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Posted: Fri Oct 17, 2008 10:43 am
by TheVictorianCobbleCo
I've picked up a lucrative contract making specialist slabs from white cement - the worst size being 2.2m x 0.5m x 100mm thick with super finish. My logic is to cast them in metal trays, vibrated, left for 7 days in the mould and then left to cure for another 2 weeks, seal with a top quality sealer, and then install on site on a bed of sharp sand. As they would be fully supported in situ, and will only see limited foot traffic, do I NEED a reinforced mesh, to my mind the chance of them breaking (because of the length versus width) will only happen during handling. I have heavy handling equipment so the weight won't be a problem. Any comments appreciated.
Posted: Fri Oct 17, 2008 7:02 pm
by Tony McC
I probably wouldn't use mesh, but I would use fibres.
Posted: Sun Oct 19, 2008 8:32 am
by lutonlagerlout
those slabs are huge,are they going to be laid on a screeded bed?
i imagine they must be close to 100kg a slab,you wouldnt want to break any levelling them
LLL
Posted: Sun Oct 19, 2008 9:25 am
by seanandruby
be easier to cast them in situ.
Posted: Mon Oct 20, 2008 8:14 am
by TheVictorianCobbleCo
I agree it would be easier to cast them in situ, but the client is adamant he wants a top class finish, which I can only achieve with a mould. A steel floated finish is unacceptable. Also, the site is 80 miles away, the slabs MUST be sealed, if I do it on site some idiot will for sure mark them before they are sealed/cured. Handling will be done with straps/slings and a crane so we will babysit that side of things. I definitely will softly softly place them on a screeded bed to ensure equally distributed load and no possibility of point loads.
Posted: Mon Oct 20, 2008 11:54 am
by Tony McC
Marlux, the Belgian/Dutch/Flemish paving manufacturer whose products are now distributed by Pavestone, package all their high-quality flags in individual placky bags to protect the surface. It's only one step away from wrapping everything in bubblewrap!
Posted: Mon Oct 20, 2008 11:58 am
by TheVictorianCobbleCo
Ta, I like that - bubblewrap here we come. Will keep you posted
Posted: Wed Nov 05, 2008 8:07 pm
by Jason Herring
At around 3100kg per cube your 2.2x0.5m @100mm thick would be just over 340kgs each. Ouch!
Posted: Fri Nov 07, 2008 3:27 pm
by mouldmaker
Fibres should work better than mesh, but at 100mm thick I doubt you'd really need either. We made slabs with fibre reinforcement 1500 x 900 x 20mm thick and they worked a treat.
Jason, I'd say more like 2400kg per cube making them 264kg each - still not something you want to drop ou your toe, though!
Posted: Sat Nov 08, 2008 5:02 pm
by SFLandscape
Mesh isnt expensive, if in doubt put it in , it wont hurt and at least if there is a problem it isnt because you didnt put mesh in the base, i find if i have thought of something it is best to do , sleep well that way
Posted: Mon Nov 17, 2008 1:52 pm
by TheVictorianCobbleCo
Thought I'd update you. We've made 22 of 130 slabs to date, at 80mm thick and using a poly type reinforcing strip (about 14mm long, 1% by volume) using marine ply moulds with auto body filler sprayed on then sanded smooth, siliconed corners. Cure 5 days before demoulding. 2 Breakages due to poor handling, but transported others safely 80km on old tyres, and wrapped in bubble wrap. 4 - 5 guys manhandle each into place - so very happy at the moment, as whole operation was foreign to me at start. Thanks again for all the advice.
Posted: Mon Nov 17, 2008 5:57 pm
by stapleme
Would love to see some pics....
Posted: Tue Feb 03, 2009 9:19 am
by TheVictorianCobbleCo
Photos as requested - with the help of Tony 
and 
148 made of which about 10 broke due to too fast curing/mishandling, 13 houses thus far.
Posted: Tue Feb 03, 2009 9:44 am
by dig dug dan
those pictures look like a typical house in the usa! is this in this country?
Posted: Tue Feb 03, 2009 12:19 pm
by TheVictorianCobbleCo
(Typ house USA) No, its Paarl, Cape Province, South Africa. We were approached by a company that builds bl**dy expensive houses exclusively on/for the Pearl Valley Golf Estate (2009 SA Open) to see if we could do these slabs, these pics the result. To quote Tony " they...echo the taste for what the teutonic nations are now calling "Mega-Tegels". The German and Flemish architects love them!" I'd never come across them before and approached them with some hesitancy, but they've come out OK - it was a big learning curve, we had to source a suitable reinforcing material - slivers of polyprop 2mm x 14mm x 40 micron or so - 0.1% content by volume, find a way to cast, demould and transport them (packed on old car tyres) - I could go on, but most importantly, the help of this forums contributors went a long way to to making this a success, so give yourselves a back pat, or better still, have a John Smiths extra Smooth for me, can't get a decent beer here, closest Kilkenny or Guiness.