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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Lime or cement mortar?
Lime or cement mortar?
This is specific to old buildings, and walls of similar construction. These houses typically use soft bricks that break easily, often have little in the way of foundations, sometimes none, and most have no dpc. Movement -------- Skimpy foundations mean minor movement is a normal event for many old houses. Cement is not movement friendly, and with any wall movement cement typically makes a single clean break. It has no self healing ability. Normal wall movement thus results in broken walls, which compromise the overall house structure, and require extra repair work. Cement mortar is stronger than soft brick, so when movement occurs it is the bricks that will break rather than the cement. Broken bricks have their core exposed, and without the protection of the fireskin these bricks will usually begin to slowly deteriorate due to wet freeze cycles. Gradual erosion of the brick leaves the wall in need of many bricks being replaced. Its a shame to see walls like this, knowing that just a little more knowledge and no damage would have occurred. Theres a building near here that has about half the bricks near ground level badly decayed, and is now in need of large numbers of bricks replaced. Lime mortar is weaker than the soft bricks, so when movement occurs it is the lime that cracks, not the bricks. This is the better option. No bricks need replacement. When moved to breaking point, instead of forming a single break, lime tends to form lots of microcracks. Lime then reacts with the CO2 in the air to grow hard crystals across these microcracks, and thus rebonds itself. It self-heals. Lime mortar is not flexible, but it behaves as if it were in this way. Lime accomodates normal minor movement without incident. Damp ---- Old houses handle damp differently to new builds. Soft bricks are porous, and rain hitting them soaks in a little. Interior condensation can also be a source of dampness in walls. Old buildings handle these sources of damp by evaporation, which, if all is well, keeps the level of damp below the point where any problems can occur. Impurities or salts sometimes have to be got rid of as well as water. Cement does not give much evaporation, and does not draw water from the bricks, so with cement mortar almost all evaporation occurs through the brick face. The problem is with salts: salt deposit crystals break the faces of soft bricks. When this happens, the brick loses its protective fireskin and begins to slowly disintegrate due to wet freeze cycles. Lime mortar evporates water, and draws water from the bricks. This saves the bricks from damage. When salt depositing occurs, the lime mortar sacrifices itself instead, and any mortar damage is dealt with by repointing on a normal timescale. No extra work is required and no damage occurs. The greater evaporation of lime also means a drier wall, and less chance of damp problems. Brick damage ------------ As well as the causes of brick damage above, cement adds one more. When cement eventually breaks up and detaches from soft brick (or stone) at the end of its life, it frequently pulls the skin off the brick with it along the edges. This causes rounding of the brick edges, with the red core exposed. It doesnt look good, and it is the start of slow deterioration of the bricks due to wet freeze cycles. Over decades cement work can do great damage to such walls. In the worst cases this eventually leads to the need to rebuild with new bricks. Lime does not cause this problem, and the wall stays in good health. Environment ----------- Lime requires lower temperatures and less energy to produce than cement. Used lime is chalk, a normal component of soil, thus use of lime leaves no ecological footprint behind, causes no environmental waste problems, and needs no disposal. Cement OTOH is a harmless bulk that needs to be disposed of. Landfill is in limited supply, and causes its own eco issues. Lime sets by reacting with CO2 in the air, and is manufactured by reversing this reaction using heat. The chemical cycle of lime is thus CO2 neutral. Workability ----------- Lime is slow setting, meaning a single batch can be used as long as you like. If you need to store it until tomorrow, this can be done by putting it in an airtight container. In centuries past all the lime used in a house may have been made in a single mix, and buried on site. It stayed there throughout the construction, being used as needed. Lime only sets when exposed to air. Lime is much fatter than cement, making it nicer/easier to work with, and reducing waste snots. Cost ---- Hydrated bagged lime is around £6 a bag, cement around £3 a bag. The lime bag however is larger as its lower density. Lime is usually used as 3:1 mix by volume of sand to lime putty. (Lime putty is lime mixed with water to a paste and stored.) It can also be used straight from the bag as a 3:1 mix. Bagged lime expands when water is added to make it putty, but by how much I dont remember. Due to the various uncertain factors I dont know which is cheaper, but I expect the initial cost difference is either none or small. Victorian properties with their original lime ceilings are still the norm. They may be getting tatty but the fact that theyre usually still there after 100-200 years says a lot. I dont have any hard data on life expectancy of lime vs cement, but given this I expect lime may last longer, and thus work out cheaper and less hassle in the long term. Appearance ---------- Cement is a nice ugly heavy grey. Lime is white, and lime mortar takes on the colour of the sand used to some extent. Golden sand makes white mortar, red sand makes pale pink mortar. In its most basic form lime mortar looks prettier, but it also gives scope for further decoration. It is simple to include aggregate to get black flecks in white mortar, or any other colour stone fleck. Also lime mortar can be dyed any colour if wanted, since it starts out white. FWIW there are also various other materials that can be included in lime mortar such as crushed bricks, tiles, cinders, shingle and so on, all of which produce a decorative effect. While these can be included in cement mortars as well, the heavy cement colour covers them and makes them non-attractive. Lime weathers by slow wear. This means it very gradually sheds its surface over the years. This means surface dirt is carried away over time. This self cleaning effect is very slow, but in any given situation lime will end up less dirty than cement after many years. g'nite NT |
#2
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Lime or cement mortar?
