David WE Roberts wibbled on Tuesday 26 January 2010 17:43
D'oh - knew I should have used kcalc...
OK - forget all that then. At least you know they really did give you a decent ish price. Round my way they all wanted stupid money until I got out the B&Q list...
It's very hard work even for someone who is fairly fit and active like myself, I'm no doctor but I wouldn't advise someone with a dicky ticker to start pushing wet concrete about against the clock.
What do you mean they have no chance? - they say what they always say, and that is that *you* have mis-measured the area / depth / whatever and threaten to leave site....what you do then is irrelevant to them
Because the readimix wagons have a gauge on the side which says how much is in the mixer, obviously it must work on weight, the wagons that deliver the stuff you are on about carry many more tonnes of dry ingredients so they don't have such a gauge.
Please yourself, I've only laid about 200 slabs for extensions, houses, garages etc over the past 30 years so my knowledge is slightly limited.
they are also suspected of skimping on the cement content- so giving you a weaker(cheaper) mix than you think you're getting.....
JimK
I recently had 2.5m^3 at £85 a m^3. Two guys, Auger mixer, barrowed about
85 feet from the road. Quick and simple. Unless you can manage to save a fortune by doing it yourself, just go with having it done for you and you can relax!SteveW
I would get a quote for mix *and* lay - that way its not your problem! ;-)
He's not wrong, but possibly overstating the case. I had to argue when I had mine mixed and barrowed recently - the counter on the wagon said I'd had my 2.5m^3, but we were between 0.5 and 0.75m^3 short. I had to get out my tape measure and calculator and prove that their counter was inaccurate before they carried on. I'd still do it this way again, but I'd make sure that they knew the measurements before delivery started!
SteveW
Apologies - I was feeling a bit disgruntled last night after a bad time with some shuttering.
I am now (as usual) between a rock and a hard place. The best way to get the correct amount of concrete seems to be to have it mixed at the roadside - no problems with a slight under order or finding yourself with too much. However if you can't trust the operator to accurately measure the volume delivered then this potentially makes the costings invalid. If you can't trust the quality of the mix this makes it even worse.
However assuming (as posted elswhere) that pre-mixed concrete is metered out by a guage on the lorry I can't see how you can trust this any more than you can trust the instant mix lorry. I also can't see the difference between skimping the mix at the roadside and skimping the mix at the mixing plant - in both cases you are in the hands of the operator.
Advice to get quotes for deliver and barrow noted from various sources - I will ask the suppliers.
Cheers
Dave R
I'm a bit shocked to hear the idea that concrete suppliers deliberately supply weak mixes and I find it somewhat hard to believe. I've never heard of this idea or read about it anywhere before. As it could be a safety-critical issue, any hint of fraud would be a scandal and make national news. If it were widespread, the guys on pavingexpert.com would surely be aware of it and would have mentioned it. On any significantly-sized construction or civil-engineering project, test cubes will be taken of every batch, so ready-mixed concrete suppliers must be au fait with producing material exactly to specification. As I understand it, these test cubes are there to check that the supplier hasn't made a mistake, rather than making sure the supplier isn't defrauding the customer. Supplier websites abound with marketing blurb about "we've got computer controlled plant and automatic admixture dosing equipment, so we can guarantee the accuracy of your specified mix", etc. ISTM that this would make it *harder* for them to cheat. You can get a BSI kitemarked approval for your mixing operation FFS.
I would suggest that all you need to do is make it clear that you will be making test cubes and, as if by magic, the mix will be right...
Give Alan Newport and co a ring at Fordham they deliver out in East Anglia used them before and found them to be very reliable . They have their own mixing plant and quarry!....
Just got a quote from Tarmac which appears to be £115 for the 3.5 cubic metres.
However the small print is pretty extenisve - apparently if I fart in their general direction it cost me an extra £100.
If I can cut&paste the contents of the PDF quote then I may be asking for help with the transalation.
Highlights are a £75 surcharge if the lorry is on site more than 5 minutes, and various charges if they have to take any back.
Living in Suffolk may also carry a surcharge - something about banjos and six fingers in para 3.2.4.1.8 annex 3.2.5(b)
Me, probably.
I wasn't aware of the distinction between auger and tub mixers - mine was the manually controlled tub-type.
A poor, sloppy, mix, barrowed by youths who didn't give a damn where they slopped it. And Phil L is quite right about the "there you are, that's what you paid for" when the job's part-done and you're in about as strong a negotiating position as the porridge they've just poured.
Theoretical rights and remedies are fine for keyboard warriors, but less useful when it's you against them on site.
I'm more comfortable with a proper company selling batch-mixed concrete, who are used to having test cubes done, but even then you have to watch the driver doesn't add a bit more water "to help it pour".
Ready-mixed and a hired dumper truck might be a good compromise, depending on the distances and access arrangements, but if I ever do another garage, I think I'll go back to trailer-loads of ballast parked next to the job and the trusty old Belle electric mixer, no matter how despised by some.
Interesting reading, Kevin.
I guess the problem is in working out which are the reputable firms and which are the cowboys before you order. I have seen the 'mix on site' equipment advertised on line as a franchise operation, so if you get one of these then you are bound to get a variable result depending on how avaricious the franchisee is. However as you say you also have to watch the ready mixed brigade to make sure they don't increase their profitability at your expense.
Care to 'name and shame' the offending company so we can avoid them in future?
I have noted that it is a good idea to carefully measure the site before the concrete is ordered, and make it clear that you have carefully measured when ordering and taking delivery.
The run is about 37 metres, although about a third is over a lawn which is waterlogged at the moment so I am not sure how practical a dumper truck is. The damage could be considerable. Also, for the £80 + VAT for the dumper truck (special half price offer) I could possibly buy an extra barrow and hire a labourer for half a day. Certainly I will price it against having the company supply an extra barrow runner.
