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"Grouting" between existing patio slabs: how to avoid dry powderymortar
Our house has a patio of stone slabs (slightly irregular size, shape and
thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I then use the hosepipe to spray a fine mist over the sections every few hours (given that it's hot and sunny here) so it has enough water to cause the cement to set. But some sections never set: even after a couple of days the mortar can be rubbed away in a powder of sand and cement. Other sections have set rock solid. The colour of the dry mortar varies from slate grey where it's set to almost white (maybe with golden sand granules on top) where it remains powdery after several days. I've tried various alternative techniques to the stiff-paste consistency: - adding a bit more water to the mix so it's a bit more runny, and letting it fall off the palette knife into the gap, building up the level gradually and then tamping it down to make it roughly level with the slabs - filling the section with dry ready-mix and then spraying a mist of water over to start the setting process: repeating the misting every few hours I've checked that all the dry powder is thoroughly wetted, to avoid dry sections. No technique seems to give better or worse results. Sometimes sections set, sometimes they dry to a firm dust that can be rubbed or washed away. I don't know what the proportions of sand and cement are - just the standard mortar mix. I'm making up small batches of a few hundred grammes of dry mix, mixed in a plastic bowl, so as not to make so much that it has started to set before I've finished the painstaking job of tamping the mortar into the gaps. Should I try soaking the ground through the cracks that I'm about to fill, to prevent the water in the mortar leaching into the ground before it has had chance to set the mortar? I don't need it to be a perfect job, as long as there are no longer gaps that weeds can grow through. |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 30/05/2021 17:48, NY wrote:
Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
"NY" wrote in message
o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 30/05/2021 18:40, NY wrote:
"NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Laying the slabs on bare soil is not a good idea for a start. |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
"RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. Laying the slabs on bare soil is not a good idea for a start. |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
"RobH" wrote in message
... When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. "Just enough water to make it damp and no more" sounds similar to the consistency I've used. I found that any more runny was very difficult to direct into the gap without it dribbling over the surface of the slabs and having to be wiped off afterwards; it also led to patches of golden sand in the wet mixture, rather than the grains of sand remaining coated in grey cement. There seems to be no rhyme or reason to which parts set like stone and which remain the consistency of damp sand. The very first batch I made was partly used to fill a couple of holes in the rendering on the brick wall of the house (and that has set solid), but the rest of the same batch has set hard in places but there are patches which haven't set -- and that's for the same batch, all used within about 30 minutes. I'm getting a success rate of about 1/3 ie 2/3 of what I've done will have to be gouged out with a screwdriver and washed out so I can redo it . How long does mortar remain workable after it has been made? I presume if it was starting to set before I'd finished using it, it would get noticeably more stiff and lumpy, rather than remaining a smooth paste. I'm sure I'm getting each batch used within about 30 minutes of adding water to the dry mix. Is the porosity of the base that the slabs are laid on relevant? Am I right in wondering if the "just enough water to make it damp and no more" mortar is drying out by water leaching into the ground (or evaporating from the surface on a hot day) before the water has had chance to react with the cement to make it set around the sand? The ready-mix is made by Tarmac (ie it's not B&Q's own brand of dubious quality) and the label says "cement 15% aggregates 85%". That's a ratio of about 5.5:1 - quite a bit less cement than the figure of between 3:1 and 4:1 that I've seen mentioned everywhere. Surprisingly the mixture ratio is not advertised in large letters - I had to search the various paragraphs of small print to find the 15%/85% figure. A lot of what I see when I google "grouting/filling gaps in patio slabs" makes it sound very easy, so there's obviously something I'm not doing right! |
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"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 30/05/2021 17:48, NY wrote:
Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I then use the hosepipe to spray a fine mist over the sections every few hours (given that it's hot and sunny here) so it has enough water to cause the cement to set. But some sections never set: even after a couple of days the mortar can be rubbed away in a powder of sand and cement. Other sections have set rock solid. The colour of the dry mortar varies from slate grey where it's set to almost white (maybe with golden sand granules on top) where it remains powdery after several days. I've tried various alternative techniques to the stiff-paste consistency: - adding a bit more water to the mix so it's a bit more runny, and letting it fall off the palette knife into the gap, building up the level gradually and then tamping it down to make it roughly level with the slabs - filling the section with dry ready-mix and then spraying a mist of water over to start the setting process: repeating the misting every few hours I've checked that all the dry powder is thoroughly wetted, to avoid dry sections. No technique seems to give better or worse results. Sometimes sections set, sometimes they dry to a firm dust that can be rubbed or washed away. I don't know what the proportions of sand and cement are - just the standard mortar mix. I'm making up small batches of a few hundred grammes of dry mix, mixed in a plastic bowl, so as not to make so much that it has started to set before I've finished the painstaking job of tamping the mortar into the gaps. Should I try soaking the ground through the cracks that I'm about to fill, to prevent the water in the mortar leaching into the ground before it has had chance to set the mortar? I don't need it to be a perfect job, as long as there are no longer gaps that weeds can grow through. It's many years since I've pointed slabs but the advice used to be: to brush-in the dry mix, brush any cement powder off the surface of the slab and then to sprinkle a *small* amount of water on the joints and let nature (humidity and/or light rain) take its course. By doing that you fill the gaps, get a strong mortar and don't smudge the slabs. |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 30/05/2021 17:48, NY wrote:
Some of the mortar "grouting" between the slabs has cracked and disintegrated, Some of the mortar "grouting" between the slabs has cracked and disintegrated, Wait until it's been dry weather for a few days, then tip a good mortar mix, dry, onto the slabs, and brush it around until it goes into the cracks. Then go round bashing the slabs with a big lump of wood to vibrate them, then brush some more in. Then leave it alone for a couple of weeks, unless you're in a very dry area, in which case sprinkle a bit of water gently all over and cover it with polythene. Bill |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
"NY" wrote in message ... "RobH" wrote in message ... When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. "Just enough water to make it damp and no more" sounds similar to the consistency I've used. I found that any more runny was very difficult to direct into the gap without it dribbling over the surface of the slabs and having to be wiped off afterwards; it also led to patches of golden sand in the wet mixture, rather than the grains of sand remaining coated in grey cement. There seems to be no rhyme or reason to which parts set like stone and which remain the consistency of damp sand. But there must be. The very first batch I made was partly used to fill a couple of holes in the rendering on the brick wall of the house (and that has set solid), but the rest of the same batch has set hard in places but there are patches which haven't set -- and that's for the same batch, all used within about 30 minutes. Bet thats due to when you add water later after the mixture is in the gap between the slabs, you are washing the cement out. You arent adding water later with the holes in the render on the brick wall of the house. I'm getting a success rate of about 1/3 ie 2/3 of what I've done will have to be gouged out with a screwdriver and washed out so I can redo it . How long does mortar remain workable after it has been made? Quite a while. I presume if it was starting to set before I'd finished using it, it would get noticeably more stiff and lumpy, rather than remaining a smooth paste. I'm sure I'm getting each batch used within about 30 minutes of adding water to the dry mix. Should be fine. Is the porosity of the base that the slabs are laid on relevant? Probably as far as the added water is concerned. Am I right in wondering if the "just enough water to make it damp and no more" mortar is drying out by water leaching into the ground (or evaporating from the surface on a hot day) before the water has had chance to react with the cement to make it set around the sand? Probably. The ready-mix is made by Tarmac (ie it's not B&Q's own brand of dubious quality) and the label says "cement 15% aggregates 85%". That's a ratio of about 5.5:1 - quite a bit less cement than the figure of between 3:1 and 4:1 that I've seen mentioned everywhere. Surprisingly the mixture ratio is not advertised in large letters - I had to search the various paragraphs of small print to find the 15%/85% figure. A lot of what I see when I google "grouting/filling gaps in patio slabs" makes it sound very easy, so there's obviously something I'm not doing right! |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 30/05/2021 19:41, NY wrote:
