Browse Forums Paving & Concreting Re: Best method of curing an exposed aggregate driveway? 3Mar 13, 2011 6:30 pm Hi I would recommend having a read of this: http://www.concrete.net.au/publications ... veways.pdf Unfortunately I am not impressed with a second generation contractor as there is no good industry training from contractors, all most of them know is how to lay and finish concrete with the minimum effort and no understanding of the long term behaviour of the slab. (My son is a concretor and I know what goes on, which is a lot different to how I was taught when I was involved in constructing concrete pavements for airports.) One common fault is that the reinforcement is put in with no plan for the joints. This mean that the you sometimes see that mesh is overlapped at the joint position which will stop the joint cracking and will cause the slab to crack across the middle instead. You can apply a spray on curing compound for concrete once it has been laid and then reapply it the following day after the aggregate is exposed. At this stage you could also put the wet hessian on for a few days. 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: Best method of curing an exposed aggregate driveway? 4Mar 13, 2011 9:54 pm That sounds funny. I know nothing about exposed agg driveways. But I would always do a driveway with SL72 mesh; it should be all tied together. No inspector would pass a slab to be poured without bar chairs. I have never seen a truck back over the mesh, very strange. It would be funny to watch with bar chairs smashing and mesh bending everywhere. Maybe suggest you supply bar chairs you can get strong steel ones. Still bend but the truck may think twice about driving over them. Hessian good idea, sounds logically to me, acid in a curing compound sounds illogical but never used curing compound and would prefer hessian. No cracks should be the norm but never truely guaranteed. Saw, cuts through the steel no problems. Just get another concreter he sounds he too should pass on to the third generation concreter. I would not be using him, he may do a great job. Good luck Pulpo Re: Best method of curing an exposed aggregate driveway? 6Mar 16, 2011 5:28 pm Hi guys, Thanks for your replies and thank you bashworth for the link- a very handy little resource. It actually answered a lot of my questions. I will pay due consideration to control and expansion joins too. Pulpo, I have to use this concreter because he is engaged by my builder, not me. The only reason I am dealing with him is because my builder is so sick of my micromanagement that they have some of the trades deal with me directly. I made a mistake in my original post where I said the concreter applies acid to the surface after the pour. The correct procedure for exposed aggregate as I understand is soaking the fresh concrete with a chemical retardant to stop it from setting. The following day this chemical is washed away with a high pressure acid wash to reveal or ‘expose’ the aggregate mix. A coat of sealant is then applied. So... given that a chemical retardant is applied to the concrete, does this mean that I should not cover the driveway with wet hessian until the following day after it has been exposed and sealed (and assuming that the sealant is the special curing type)? Would love to hear if there are alternatives to curing exposed aggregate driveways, or am I just over thinking all of this like I tend to?! Oh and just quickly, is 32mpa reasonable for concrete with the specifications in my original post, or will 25mpa suffice? Is it the stronger the concreter the more expensive? I would think so logically, as otherwise everyone would be getting the strongest possible! Cheers Re: Best method of curing an exposed aggregate driveway? 8Mar 16, 2011 7:35 pm Hey BW - bashworth Unfortunately I am not impressed with a second generation contractor as there is no good industry training from contractors, all most of them know is how to lay and finish concrete with the minimum effort and no understanding of the long term behaviour of the slab. (My son is a concretor and I know what goes on, which is a lot different to how I was taught when I was involved in constructing concrete pavements for airports.) I might have missed something?? Reveal as it is known is a sugar based product the 'breaks' the hydration process of cement for the few mm that it ingresses. Acid is to remove residue cement( a thin layer ) that covers the stones, the sealant 'enhances' the colour of the stones. Driving over a compacted sand base with a truck?? over mesh and chairs WTF?? Second generation Knob by the sounds of it... sorry to be course but really WTF? Onsite training is for 'best practice' no one whom attends a concrete pour for the first time would be allowed to do anything of a serious nature. Lots of BAD info is out there, lots of BAD contractors are out there.... Same as ANY trade.. Yes trade!!!!!!!!! Where you are coming from is where you are going to... Re: Best method of curing an exposed aggregate driveway? 9Mar 17, 2011 9:14 am inverell Oh and just quickly, is 32mpa reasonable for concrete with the specifications in my original post, or will 25mpa suffice? Is it the stronger the concreter the more expensive? I would think so logically, as otherwise everyone would be getting the strongest possible! Also heard that it's not a bad idea to use F82 for dwys, as well as a sand base and, of course, the chairs. And that's all I heard about that ... My signature is distracting people from my wise posts ... Re: Best method of curing an exposed aggregate driveway? 