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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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Mortar setting time
I am lifting the roof on an old pig farrowing barn to accommodate a
furniture restorer. The roof is heavy but can be moved in one piece. So far I have raised one side on Acrows and intend to lay two courses of brick to gain the height needed. What is a reasonable time to wait before heavily loading fresh brickwork? I am particularly nervous of any side thrust encountered as I start to jack up the other side. regards -- Tim Lamb |
#2
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Mortar setting time
On 29 Oct, 11:19, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate a furniture restorer. The roof is heavy but can be moved in one piece. So far I have raised one side on Acrows and intend to lay two courses of brick to gain the height needed. What is a reasonable time to wait before heavily loading fresh brickwork? I am particularly nervous of any side thrust encountered as I start to jack up the other side. regards -- Tim Lamb I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed load, but as you point out there is side thrust, and bricks not particularly strong in that direction. use a good 3:1 mix and suitable bricks, deep frog frettons as a minimum, laid frog up, and fully filled ... or engineering if you have them. |
#3
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Mortar setting time
I would leave it 48Hrs ... That seems very, very short. Watching my brickies recently take off a couple of courses where they'd made a mistake on a chimney stack, 2 days after they'd gone on - they had not the slightest difficulty in such green mortar - still very easy to clean off. ISTR - a long, long time ago when I worked for Costain - the cure time for mass concrete (in the Summer) was 4 weeks after the shutters came off. Certainly when I'm using concrete, I'm surprised how easy it is to chip for the first week or two - compared to how hard it gets eventually. In the current cold weather I'd plan on doing some other job - before putting, as you say, a significant sheer load on your new courses. You might find useful manufacturers data here - certainly their advice on concrete I found useful: http://www.lafargecement.co.uk/site_...ge/default.asp |
#4
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In message
, Osprey writes On 29 Oct, 11:19, Tim Lamb wrote: I am lifting the roof on an old pig farrowing barn to accommodate a furniture restorer. The roof is heavy but can be moved in one piece. So far I have raised one side on Acrows and intend to lay two courses of brick to gain the height needed. What is a reasonable time to wait before heavily loading fresh brickwork? I am particularly nervous of any side thrust encountered as I start to jack up the other side. regards -- Tim Lamb I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed load, but as you point out there is side thrust, and bricks not particularly strong in that direction. use a good 3:1 mix and suitable bricks, deep frog frettons as a minimum, laid frog up, and fully filled ... or engineering if you have them. OK. The brickwork will be Flettons for the first course and semi-engineering for the top. Basically because that is what I have lying about the farm:-) I can easily wait 3 days as I also have to fit a wider door and re-plumb the electrical conduit. regards -- Tim Lamb |
#5
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Mortar setting time
In message
, " writes I would leave it 48Hrs ... That seems very, very short. Watching my brickies recently take off a couple of courses where they'd made a mistake on a chimney stack, 2 days after they'd gone on - they had not the slightest difficulty in such green mortar - still very easy to clean off. ISTR - a long, long time ago when I worked for Costain - the cure time for mass concrete (in the Summer) was 4 weeks after the shutters came off. Certainly when I'm using concrete, I'm surprised how easy it is to chip for the first week or two - compared to how hard it gets eventually. In the current cold weather I'd plan on doing some other job - before putting, as you say, a significant sheer load on your new courses. You might find useful manufacturers data here - certainly their advice on concrete I found useful: http://www.lafargecement.co.uk/site_...ge/default.asp Interesting site. They give 2 days = 16-26 N/mm2 7 days= 27-37 N/mm2 28 days= 37-47 N/mm2 for compressive strength on CEM 1 product. I should be able to wait 5 days and get roughly half final strength. regards -- Tim Lamb |
#6
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Mortar setting time
