cellplast compresses, but if it's poorly compacted, it can compress by the singlet being pressed into the styrofoam.
If you pump concrete, you have to allow for an extra 300 liters. Have you calculated the amount correctly including the vot? Deducting liters because of reinforcement and underfloor heating pipes feels a bit overkill.
Unfortunately, I would have to believe that the concrete truck delivered the right amount of concrete. Even if, against all odds, it wasn't the case, it would probably be really difficult for you to prove otherwise.
I also like when theory and practice align and have calculated quite accurately on a 75 sqm slab. The concrete guy was skeptical: "This will never be enough!". It ended with him shaking out the last bit so that there was too much concrete, which created quite a bit of extra work for me to remove the excess.
I also like when theory and practice align and have calculated quite accurately on a 75 sqm slab. The concrete guy was skeptical: "This will never be enough!". It ended with him shaking out the last bit so that there was too much concrete, which created quite a bit of extra work for me to remove the excess.
Yes, I calculated exactly right, excluding fall etc. (I work as a calculator, you could say, so if there's anything I know, it's that )
But when I, as a private person, call the concrete factory and say that it takes 18.73 m3 and they know that 1 m3 is left in the trucks, they should of course inform me of that, right?
I calculated for fun the volume of the reinforcement and floor heating pipes to know how much would be leftover, but of course, I was surprised when the last truck was empty and 1 m3 was missing....
)But when I, as a private person, call the concrete factory and say that it takes 18.73 m3 and they know that 1 m3 is left in the trucks, they should of course inform me of that, right?
I calculated for fun the volume of the reinforcement and floor heating pipes to know how much would be leftover, but of course, I was surprised when the last truck was empty and 1 m3 was missing....
did you then account for the cellplast settling a bit?injonil said:I would unfortunately believe that the concrete truck had the right amount of concrete. Even if by any chance it wasn't, it's probably really hard for you to prove otherwise.
I also like it when theory and practice align and have calculated quite accurately for a 75 sqm slab. The concrete guy was skeptical: "This is never going to be enough!". It ended with him shaking out the last bit so that there was too much concrete, which created quite a bit of extra work for me to remove the excess.
will call the company and see what they say,,, should be able to haggle a little at least... if nothing else on the fact that they didn't arrive on time when the loads were ordered =)
what type of concrete did you use?
was it "just" a flat slab? or with reinforcements?
was it "just" a flat slab? or with reinforcements?
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wonder if the concrete was called c 28/32, it was regular concrete anyway,
a regular flat slab with a surrounding edge beam
a regular flat slab with a surrounding edge beam
if it had been skb I would have understood.
it's difficult to calculate exactly what is required in cubic meters.
but for it to differ as much as you wrote.
what measurements did you have for the casting?
it's difficult to calculate exactly what is required in cubic meters.
but for it to differ as much as you wrote.
what measurements did you have for the casting?
Have cast 2 slabs at 33 and 60 square meters. Calculated and ordered according to my calculations and rounded up to the nearest cubic. According to my calculations, there should be around 400 liters in reserve, and in both cases, they drove home with 200-300 liters left in the pot. If you order a volume, you're supposed to get that volume. If you've calculated correctly, you've most likely been deceived. I don't find it likely that the foam plastic would sink that much.
skb? is it vibbfri?
this is how I calculated:
14.4*9.2 = 132.48 m2
since it has varying thickness, 15cm on one gable and 12 on the other with a smooth slope
it becomes: (132.48x0.15+132.48x0.12)/2 = 19.872+15.897 / 2 = 17.88 m3
edge beam 20*10cm = 14.4+14.4+9.2+9.2 x0.1x0.2 = 47.2 meters long x 0.1*0.2 = 0.944 m3 the edge beam is slightly shorter because it is not at the outer edge of the slab since there is an upright insulation outside of 10 cm so in reality, a little should be subtracted but this is compensated by the angled cut of the L-elements
then we can subtract the slope on 2 floor drains with an area of 6*7.2 which becomes 360 liters each as the drains are 2.5 cm lower. = minus 0.72m3
17.88+0.944-0.72=18.1 m3
BUT now the old garage "encroaches" on an area of 8.6*0.2 which gives minus 0.17 m3 then reinforcement and underfloor heating are added which gives minus 0.3 m3 so it shouldn't have been so much concrete as it was....
now the calculation became very unclear but as you see I have considered everything
this is how I calculated:
14.4*9.2 = 132.48 m2
since it has varying thickness, 15cm on one gable and 12 on the other with a smooth slope
it becomes: (132.48x0.15+132.48x0.12)/2 = 19.872+15.897 / 2 = 17.88 m3
edge beam 20*10cm = 14.4+14.4+9.2+9.2 x0.1x0.2 = 47.2 meters long x 0.1*0.2 = 0.944 m3 the edge beam is slightly shorter because it is not at the outer edge of the slab since there is an upright insulation outside of 10 cm so in reality, a little should be subtracted but this is compensated by the angled cut of the L-elements
then we can subtract the slope on 2 floor drains with an area of 6*7.2 which becomes 360 liters each as the drains are 2.5 cm lower. = minus 0.72m3
17.88+0.944-0.72=18.1 m3
BUT now the old garage "encroaches" on an area of 8.6*0.2 which gives minus 0.17 m3 then reinforcement and underfloor heating are added which gives minus 0.3 m3 so it shouldn't have been so much concrete as it was....
now the calculation became very unclear but as you see I have considered everything
never count anything out when doing stuff like this
just the slab I get to 20cubics (without edge beam).
just the slab I get to 20cubics (without edge beam).