10Mar 17, 2011 9:19 am OK, I'm reading this thread back to front (almost) ... jsut noticed that he wants to dowel your dwy into the garage slab??? Is it really warranted?? I would definitely just ask him for the expansion "sponge" to be placed against the old concrete (ie. your house slab) and not let him touch the slab. BTW, from all that you've mentioned, I would also not give him the job. My signature is distracting people from my wise posts ... Re: Best method of curing an exposed aggregate driveway? 11Mar 17, 2011 10:45 am Dowelled & expansion jointing foam.(to prevent 'sandjacking') ...and yes probably not the person for the job Where you are coming from is where you are going to... Re: Best method of curing an exposed aggregate driveway? 12Mar 17, 2011 12:31 pm I need to ask a silly concreting question and don't want to start a new thread just for that, so I will hijack this a little. OK, here it goes: How can we know if the truck driver is adding water to the mix? I mean, is that really easily visible from the outside, or does he have a 'secret' pipe passageway hidden or more protected from external view, where the water pipe plugs directly into the mix 'drum'? I found this doco http://www.concrete.net.au/concrete_structures/residential_documents.php?id=176&page=1 where it says: "3. If additional water is requested, the driver has been instructed [by who?? the concretor??] to obtain a legible name and signature from an authorised person on the delivery docket before adding any water." Onc, so dowelling is OK? What is 'sandjacking' - escape of sand in between the heavy concrete and the sponge? Or not ... My signature is distracting people from my wise posts ... Re: Best method of curing an exposed aggregate driveway? 13Mar 17, 2011 1:50 pm Sand jacking is where water enters the 'joint' and either washes away(compacts) sand from under the concrete 'without' a footing. Water added is upto the grano... ... if the grano is any good they will know exactly how much water to add to bring the mix upto 80 slump or more if needed(& within spec). Some will add more, some will struggle with less and the concrete will suffer as the surface could be difficult to 'close' & and compaction might be under done. The water adding pump and hose is at the back of the truck and the water goes through a meter, so that and exact idea of added water is known. The whole thing is too complex to discuss here.. but I have NEVER been asked to sign for adding water.. in 25+ years and we go to very highly specified jobs. Added water is not the responsibility of the driver, they are drivers NOT concretors(Granos) Where you are coming from is where you are going to... Re: Best method of curing an exposed aggregate driveway? 14Mar 17, 2011 1:58 pm Thanks, onc ... So, I can easily see if some water-adding action is happening?? Also, would you agree that it is easier for the grano to work with a higher strength concrete, 32 and above? My signature is distracting people from my wise posts ... Re: Best method of curing an exposed aggregate driveway? 15Mar 17, 2011 2:31 pm Some will complain, some will be happy. For me it is about the needs(engineering of the job) neither are easy, The grey lady is a strange beast, treat her well and you are in front, poorly treated the she will control you and that is where the problem arises. The more cement the faster hydration occurs and becomes 'plastic... bleed water then cure' in a hurry. Closing the surface becomes problematic and why chips, blowout, crazing and cracks happen. Where you are coming from is where you are going to... Re: Best method of curing an exposed aggregate driveway? 16Mar 17, 2011 6:16 pm So much fear and distrust associated with the placement of concrete, We need a thread with positive concrete stories complete with pics of the awesome and unusual applications it can be used for. Make it happen Onc. Re: Best method of curing an exposed aggregate driveway? 17Mar 17, 2011 11:01 pm Where you are coming from is where you are going to... Re: Best method of curing an exposed aggregate driveway? 18Mar 18, 2011 8:44 am Aiah So much fear and distrust associated with the placement of concrete, We need a thread with positive concrete stories complete with pics of the awesome and unusual applications it can be used for. ... I always wonder how come most of the threads I read go like "Our installer / concretor / trader took care of everything ... he took care that xxxxxx, so the finished job was beautiful ..." and so on. We had no such experiences (yet). Therefore all the fear and anxiousness. Another really bad thing for the owner - the more you know about the steps or materials, etc., it simply doesn't help in the end. Just gets you more frustrated when you see how and what they do. We're talking about things that are so simple and common sense, not worth discussing, as they are a given in specific trades. Still, opposite happens. My signature is distracting people from my wise posts ... Re: Best method of curing an exposed aggregate driveway? 19Mar 18, 2011 11:46 am Uhuh, and is why I don't question the mechanic, but sometimes he doesn't get it right. I have to suck it up and move on... Lots of pro's don't offer any kind of warrantee, except you will pay their bill or legal action will follow. Where you are coming from is where you are going to... 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