Lime or cement mortar?
Congrats on a cracking post :-) PS: any ideas whether lime mortar is suitable for repointing a cemented wall ? |
#3
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Lime or cement mortar?
Colin Wilson wrote: Any ideas whether lime mortar is suitable for repointing a cemented wall ? You can use it but it isn't as likely to stay in place. The colour of the sand used in cement mortar controls the colour of the mortar and the strength of the mix controls the damage it is likely to do. If using soft bricks you would use an eight to one mix -which at the price given in the OP (and the quantities of lime needed as three to one) makes it a far cheaper alternative. It is with the overall concern of the project and the consumer's tastes that the costs may seem small. It isn't in the same category for example as the price of a new car compared to a three year old one. You can of course use any inert admixture to either sand or cement to make mortar. And you can get a pleasant effect with different sands if shortly after the bricks are pointed, the wall is washed. Maching it all the way through the different courses would require some skill though. Too many would-be bricklayers can't even put a wall up without a great variety of shade in the allegedly same mix. Errors to watch out for are bricks laid upside down and the poor selection of bricks by the labourer. Each course must be laid with a few bricks from each pallet to prevent the differences in batches showing up. Also a load of bricks should never be tipped out of a lorry. This isn't so much a problem these days with most lorries transporting them having grabs. Too frequently the developer will not have all the bricks for an house delivered on site in one or two loads. Often this is a space or security limitation. And these days most labourers have little or no training, with bricklayers on pricework not caring nor being paid to point out tips in such craftsmanship. |
#4
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Lime or cement mortar?
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#5
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Lime or cement mortar?
Tiptop post on lime - and very much my practice.
My process for small quantities of lime putty - buy a new plastic dustbin with tight fitting lid, half fill with water, empty a bag of hydrated (builders) lime into it, leave for as long as possible (ideally months). I make up lime mortar when needed, half fill bucket with SHARP sand, add a third more to the volume of lime putty by eye - mix with paddle attachment on big drill, then keep bucket in binbag for ready supply- as you say, it keeps so long as it's wet. Might be worth saying a bit about mixing - as lime mortar is so senstive to water content - the difference between a stiff mixture and soup may be half a cup of water in a bucket. Often the moisture in the sand plus the lime putty is just about the right water content - but if the sand is a bit dry, getting that easy to work with softish butter may take a little added water - go very gently to avoid ending up with soup! Would the OP like to add a bit about using hydraulic lime? |
#6
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Lime or cement mortar?
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#7
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Lime or cement mortar?
The Natural Philosopher wrote: Yeah, lime is so bloody marvellous that when they built the London sewer they scraped it entirely in favour of Portland cement, which has stood the test of time underground in the damp. The great advantage of portland cement is that it undergoes a very predictable/repeatable chemical set, and it's fast - making it more suitable for modern site bricklaying practice. For the same reasons large quantities of concrete can be cast with highly consistent properties. I won;t bother to go through pickling out the things that are plain wrong, and those that are simply exaggerated through prejudice. Oh please do. Suffice to say there are good reasons why Portland cement is used rather than lime, these days. Any others than the 2 I've mentioned above? For the DIY'er with a slower work rate on buildings originally constructed with lime mortar, there really isn't a downside. It's easier to use, it can be kept indefinitely and it's better for the building - and especially with soft bricks or limestone, it's a necessity. |
#8
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Lime or cement mortar?
The Natural Philosopher wrote: wrote: Lime or cement mortar? I won't bother to go through pickling out the things that are plain wrong, and those that are simply exaggerated through prejudice. PLEASE do. Most of the OP seemed very reasonable to me, but I would love to hear opposing views. (I have to say that the paens of praise for the visual appearance of lime mortar struck me as over-egging the pudding). Suffice to say there are good reasons why Portland cement is used rather than lime, these days. To be fair, the OP did start: This is specific to old buildings, and walls of similar construction. With a new build, hard-fired bricks, DPC, and extensive foundations, a lot of the arguments for lime go away. |
#9
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Lime or cement mortar?
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#10
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Lime or cement mortar?
Martin Bonner wrote:
The Natural Philosopher wrote: wrote: Lime or cement mortar? I won't bother to go through pickling out the things that are plain wrong, and those that are simply exaggerated through prejudice. PLEASE do. Most of the OP seemed very reasonable to me, but I would love to hear opposing views. (I have to say that the paens of praise for the visual appearance of lime mortar struck me as over-egging the pudding). Suffice to say there are good reasons why Portland cement is used rather than lime, these days. To be fair, the OP did start: This is specific to old buildings, and walls of similar construction. With a new build, hard-fired bricks, DPC, and extensive foundations, a lot of the arguments for lime go away. As someone has already said, there is no mention of hydraulic lime. For example, brick dust acts as a pozzolan (as does any material that has previously been baked, volcanic ash, iron oxide dyes etc.) and this causes the mortar to set in varying degrees. This aspect seems to be shrouded in mystery (I suspect deliberately). How much of the alleged self healing property is lost, and how does it then differ from cement? I doubt the Victorians could build houses at the rate they did without some form of set taking place. IME, if you can't protect ordinary lime mortar from the weather, shallow applications such as pointing will be washed away by the first rainfall. Hanging damp sacks all over the place doesn't seem that practical to me. The other issue is the degree to which modern additives have improved the properties of cement. At a basic level I'm sure we're all familiar with how pva reduces cracking and doubtless there are more sophisticated products around. There is of course a large element of brown eggs and bicycles about all this too. Right on types who want to turn the whole thing into an art form and congratulate each other on their good taste via various conservation websites. |
#11
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Lime or cement mortar?
