I used a mixture of 2 parts silica sand; 2 parts Koalin, 1 part portland cement, small amount of nylon fiber and small amount of Q cells. I used latex as activator for the concrete. I had quite a bit more shinkage than I thought I would get. I mixed ingrediaents and then poured. Should I have waited to pour until concrete started to set up? Should I alsways expect shinkage? What can I do to minimise it? Thanks for any help.
Hmmm, I thought concrete had less shrinkage than cocobolo. Maybe not. I'm not sure how this is related to woodworking.
Stop swimming in cold water.
It's already minimized.
Add some sawdust. It will swell to counteract the concrete shrinkage.
"It shrinks?"
"Like a scared turtle."
"I don't know how you guys walk around with those things."
Oops. Sorry. Wrong newsgroup.
Billy Bob, As the concrete cures, water evaporates out. This is part of the shrinkage. Less water means less shrinkage. Stiffer conctrete requires vibration and or more working to get all of the voids out. There are a number of additives that can be used. One is called Recover. I used it a lot when pouring counter tops. Others are called 'plasticizers'. They allow the concrete to act like it has more water in it than it really does. The down side to these is that it tends to give the conctete a texture like silly putty, and makes it harder to work. Concrete will shrink and expand with temperature changes. On smaller slabe this isn't significant. On the Golden Gate Bridge, this can mean elevation changes of 5 or so feet during the day. robo hippy
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