Exposed Aggreget Concrete ??

markemark99

Hey guys, I've done exposed walk ways & drive ways but when it comes to stairs I'm not 100 % on a couple of issues! I just completed a set of stairs on a Residential site, a large set approx. 24ft x9 hi and it was 10 yards of folly lake concrete exposed, With a set this large it left lots of room for error! Well as far as I was concerned! I was told not to vibrate nor tamp too much BUT for the second time I striped the panels to find ( "honey combing" and flat spots ) any suggestions? And yes we do use a releasing agent, covered with poly, acid and pressure washed it the following morning!

scrapecc

Give this man a call, his name is Terry Collins. He is very seasoned, and runs a technical hotline. I guess it helps he is my dad. but he is a very well experienced engineer with 26 years of field experience. and has co written publications on placement of concrete. his Hot line number is 847-972-9170. and its his job to answer questions for free. dont hesitate to give him a call!

B.K

Why in the world were you told not to vibrate/tamp it? Of cource your going to see honey combing.

Anytime we do exposed aggregate, its just like a regular pour, but instead of troweling it off, we use the a releasing agent, cover with poly and blast her off in the morning with water.

My only suggestion to cover that up, is parge over it. With maybe a colored grout...

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markemark99

Thanks for your reply, I really have no idea why i was told not too vibrate! and well i guess it made me nervous to try, but i guess if their not turning out already why not! Now I'm not saying yer wrong cuz honestly and obviously i don't know, I was just hoping for more responses! maybe people simply don't know. So thank you and the next set we do I'll try vibrating! Ps: would you say that you vibrate the same amount as you would a regular pour?

B.K

Treat it just like a regular pour. Vibrating it will not hurt it (unless your over vibrate it) by the sounds of it, you've been doing it long enough to know that though.

Level and trowel it off, just like normal. Than put your releasing agent over it, and do what you've been doing. It should come out perfect.

Its not like if you tamp it/vibrate it, all the aggregate is going to fall to the bottom of the forms. All vibrating/tamping does is release air bubbles in the concrete mix, letting the aggregate and cement paste bond closer together, to give a nice finish surface.

-Bill

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