I have to say that the paens of praise
for the visual appearance of lime mortar struck me as over-egging the pudding To me that's quite a plus. When repointing, you wait for an initial set, then give it a going over with a stiff brush. Result is an appearance very close to undamaged areas and is very forgiving of skill levels - uniform consistant results for all of us. |
#13
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Lime or cement mortar?
Stuart Noble wrote: Martin Bonner wrote: The Natural Philosopher wrote: wrote: Lime or cement mortar? I won't bother to go through pickling out the things that are plain wrong, and those that are simply exaggerated through prejudice. PLEASE do. Most of the OP seemed very reasonable to me, but I would love to hear opposing views. (I have to say that the paens of praise for the visual appearance of lime mortar struck me as over-egging the pudding). Suffice to say there are good reasons why Portland cement is used rather than lime, these days. To be fair, the OP did start: This is specific to old buildings, and walls of similar construction. With a new build, hard-fired bricks, DPC, and extensive foundations, a lot of the arguments for lime go away. As someone has already said, there is no mention of hydraulic lime. For example, brick dust acts as a pozzolan (as does any material that has previously been baked, volcanic ash, iron oxide dyes etc.) and this causes the mortar to set in varying degrees. This aspect seems to be shrouded in mystery. How much of the alleged self healing property is lost, and how does it then differ from cement? I doubt the Victorians could build houses at the rate they did without some form of set taking place. IME, if you can't protect ordinary lime mortar from the weather, shallow applications such as pointing will be washed away by the first rainfall. Hanging damp sacks all over the place doesn't seem that practical to me. The other issue is the degree to which modern additives have improved the properties of cement. At a basic level I'm sure we're all familiar with how pva reduces cracking and doubtless there are more sophisticated products around. There is of course a large element of brown eggs and bicycles about all this too. Right on types who want to turn the whole thing into an art form and congratulate each other on their good taste via various conservation websites. What a silly post. The OP was discusing the use of limes as a compound best suited for soft bricks. As it happens the Romans who were responsible for the building of sewers in the first century, built with concrete materials. I don't know if that came from Pozzolan but it sounds suspiciously like it may have: Materials which enable lime mortars to set more rapidly include ash and brick dust. Known as 'pozzolans' after the volcanic additives used by the Romans, these materials are widely found in the lime mortars used in old buildings and monuments. Where conservation work is required, new mortars ought to match these mortars, not only to ensure continuity with the past, but also to ensure that the new work is both visually and physically compatible with the old. It is therefore important that we know more about the performance of these additives. A simple everyday definition of 'pozzolan' could be 'a finely powdered material which can be added to lime mortar (or to Portland cement mortar) to increase durability and, in the case of lime mortars, to provide a positive set'. A more formal definition is given by ASTM C618 as 'a siliceous or siliceous and aluminous material which, in itself, possesses little or no cementitious value but which will, in finely divided form in the presence of moisture, react chemically with calcium hydroxide at ordinary temperature to form compounds possessing cementitious properties'. http://www.buildingconservation.com/...ozzo/pozzo.htm The sewers built in Britain were not built until the Victorian era for precisely that reason. Cement is a far better material to use such places. As the bricks were of the very finest available, capable of withstanding traffic in the world's busiest cities, you can see that they chose well. As for the Victorians building houses quickly; to build the sewers they removed thousands of squalid hosuese and dug trenches by the mile in which the sewers were laid. They then had gangs upon gangs putting the housing on top of them. I the eras befor modern planning laws it was very easy to use skilled with semiskilled men to get the most out of both. Such a situation is recurring these days now that there are no apprentices growing into the trades. But that is a topic for alt.politics.thatcherism. *** One can use lime mortar in modern facework. Just remember to close the gaps up. If you look at some of the fines examples of redbrick face work still standing after a cetury or so, you may notice that they too used lime mortar but that the distances between bricks are a lot smaller than the present standards. But the OP was not discussing modern standards you damn fool. |
#14
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Lime or cement mortar?
The OP was discusing the use of limes as a compound best suited for soft bricks. As usual the OP wasn't *discussing* anything, just delivering another sermon. |
#15
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Lime or cement mortar?
