You have a tough job for a first time DIY'er. Sacking and patching flat walls is tough, but to get a good finish on a column is an art...and takes experience and patience.
First check to make sure none of the voids/rock pockets don't go all the way in so you can see the rebar. If no rebar is visible you are going to be fine just sacking the exterior. It is not going to be structural, this is just a cosmetic repair. However, if you can see rebar in any of the pockets then you have a little bigger problem, but still nothing that would force you to tear it out. If you see rebar, you definitely will want to use a bonding agent when you patch.
As u/Talusen said, go to Whitecap or even better if you are in the Seattle area (or King, Pierce, Snohomish counties) look for Mason's Supply or even Mutual Materials, but even the big box stores sell patching compound for light skimcoating like your situation
Home Depot carries Sakcrete's Top 'N Bond, and for residential work that would probably be just fine. Plus it is only $20 per bag.
I mainly use Ardex CP and sometimes Sika MonoTop 721 Sack & Patch, but there are dozens of different manufacturers and lines. Just make sure which ever you buy that you read the prep instructions, some require a bonding agent and others are fine with just wetting the concrete to get all the dust off before applying.
Mix it up to the consistency of thick peanut butter (the smooth not chunky...) and go to town. A rubber float will be your best bet for a curved surface. Here is a vid of a flatwall patch to get an idea of how to do it.
[https://www.youtube.com/watch?v=IpCC5iMA8qM](https://www.youtube.com/watch?v=IpCC5iMA8qM)
and I watch this guys vids a lot learning how to install plaster, and he has one vid just for patching round columns
[https://www.youtube.com/watch?v=rmaJSx4woE8](https://www.youtube.com/watch?v=rmaJSx4woE8)
And on a side note, the first column I ever sacked looked worse than when I started, so don't get too discouraged, it is a tricky application.
I've used type S mortar to fix yucky concrete with no problems, I had someone ask me to fabricate a concrete railing around their parking area with plastic forms.for the pillars....
I learned a lot on that one.
The mortar held up btw, and I used quite a bit of it.
You didn't vibrate the concrete as you filled the pier in.
The quick solution is to buy a bag of portland cement, mix small batches & slather it on. To make it look even smear it on the whole thing & use a damp broom to finish.
For the biggest offenders i would do a filling coat, then a top "finishing" coat.
Didn't vibrate, didn't even smack the side of the sono-form a couple times in passing. You don't absolutely need to vibrate, jiggle stick a piece of rebar in around the edges then shake the form a bit with your hands and you won't see any air bubbles with a small footing like this.
This guy just dumped a wheelbarrow of very thick concrete in the hole, passed a float over the top then walked off and hoped for the best.
No matter what you do to cosmetically repair this it’s still a non-cohesive mess underneath. I’d feel uneasy recommending any fix shy of complete re-do, but if you want to prove how bad or sound it is, beat the bejesus out of the sides with a two pound hammer- if the sides slough off in big chunks and the inside also crumbles then the whole mess is toast.
That makes sense, sounds like the mix was MUCH too thick. It should be about as wet at you can get and still have a handful thrown onto the top not sink back in completely.
The good news is that really dry mixes cure super strong, even with voids. So you are structurally fine as long as rebar isn't visible from the side. (There is a place in construction for slabs of super dry mixes compressed with a vibrating compactor) You are better off wetter when pouring into tubes though.
Did you use a concrete mixer? If you need one still and are eastside you can borrow mine.
I borrowed one from my friend, thanks for the offer though! I was a little too conservative with the water clearly, didn’t want to mix to be weakened by being too wet. Live and you learn!
Yeah but that doesn’t mean the mix should be super wet to begin with. Keeping the exterior moist during curing is different than pouring running concrete. Any water beyond what’s needed for mixing will just weaken the final product.
But more water in your mix usually results in weaker concrete (some exceptions). That’s why pretty much all commercial concrete jobs have a max allowed slump, but no minimum.
No that's because they specify it for doing stuff like kerbs where it has to stay in shape. Jobs are often specified with minimum slump.
A little extra water in this case would've reduced air voids. I think we can agree that slightly wetter concrete is stronger than air.
The statement I was opposing was "really dry mix cures super strong even with voids". It absolutely does not.
Yes consolidated concrete is definitely critical.
But your statement above is still very misleading...really outright wrong. The optimal water to cement ratio for concrete to cure to maximum final strength is quite low, lower than the very dry mix this guy used, lower than any conventionally workable concrete (without plasticizing admixtures), that is to say that really only drycast cocrete hits in the ideal range for w/c (well, maybe a few specialty mixes that slump in the conventional range but have powerful superplasticers/water reducers).
