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Bricklaying on your own
- Thread starter 23vc
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different thing.
Concrete is usually somewhat porous, and has tiny cracks. Denser and better quality less so, and additives are available.
The concept is that every particle of aggregate should be coated in sand, every particle of sand should be coated in cement, and every particle of cement should be coated in water, with no excess beyond that required. It is not possible to achieve perfection, though some experimental concretes in laboratory condition can perform much better than ordinary mix.
Water also lubricates the mix so it can be placed and flows better. But excess water evaporates, leaving air spaces which have no strength.
Concrete is usually somewhat porous, and has tiny cracks. Denser and better quality less so, and additives are available.
The concept is that every particle of aggregate should be coated in sand, every particle of sand should be coated in cement, and every particle of cement should be coated in water, with no excess beyond that required. It is not possible to achieve perfection, though some experimental concretes in laboratory condition can perform much better than ordinary mix.
Water also lubricates the mix so it can be placed and flows better. But excess water evaporates, leaving air spaces which have no strength.
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Interesting, so doors that mean only the excess water evaporates, the water needed to coat the cement is actually used in the reaction and never evaporates?
So the point is the bulk water can evaporate through tiny cracks (and new water can soak through these cracks later) but overall, the water is sealed in/out by the cured cement.
Interestingly, this suggests that the concrete could have a slight self healing quality if you let it dry out before full strength, as if it cracks/moves slightly, cement that wasn't fully cured will be exposed to the atmosphere. As you mentioned further up the thread.
So the point is the bulk water can evaporate through tiny cracks (and new water can soak through these cracks later) but overall, the water is sealed in/out by the cured cement.
Interestingly, this suggests that the concrete could have a slight self healing quality if you let it dry out before full strength, as if it cracks/moves slightly, cement that wasn't fully cured will be exposed to the atmosphere. As you mentioned further up the thread.
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I wonder why the speed of "crystallisation" is much faster on a hot dry summer's day than on a cold damp winter's day.
Obviously nothing to do with drying out then.
Same reason that a teaspoon of sugar in your hot cup of tea dissolves faster than in a cold glass of water. Higher temperatures cause molecular interactions to happen faster.
You acknowledge the problem in your next post, when you say that summer heat can turn mortar back into sand/cement - if the water is evaporated before the curing occurs, the aggregates will not bind, because the presence of water is necessary for the crystallisation.
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I laid a few bricks last night that I removed earlier the same day. After reading this thread I decided to chuck them in a bucket of water, I could hear them fizz!!!
The were bone dry within seconds of taking them out so I dunked them again until the surface stayed moist. I bet they would have soon sucked the water from the mortar.
The were bone dry within seconds of taking them out so I dunked them again until the surface stayed moist. I bet they would have soon sucked the water from the mortar.
I'm building an 8m long fella as we speak. I get the line taught - and I mean taught. I actually tune the line to an E flat.
Noseall, do you use profiles or line pins, or wrap it round bricks. I've never used pins, and when I'm using profiles I can get it really tight, but when stringing across I wrap it round a couple of bricks, which means I can only get it as tight as it takes to move the bricks, which normally happens when I accidentally knock it half way along. I guess I'm missing a trick. (I never said I was a bricky )
)But only from external corner at each end, right? Agree they're great once you stop dropping them every time the line is released ... Oh no wait I still do
I'm a pin man and use corner blocks where I can.
But only from external corner at each end, right? Agree they're great once you stop dropping them every time the line is released ... Oh no wait I still do
Yes - only external corners. I also spent £25 on some of the fancy spring clamps which I'm very pleased with. Ideal when you don't have external corners, but they're a tad pricey.
Are they the armeg line runners?
I like the idea of pins but when i see them used by brickies they seem to pin the end then hook the line over or under a brick rather than just strung directly across a course, and I've never really worked out how that works!
I like the idea of pins but when i see them used by brickies they seem to pin the end then hook the line over or under a brick rather than just strung directly across a course, and I've never really worked out how that works!
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