On Thu, 10 Aug 2006 17:19:13 -0700, meow2222 wrote:
Environment ----------- .... Lime sets by reacting with CO2 in the air, and is manufactured by reversing this reaction using heat. The chemical cycle of lime is thus CO2 neutral. Only in respect of the CO2 used in the reaction: if production takes heat then that will probably involve CO2 release (unless there are solar lime kilns? :-)) I undersdood cement production was particularly energy-intensive. Anyone know how much (or at lease how it compares with lime)? And what is cement anyway? I thought it was at least related to lime. Workability ----------- Lime is slow setting, meaning a single batch can be used as long as you like. If you need to store it until tomorrow, this can be done by putting it in an airtight container. In centuries past all the lime used in a house may have been made in a single mix, and buried on site. It stayed there throughout the construction, being used as needed. Lime only sets when exposed to air. I remember finding a trough of mortar outside a building site on a sunday evening. Assuming it had been left there some time I dipped my toe in it to feel how hard it had set. It hadn't: it was soft and workable. Presumably some sort of additive that made it keep for days? (I'm guessing it was a cement mortar: this was in central London, not Briansville[1] Lime is much fatter than cement, making it nicer/easier to work with, and reducing waste snots. What does fatter mean (in this context)? Victorian properties with their original lime ceilings are still the norm. They may be getting tatty but the fact that theyre usually still there after 100-200 years says a lot. I dont have any hard data on life expectancy of lime vs cement, but given this I expect lime may last longer, and thus work out cheaper and less hassle in the long term. Have there ever been cement ceilings? I thought the alternative to lime plaster (and laths) was plasterboard. Appearance ---------- Cement is a nice ugly heavy grey. Nice ugly?!! [1] Poundland? Poundbury? The new town/village on HRH's organic eco estate |
#16
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Lime or cement mortar?
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#17
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Lime or cement mortar?
John Stumbles wrote: On Thu, 10 Aug 2006 17:19:13 -0700, meow2222 wrote: Lime sets by reacting with CO2 in the air, and is manufactured by reversing this reaction using heat. The chemical cycle of lime is thus CO2 neutral. Only in respect of the CO2 used in the reaction: if production takes heat then that will probably involve CO2 release (unless there are solar lime kilns? All power is solar power is it not? Or did God create fossil fuels out of nothing? I undersdood cement production was particularly energy-intensive. Anyone know how much (or at lease how it compares with lime)? But modern plants use residues that can otherwise be a niusance to get rid of. (Old tyres for example.) I remember finding a trough of mortar outside a building site on a sunday evening. Assuming it had been left there some time I dipped my toe in it to feel how hard it had set. It hadn't: it was soft and workable. Presumably some sort of additive that made it keep for days? An additive is put in the mixture so that tubs of it can be stored on site. It is ideal in confined conditions and saves a labourer or two. The problem is that the people who make it can sometimes send out a poorly co-ordinated set of batches. That and it might be crap. I wouldn't know. Lime is much fatter than cement, making it nicer/easier to work with, and reducing waste snots. What does fatter mean (in this context)? It means spreadability. The stuff is splodgy. Wet sand is workable as long as you keep it aereated that means continuallyt stirring it. When it is fatty it can be left standing for ages. Victorian properties with their original lime ceilings are still the norm. They may be getting tatty but the fact that theyre usually still there after 100-200 years says a lot. I dont have any hard data on life expectancy of lime vs cement, but given this I expect lime may last longer, and thus work out cheaper and less hassle in the long term. Have there ever been cement ceilings? I thought the alternative to lime plaster (and laths) was plasterboard. I know that plasterboard has been in use for 40 to 50 years or more. Which about the same time finishing plaster was sold in bags the way it is now. Prior to that ceilings were a bugger to do. And they had to be done using reinforced mortar. I imagine that cement mortar would set too quickly for the facilities available in those days and of course - before. Cement or lime, the process was a real bugger to do with all the laths nailed at 14 or 16 inch centres. |
#18
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Lime or cement mortar?
Weatherlawyer wrote:
John Stumbles wrote: Have there ever been cement ceilings? I thought the alternative to lime plaster (and laths) was plasterboard. I know that plasterboard has been in use for 40 to 50 years or more. Which about the same time finishing plaster was sold in bags the way it is now. Prior to that ceilings were a bugger to do. And they had to be done using reinforced mortar. When PB came out it had a coarser surface than todays and was nailed in place then all the joints covered with strips of 2" or so wide wood. I saw a place done like this once, it looked terrible. Whatever possessed them to do it like that? I thought it dated back to the 30s, but not sure. NT |
#19
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Lime or cement mortar?
wrote in message When PB came out it had a coarser surface than todays and was nailed in place then all the joints covered with strips of 2" or so wide wood. I saw a place done like this once, it looked terrible. Whatever possessed them to do it like that? I thought it dated back to the 30s, but not sure. LOL That was not plasterboard, it was white asbestos sheets quite common in early 30s houses. I can even supply a picture of a ceiling still like that. - |
#20
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Lime or cement mortar?
As usual the OP wasn't *discussing* anything, just delivering another sermon. You can join in the discussion if you have something to add, or not, upto you. Not much point just whimpering. I have raised the issue of pozzolans (yet again) and to what extent they reduce the self healing properties. By whimpering I guess you mean daring to question |
#21
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Lime or cement mortar?