A lot of what I see when I google "grouting/filling gaps in patio slabs" makes it sound very easy, so there's obviously something I'm not doing right! if you are getting non setting crumbly **** there is not enough cement the problem with a pre iced bag is that it may after a while not have the mixture uniform and if you use it in small quantities you may get all cement or no cement. It better to buy separately for small jobs and it doesn't cost a lot more -- People believe certain stories because everyone important tells them, and people tell those stories because everyone important believes them. Indeed, when a conventional wisdom is at its fullest strength, ones agreement with that conventional wisdom becomes almost a litmus test of ones suitability to be taken seriously. Paul Krugman |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
The Natural Philosopher wrote:
On 30/05/2021 19:41, NY wrote: A lot of what I see when I google "grouting/filling gaps in patio slabs" makes it sound very easy, so there's obviously something I'm not doing right! if you are getting non setting crumbly **** there is not enough cement the problem with a pre iced bag is that it may after a while not have the mixture uniform and if you use it in small quantities you may get all cement or no cement. It better to buy separately for small jobs and it doesn't cost a lot more I've been doing some of this recently, I have separate cement and sand and I've been using a 'strong' mix of maybe 2 or 3 sand to 1 cement. I've also been using a pretty wet sort of mix which makes it easy to get it into the gaps, they are cement slabs so a bit of splash round the edges doesn't matter at all. The results seem pretty solid so far (but it has only been done for a month or so). -- Chris Green · |
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"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 30/05/2021 18:57, Rod Speed wrote:
"RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand* / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. That was over a 20 year period tho'. I'm not a builder so I have been learning as I go along so to speak. Also I put it down to frost / extremely cold weather that has caused the mortar to break up or go crumbly on the surface |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
In article ,
RobH wrote: On 30/05/2021 18:57, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. That was over a 20 year period tho'. I'm not a builder so I have been learning as I go along so to speak. Also I put it down to frost / extremely cold weather that has caused the mortar to break up or go crumbly on the surface When we moved into this house 44 years ago, the previous owner had left a pile to irregularly shaped paving for a path at the side of the house. He's already laid a terrace at the back of the house. I laid the path and 40+ years later it's still looking good - no cracks between the slabs. On the other hand, the terrace ..... -- from KT24 in Surrey, England "I'd rather die of exhaustion than die of boredom" Thomas Carlyle |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
"RobH" wrote in message ... On 30/05/2021 18:57, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. That was over a 20 year period tho'. Still nothing like what it should be. You dont have to repoint brickwork at anything even remotely like a 7 year interval. I'm not a builder so I have been learning as I go along so to speak. Also I put it down to frost / extremely cold weather that has caused the mortar to break up or go crumbly on the surface You dont get that with brickwork either. |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 31/05/2021 09:08, Chris Green wrote:
The Natural Philosopher wrote: On 30/05/2021 19:41, NY wrote: A lot of what I see when I google "grouting/filling gaps in patio slabs" makes it sound very easy, so there's obviously something I'm not doing right! if you are getting non setting crumbly **** there is not enough cement the problem with a pre iced bag is that it may after a while not have the mixture uniform and if you use it in small quantities you may get all cement or no cement. It better to buy separately for small jobs and it doesn't cost a lot more I've been doing some of this recently, I have separate cement and sand and I've been using a 'strong' mix of maybe 2 or 3 sand to 1 cement. I've also been using a pretty wet sort of mix which makes it easy to get it into the gaps, they are cement slabs so a bit of splash round the edges doesn't matter at all. The results seem pretty solid so far (but it has only been done for a month or so). If the bag says 85% aggregates then you have bought the wrong stuff. That sounds more like postcrete or concrete mix. You need a bag of sand and a smaller bag of portland cement and make up a 5:1 mix of sand:cement. |
