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#1
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Mortar question Type S
Hi,
I'm at a loss why the mortar I'm using for patching mostly at this point, can be practically rubbed off, after setting. I got a bag of Mason Mix Type S Mortar Mix (Commercial Grade) Quickrete. Been mixing small amounts for patching other concrete, repointing, etc. In most cases, even after a few days I can rub off the mortar with my shoe. It turns to sand. Appears hard to touch with my fingers, bus seems to have no strength. What am I doing wrong? Regards, RichK |
#2
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Mortar question Type S
In article , "RichK" wrote:
Hi, I'm at a loss why the mortar I'm using for patching mostly at this point, can be practically rubbed off, after setting. I got a bag of Mason Mix Type S Mortar Mix (Commercial Grade) Quickrete. Been mixing small amounts for patching other concrete, repointing, etc. How long ago did you get it? In most cases, even after a few days I can rub off the mortar with my shoe. It turns to sand. Appears hard to touch with my fingers, bus seems to have no strength. What am I doing wrong? Using old mortar, probably. Try a new bag. If you bought the other bag within the last few weeks, buy your new bag somewhere else. -- Regards, Doug Miller (alphageek at milmac dot com) It's time to throw all their damned tea in the harbor again. |
#3
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Mortar question Type S
----- Original Message ----- From: "Doug Miller" In article , "RichK" wrote: I got a bag of Mason Mix Type S Mortar Mix (Commercial Grade) Quickrete. Been mixing small amounts for patching other concrete, repointing, etc. How long ago did you get it? Got it a couple of weeks ago just for this purpose. Did not see any obvious exp date. Did not look to be honest. Had not idea mortar had a short self life. In most cases, even after a few days I can rub off the mortar with my shoe. Using old mortar, probably. Try a new bag. If you bought the other bag within the last few weeks, buy your new bag somewhere else. Would have returnd this bag, but assumed I was doing something wrong. RichK |
#4
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Mortar question Type S
RichK wrote:
Hi, I'm at a loss why the mortar I'm using for patching mostly at this point, can be practically rubbed off, after setting. I got a bag of Mason Mix Type S Mortar Mix (Commercial Grade) Quickrete. Been mixing small amounts for patching other concrete, repointing, etc. In most cases, even after a few days I can rub off the mortar with my shoe. It turns to sand. Appears hard to touch with my fingers, bus seems to have no strength. What am I doing wrong? How thick are you applying it? It is no good in thin layers. What consistency is it after you mix it? It should easily stand up...if not, you are using too much water. -- dadiOH ____________________________ dadiOH's dandies v3.06... ....a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at http://mysite.verizon.net/xico |
#5
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Mortar question Type S
In article , "RichK" wrote:
----- Original Message ----- From: "Doug Miller" In article , "RichK" wrote: I got a bag of Mason Mix Type S Mortar Mix (Commercial Grade) Quickrete. Been mixing small amounts for patching other concrete, repointing, etc. How long ago did you get it? Got it a couple of weeks ago just for this purpose. Did not see any obvious exp date. Did not look to be honest. Had not idea mortar had a short self life. In humid weather the shelf life of an opened bag could be measured in days. Unopened, it should easily be good for several weeks. In most cases, even after a few days I can rub off the mortar with my shoe. Using old mortar, probably. Try a new bag. If you bought the other bag within the last few weeks, buy your new bag somewhere else. Would have returnd this bag, but assumed I was doing something wrong. Well, you might be. Old mortar isn't the only thing that can cause that, but it's the most common. Other causes I'm aware of a a) not using enough water b) using waaaaaaay too much water c) using sea water or ion-exchange soft water (sodium isn't good for mortar) d) water being wicked out of the mortar while it's drying (wet down the area you're patching first - new bricks should be soaked in water) The consistency should be similar to -- well, to fresh s**t. If it's runny, you used too much water; if it's dry and stiff, you didn't use enough. The mortar, I mean. If you've been mixing it with the amount of water recommended by the instructions on the bag, try mixing a new batch with about 1/3 *more* water than the bag says. If that batch hardens properly, then you've solved the problem; if it doesn't, try a new bag. -- Regards, Doug Miller (alphageek at milmac dot com) It's time to throw all their damned tea in the harbor again. |
#6
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Mortar question Type S
