We poured the garage floor this week, too. Rob, the concrete placer, did not like working with the 32% fly-ash concrete. He says it’s “sticky” and doesn’t allow a smooth floating motion. He says if this is the way of the future, to build with fly-ash concrete for environmental reasons, he will just have to leave the industry!
This 2×4 he was using as a float is his example of how sticky this material is; it should not be gumming up on the wood.
Insulation under garage floor
{ 5 comments… read them below or add one }
You really let the pictures speak for themselves this week, eh? What’s environmental about fly-ash? Why have you chosen the styrofoam for the studio?
-t
Dearest Tess,
So, fly ash is actually a by-product from other industries (Coal production? Something like that? I kinda crammed for this part of the exam for my concrete technology class.) so you are using a material that would otherwise just be disposed of. And it acts as a cementitious material, helping create the paste that holds the aggregate together.
Also, those styrofoam blocks are SO COOL! The rebar slides right in to grooves inside, and its really neat. Well, I think so
I’m sure there are a multitude of reasons why it was chosen…
Love,
Guest Blogger Alice
Aha! This was bugging me the whole bike ride home… So I looked it up!
Fly ash is the “residue of powdered coal after burning in power plants”. While concretes with high fly ash content take longer to gain compressive strength, they eventually reach the same strength as regular concrete, given proper curing. (Source: “Concrete: Second Edition”, Mindess et al.)
One question, though… usually, if the concrete is determined to have low workability in the field, it is possible to add a superplasticizer to create the slump needed… anyone have an idea why this wasn’t done?
Alice (again)
Answers accepted. But what’s green about producing more styro?
-t
What’s green about styro is that it is such an effective insulator that it keeps heat in very efficiently, thus using many fewer natural resources (electricity or natural gas, in this case).