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"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 31/05/2021 11:01, Rod Speed wrote:
"RobH" wrote in message ... On 30/05/2021 18:57, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand* / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. That was over a 20 year period tho'. Still nothing like what it should be. You dont have to repoint brickwork at anything even remotely like a 7 year interval. I'm not a builder so I have been learning as I go along so to speak. Also I put it down to frost / extremely cold weather that has caused the mortar to break up or go crumbly on the surface You dont get that with brickwork either. No I know that you don't get that with brickwork, but as I'm not a builder what should I have done, ie method, mix or anything else, so it doesn't crack, crumble or break up with cold weather. |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
"Andrew" wrote in message
... If the bag says 85% aggregates then you have bought the wrong stuff. That sounds more like postcrete or concrete mix. You need a bag of sand and a smaller bag of portland cement and make up a 5:1 mix of sand:cement. 85% sand : 15% cement is 5.7:1 (ie 85/15 : 1) That's not *too* far from the 5:1 that you suggest. If I need to buy any more (depends how long the 25 kg bag of pre-mixed lasts) then I might buy separate sand and cement and make up a slightly stronger (more cement) mix. Is 5:1 enough? I've seen some web sites which recommend 4:1 or even 3:1. The bag is definitely labelled "mortar". B&Q did also sell other bags labelled "post mix". I've done some more mortaring today, so I'll see how it sets. A patch of the mortar that I did three days ago had dried to an almost white solid which was actually cement/sand dust (almost like the un-wetted stuff I bought!) even though I'd mixed it to a stiff paste just like all the other batches. I prodded it with a screwdriver and I was left with dust - I was *almost* tempted to mix it back to a paste with water and reuse it ;-) I presume I want builder's sand, if I buy it separately. Is there any significance in the colour of the "set" mortar? Dark grey (after three days) is rock solid. Much lighter grey seems to be powder. And that's light grey all the way through, so it's not just the surface that has more cement to sand that what's underneath. I'll see how it goes. It's a long slow job because the more I look the more I find grouting that has cracked and can be pushed down into the void between the slabs, or has turned to dust. Not sure how long ago it was done - maybe 10 years. The cracking all occurred this more recent winter (frost?), after looking fine before that. When I've finished that, I need to make up wooden ramps so we can wheel a trolley (*) up and down between three different levels of patio - and the step height is different in each case. (*) For bringing up loads of wood/peat/sawdust-blocks for the wood-burning stove, and for moving loads of plant pots of bulbs onto the patio in time for daffodils etc to flower, and then off the patio to make way for other things in the summer. |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
On 31 May 2021 at 14:40:04 BST, ""NY"" wrote:
"Andrew" wrote in message ... If the bag says 85% aggregates then you have bought the wrong stuff. That sounds more like postcrete or concrete mix. You need a bag of sand and a smaller bag of portland cement and make up a 5:1 mix of sand:cement. 85% sand : 15% cement is 5.7:1 (ie 85/15 : 1) That's not *too* far from the 5:1 that you suggest. If I need to buy any more (depends how long the 25 kg bag of pre-mixed lasts) then I might buy separate sand and cement and make up a slightly stronger (more cement) mix. Is 5:1 enough? I've seen some web sites which recommend 4:1 or even 3:1. The bag is definitely labelled "mortar". B&Q did also sell other bags labelled "post mix". I've done some more mortaring today, so I'll see how it sets. A patch of the mortar that I did three days ago had dried to an almost white solid which was actually cement/sand dust (almost like the un-wetted stuff I bought!) even though I'd mixed it to a stiff paste just like all the other batches. I prodded it with a screwdriver and I was left with dust - I was *almost* tempted to mix it back to a paste with water and reuse it ;-) I presume I want builder's sand, if I buy it separately. Is there any significance in the colour of the "set" mortar? Dark grey (after three days) is rock solid. Much lighter grey seems to be powder. And that's light grey all the way through, so it's not just the surface that has more cement to sand that what's underneath. I'll see how it goes. It's a long slow job because the more I look the more I find grouting that has