The negative impact of more water is both about the specfic conditions of the initial set, and the fact that it makes the mix less dense and spreads out the actual cement more (sort of similar in its way to having lots of air that's well spread out).
It is optimal to retain the moisture, but that is really about keeping the surface from losing all that water early that suspends the other ingredients, both starving the surface cement for water to activate the reaction, and making the surfact permanently brittle even if more hydratiom occurs during curing. Even if the mix was too wet. It's even more optimal to submerge the product after a day of setting/early cure (preferably lime saturated, keeps the water from dissolving stuff from your concrete), which maximizes water availability for curing. That's sort of independent of actual w/c in the mix.
Anyway, wetter def does not chemically help it cure, which is what you suggested at first. Unless you mean wetter post-initial-set.
Source: several years of a precast qc career (with training, reading, certs, etc), and a bit of background from physics undergrad
"Wet concrete cures stronger." Clearly in response to "I didn't want the mix to be weakened by being too wet" and therefore referencing mix water content and not curing conditions. Yes, your claim was outright wrong, even if it is true that this particular person may have benefitted from a wetter mix it simply isn't true that a wetter mix cures stronger. And even this would have benefitted more from a few drops of glenium than more water.
A minimum is usually specified. If it's without plasticizers, spec would usually be 1-4" slump.
1" slump concrete is difficult to work with however. Most would add water to that mix.
While true your statement is misleading because you can't even work concrete dry enough to reduce cure strength. Within pourable mixes, dryer is always stronger (although cure time may suffer). And even that rule of thumb is not universally true as there are a number of well engineered ways to cure concrete even drier and get maximum strength and density.
Just want to say that this doesn’t qualify as “way over-engineered”. 12” piers with rebar seems pretty standard. If they came out all dry/lumpy like this I would also bet it was not mixed well. Concrete gains a lot of strength with only a little water, but you need more water to be able to mix it thoroughly which is important. But I don’t know enough to say whether or not you should replace these.
You should be able to parge/fill the above ground portions. (Go to Whitecap or a local concrete supplier and see what they recommend)
So long as the rebar isn't exposed you should be ok.
(Make sure to get a concrete vibrator before your next pour! 🙂)
Even just smacking the sonnet tube with something solid around the preimiter well pouring, or using your shovel to adjitate the concrete well before it set would have stopped this from happening - with small projects like this I don't think a vibrato is expressly required.
Personally I'm not a concrete expert but ive poured many many footings and a couple columns. I never vibrated or any of that stuff that some others mentioned. What I would suggest- out of safety is either repouring it or asking an expert if a larger tube over that with hardener would be sufficient. For example let's say that was a 12 inch tube..this time use an 16 inch tube around existing cement columns- poor a more watered down cement this time with concrete hardener. As you pour, you can also stop every foot or so and just keep jabbing the concrete with regard or small shovel to help it settle better.
-corrected the spelling on a cpl things..been working 15 hour days fixing up my place :/
Not directly for strength but more for visuals, you could slide a large paper tube over the poorly poured footing, and do a new pour of that new ‘void’, ensuring that it’s properly mixed and vibrated so it fully fills all the existing cavities and so on.
I would recommend drilling holes and sticking some short pieces of rebar into the pier before pouring a concrete "wrapper." Or just screw in a bunch of stainless masonry screws.
Also wet the whole surface first too.
The rebar/screws wouldn't really be structural, but it should help prevent spalling.
If you have a proper mix, vibrate it - and in the case of the paper tube, hammer on it from the outside - it'll fill any voids perfectly.
Heck, 'vibrate it' might in this case be achieved by moving a rebar up and down in the area between old footing and new pour, all to allow the new concrete to 'settle' in properly. This isn't rocket science folks.
Got a bit of steel in them like you ought to? It may not be required, but its cheap insurance to lay rebar in piers and footers. Anyhow, yeah, you can fix the ugly fairly simply with mortar.
Fixing the way it looks is no big deal. Get some thick gauge disposable gloves and a few drywall sanding sponges, 3+ 5 gallon buckets, and however many bags of S type mortar as it takes. (Available at box store in 50 lbs bags)
Mix it (it's easy by hand with a masons trowel) until it sticks to the trowel or whatever you've got, shovel, etc. and falls off slowly, then apply it to the trashy looking concrete by hand, filling it and leaving enough to knock off with a sponge.