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#22
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Lime or cement mortar?
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#23
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Lime or cement mortar?
Mark wrote:
wrote in message When PB came out it had a coarser surface than todays and was nailed in place then all the joints covered with strips of 2" or so wide wood. I saw a place done like this once, it looked terrible. Whatever possessed them to do it like that? I thought it dated back to the 30s, but not sure. LOL That was not plasterboard, it was white asbestos sheets quite common in early 30s houses. I can even supply a picture of a ceiling still like that. No these were relatively soft, unlike asbestos cement which is very hard. Could be dented with fingernails. I've seen these boards occasionally but dont know exactly what theyre called. NT |
#24
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Lime or cement mortar?
Tim Lamb wrote:
In message .com, writes So I can add a few more points to the discussion... Re adding lime to cement mortars, this doesnt give any of the properties of a lime mortar. Also most lime/cement mixes are liable to fail prematurely, so adding a bit of lime to cement mortar or adding a bit of cement to lime mortar are both not recommended. There has been research done on this. Oh. When this farmhouse was rebuilt, the builders added a couple of shovels of lime to the mix to *whiten* the end result. The bricks are somewhere between soft and hard with normal foundations. Ten years on, the mortar is still sound:-) Not a good match for exposed bits of Victorian stuff as it is slightly yellow but much better than the khaki colour of my masonry mix garage. There is plenty of chalk locally and also grey river clay. I don't know what the original builders used but it has visible chunks of chalk as though through improper crushing. The chimney mortar was still soft and very similar to river clay. I note that Rugby masonry cement currently contains *fly ash* and that the concrete floor recommendation included *slag cement* as a retarder. regards I thought they still used sugar as a retarder. Jim'll Mix It etc Anyway, to return to the lime discussion. If the uncarbonated lime in Durham Cathedral has been protected from carbon dioxide by the carbonated mortar on the surface, it suggests that lime is capable of forming an airtight seal, which in turn suggests that the building would be unable to breathe..... |
#25
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Lime or cement mortar?
To the lime skeptics here, I suggest a little more trying it out.
For an investment of £5 for a bag of builders lime you can experiment for yourselves (and pound for a bucket, pound for some sharp sand - if you don't have them lying about). Find out for yourselves how easy it is to work with, experiment with mixes, find out how long different sized lumps take to form a first and second set and to gain most of it's strength. And if you're not happy, you can rake it out again much more easily than cement. (and if you are, you have the rest ready to use in a covered bucket). |
#26
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Lime or cement mortar?
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#27
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Lime or cement mortar?
On Sat, 12 Aug 2006 01:36:14 -0700, meow2222 wrote:
Mark wrote: wrote in message When PB came out it had a coarser surface than todays and was nailed in place then all the joints covered with strips of 2" or so wide wood. I saw a place done like this once, it looked terrible. Whatever possessed them to do it like that? I thought it dated back to the 30s, but not sure. That was not plasterboard, it was white asbestos sheets quite common in early 30s houses. I can even supply a picture of a ceiling still like that. No these were relatively soft, unlike asbestos cement which is very hard. Could be dented with fingernails. I've seen these boards occasionally but dont know exactly what theyre called. Must check my mum's bathroom when I'm up there in the next few weeks - she's got panels about 2-3' square with strips of wood about 2-3" wide edging them, in a 1920s-1930s house. I just thought it was a feature. |
#28
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Lime or cement mortar?
The message
from "Mark" contains these words: When PB came out it had a coarser surface than todays and was nailed in place then all the joints covered with strips of 2" or so wide wood. I saw a place done like this once, it looked terrible. Whatever possessed them to do it like that? I thought it dated back to the 30s, but not sure. LOL That was not plasterboard, it was white asbestos sheets quite common in early 30s houses. I can even supply a picture of a ceiling still like that. One of my rooms has a ceiling like that although the board in question is neither plaster nor asbestos but fibre. -- Roger Chapman |
#29
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Lime or cement mortar?
In article ,
Tim Lamb writes: When this farmhouse was rebuilt, the builders added a couple of shovels of lime to the mix to *whiten* the end result. You can buy white cement, if you are just concerned about colour matching (probably need to go to a good builder's merchant. Sand can have a lot of pigment in it too -- that varies enormously. -- Andrew Gabriel |
#30
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Lime or cement mortar?
On Fri, 11 Aug 2006 13:58:29 -0700, Weatherlawyer wrote:
All power is solar power is it not? So where did the sun get its energy? Or did God create fossil fuels out of nothing? Well if God can be created out of nothing, why not? |
#31
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Lime or cement mortar?
Ooooh goodie an opportunity to wibble about lime ...