cracked and can be pushed down into the void between the slabs, or has turned to dust. Not sure how long ago it was done - maybe 10 years. The cracking all occurred this more recent winter (frost?), after looking fine before that. When I've finished that, I need to make up wooden ramps so we can wheel a trolley (*) up and down between three different levels of patio - and the step height is different in each case. (*) For bringing up loads of wood/peat/sawdust-blocks for the wood-burning stove, and for moving loads of plant pots of bulbs onto the patio in time for daffodils etc to flower, and then off the patio to make way for other things in the summer. Two practical points. Firstly, the 5;1 mix is traditionally in volumes, and bears no simple (AFAIK) relation to proportions by weight. And secondly, a bag of mortar mix separates in store (if indeed the contents were ever mixed) and the whole bagful needs thorough mixing in a tub or barrow before taking some out to mix with water. -- Roger Hayter |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 30/05/2021 17:48, NY wrote:
Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. Have you ruled out joint compound? I've just laid a new patio and i'm deciding what to do as the jointing compound is expensive, but if it outlives mortar it might be worth it. |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
"RobH" wrote in message ... On 31/05/2021 11:01, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:57, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. That was over a 20 year period tho'. Still nothing like what it should be. You dont have to repoint brickwork at anything even remotely like a 7 year interval. I'm not a builder so I have been learning as I go along so to speak. Also I put it down to frost / extremely cold weather that has caused the mortar to break up or go crumbly on the surface You dont get that with brickwork either. No I know that you don't get that with brickwork, but as I'm not a builder what should I have done, ie method, mix or anything else, so it doesn't crack, crumble or break up with cold weather. Do a better job of point the slabs, correct mix, correct water level, correct time of year when doing it. |
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"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 31/05/2021 21:27, Rod Speed wrote:
"RobH" wrote in message ... On 31/05/2021 11:01, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:57, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand* / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. That was over a 20 year period tho'. Still nothing like what it should be. You dont have to repoint brickwork at anything even remotely like a 7 year interval. I'm not a builder so I have been learning as I go along so to speak. Also I put it down to frost / extremely cold weather that has caused the mortar to break up or go crumbly on the surface You dont get that with brickwork either. No I know that you don't get that with brickwork, but as I'm not a builder what should I have done, ie method, mix or anything else, so it doesn't crack, crumble or break up with cold weather. Do a better job of point the slabs, correct mix, correct water level, correct time of year when doing it. Ok, so what is the correct way of pointing the slabs, if not with a trowel What is the correct mix if not 3:1 What is the correct water level if not just enough to dampen the mix And finally what is the correct time of year to do the job. Thanks |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
"RobH" wrote in message ... On 31/05/2021 21:27, Rod Speed wrote: "RobH" wrote in message ... On 31/05/2021 11:01, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:57, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. That was over a 20 year period tho'. Still nothing like what it should be. You dont have to repoint brickwork at anything even remotely like a 7 year interval. I'm not a builder so I have been learning as I go along so to speak. Also I put it down to frost / extremely cold weather that has caused the mortar to break up or go crumbly on the surface You dont get that with brickwork either. No I know that you don't get that with brickwork, but as I'm not a builder what should I have done, ie method, mix or anything else, so it doesn't crack, crumble or break up with cold weather. Do a better job of point the slabs, correct mix, correct water level, correct time of year when doing it. Ok, so what is the correct way of pointing the slabs, if not with a trowel What is the correct mix if not 3:1 What is the correct water level if not just enough to dampen the mix Thats your problem. Thats not what is done with bricklaying. And finally what is the correct time of year to do the job. When the cement isnt washed away. |
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"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 31/05/2021 23:23, Rod Speed wrote:
"RobH" wrote in message ... On 31/05/2021 21:27, Rod Speed wrote: "RobH" wrote in message ... On 31/05/2021 11:01, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:57, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand* / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. That was over a 20 year period tho'. Still nothing like what it should be. You dont have to repoint brickwork at anything even remotely like a 7 year interval. I'm not a builder so I have been learning as I go along so to speak. Also I put it down to frost / extremely cold weather that has caused the mortar to break up or go crumbly on the surface You dont get that with brickwork either. No I know that you don't get that with brickwork, but as I'm not a builder what should I have done, ie method, mix or anything else, so it doesn't crack, crumble or break up with cold weather. Do a better job of point the slabs, correct mix, correct water level, correct time of year when doing it. Ok, so what is the correct way of pointing the slabs, if not with a trowel What is the correct mix if not 3:1 What is the correct water level if not just enough* to dampen the mix Thats your problem. Thats not what is done with bricklaying. And finally what is the correct time of year to do the job. When the cement isnt washed away. Thanks for not answering the questions about mix and water level. Bricklaying is a different matter as it is vertical, slab laying is horizontal and therefore more chance of frost and ice adhering to the mortar. The cement is not washed away, as I did not say it was. Never mind, if you don't know, some one else will tell me. |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 01/06/2021 07:50, RobH wrote:
The cement is not washed away, as I did not say it was. Never mind, if you don't know, some one else will tell me. best time is when its about half as hot as it gets, and is damp. so cool and damp. cement will set, slowly, wont get washed away by rain, and slabs wont expand as hot. don't want overnight frosts that will destroy it before its sets either -- "When one man dies it's a tragedy. When thousands die it's statistics." Josef Stalin |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 01/06/2021 11:44, The Natural Philosopher wrote:
On 01/06/2021 07:50, RobH wrote: The cement is not washed away, as I did not say it was. Never mind, if you don't know, some one else will tell me. best time is when its about half as hot as it gets, and is damp. so cool and damp. cement will set, slowly, wont get washed away by rain, and slabs wont expand as hot. don't want overnight frosts that will destroy it before its sets either Thanks, as I normally or have done it either spring time or maybe September when needed. When I have looked up what mix and how much water, all I found was anything between 4:1 and 3:1, and just enough water so it clags or holds in your hand. Then trowel it in the gaps, and tamping it down as I go along. I also us a 'iron' to smooth each joint, then lightly water afterwards, then leave it dry off |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 01/06/2021 13:48, RobH wrote:
On 01/06/2021 11:44, The Natural Philosopher wrote: On 01/06/2021 07:50, RobH wrote: The cement is not washed away, as I did not say it was. Never mind, if you don't know, some one else will tell me. best time is when its about half as hot as it gets, and is damp. so cool and damp. cement will set, slowly, wont get washed away by rain, and slabs wont expand as hot. don't want overnight frosts that will destroy it before its sets either Thanks, as I normally or have done it either spring time or maybe September when needed. When I have looked up what mix and how much water, all I found was anything between 4:1 and 3:1, and just enough water so it clags or holds in your hand. Then trowel it in the gaps, and tamping it down as I go along. I also us a 'iron' to smooth each joint, then lightly water afterwards, then leave it dry off I am a fairly poor amateur bricklayer and can tell you that 5:1 is weak crumbly and leaves spaces fir water which freezes. 2:1 is hitler bunker grade. It doesn't matter how much water you add - not as far as setting goes, as anyone who has left a bag of opened cement over winter will tell you, It absorbs all the CO2 and H2O it needs from the air... My technique is utterly amateur. I mash it in with fingerss, a trowel - anything and its sort of mud pie consistency Then I remove the excess with a damp sponge RINSING EVERY STROKE That is the key., what's left is a faint cement film and brick acid washes that off. -- A lie can travel halfway around the world while the truth is putting on its shoes. |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
It is possible that the bag had been in store for awhile and had a