I have been barrowing MOT (in the rain) and estimating by counting suggests about 30 seconds from road to site with a full barrow. This is taking it steady in both directions - always a good idea on muddy scaffold planks in the rain - so if a previous suggestion of up to 70 barrow loads is correct then it looks doable in 90 minutes with regards to the barrowing.
40 seconds for the round trip including emptying and filling the barrow to do the lot in 45 minutes seems a suicidal pace for one barrow, however.As calculated elsewhere, the price of the raw materials is significantly higher than the cheapest and probably still higher than the most expensive ready mixed quotation (once I have confirmed that I will be charged an extra £75 if I dont shift it 17.5 minutes). Interestingly this would just about pay for the dumper truck to enable me to move it in 17.5 minutes. Still well over £100 more than my 'small load' (First Choice Mini Mix) and mix-on-site (Eastern Concrete) quotations. This doesn't include the mixer hire, either, although I may end up buying a small mixer for building the block walls.
Thanks to all for the helpful information and suggestions in the various ongoing threads.
All I have to do now is pick a couple of days without snow and heavy frost to lay the DPM and reinforcing, then lay the concrete (allowing two days so I can get the concrete down in the morning for the best chance of getting it setting before any overnight frost).
Oh, and I am assuming that the major part of the levelling and tamping will come towards the end of the load - initially it should just be 'barrow and pour' with a bit of minor raking about until the area is nearly full at which point the final levelling and tamping takes place. At least this is the way I remember it from the distant past. Based on this I think that if I can share the main part of the barrow running with one other, and then concentrate on the levelling whilst the other barrower finishes off then that should work out O.K.
Cheers
Dave R
Just noticed that the label on the back of my barrow says " 3 cubic feet". Fed this into my trusty spreadsheet which says 42 barrow loads if all are full. Which has also led me to consider counting barrow loads - as a method of cross checking the volume supplied.
1;2;3;4;5; - oh bugger - 1;2;3.........
Yes they do (generally) give you a weaker mix than you would get from a readimix company, mainly because they know that it's only going to be used for slabs, foundations, drives etc and nothing too important - as my earlier post says, even quite weak mixes are more than sufficient for this type of work. Think of buildings that were put up 50 or 60 years ago - the concrete under them is similar to the weak mixes we've been discussing, brick-bat and little cement, but it still holds up and will continue to do so probably for another century or so with no trouble
The Barrowmix lot that did mine came as wagon, driver and mate and both of them barrowed it. They emptied their barrows in slightly different spots each time, so there wasn't much moving it about for me to do, just consolidate it, level to the shuttering edge and smooth.
SteveW
Yes - I think the lot I used may have been, but I can't remember the name. They were based somewhere east of Nottingham, iirc
Batch-mixed is likely to be more consistent than site-mixed with a yoof tipping bags of cement into a drum. Consistently good, is another matter, but it somehow seems more likely.
See above
Well, yes, but the sort of people I had would not be capable of coping with the maths if you gave them your calculations and asked them to check the measurements before they start pouring.
Yup.
Probably the better choice for you, depending on how easy you'd find it to hire (and supervise) the labourer.
Hmmm. You must be fitter than me to keep that pace up, with no breaks (but most people are fitter, and younger). ISTR you talked earlier about barrowing on planks or sheets over the wet concrete. Unless they give you quite a stiff mix, I think your boards will sink.
It's interesting to speculate whether this is all down to RMC having rather more buying power for raw materials, or whether some of it is because we amateurs tend to over-egg the pudding, and make concrete far stronger than it needs to be.
How are you planning to leave the surface? Professionals seem to like to leave either a spade or tamped finish, then screed it. I'm too mean for that, so I try to float to an acceptable finish - but it all takes time.
My instinct is that a simple polythene sheet cover would protect sufficiently against a brief "clear sky" type of ground frost, but not against the sort of spells we've had recently.
I've taken advice from various sources and ordered some sacking in a roll to cover the surface. I assume this is used to allow some evapouration as the concrete cures. I then plan to cover it with whatever odds and sods of plastic I have to negate the advantages named above but keep in a bit more heat.
I was planning to leave a tamped surface because I don't think I need an especially smooth surface for the inside of a garden store cum workshop. If I feel exuberant and bored and the concrete is still workable after the slab is tamped I might have a go at floating the surface for a smoother finish, but the main aim of the exercise is to get it down and level in the alloted time.
David WE Roberts wibbled on Friday 29 January 2010 10:42
When it's all dry and the workshop is up, might be worth a coat of floor paint (good stuff, not crap). Will keep the dust down and make dealing with oil spills or whatever easier.
Why is water evaporation an advantage? Concrete cures by a chemical reaction which requires water to be present - test cubes are cured under water once the initial set has occurred.
Indeed, but it will remain workable enough to float for hours rather than minutes.
Tamped concrete is much harder to keep clean, and quite hard to paint. I'd disagree with Tim (below) about the need for a good quality paint - I used a very cheap grey paint that's been fine for regular use, admittedly not for fork-lift trucks or hundreds of people. I used a fizzy-type (acid) cleaner first, mainly to get rid of the laitence from the sloppy bought-in concrete. You'll be pleased you painted it the first time you drop a grease-covered screw (you do grease your screws, I hope), or knock over the can of lawnmower oil.
Kevin Poole wibbled on Saturday 30 January 2010 08:29
Yeah - I wasn't alluding to buying an epoxy floor paint - but some of the "floor paint" that B&Q sells is barely much more substantial than emulsion.
Good tip on the laitance...
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