Cost ---- Hydrated bagged lime is around =A36 a bag, cement around =A33 a bag. The lime bag however is larger as its lower density. Lime is usually used as 3:1 mix by volume of sand to lime putty. (Lime putty is lime mixed with water to a paste and stored.) It can also be used straight from the bag as a 3:1 mix. For some jobs Dunno which jobs tho cos I wouldnt do this - bricklaying perhaps? Dont risk it for external rendering Bagged lime expands when water is added to make it putty, but by how much I dont remember. Due to the various uncertain factors I dont know which is cheaper, but I expect the initial cost difference is either none or small. Homemade putty with bagged lime is much cheaper than bought putty Victorian properties with their original lime ceilings are still the norm. They may be getting tatty but the fact that theyre usually still there after 100-200 years says a lot. I dont have any hard data on life expectancy of lime vs cement, but given this I expect lime may last longer, and thus work out cheaper and less hassle in the long term. Labour costs are higher with lime cos more tending is needed due to slower setting time and also cos there is a shortage of good lime plasterers so they charge more ========= I make up lime mortar when needed, half fill bucket with SHARP sand, Better to use a well graded sand. My supplier sells it as 'plastering sand'. For rendering I would try 3 sharp to 1 soft sand as a substitute for well graded sand (um never have needed to tho ...) For bricklaying a softer mix is better ========== eah, lime is so bloody marvellous that when they built the London sewer hey scraped it entirely in favour of Portland cement, which has stood he test of time underground in the damp. TNP playing devils advocate again I see Cement based mortars are better in continually damp stuations There is a spectrum of products Lime putty mortar Weak hydraulic lime mortar Strong hydraulic lime mortar Cement mortar (concrete) and you should choose the one appropriate to the situation, bearing in mind that big business has been promoting the concrete and strong hydraulic lime end of the spectrum for many years ============ Hanging damp sacks all over the place doesn't seem that practical to me. Its not. I use hessian sheeting ============= One can use lime mortar in modern facework. Just remember to close the gaps up. If you look at some of the fines examples of redbrick face work still standing after a cetury or so, you may notice that they too used lime mortar but that the distances between bricks are a lot smaller than the present standards. With lime you dont need to leave expansion joints so it looks more aesthetically pleasing ============= What's the "chemical cycle" of cement? Difference of cement to lime putty is more impurities (silicon mostly) and higher temperature of production Lime putty cycle is: Chalk or limestone + heat Drives off CO2 and H20, producing quicklime (dangerous!) Add H2O to produce lime putty Take it out of the tub and put it on the wall Add CO2 from the air and it becomes chemically equivalent to limestone / chalk once again The cement cycle is the same with added twiddles What about the production cycle? How much CO2 is released in processing and transporting v. cement? Processing lime uses less CO2 cos it is not cooked so much. Transportation of lime uses more CO2 because there are less economies of scale, unless you make your own quicklime (and loads of enthusiasts do) ========== What does fatter mean (in this context)? More workable, user friendly. Cement mortar often has lime added simply to make it fatter. Cement + Lime + sand is a cement mortar not a lime mortar. These days FebXXX often gets used instead of lime ============ Have there ever been cement ceilings? I thought the alternative to lime plaster (and laths) was plasterboard. There we open up another can of worms. Lime mortar used to be used both indoors and out. Nowadays cement mortar is used outdoors and gypsum mortar / plasterboard is used indoors =========== Re adding lime to cement mortars, this doesnt give any of the properties of a lime mortar. Also most lime/cement mixes are liable to fail prematurely, so adding a bit of lime to cement mortar or adding a bit of cement to lime mortar are both not recommended. There has been research done on this. Lime mortar with no cement sets OK Cement mortar with no lime sets OK Cement mortar with a little lime as a plasticiser sets OK Lime mortar with a little cement added 'to help it set' may not set OK Cement is very fine, fills up the pores in the mortar, CO2 cant get to the lime so poor lime set. Not much cement so poor cement set and the result is a poorly set mortar Sadly many good and experienced builders do not know this. They know lots about concrete but lime mortar is very poorly understood ================ Anna ~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repair and conservation / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____| www.kettlenet.co.uk 01359 230642 |
#32
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Lime or cement mortar?
On Sat, 12 Aug 2006 07:34:54 GMT, Stuart Noble
wrote: I have raised the issue of pozzolans (yet again) and to what extent they reduce the self healing properties. By whimpering I guess you mean daring to question Yes it does reduce the self healing properties but by how much i dont know ========= Maybe you could spray it with soda water to accelerate the initial set. Joke not - It has been done! It works fine but the clients start lookig suspicious ========= Anna ~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repair and conservation / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____| www.kettlenet.co.uk 01359 230642 |
#33
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Lime or cement mortar?
John Stumbles wrote: On Fri, 11 Aug 2006 13:58:29 -0700, Weatherlawyer wrote: Well if God can be created out of nothing, why not? What makes you think that he did? The bible says he "hung it upon nothing" and that he "created it not for nothing". I don't remember a quote from that source implying he made it "out of nothing". Notwithstanding wild guesses about cosmogeny, I was actually asking you where the oil came from. Not that I don't already know. I was just wondering how circular your reasoning could get around to. Not that I don't already know, of course. |
#34
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Lime or cement mortar?
wrote in message oups.com... Mark wrote: wrote in message When PB came out it had a coarser surface than todays and was nailed in place then all the joints covered with strips of 2" or so wide wood. I saw a place done like this once, it looked terrible. Whatever possessed them to do it like that? I thought it dated back to the 30s, but not sure. LOL That was not plasterboard, it was white asbestos sheets quite common in early 30s houses. I can even supply a picture of a ceiling still like that. No these were relatively soft, unlike asbestos cement which is very hard. Could be dented with fingernails. I've seen these boards occasionally but dont know exactly what theyre called. That would be fibreboard but personally I have only seen that used for ceilings in cheep council houses. Reading anyone ? - |
#35
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Lime or cement mortar?