small hole or other damage which has allowed the cement fines to start to set but without turning the whole lot hard. It's possible instore staff had noticed some harness and bashed it to break up any fine lumps. This is never going to be any use for a decent mortar. Also, when mixed and a proper admix used it should give a nice 'fatty' mortar. If it doesn't, don't use it. If the soil is liable to 'heave' in cold weather, a lime-based mortar might be better but this needs weather protection while it achieves full strngth. Also possible that the whole batch was poorly mixed by the store supplier and has less cement than it should. For grouting slabs, it must be protected from frost for at least 7 days. On 31/05/2021 16:23, Brian Gaff (Sofa) wrote: No he needs to bite the bullet and look under one and see what was done properly. If its on soil, depending on the composition, round here its got a lot of clay, the soil swells and contracts, as I found at a feeble attempt at crazy paving some years ago! That is enough to crack any cement between stones. As for drying but not setting, is it the narrowest slits that dry out? I would imagine that would be the case. Cement is not very strong unless under compression and the less there is the less the compression and the more it turns to just powder again. Brian |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
On Sunday, May 30, 2021 at 5:48:14 PM UTC+1, NY wrote:
Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I then use the hosepipe to spray a fine mist over the sections every few hours (given that it's hot and sunny here) so it has enough water to cause the cement to set. But some sections never set: even after a couple of days the mortar can be rubbed away in a powder of sand and cement. Other sections have set rock solid. The colour of the dry mortar varies from slate grey where it's set to almost white (maybe with golden sand granules on top) where it remains powdery after several days. I've tried various alternative techniques to the stiff-paste consistency: - adding a bit more water to the mix so it's a bit more runny, and letting it fall off the palette knife into the gap, building up the level gradually and then tamping it down to make it roughly level with the slabs - filling the section with dry ready-mix and then spraying a mist of water over to start the setting process: repeating the misting every few hours I've checked that all the dry powder is thoroughly wetted, to avoid dry sections. No technique seems to give better or worse results. Sometimes sections set, sometimes they dry to a firm dust that can be rubbed or washed away. I don't know what the proportions of sand and cement are - just the standard mortar mix. I'm making up small batches of a few hundred grammes of dry mix, mixed in a plastic bowl, so as not to make so much that it has started to set before I've finished the painstaking job of tamping the mortar into the gaps. Should I try soaking the ground through the cracks that I'm about to fill, to prevent the water in the mortar leaching into the ground before it has had chance to set the mortar? I don't need it to be a perfect job, as long as there are no longer gaps that weeds can grow through. I have used this stuff just to seal up a mowing strip, it is easy peasie to use and gives a good hard wearing finish and importantly no staining. https://www.bcprofiles.co.uk/product...kg-stone-grey/ Richard |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
"RobH" wrote in message ... On 31/05/2021 23:23, Rod Speed wrote: "RobH" wrote in message ... On 31/05/2021 21:27, Rod Speed wrote: "RobH" wrote in message ... On 31/05/2021 11:01, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:57, Rod Speed wrote: "RobH" wrote in message ... On 30/05/2021 18:40, NY wrote: "NY" wrote in message o.uk... On 30/05/2021 17:48, NY wrote: Our house has a patio of stone slabs (slightly irregular size, shape and thickness - not rectangular concrete slabs). They seem to have been laid on bare earth, as far as I can see from looking into the gaps, without levering up a slab to look. Some of the mortar "grouting" between the slabs has cracked and disintegrated, so I'm trying to re-mortar the broken bits. I've removed the broken bits and brush away as much of the powder residue that remains. I'm using ready-mixed mortar from B&Q, with water added to form a stiff paste which is thick enough to adhere to a palette knife so I can direct it into the gap (typically 5-20 mm) and then tamp it down with my fingers (wearing rubber gloves in case the cement causes skin irritation). I forgot to say: the mortar is brand new and the bag was only opened a few days ago and has been kept in a dry garage. It's made with grey Portland cement, not white lime. Another thing I forgot to say. Where I've dug up the loose mortar from when the patio was first laid (about 10 years, according to neighbours), it's been a thin crust, in some places only about 5 mm thick, with a large void below it down to the level of the base on which the slabs have been laid. Is this normal? I'd have thought the whole depth of the crack between slabs would have been filled with mortar. When I laid my patio , about 20 years ago, I put all the pavers / slabs on a bed of sharp sand / cement mixed