Laying Long Runs And String Sag

stacker

i cant find a drawing of what we have used for slip joints.
basically what it is,is a piece of metal in which the rebar is slipped into each end.it is abour 10 inches or slow long and lays thru the control joint.this allows for each section of wall to move while still being pinned together.
28 lbs for a lw 801 is about right.
gotta look at it this way,they are masons,they are going to bitch if you got 5 lb block.masons find something to bitch about all the time. but i never do.

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tkle

I like this thread.I'm learning some good stuff.I'm a bit slow,I'm envisioning a piece of pipe but I think you would have said "pipe" if that was what it was.Not sure how that would work if both ends were embedded in grout.Now you got me curious.

concretemasonry

lukachuki -

The simple way if getting a "slip joint" is to make sure at least ONE end of the rod between panels can slide or slip. The purpose is to keep the adjacent wall panels in line lenghtwise and still and transfer any horizontal load on the wall face to a larger area. You can just grease a plain rod that goes between panels or use rebar, grease ONE end and then wrap that end with paper so it can slide after the gout in the bond beam has cured. You can then run the regular rebar the length of the wall and stop it at the joint. Then, the only thing tieing the panels together is the greased bar that can slip on one end. On highway jobs, they frequently use expensive fabricated "dowel boxes" that are a supported pipe that a steel rod from the adjacent slab can fit into and slide when the slabs move.

Regarding the weight of lightweight block, a normal weight 8" is about 38# and a legitimate lightweight is about 28# depending on the lightweight aggregate available and the percentage of heavier (and cheaper) sand is blended into the mix. This varies depending on what lightweight available in your area. In some areas, people try to sell a 32# block and call it lightweight. No matter where you are, making block lighter requires more lightweight aggregate, making it more expensive. There are 3 different densities or categories of block (normal weight, medium weight and lightweight). Some areas sell one or two, depending on what the market wants or will accept.

I had a brick and block cavity wall lake home built using 18 to 19# - 8" lightweight block(loadbearing). They guys threw them in very fast, but normal block seemed much heavier after they got to the next job. It would be hard to justify the cost of those light block for a normal job, but I had access to some test samples.

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CJKarl

Yeah, what he said.

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lukachuki

Thanks CJ

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Less with the jaw more with the paw!

hurricane hogan

Durawall has some good info (or used to anyway) about control joints on their web site. As tkle said- steel is cheap - law suits ain't. Overkill is easy. I don't do a lot of block walls anymore, apprenticed in So Cal surrounding track homes with them- ventrua to the border- but the last couple jobs I did we used H block, lighter and EASY to grout. Engineered, Yeah! you bet, let some guy with a couple of letters after his name take the responsibility. The owners pay anyway.
As to the original question- isn't that what transits are for?, then just build, very carefully and plumb, the intermediate leads or trigs. I was taught that a plumb brick is a level brick is a plumb brick..use the torpedo level like the man said..stretch the line and go to'er.
hey, cm is that a real fish your holding? Tyee? nice!

tkle

For the most part a plumb brick is a level brick,that is if you have square brick.The out of square problem is accentuated with block and even more so with pier block.When going up on the wall I plumb from the top of the top of the first course where it meets the line and I know it's correct,but yes for the first course a torpedo is good enough.