Anna Kettle wrote:
On Sat, 12 Aug 2006 07:34:54 GMT, Stuart Noble wrote: Maybe you could spray it with soda water to accelerate the initial set. Joke not - It has been done! It works fine but the clients start lookig suspicious ISTR a thread about making motrar with soda water for quicker set, and I tihnk someone calculated that the amount of CO2 would be a drop in the ocean of what the lime will use as it sets. But maybe it provides a little head start. NT |
#36
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Lime or cement mortar?
Anna Kettle wrote:
Ooooh goodie an opportunity to wibble about lime ... Lime putty is sometimes made from quicklime (producing warm mortar), but usually its slaked to produce hydrated lime, distributed, then water is addded again to produce the putty. NT |
#37
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Lime or cement mortar?
Anna Kettle wrote: Re adding lime to cement mortars, this doesnt give any of the properties of a lime mortar. Also most lime/cement mixes are liable to fail prematurely, so adding a bit of lime to cement mortar or adding a bit of cement to lime mortar are both not recommended. There has been research done on this. Lime mortar with no cement sets OK Cement mortar with no lime sets OK Cement mortar with a little lime as a plasticiser sets OK Lime mortar with a little cement added 'to help it set' may not set OK Cement is very fine, fills up the pores in the mortar, CO2 cant get to the lime so poor lime set. Not much cement so poor cement set and the result is a poorly set mortar Sadly many good and experienced builders do not know this. They know lots about concrete but lime mortar is very poorly understood Cement properties are rarely understood, there is no doubt a loss of quality control between research laboratories and bricklayers who have been working for decades. Both think they know it all. Een so clled experts tend to overlook the types of cements. That quick setting stuff that used to be used in precast huge structures such as swimming pool beams and motorway bridges for example, took everyone by surprise. I wonder if a little lime might have supported things a bit better. |
#38
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Lime or cement mortar?
Anna Kettle wrote:
On Sat, 12 Aug 2006 07:34:54 GMT, Stuart Noble wrote: I have raised the issue of pozzolans (yet again) and to what extent they reduce the self healing properties. By whimpering I guess you mean daring to question Yes it does reduce the self healing properties but by how much i dont know ========= Maybe you could spray it with soda water to accelerate the initial set. Joke not - It has been done! It works fine but the clients start lookig suspicious How about dry ice? |
#39
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Lime or cement mortar?
Weatherlawyer wrote:
Cement properties are rarely understood, there is no doubt a loss of quality control between research laboratories and bricklayers who have been working for decades. Both think they know it all. Een so clled experts tend to overlook the types of cements. That quick setting stuff that used to be used in precast huge structures such as swimming pool beams and motorway bridges for example, took everyone by surprise. I wonder if a little lime might have supported things a bit better. Where can we read more about types of cement? IIRC theres opc, hac, sulphate resisting, weld cement, no doubt more too. NT |
#40
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Cement.
wrote:
Where can we read more about types of cement? IIRC theres opc, hac, sulphate resisting, weld cement, no doubt more too. In recent years, the market for packed cement products has become much more sophisticated. New standards have introduced the opportunity to develop more durable cements to meet the needs of the market. To align our product offering with the needs of the end user an extensive national research programme was carried out. The research was carried out during 2004 and 2005 and covered hundreds of interviews, focus groups, usage and attitude surveys and conjoint analysis with merchants and end users including product demonstrations and selection processes. The results of the study together with further investigation of which products should be included in our packed cement range of choices have led to our '3 cement product range'. http://www.lafargecement.co.uk http://www.lafargecement.co.uk/defau...skipCheck=true Portland cement is the most common type of cement in general usage, as it is a basic ingredient of concrete, mortar and most non-speciality grout. It is a finely-ground powder produced by grinding Portland cement clinker (more than 90%), about a maximum of 5% gypsum which controls the set time and up to 5% minor constituents (as allowed by various standards). As defined by the European Standard EN197.1, Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of Calcium silicates (3CaO.SiO2 and 2CaO,SiO2), the remainder consisting of aluminium- and iron-containing clinker phases and other compounds. The ratio of (CaO/SiO2) shall not be less than 2.0. The magnesium content (MgO) shall not exceed 5.0% by mass. (the last two requirements were already set out in the German Standard, issued in 1909). Portland cement clinker is made by heating, in a kiln unit, an homogenous mixture of raw materials to a sintering temperature, which is about 1450°C for modern cements. The aluminium oxide and iron oxide are present as a flux and contribute little to the strength properties of Portland cement. For special cements, such as Low Heat (LH) and Sulfate Resistance (SR), it is necessary to limit the amount of tricalcium aluminate (3CaO.Al2O3) formed. The major raw material for the clinker-making is limestone (CaCO3). Normally, an impure limestone which contains SiO2 is used - the CaCO3 content