at about 7 or 8:1. I have had to re point the gaps about 3/4 times since and I use a 3:1 mix of builders sand and cement with just enough water to make it damp and no more. . That works of for me. Not very well tho given that you have had to redo the mortar 3/4 times. That was over a 20 year period tho'. Still nothing like what it should be. You dont have to repoint brickwork at anything even remotely like a 7 year interval. I'm not a builder so I have been learning as I go along so to speak. Also I put it down to frost / extremely cold weather that has caused the mortar to break up or go crumbly on the surface You dont get that with brickwork either. No I know that you don't get that with brickwork, but as I'm not a builder what should I have done, ie method, mix or anything else, so it doesn't crack, crumble or break up with cold weather. Do a better job of point the slabs, correct mix, correct water level, correct time of year when doing it. Ok, so what is the correct way of pointing the slabs, if not with a trowel What is the correct mix if not 3:1 What is the correct water level if not just enough to dampen the mix Thats your problem. Thats not what is done with bricklaying. And finally what is the correct time of year to do the job. When the cement isnt washed away. Thanks for not answering the questions about mix The mix is fine, I would have said if it wasnt. and water level. I did in fact answer that one. Bricklaying is a different matter as it is vertical, slab laying is horizontal and therefore more chance of frost and ice adhering to the mortar. Thats wrong with garden walls etc. The cement is not washed away, as I did not say it was. It must be if you dont get permanent grout. Never mind, if you don't know, some one else will tell me. I do know and did tell you. |
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"Grouting" between existing patio slabs: how to avoid dry powdery mortar
RobH wrote
The Natural Philosopher wrote RobH wrote The cement is not washed away, as I did not say it was. Never mind, if you don't know, some one else will tell me. best time is when its about half as hot as it gets, and is damp. so cool and damp. cement will set, slowly, wont get washed away by rain, and slabs wont expand as hot. don't want overnight frosts that will destroy it before its sets either Thanks, as I normally or have done it either spring time or maybe September when needed. When I have looked up what mix and how much water, all I found was anything between 4:1 and 3:1, and just enough water so it clags or holds in your hand. Then trowel it in the gaps, and tamping it down as I go along. I also us a 'iron' to smooth each joint, then lightly water afterwards, then leave it dry off You clearly arent doing it right if you have to keep redoing it so often. Like I said, the mix is fine, so it must be the water or the time when you do it. Its not rocket science, others manage to get it right. |
"Grouting" between existing patio slabs: how to avoid dry powdery mortar
In article , Rod Speed
wrote: RobH wrote The Natural Philosopher wrote RobH wrote The cement is not washed away, as I did not say it was. Never mind, if you don't know, some one else will tell me. best time is when its about half as hot as it gets, and is damp. so cool and damp. cement will set, slowly, wont get washed away by rain, and slabs wont expand as hot. don't want overnight frosts that will destroy it before its sets either Thanks, as I normally or have done it either spring time or maybe September when needed. When I have looked up what mix and how much water, all I found was anything between 4:1 and 3:1, and just enough water so it clags or holds in your hand. Then trowel it in the gaps, and tamping it down as I go along. I also us a 'iron' to smooth each joint, then lightly water afterwards, then leave it dry off You clearly arent doing it right if you have to keep redoing it so often. Like I said, the mix is fine, so it must be the water or the time when you do it. Its not rocket science, others manage to get it right. Could it be that the product is not properly mixed in the bag? -- from KT24 in Surrey, England "I'd rather die of exhaustion than die of boredom" Thomas Carlyle |
Lonely Obnoxious Cantankerous Auto-contradicting Senile Ozzie Troll Alert!
On Wed, 2 Jun 2021 05:24:46 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again: FLUSH the trolling senile asshole's latest troll**** unread -- Website (from 2007) dedicated to the 86-year-old senile Australian cretin's pathological trolling: https://www.pcreview.co.uk/threads/r...d-faq.2973853/ |
"Grouting" between existing patio slabs: how to avoid dry powderymortar
On 01/06/2021 20:40, charles wrote:
Could it be that the product is not properly mixed in the bag? Of course that's the problem. But it takes 30 armchair experts to completely confuse the OP -- In a Time of Universal Deceit, Telling the Truth Is a Revolutionary Act. - George Orwell |
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