Browse Forums Paving & Concreting 1 Jun 28, 2011 5:59 pm Just wondering what can be considered a cold joint?? What timeframe between the 2 pours are we talking about?? If it has to be done, are there any tricks to make the consequences of a cold joint less damaging? My signature is distracting people from my wise posts ... Re: What is a cold joint in concrete construction? 2Jun 28, 2011 6:33 pm More than a couple of hours and there's going to be a cold joint. Best things is to make a construction joint out of it. if you don't use a construction joint than you need to: 1. Roughen up the surface with an air chisel. 2. Keep the surface continously wet for several hours 3. Paint the surface with a cement paste (1 part cement to about 4 parts water) immediately before placing the next concrete. Some people suggest using PVA glue as a primer but if you follow the above you don't need it. In other words its better to get enough concrete to avoid cold joints The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: What is a cold joint in concrete construction? 3Jun 28, 2011 7:22 pm Thanks so much, Bash We are doing an outdoor slab, about 34 m2. They said they will pour half, ?finish that?? and then the second half (not enough people!! ) Would this cause a cold joint?? I have no idea of timings ... My signature is distracting people from my wise posts ... Re: What is a cold joint in concrete construction? 4Jun 28, 2011 7:32 pm I would say that if the concrete was placed as you describe it sounds like it would be a cold joint. My preference would be a construction joint and do it on two separate days. Or if done the same day but a few hours apart, cut the finished surface vertically at the edge brush with a cement paste and immediately lay against the edge. Don't lay against a surface that has air dried for a few hours. Perhaps ONC artisan has an opinion as well. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: What is a cold joint in concrete construction? 5Jun 28, 2011 7:49 pm Thanks again, Bash. B***** concretors, I should not have to think of this at all, this was never part of the deal. I explicitly inquired about the number of people and was brushed off My signature is distracting people from my wise posts ... Re: What is a cold joint in concrete construction? 6Jun 29, 2011 12:09 am 34m² not that big an area, they must have only a couple of blokes or the access is tricky? Winter time that should be a doddle, it won't cure too quick even with fast medicine added into the mix. I would be getting someone with a crew who will knock it off in a morning no worries, with a continuous concrete slab and no joints (except for control joints or sawcuts) Planned Landscape Constructions http://www.plannedlandscape.com.au Find us on facebook http://www.facebook.com/profile.php?id= ... 9907611509 Re: What is a cold joint in concrete construction? 7Jun 29, 2011 7:19 am And they get all offended if you start inquiring about a thing or two ... it doesn't even matter how you bring it up. Thanks PL My signature is distracting people from my wise posts ... Re: What is a cold joint in concrete construction? 8Jul 03, 2011 6:18 pm Lex, Doing a pour the way you describe is not a problem as long as the joint is correct for the application. This would need to be a expansion joint, there are a number of different products that can be used, but essentially the joint needs to be reinforced to allow the two abuted slabs to move independantly of each other but still remain aligned. Placed properly these joints also act as your control joints. Re: What is a cold joint in concrete construction? 9Jul 03, 2011 6:32 pm Thanks evo ... well, they poured it and all was done in about 1 hour I haven't noticed any cold joints being created, and unless some 30 minutes on a cloudy and cold day is a problem, because that's about the longest that trench footings were waiting for the rest of the concrete to be poured on top of it ... We didn't have any expansion joints constructed (or engineered), but we did have one control joint. Being just a control joint, it was not treated any different during the pour & finishing. My signature is distracting people from my wise posts ... Hi guys, I want to butt a concrete vegetable garden bed against a concrete build up of a carport. It will be a 700mm high wall about 120mm thick and I will run a 12mm rio… 0 2588 To my understanding early saw cuts are to control shrinkage cracks, so doing them now would be pointless. Control joints may reduce ugly cracking during periods of soil… 3 9831 Hi all I need a guidance on how far I need to space expansion joints in the concrete driveway and its type (keyway/foam.) Contraction joints are at 3m max for a 125 slab. Thanks 0 10929 |