can be as low as 80%. Secondary raw materials depend on the purity of the limestone. Some of the secondary raw materials used a sand, shale, iron ore, bauxite, fly ash and slag. When a kiln is fired by coal, the ash of the coal becomes a secondary raw material. In the 19th and early 20th century, clay was a common secondary raw material, particulary in the wet process which is no longer used. In the 21st century, it would be rare for clay to be used in a raw mix, because it gives handling problems and contributes unnecessary aluminium oxide. Cement plants as alternatives to conventional waste disposal or processing Due to the high temperatures inside the cement kilns, combined with the oxidizing (oxygen-rich) atmosphere and long residence times, it has proven to be an excellent processing option for various types of waste streams. The waste streams often contain combustible material which allows the substitution of part of the fossil fuel normally used in the process. Waste materials used in cement kilns as a fuel supplement: [8] 1. Car and truck tires; steel belts are easily tolerated in the kilns 2. Waste solvents and lubricants. 3. Hazardous waste; cement kilns completely destroy hazardous organic compounds 4. Bone meal; slaughter house waste due to bovine spongiform encephalopathy contamination concerns (in Europe) 5. Waste plastics 6. Sewage sludge 7. Rice shells 8. Sugar cane waste Industrial by-products used as a raw material: 1. Blastfurnace slag (granulated, water quenched) 2. Fly ash (from power plants) 3. Silica fume (from steel mills) 4. Synthetic gypsum (from desulfurization) http://en.wikipedia.org/wiki/Portland_cement Fly ash is the finely divided mineral residue resulting from the combustion of powdered coal in electric generating plants. Fly ash consists of inorganic, incombustible matter present in the coal that has been fused during combustion into a glassy, amorphous structure. Coal can range in ash content from 2%-30%, and of this around 85% becomes fly ash. (The remaining 15% is called bottom ash and isn't lifted up by the flue gases.) Fly ash material is solidified while suspended in the exhaust gases and is collected by electrostatic precipitators or filter bags. Since the particles solidify while suspended in the exhaust gases, fly ash particles are generally spherical in shape and range in size from 0.5 µm to 100 µm. They consist mostly of silicon dioxide (SiO2), aluminium oxide (Al2O3) and iron oxide (Fe2O3), and are hence a suitable source of aluminum and silicon for geopolymers. They are also pozzolanic in nature and react with calcium hydroxide and alkali to form cementitious compounds. Fly ash also contains some heavy metals. http://en.wikipedia.org/wiki/Fly_ash Some pie in the sky about asphalt replacing cement in roads: http://technology.guardian.co.uk/wee...771589,00.html (I thought that was a substance alreay in use.) ((And anyway transport costs could be decimated (maybe even cementimated) with the use of neither, if more canals were made using clay as the waterproof liner the way that they were made 200 years or so back. That would cut out modern water problems too; as well as supplying drought stricken areas, the creation of more and larger canals would be the creation of resevoirs at the same time.)) Then there are geopolymers: http://www.geopolymer.org/ Thinking about that ancient process reminds me of the silly ideas our scientific monkeys have about ancient copper and lead mines in this archipelago. I suspected that there must have been some sort of crushing machine at the brochs and other long lost mining sites. And why would they not also be utilised in the production of lime, cement and pottery as well as ore milling? Digging huge caverns with bones and antlers. As if! http://www.orkneyjar.com/history/brochs/index.html Slipping slightly off topic: Ray Mears in one of his survival programmes, remarked that ancient Britons consumed vast quantities of shelfish at the water's edge. That we know this from the vast heaps of shells from the eaten fish that have been found and dated to the long ago. Thinking about that concept leads me to believe how unlikely it is. Just supposing a clan held togehter long enough to consume that amount actually at the beach or riverside - even over a period of years, makes me wonder why they saw fit to collect the residue togehter in neat stacks. You just wouldn't do it. First of because the tribe would just gravitate to a newer harvest site. Secondly the waste heaps would stink and thirdly, the chances of their waste being piled in places that they would survive intact for all time at, is ridiculous. The piles were obviously stored in a secure location from the tide and the weather. But what for? I had supposed for fertilising acid clay soils. But also they would have been part og the lime cache that these brochs would have crushed. (Yes I know that the full use of the ancient buildings remains unknown. But the DO seem like windmills to me.) And slipping further still: Several semi historical shows on the TV have attempted to demonstrate how a blacksmith might have produced an iron sword. OK the method of welding red hot iron bars byt smiting them together on an anvil is the most likely way of doing it. But with wind or water power the ancients could have drop forged a sword in a couple of smacks with a hammer lifted by a powered axle. Likewise a coin would have been fairly easy to mint. And the same process would have been used -maybe the same mill, if they wanted to crush ore or baked clay as well as pulverise limestone or shell. Of course the transportable and least durable pars of a mill would not survive the centuries. But somewhere in the mud of copper producing regions, there may yet be found some preserved centreposts. Who can say? |
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