Browse Forums General Discussion 1 Apr 05, 2009 6:30 pm Hi guys, we are now a few weeks into the reno and i have a few concerns. This is the first time we have done any building of any sort, so we really have no idea what is right and what is wrong. But the back of the house has been knocked off and the new slab has been poured. Brickie starts tomorrow. (Been 2 1/2 weeks since slab was poured) BUT... On the sides of the slab where it was boarded up, it is like they did not vibrate the concrete enough as I can see quite a bit of the reinforcement bars that are in the slab. I am thinking that because these are exposed, they could rust and then expand and crack the slab. Am I right to be concerned about this or can it be easily fixed when they start the brick work.??? The house is double brick if that makes any difference. I have not seen the builder since the slab was poured, (I get the feeling that he is avoiding me... But the wife says he is probably just busy, but I guess he as no reason to come here as there was nothing to do) But the builder has been here when I have not been here and says the slab is fine. and "and anomilies can be easily fixed". He will be here with the brickies first thing in the morning. Just want to get you guys expert opinion before asking him about it in the morning. Thank you Re: SLAB CONCERNS??? 3Apr 05, 2009 7:28 pm Ok.. I just worked out how to attach a pic. Here it is. There is probably 4 sections like this where the reo is exposed. Should I be concerned?? or just tell him that it needs to be fixed.. or is there no issue seeing as it is going to be covered with bricks any way?? Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: SLAB CONCERNS??? 4Apr 05, 2009 7:38 pm Looks like concrete was actually vibrated correct - looks good on that front. Issue is reo left to close to edge. Not really an issue because it is above the rebate and to be covered like you say. However simple way to over come any concern is to paint with primer, sealer or something similar. Re: SLAB CONCERNS??? 7Apr 05, 2009 9:46 pm Hi Atkman I'm no expert on the matter but all footing design work is done by an engineer. Usually all reo must be covered by at least 25mm of concrete. I have heard of cases on the gold coast where the reo was to close to the surface and blow out the concrete as it rusted but the soil was high in salt. Our Blog Page http://buildingthelittledream.blogspot.com Re: SLAB CONCERNS??? 10Apr 06, 2009 2:00 am bit late replying so i guess u still mightn't sleep too well with worry (having done a few o/bs over the years i know about that ) but from my experience over the years it looks a very strong pour & i've seen far worse slabs than that....yes i see the gap that ur concerned about, but that happens sometimes when pulling off formwork. remember thats an inside wall cavity, not exposed - generally when this happens the brickies can trowel in some mortar to keep air/moisture out. IMO the first few courses of mortar should have a "damp course" additive which would seal that gap when trowelled in. if u want to go a step further talk to the builder or brickies & ask if a "slurry" mix of cement with a splash of "damp course" additive trowelled into a flush finish is needed, it might be stronger than mortar & have better dencity than mortar as far as keeping air/moisture out of the reo? i'm sure both the the builder & brickies would have come accross this b4, but its not unreasonable to ask about something being done to flush it off & it can be done quickly at no cost. cheers tony Re: SLAB CONCERNS??? 11Apr 06, 2009 8:35 am Hi Tony,
In response to your comments above i am a bit concerned that if the concrete blew out once wouldnt it just blow out again? At the very least one could add bondcrete however I have heard in the past inspectors have advised to simply prime/seal over it. Re: SLAB CONCERNS??? 12Apr 06, 2009 8:40 am Hey georgia, you just got me thinking, when you said engineer!! lol. Looking at the reo it appears to be to low. The reao depending on design of course should be abount1/4 down from the surface, and in most cases that is amount is 25mm. In this case it appears to be down a lot more than that. I would be bring this issue up as well. Re: SLAB CONCERNS??? 13Apr 06, 2009 7:57 pm IMHO only, the reo in view could be an issue. The minimum cover of reo is 45mm. In saying that, there are many parging compounds on the market.... I would be rust inhibiting the reo... even go so far as to knock out honeycombed conc.. to expose the mesh rebar etc, and rust convert. Where you are coming from is where you are going to... Re: SLAB CONCERNS??? 14Apr 07, 2009 1:41 am Hi Borg & onc- how i love to meet people who when things need fixing think "boncrete" - we might be ralated Borg .....i would use 1 to 10 boncrete in the water that i mixed the cement with, & paint the area to be treated with straight boncrete b4 parging if it needs it. its a bit hard for me to see exactly why that section has come out, but i thought it might be where 2 form boards met - sometimes the water runs thru there & carries the "cement" out of the wet concrete. when it sets & the boards r removed that section "pulls away" leaving that gap...thats what i thought it looked like. IMO seeing its only a small section & the rest looks like a good pour to me, again IMO i would just seal with slurry or strong mortar to protect the mesh. not actually seeing it makes it hard, but at least ATKman had a few good questions to put builder & brickies, it will be interesting to hear the outcome. Onc- i can't quite work out the slab depth to comment on the mesh position? other question is if the mesh was flat, or turned down on outer edge - i've seen that done b4 on these "step down" one shot pours - don't know how "correct" that is but i understand why they do it. down here on 100mm they want it in the middle (50x65 chairs) on the footings A B Codes for full masonry 450 X 300 again its 50 mm off bottom, so i wonder how the 2 levels r joined in this case? i know this "one pour" idea is mostly used now, but i'm too set in my ways & would still use a "brick up" on outside of footings with "z" bars & then pour slab with stiffened raft over the top as a second pour, IMO makes setting up formwork lot easier....but thats just a personal preference & doesn't matter here. again it will be interesting to see how this is handled, just hope ATKMan not too worried & it all goes well from here on! cheers tony Thanks for all replies. I just noticed now the pictures I added to post right on top of page were wrong. I attached pictures showing "current" and my "suggested" floor… 9 14645 Regardless of wall hung toilet or floor pan toilet your feet will be right on drain, seems to me the waste should not be in that location given the design. Also are you… 6 7043 Thanks for the insights, that makes perfect sense, and yeah, I will be leaning on the experience of the excavator operator entirely. 6 16149 |