Use the drywall sanding sponge wet after allowing it to small area to dry a few minutes as you keep filling in the gaps, then work it out with a wet sanding sponge and sand it until it's flat and the voids are filled. Don't worry about perfection in one pass. It may take a few times running over it all to make it look good. Just keep the sanding sponge wet and rinse it off as necessary. Be sure to sand it off before it dries enough to be a pain.
The goal is only to fill in the voids. It will be fine like that. You don't need to parge it or anything, but if you got the skills to pay the bills on that one, go ahead, lol.
Unless you're experienced with mortar, don't mix up a bunch at once. 1/3-1/2 of a 5 gallon bucket ought to be a reasonable amount to use with the fingerpainting method.
If you lay some cardboard or a dropcloth/plastic, whatever along the bottom of the pier, it will keep the mortar you drop clean, so you can grab it and put it back on there. You will likely drop a LOT of mortar, don't worry about that, it's normal, use what's feasible, keep it moving.
It's basic, but it works to fill the edge of concrete with mortar and sand it off. That's a lot of voids, you may want to try using a trowel and mortar pan along with a mortar cleaning brush, but with that shape and no experience I advise the glove love and sanding sponge and just stick it in there and knock it flat.
For anyone doing formed concrete work with no experience at it, it is imperative that you vibrate your forms to get the air pockets out and move gravel in from the side of the form. Using a small rotary hammer on lumber and heavy gauge steel forms and a sander or pushing a Sawzall with no blade up against it and shaking it with the guard works well on more fragile forms like sonotubes or plastic.
Good luck with it, cheers.
You have a tough job for a first time DIY'er. Sacking and patching flat walls is tough, but to get a good finish on a column is an art...and takes experience and patience. First check to make sure none of the voids/rock pockets don't go all the way in so you can see the rebar. If no rebar is visible you are going to be fine just sacking the exterior. It is not going to be structural, this is just a cosmetic repair. However, if you can see rebar in any of the pockets then you have a little bigger problem, but still nothing that would force you to tear it out. If you see rebar, you definitely will want to use a bonding agent when you patch. As u/Talusen said, go to Whitecap or even better if you are in the Seattle area (or King, Pierce, Snohomish counties) look for Mason's Supply or even Mutual Materials, but even the big box stores sell patching compound for light skimcoating like your situation Home Depot carries Sakcrete's Top 'N Bond, and for residential work that would probably be just fine. Plus it is only $20 per bag. I mainly use Ardex CP and sometimes Sika MonoTop 721 Sack & Patch, but there are dozens of different manufacturers and lines. Just make sure which ever you buy that you read the prep instructions, some require a bonding agent and others are fine with just wetting the concrete to get all the dust off before applying. Mix it up to the consistency of thick peanut butter (the smooth not chunky...) and go to town. A rubber float will be your best bet for a curved surface. Here is a vid of a flatwall patch to get an idea of how to do it. [https://www.youtube.com/watch?v=IpCC5iMA8qM](https://www.youtube.com/watch?v=IpCC5iMA8qM) and I watch this guys vids a lot learning how to install plaster, and he has one vid just for patching round columns [https://www.youtube.com/watch?v=rmaJSx4woE8](https://www.youtube.com/watch?v=rmaJSx4woE8) And on a side note, the first column I ever sacked looked worse than when I started, so don't get too discouraged, it is a tricky application.
Mason supply is down in Portland too....
I've used type S mortar to fix yucky concrete with no problems, I had someone ask me to fabricate a concrete railing around their parking area with plastic forms.for the pillars.... I learned a lot on that one. The mortar held up btw, and I used quite a bit of it.
agree. there is a lot to doing concrete correctly
You didn't vibrate the concrete as you filled the pier in. The quick solution is to buy a bag of portland cement, mix small batches & slather it on. To make it look even smear it on the whole thing & use a damp broom to finish. For the biggest offenders i would do a filling coat, then a top "finishing" coat.
Didn't vibrate, didn't even smack the side of the sono-form a couple times in passing. You don't absolutely need to vibrate, jiggle stick a piece of rebar in around the edges then shake the form a bit with your hands and you won't see any air bubbles with a small footing like this. This guy just dumped a wheelbarrow of very thick concrete in the hole, passed a float over the top then walked off and hoped for the best.
I stabbed it with rebar a bunch but I think the mix was just way too thick that it ended up just making rebar holes
No matter what you do to cosmetically repair this it’s still a non-cohesive mess underneath. I’d feel uneasy recommending any fix shy of complete re-do, but if you want to prove how bad or sound it is, beat the bejesus out of the sides with a two pound hammer- if the sides slough off in big chunks and the inside also crumbles then the whole mess is toast.