"Tim Lamb" wrote in message ... In message , Osprey writes On 29 Oct, 11:19, Tim Lamb wrote: I am lifting the roof on an old pig farrowing barn to accommodate a furniture restorer. The roof is heavy but can be moved in one piece. So far I have raised one side on Acrows and intend to lay two courses of brick to gain the height needed. What is a reasonable time to wait before heavily loading fresh brickwork? I am particularly nervous of any side thrust encountered as I start to jack up the other side. regards -- Tim Lamb I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed load, but as you point out there is side thrust, and bricks not particularly strong in that direction. use a good 3:1 mix and suitable bricks, deep frog frettons as a minimum, laid frog up, and fully filled ... or engineering if you have them. OK. The brickwork will be Flettons for the first course and semi-engineering for the top. Basically because that is what I have lying about the farm:-) I can easily wait 3 days as I also have to fit a wider door and re-plumb the electrical conduit. regards -- Tim Lamb Tim, Very temperature dependant: I've just laid 8 cu m of RC40 concrete and it took two days in the current cold snap to 'not' take a finger impression. Earlier in the year I laid a batch of the very same stuff on a blazing hot day and we couldn't finish tamping before it set solid (perhaps 1.5 hours from delivery) Cement re-hydradtion (ie setting) is a chemical reaction and thus very dependent on the temp. When it starts to go off though it is exothermic - ie gives off heat. AWEM |
#7
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Mortar setting time
In message , Andrew Mawson
writes Tim, Very temperature dependant: I've just laid 8 cu m of RC40 concrete and it took two days in the current cold snap to 'not' take a finger impression. Earlier in the year I laid a batch of the very same stuff on a blazing hot day and we couldn't finish tamping before it set solid (perhaps 1.5 hours from delivery) Cement re-hydradtion (ie setting) is a chemical reaction and thus very dependent on the temp. When it starts to go off though it is exothermic - ie gives off heat. Hmm.. only a few degrees above freezing for the next few days:-( I suppose I could make a temporary timber frame to support side 1 while I move the acrows to side 2. Lots of extra work though. I think I will avoid bricks with a high moisture content (stored outside) and try poking the mortar after a few days. The wall plate will be strapped down anyway. Temporary buttresses could be screwed to various bits of concrete if it still looks dodgy. Thanks all. regards -- Tim Lamb |
#8
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Mortar setting time
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#9
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Mortar setting time
On Oct 29, 10:54 pm, "Andrew Mawson"
wrote: "Tim Lamb" wrote in message ... In message , Osprey writes On 29 Oct, 11:19, Tim Lamb wrote: I am lifting the roof on an old pig farrowing barn to accommodate a furniture restorer. The roof is heavy but can be moved in one piece. So far I have raised one side on Acrows and intend to lay two courses of brick to gain the height needed. What is a reasonable time to wait before heavily loading fresh brickwork? I am particularly nervous of any side thrust encountered as I start to jack up the other side. regards -- Tim Lamb I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed load, but as you point out there is side thrust, and bricks not particularly strong in that direction. use a good 3:1 mix and suitable bricks, deep frog frettons as a minimum, laid frog up, and fully filled ... or engineering if you have them. OK. The brickwork will be Flettons for the first course and semi-engineering for the top. Basically because that is what I have lying about the farm:-) I can easily wait 3 days as I also have to fit a wider door and re-plumb the electrical conduit. regards -- Tim Lamb Tim, Very temperature dependant: I've just laid 8 cu m of RC40 concrete and it took two days in the current cold snap to 'not' take a finger impression. Earlier in the year I laid a batch of the very same stuff on a blazing hot day and we couldn't finish tamping before it set solid (perhaps 1.5 hours from delivery) Cement re-hydradtion (ie setting) is a chemical reaction and thus very dependent on the temp. When it starts to go off though it is exothermic - ie gives off heat. The heat given off can be an issue with bulk concrete (they incorporated cooling pipes in the Hoover Dam), but it's extremely likely to be detectable for mortar joints between bricks - there just isn't enough of it! (But the point about temperature dependance is /very/ relevant.) |
