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exterior concrete flatwork

Posted by Rob Dykeman on March 12th, 1998 08:24 PM
In reply to A few questions. by JT on March 11th, 1998 06:42 PM [Go to top of thread]

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The steel trowel will produce a finish that seals in any water that comes to the top of the pour which can then freeze and cause spaling. A magnesium trowel will not do that it lets the concrete "breathe" so to say.
That is why when sidewalks are done a common finish is with a broom, it "opens" ths concrete rather than sealing it.
Admixtures are what has brought the concrete industry so far in recent years, especially exterior flatwork.
I use admixtures in all concrete I pour. What admixture will depend on what I'm trying to do with the concrete.
Plastisizers are used to give concrete flowability without adding water to the design mix. I want the concrete to be about a 4 slump but there is no way that I can get that mix to flow so I use a midrange Plastisizer.
I can then pour the design mix at a 6-7 slump, which has flowability, but still have the water ratio of a 4 slump.
Water to cement ratio equals strength.
There are a number of good sealers on the market, the product I use the most is Cure and Seal, it happens to the product stocked by both concrete suppliers around here.
Sealers can range from Thompsons Water Seal to Diamond Clear which is an industrial purpose sealer.
Scofield Products out of Atlanta has come out recently with a water based sealer which I have heard is very good and non-toxic.
Air entrainment and fibers are a must for exterior concrete. If someone is pouring exterior concrete without it in a climate where is can freeze don't use them get someone who will
Air entrainment-fibers-midrange plastisizer-sealer and no steel trowel are keys to good exterior flatwork. Pour- finish- and seal immediately dont' wait until tommorrow as soon as you are done with the finish seal.
Web sites to get more info
hope I answered your questions if there are more let me know quality concrete is not athing of the past
think green - build smart - use concrete


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