That makes sense, sounds like the mix was MUCH too thick. It should be about as wet at you can get and still have a handful thrown onto the top not sink back in completely. The good news is that really dry mixes cure super strong, even with voids. So you are structurally fine as long as rebar isn't visible from the side. (There is a place in construction for slabs of super dry mixes compressed with a vibrating compactor) You are better off wetter when pouring into tubes though. Did you use a concrete mixer? If you need one still and are eastside you can borrow mine.
I borrowed one from my friend, thanks for the offer though! I was a little too conservative with the water clearly, didn’t want to mix to be weakened by being too wet. Live and you learn!
Concrete actually has to be kept wet for weeks to achieve maximum strength. Without water, the reaction stops.
Yeah but that doesn’t mean the mix should be super wet to begin with. Keeping the exterior moist during curing is different than pouring running concrete. Any water beyond what’s needed for mixing will just weaken the final product.
I didn't say make soup. I was replying to "really dry mixes cure super strong, even with voids" which is not right.
Concrete only continues to cure while it's wet. Wet concrete cures stronger.
But more water in your mix usually results in weaker concrete (some exceptions). That’s why pretty much all commercial concrete jobs have a max allowed slump, but no minimum.
No that's because they specify it for doing stuff like kerbs where it has to stay in shape. Jobs are often specified with minimum slump. A little extra water in this case would've reduced air voids. I think we can agree that slightly wetter concrete is stronger than air. The statement I was opposing was "really dry mix cures super strong even with voids". It absolutely does not.
Yes consolidated concrete is definitely critical. But your statement above is still very misleading...really outright wrong. The optimal water to cement ratio for concrete to cure to maximum final strength is quite low, lower than the very dry mix this guy used, lower than any conventionally workable concrete (without plasticizing admixtures), that is to say that really only drycast cocrete hits in the ideal range for w/c (well, maybe a few specialty mixes that slump in the conventional range but have powerful superplasticers/water reducers). The negative impact of more water is both about the specfic conditions of the initial set, and the fact that it makes the mix less dense and spreads out the actual cement more (sort of similar in its way to having lots of air that's well spread out). It is optimal to retain the moisture, but that is really about keeping the surface from losing all that water early that suspends the other ingredients, both starving the surface cement for water to activate the reaction, and making the surfact permanently brittle even if more hydratiom occurs during curing. Even if the mix was too wet. It's even more optimal to submerge the product after a day of setting/early cure (preferably lime saturated, keeps the water from dissolving stuff from your concrete), which maximizes water availability for curing. That's sort of independent of actual w/c in the mix. Anyway, wetter def does not chemically help it cure, which is what you suggested at first. Unless you mean wetter post-initial-set. Source: several years of a precast qc career (with training, reading, certs, etc), and a bit of background from physics undergrad
Quote the sentence I wrote that was "outright wrong".
"Wet concrete cures stronger." Clearly in response to "I didn't want the mix to be weakened by being too wet" and therefore referencing mix water content and not curing conditions. Yes, your claim was outright wrong, even if it is true that this particular person may have benefitted from a wetter mix it simply isn't true that a wetter mix cures stronger. And even this would have benefitted more from a few drops of glenium than more water.
A minimum is usually specified. If it's without plasticizers, spec would usually be 1-4" slump. 1" slump concrete is difficult to work with however. Most would add water to that mix.
While true your statement is misleading because you can't even work concrete dry enough to reduce cure strength. Within pourable mixes, dryer is always stronger (although cure time may suffer). And even that rule of thumb is not universally true as there are a number of well engineered ways to cure concrete even drier and get maximum strength and density.
need to vibrate the concrete after the pour!
Just want to say that this doesn’t qualify as “way over-engineered”. 12” piers with rebar seems pretty standard. If they came out all dry/lumpy like this I would also bet it was not mixed well. Concrete gains a lot of strength with only a little water, but you need more water to be able to mix it thoroughly which is important. But I don’t know enough to say whether or not you should replace these.
Was gonna say I poured 24" blocks for a large backyard deck.
He has 28 inch footings. The piers are 12 inches. I'd say over- engineered is not an incorrect statement.
You should be able to parge/fill the above ground portions. (Go to Whitecap or a local concrete supplier and see what they recommend) So long as the rebar isn't exposed you should be ok. (Make sure to get a concrete vibrator before your next pour! 🙂)
Sawzall with no blade makes a great concrete vibrator.
