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Posted: Mon Mar 16, 2015 1:39 pm
by jimbo1981
Afternoon all. I've got a bit of a query and this site has been a huge help over the years. Thought it was time to join up and get some opinions. We've been asked to replace some concrete at a factory site we look after. That's the simple part. Unfortunately the section is 25m x 3m and runs right through the middle of the site. Basically whatever we do will hgv's over it much sooner than I would like. Existing is 150mm thick, no reinforcement over limestone. Limestone is so well compacted ( probably been down 30 years plus ) I have struggled to get through it in the past with a 3t digger. Biggest time window I can hope for is dig out Wednesday before Easter, pour on Thursday and won't be run on until the following tuesday. I know it's not long enough but need to keep what is a very good customer happy. Any ideas? Didn't know if steel plates would offer enough protection?
Cheers
James
Posted: Mon Mar 16, 2015 4:23 pm
by Captain Concrete
I am doing the self same thing over Easter in a builders yard, ask for a very strong concrete, say a C40 with OPC cem 1 52.5 and keep it reasonably stiff. Steel plates will help spread the lorry weight, the sub base seems very hard so that's all good I would use a decent mesh A 393 and make sure you poker it. You could use something like these to spread the weight: https://www.google.co.uk/search?....0%3B750
Posted: Tue Mar 17, 2015 7:09 am
by GB_Groundworks
Do you mean 10mm a393
I'd road plate it, 7 days recommended before loading whats the engineer saying?
I'd have thought 250mm with 393 mesh in bottom and 142 in the top for crack control be fine but should be an engineer involved for peace of mind. Just don't wet it up and weaken it.
Posted: Tue Mar 17, 2015 1:01 pm
by Captain Concrete
Yes sorry slip of the key-board, on another note you may want to consider putting in some accelerator in the mix to speed up the curing process.
Posted: Tue Mar 17, 2015 1:28 pm
by jimbo1981
Many thanks chaps.
Posted: Thu Mar 19, 2015 8:10 am
by seanandruby
At t2 Heathrow airport we covered an entire apron (where the jetways rolls out for unloading passengers) in the temporary thick rubber mats. The PQ Concrete laid by machine had been down for weeks. It had to be used as an access rd to the main site. When it came to be taken up 2 years later, the whole lot, maybe 200ft long was covered the same pattern as the little square treads of the mats, about 1/4'' deep. The weight of the heavy plant' lorries, navvy cranes (oops showing my age, meant crawler cranes),artics' etc; over 2 years had made a nice imprint. There was talk of ripping the whole lot out and re-doing. i was transfered before i knew the outcome but if you ever are getting a plane from t2 let us know if the apron is still imprinted with millions of small squares :;): 
Posted: Sat Mar 21, 2015 7:14 pm
by TheRockConcreting
Poured plenty of early load bearing slabs without any problems just make sure you use high spec concrete from a good suppler.
I'd used Lafarge if you can, stay away from Hope at the moment even though they used to be lafarge they constantly having problems with any mix that's not your standard, even then they never seem to have the quarry's to supply the agg!
Use a beefed up PAV 2 mix, C50 MCC 400 kg, with a rapid set super plaz
Posted: Sun Mar 22, 2015 10:55 pm
by jimbo1981
Cheers. Going belt and braces I think. I've got a rep out on Monday to quote for plating the whole thing for a couple of weeks. Will let you know how it turns out.
Posted: Tue Mar 24, 2015 4:12 pm
by KLS
seanandruby wrote:At t2 Heathrow airport we covered an entire apron (where the jetways rolls out for unloading passengers) in the temporary thick rubber mats. The PQ Concrete laid by machine had been down for weeks. It had to be used as an access rd to the main site. When it came to be taken up 2 years later, the whole lot, maybe 200ft long was covered the same pattern as the little square treads of the mats, about 1/4'' deep. The weight of the heavy plant' lorries, navvy cranes (oops showing my age, meant crawler cranes),artics' etc; over 2 years had made a nice imprint. There was talk of ripping the whole lot out and re-doing. i was transfered before i knew the outcome but if you ever are getting a plane from t2 let us know if the apron is still imprinted with millions of small squares :;):
What Part of the apron? I don't recall it last time I was driving around t2.
Posted: Tue Mar 24, 2015 5:31 pm
by TheRockConcreting
jimbo1981 wrote:Cheers. Going belt and braces I think. I've got a rep out on Monday to quote for plating the whole thing for a couple of weeks. Will let you know how it turns out.
I wouldn't bother if you spend the money on the concrete you'll have no problems, but if you really want to plate it use this its great Lion Track
Posted: Tue Mar 24, 2015 7:21 pm
by seanandruby
Say you had the entrance on your left and car park on your right, drive to the end and round to the left along that strip where the airways roll out. Maybe was condemned by B A and redone, there was talk about it at the time. Money no object there, the steel work was redone half way through at a cost of £ 50 mill'. ???