#10
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Mortar setting time
Martin Bonner wrote:
On Oct 29, 10:54 pm, "Andrew Mawson" wrote: "Tim Lamb" wrote in message ... In message , Osprey writes On 29 Oct, 11:19, Tim Lamb wrote: I am lifting the roof on an old pig farrowing barn to accommodate a furniture restorer. The roof is heavy but can be moved in one piece. So far I have raised one side on Acrows and intend to lay two courses of brick to gain the height needed. What is a reasonable time to wait before heavily loading fresh brickwork? I am particularly nervous of any side thrust encountered as I start to jack up the other side. regards -- Tim Lamb I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed load, but as you point out there is side thrust, and bricks not particularly strong in that direction. use a good 3:1 mix and suitable bricks, deep frog frettons as a minimum, laid frog up, and fully filled ... or engineering if you have them. OK. The brickwork will be Flettons for the first course and semi-engineering for the top. Basically because that is what I have lying about the farm:-) I can easily wait 3 days as I also have to fit a wider door and re-plumb the electrical conduit. regards -- Tim Lamb Tim, Very temperature dependant: I've just laid 8 cu m of RC40 concrete and it took two days in the current cold snap to 'not' take a finger impression. Earlier in the year I laid a batch of the very same stuff on a blazing hot day and we couldn't finish tamping before it set solid (perhaps 1.5 hours from delivery) Cement re-hydradtion (ie setting) is a chemical reaction and thus very dependent on the temp. When it starts to go off though it is exothermic - ie gives off heat. The heat given off can be an issue with bulk concrete (they incorporated cooling pipes in the Hoover Dam), but it's extremely likely to be detectable for mortar joints between bricks - there just isn't enough of it! (But the point about temperature dependance is /very/ relevant.) Indeed. 2 hours to 2 days to just go 'crunchy' is the variation I have noted. Over 0C-30C temp range. |
#11
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Mortar setting time
"Tim Lamb" wrote in message ... In message , Osprey writes On 29 Oct, 11:19, Tim Lamb wrote: I am lifting the roof on an old pig farrowing barn to accommodate a furniture restorer. The roof is heavy but can be moved in one piece. So far I have raised one side on Acrows and intend to lay two courses of brick to gain the height needed. What is a reasonable time to wait before heavily loading fresh brickwork? I am particularly nervous of any side thrust encountered as I start to jack up the other side. regards -- Tim Lamb I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed load, but as you point out there is side thrust, and bricks not particularly strong in that direction. use a good 3:1 mix and suitable bricks, deep frog frettons as a minimum, laid frog up, and fully filled ... or engineering if you have them. OK. The brickwork will be Flettons for the first course and semi-engineering for the top. Basically because that is what I have lying about the farm:-) I can easily wait 3 days as I also have to fit a wider door and re-plumb the electrical conduit. regards -- Tim Lamb Tim .... my comment about 48 Hrs is a practical one, if you are using an OPC & sand mix .... it would have enough partial strength after 48 Hrs. If you have any doubt use rapid set cement ... or an accelerator additive. If you can leave it longer then all the better. Some of the other comments about exothernmic reactions, and time to compressive strength are valid for bulk concrete, but not that relevant for coursed brickwork. Obviously the longer you leave it the more strength it has, but courses and lintols (=dead load) are built up next working day on site. |
#12
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On Oct 29, 11:19*am, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate a furniture restorer. The roof is heavy but can be moved in one piece. So far I have raised one side on Acrows and intend to lay two courses of brick to gain the height needed. What is a reasonable time to wait before heavily loading fresh brickwork? I am particularly nervous of any side thrust encountered as I start to jack up the other side. regards would it be practical to add temporary wooden legs to the roof structure so it sits on the original brickwork, then the fill-in brickwork doesn't support the load. At a later date the legs could be cut away and brickwork finished. Or perhaps timber legs, if they ever deteriorate the roof will already be sitting on the newer fully cured brickwork by then. NT |
#13
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