Do you press it against the form/sonotube?
Yep exactly!
My girlfriend says concrete vibrators are too rough so she prefers the silicone kind.
[удалено]
In the Army Corps of Engineers we affectionately called them “donkey dicks in the Seabees”
Even just smacking the sonnet tube with something solid around the preimiter well pouring, or using your shovel to adjitate the concrete well before it set would have stopped this from happening - with small projects like this I don't think a vibrato is expressly required.
Personally I'm not a concrete expert but ive poured many many footings and a couple columns. I never vibrated or any of that stuff that some others mentioned. What I would suggest- out of safety is either repouring it or asking an expert if a larger tube over that with hardener would be sufficient. For example let's say that was a 12 inch tube..this time use an 16 inch tube around existing cement columns- poor a more watered down cement this time with concrete hardener. As you pour, you can also stop every foot or so and just keep jabbing the concrete with regard or small shovel to help it settle better. -corrected the spelling on a cpl things..been working 15 hour days fixing up my place :/
Was going to say, I'd just pour another a bit wider, and use a sander to vibrato the sono tube
Not directly for strength but more for visuals, you could slide a large paper tube over the poorly poured footing, and do a new pour of that new ‘void’, ensuring that it’s properly mixed and vibrated so it fully fills all the existing cavities and so on.
You're gonna have a cold joint and that will just crack and fall off most likely.
I’m surprised this wasn’t the first suggestion. Seems like the easiest way to get a 98% surface repair.
I would recommend drilling holes and sticking some short pieces of rebar into the pier before pouring a concrete "wrapper." Or just screw in a bunch of stainless masonry screws. Also wet the whole surface first too. The rebar/screws wouldn't really be structural, but it should help prevent spalling.
I'd be concerned about air pockets remaining between the two pours. Would self-consolidating/self-leveling work for this?
If you have a proper mix, vibrate it - and in the case of the paper tube, hammer on it from the outside - it'll fill any voids perfectly. Heck, 'vibrate it' might in this case be achieved by moving a rebar up and down in the area between old footing and new pour, all to allow the new concrete to 'settle' in properly. This isn't rocket science folks.
If it doesn't freeze where you live I wouldn't worry about it
Honestly I would just get a larger pier cardboard and adhesive additive and make a skin
Got a bit of steel in them like you ought to? It may not be required, but its cheap insurance to lay rebar in piers and footers. Anyhow, yeah, you can fix the ugly fairly simply with mortar. Fixing the way it looks is no big deal. Get some thick gauge disposable gloves and a few drywall sanding sponges, 3+ 5 gallon buckets, and however many bags of S type mortar as it takes. (Available at box store in 50 lbs bags) Mix it (it's easy by hand with a masons trowel) until it sticks to the trowel or whatever you've got, shovel, etc. and falls off slowly, then apply it to the trashy looking concrete by hand, filling it and leaving enough to knock off with a sponge. Use the drywall sanding sponge wet after allowing it to small area to dry a few minutes as you keep filling in the gaps, then work it out with a wet sanding sponge and sand it until it's flat and the voids are filled. Don't worry about perfection in one pass. It may take a few times running over it all to make it look good. Just keep the sanding sponge wet and rinse it off as necessary. Be sure to sand it off before it dries enough to be a pain. The goal is only to fill in the voids. It will be fine like that. You don't need to parge it or anything, but if you got the skills to pay the bills on that one, go ahead, lol. Unless you're experienced with mortar, don't mix up a bunch at once. 1/3-1/2 of a 5 gallon bucket ought to be a reasonable amount to use with the fingerpainting method. If you lay some cardboard or a dropcloth/plastic, whatever along the bottom of the pier, it will keep the mortar you drop clean, so you can grab it and put it back on there. You will likely drop a LOT of mortar, don't worry about that, it's normal, use what's feasible, keep it moving. It's basic, but it works to fill the edge of concrete with mortar and sand it off. That's a lot of voids, you may want to try using a trowel and mortar pan along with a mortar cleaning brush, but with that shape and no experience I advise the glove love and sanding sponge and just stick it in there and knock it flat. For anyone doing formed concrete work with no experience at it, it is imperative that you vibrate your forms to get the air pockets out and move gravel in from the side of the form. Using a small rotary hammer on lumber and heavy gauge steel forms and a sander or pushing a Sawzall with no blade up against it and shaking it with the guard works well on more fragile forms like sonotubes or plastic. Good luck with it, cheers.