"dadiOH" wrote in message In most cases, even after a few days I can rub off the mortar with my shoe. It turns to sand. Appears hard to touch with my fingers, bus seems to have no strength. What am I doing wrong? How thick are you applying it? It is no good in thin layers. Some of these were thin, when I was filling some small gaps, and featherd out tp nothing. Is there a practical minimum thickness, where it will stay hard? What consistency is it after you mix it? It should easily stand up...if not, you are using too much water. Did both and had same results. Was doing it on very dry days, so thought bit more water would be of benefit - but apparently not. So words of wisdom: don't make it to thin (wet) and don't apply it to thin? Regards, RichK |
#7
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Mortar question Type S
In article , "RichK" wrote:
So words of wisdom: don't make it to thin (wet) and don't apply it to thin? Don't apply it too thin, certainly. Pretty hard to make it too wet unless it's actually runny -- if it's stiff enough to stay where you put it on a vertical surface, it's not too wet. Mortar, concrete, and plaster cure by chemical reaction between water and the Portland cement in the mix, so if you don't use enough water, they won't harden properly. That's why the shelf life of opened bags is limited: the stuff will react with water vapor in the air; when you go to use it, the reaction has already taken place, and won't happen again. That's also why you should wet the surrounding area first, and not apply the mortar too thin: if water wicks out of the mortar into dry brick, or evaporates into the air from a too-thin layer, there won't be enough water left in it to react with the cement, and it won't cure. -- Regards, Doug Miller (alphageek at milmac dot com) It's time to throw all their damned tea in the harbor again. |
#8
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Mortar question Type S
Thanks Doug,
I may be guilty of several errors. Did not know there was so much to it :-) Guys I've asked in person, including the youngster at HD, had no idea about any of this. Yes, bag has been open for a couple of weeks now. Been applying too thin in places. Some may have been too thick and some too thin. Using normal tap water. Working mostly on dry days 50% humidity, but wetting whatever I apply it. Looks like on any time I may have made at least one error, including now expired mortar mix. Regards, RichK "Doug Miller" wrote in message In humid weather the shelf life of an opened bag could be measured in days. Unopened, it should easily be good for several weeks. Well, you might be. Old mortar isn't the only thing that can cause that, but it's the most common. Other causes I'm aware of a a) not using enough water b) using waaaaaaay too much water c) using sea water or ion-exchange soft water (sodium isn't good for mortar) d) water being wicked out of the mortar while it's drying (wet down the area you're patching first - new bricks should be soaked in water) The consistency should be similar to -- well, to fresh s**t. If it's runny, you used too much water; if it's dry and stiff, you didn't use enough. The mortar, I mean. If you've been mixing it with the amount of water recommended by the instructions on the bag, try mixing a new batch with about 1/3 *more* water than the bag says. If that batch hardens properly, then you've solved the problem; if it doesn't, try a new bag. |
#9
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Mortar question Type S
In article , "RichK" wrote:
Thanks Doug, You're welcome. Glad I could help. I may be guilty of several errors. Did not know there was so much to it :-) Guys I've asked in person, including the youngster at HD, had no idea about any of this. The kid at HD didn't know? Gee, there's a surprise. :-) Yes, bag has been open for a couple of weeks now. That's probably a large part of the problem. Next time, if you won't be using the entire bag at once, put the rest in a bucket with an airtight lid. An empty drywall-compound bucket works fine, or you can buy five-gallon buckets with lids at HD or Lowe's fairly cheap. Been applying too thin in places. Some may have been too thick If you mean the thickness of the layer, there's no such thing as too thick. Remember, it cures by a chemical reaction. It doesn't need to be exposed to air or light. In fact, all other things being equal, the thicker the layer is, the more likely it is to cure properly. OTOH, if you mean the consistency of the mortar, yes, too thick equals too dry, and too dry means won't cure. and some too thin. Using normal tap water. As long as your tap water isn't softened, that should be good. Working mostly on dry days 50% humidity, but wetting whatever I apply it. Looks like on any time I may have made at least one error, including now expired mortar mix. Yeah, well, it's part of the learning process. No real harm done, apparently, except wasted time. -- Regards, Doug Miller (alphageek at milmac dot com) It's time to throw all their damned tea in the harbor again. |
