Pump me happy. That means the right slump. How?

[ToughButterCup]

To pump an ICF, you need two things: a pump and concrete. Pumps cost £550 +VAT. The concrete costs what it costs.

 

What do you do if the company sends out concrete that's too stiff? Durisol needs to be of  Scotch Broth type consistency.  I'm trying to avoid wasting the poor pump driver's time, and lightening our bank balance by £550 at the same time.

 

And how -on the spot- do I judge what the correct slump is?

 

The only way I can think to get it right, is to order a small amount of concrete at XYZ slump and see if the company actually delivers it. 

 

Concrete's interestingly tricky stuff innit? Fascinates me

 

 

[Oz07]

Some suppliers will offer pump and conc. save the vat and also no risk of paying for pump if the gear is no good 

[Vijay]

Going through exactly the same thing at the moment, trying to get quotes and drilling home that if the spec is off on delivery, the lot will be turned away. I think the only way of telling is with a slump cone

[Declan52]

You get the details from durisol about what they advise. Probably be 60-90mm of a slump. You phone the concrete place and order it to suit what you have been told. When it comes do a slump test and check it's what it meant to be.

A traffic cone cut at 2/3 and 1/3 makes a decent cone shape to do a test of the driver doesn't have one. Add water if it needs some do a retest and only do a pour when it's spot on.

[Vijay]

From what I gather, it's not just the slump rate that has to be spot on, you basically want it to start setting as you go up - that way it helps to stop bursts as there is less pressure on the concrete at the bottom as it's already setting

[ToughButterCup]

47 minutes ago, Vijay said:

Going through exactly the same thing at the moment, trying to get quotes and drilling home that if the spec is off on delivery, the lot will be turned away. I think the only way of telling is with a slump cone

 

Ok. But @Vijay, what if you turn away the concrete and you have a pump sitting there charging you money for doing nowt?

[Russell griffiths]

talk to the pumpy and see if he will supply the concrete a lot of them have accounts and have a good working relationship with the batching plant. 

 

As a bit of advice you want the pump pump on site at 8.00 am and first load at 8.30, if you have any problems you have all day to sort it. 

If it all goes tits up at 3.30pm you are in trouble. 

[Vijay]

1 hour ago, recoveringacademic said:

 

Ok. But @Vijay, what if you turn away the concrete and you have a pump sitting there charging you money for doing nowt?

Only way around that is as others have said, hopefully finding a company who can supply concrete and pump

Edited August 10, 2017 by Vijay

[PeterW]

@recoveringacademic - go find your local supplier and talk to them. Face to face. 

 

I have a local, a regional and 2 national companies within 10 miles of the site. The local company :

- beat the nationals on price hands down

- let me change the order right up to the last wagon left the plant

- rang me to check if we were ready on the Monday morning 

- specced the product for me when we told them what we were doing 

- delivered a quality product that worked for me and tbh everyone that had to work with it said it was superb, not bad for a flowing fibre reinforced slab at a wicked slump ..!

 

Local concrete company number came via the local skip company owner and verified by the local tool hire place .. get the picture..??  

 

Batching plants aren't difficult to find - a quick google found these guys who do batch mix and pump too which may help you. http://quayconcrete.co.uk/

 

I wouldn't hesitate to use a local and pay a bit more over using AI or one of the others - they make money by having those wagons on the site for minimum time and you need someone who can work with you. 

[jamiehamy]

Absolutely spend time getting what you believe through research is the right mix - choose a mix company that will let you speak to the lab (rather than just the sames person) and get a sense of whether they are reputable. 

 

But when a jeager full of concrete turns up - unless it's like water or treacle, I don't think there is a huge amount of merit in doing detail slump tests - let's say it's a bit thick - they'll put up to 50litres water in it (answer to first point). If it's too high a slump you'll need to make a call - it's going to go in no problem and will compact round every nook and cranny - and as long as it's not going down more than say 3m will be fine. You're going to give yourself some serious stress trying to turn round a truck full of concrete and any others that are following at 30mins intervals and already en-route from the batching plant. If you want 80 slump and you measure it at 110 - it's not the end of the world. Some companies will be fine with a slump test but it's going to take up time and as I say - if you don't like the results... For ICF, yes you need to be more particular, but Polarwall is pretty robust stuff. And I think Durisol has a far higher slump recommendation anyway. 

 

I know @recoveringacademicand @Vijay you're probably grimacing and I don't mean to be flippant - I'm not - I'm a pragmatist at heart but also having done two pours I've realised I fretted too much about the mix when it turned up - it's not the Empire State building and the structural loads are in the grand scheme of it, miniscule. Vijay - Alan always seems to relaxed about concrete but that's because he's done it so often - get the mix specified right and a reputable company to mix and try not to worry too much about whether they mix it right. The problem I had with the garage floor mix was that the contractor hadn't paid enough attention to the mix specification and it got lost in translation - they delivered what they were supposed to as opposed to making an arse of the mix. .  

 

As important, if not more, it planning exactly how you will place it - where you will start, how high, where a jeager should take you two, how many you need, where the excess will go, how they will move about the scaffolding, your burst control strategy, tracking the other trucks, where they will stop to off load, how you can stop any excess ending up on the roadside ( @Vijay) - if the trucks cannot get right on site, I would recommend in your case getting cheap ply/osb sheets and placing them where you want the tail of the truck to be, and mark out in spray where they should park - the last thing you want is any overspill or a lazy driver washing down onto the street!), how ) @recoveringacademic) you will get the concrete it - will you use the nozzle or make up something that avoids spillage down the walls?, how will you finish the wallhead - do you need to leave it rough of smooth, how will you place your wallplates if using?

 

Btw - if you turn away the concrete there's a chance you'll not get that batch remade up depending on what time of day. When I under ordered for the walls they told me at first they couldn't get it batched that day as all the trucks were now out, but thankfully they sorted it somehow and got a final 3m3 up to us to finish off. 

 

I suppose all I'm saying is get the right mix specified but be pragmatic when it turns up. 

[MikeSharp01]

Another approach is to get it mixed on site by a mixer truck that way you can control the mix as you go.

 

 

[jamiehamy]

33 minutes ago, MikeSharp01 said:

Another approach is to get it mixed on site by a mixer truck that way you can control the mix as you go.

 

 

that might be a pretty god approach for @recoveringacademic if your volume is not huge?

[Alexphd1]

Jamiehamy hits it pretty spot on! 

I dont think I would be playing around with concrete mix on site as I dont know enough about it. 

We speccd a lot higher of sump than mentioned above but this varys form icf supplier to another. We spoke the concrete supplier telling we needed x amount but was in contact during the pour when to send the next lorry etc we used a bit more than we expected but not much.

We received varying mixes, all pump able and tbh it done the same job. The dryer mix took a bit longer to compact down with the poker but any bits we have opend up ie for steel beams , fixings etc there has been good no air pockets!

One thing which provided reassurance during the pour we had another job that needed 6m2 concrete. Inn case we had a burst we could stick one guy with a lorry load to do that job and buy as some time to fix the burst... that job still need to be done!