#10
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Mortar question Type S
RichK wrote:
Thanks Doug, I may be guilty of several errors. Did not know there was so much to it :-) Guys I've asked in person, including the youngster at HD, had no idea about any of this. I wouldn't expect any different. They just claim their "associates" know everything. Yes, bag has been open for a couple of weeks now. Been applying too thin in places. Some may have been too thick and some too thin. Using normal tap water. Working mostly on dry days 50% humidity, but wetting whatever I apply it. Looks like on any time I may have made at least one error, including now expired mortar mix. Regards, RichK |
#11
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Mortar question Type S
RichK wrote:
"dadiOH" wrote in message In most cases, even after a few days I can rub off the mortar with my shoe. It turns to sand. Appears hard to touch with my fingers, bus seems to have no strength. What am I doing wrong? How thick are you applying it? It is no good in thin layers. Some of these were thin, when I was filling some small gaps, and featherd out tp nothing. Is there a practical minimum thickness, where it will stay hard? It simply isn't possible to feather out mortar. The grains of sand in it have a finite size...the cement is to hold those grains together and the layer has to be thick enough to do so. How thick? Experiment and see. There are materials made for patching...I have never used them but they might be more appropriate. _____________________ What consistency is it after you mix it? It should easily stand up...if not, you are using too much water. Did both and had same results. Was doing it on very dry days, so thought bit more water would be of benefit - but apparently not. Excess water weakens concrete/mortar. The usual advice for mortar is for it to be able to maintain sharp ridges without slumping; however, when grouting very porous tile I often make it soupy...really runny. The tile sucks out the excess water almost instantly and the grout joints (about 1/2" thick) set up rock hard. __________________ So words of wisdom: don't make it to thin (wet) and don't apply it to thin? And experiment a bit. You can improve the curing by slowing evaporation. You can do that with a sheet of thin plastic. Misting daily will help too. __________________ IMO, your biggest problem is that you are expecting too much from the material; i.e., trying to make it too thin. The strength of concrete/mortar arises from the aggregate rather than the cement itself. Doubt it? Mix some cement with water (no aggregate) and plop out some an inch or so thick; do the same but with aggregate. After a couple of weeks, compare the relative strengths. I don't think your problem is from "bad" mortar". I don't do anything with mortar other than laying 3000+ sq.ft. of Saltillo tile in my house and I certainly agree that unopened bags of material can harden by themselves from humidty in the air but in my experience in humid central Florida it takes weeks/months for that to happen. I have never had a problem using partial bags 3-4 weeks after opening. -- dadiOH ____________________________ dadiOH's dandies v3.06... ....a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at http://mysite.verizon.net/xico |
#12
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Mortar question Type S
RichK wrote:
.... Yes, bag has been open for a couple of weeks now. ... ...on dry days 50% humidity, ... A couple of weeks if it hasn't actually been in the wet but just 50% humidity unless the bag were left completely wide open I don't think is long enough to have a major effect just from hygroscopic absorption/hydration, unless it was really old stock to start with... I've kept bags partially used for months only closed w/ string or similar and had no problems w/ it... -- |
#13
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Mortar question Type S
On Mon, 16 Jul 2007 07:53:30 -0400, "RichK" wrote:
Hi, I'm at a loss why the mortar I'm using for patching mostly at this point, can be practically rubbed off, after setting. I got a bag of Mason Mix Type S Mortar Mix (Commercial Grade) Quickrete. Been mixing small amounts for patching other concrete, repointing, etc. In most cases, even after a few days I can rub off the mortar with my shoe. It turns to sand. Appears hard to touch with my fingers, bus seems to have no strength. What am I doing wrong? Regards, RichK No one mentioned that some of the premixed mortar (and concrete) are weak to start with. They dont contain enough of the actual portland cement or mortar. In fact, I have found that most of them are weak. Get some raw mortar and add it to the mix, or just get raw mortar and sand and make your own (cheaper too). You can also add portland cement and get a very hard mortar, but it will be darker gray. |
#14
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Mortar question Type S
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