[CONCRETE MIKE]

has anyone ever attempted to use pea stone crushed granite with concrete to make a faux granite step or walkway?

I am in the process of making some samples for practice and so far i am running into a few issues.

1. The portland cement is grey not white or light grey so the cement voids around the crushed granite makes it all look to dark and unnatural. Adding some tera cotta integral color helps a little to remove the grey but its still dark.
2. Need a very high granite to cement ratio. Not sure what this will do for durability.
3. I need to grind the cream of the surface to expose the granite. This is very time consuming. I have tried rinsing the cream just before its cured but this does not create the effect i am looking for and causes some granite to be loose.
4. After adding calcium to the portland it still takes so damn long to cure!

I add calcium to the water before putting it in the cement since its not a powder, its small flakes, does this reduce its effect on the portland? I never have to use portland alone so this is a semi new area. The only time i use portland cement is for fiber reinforced concrete which is different. I use acryl60 at that point and it cures much faster but acryl60 is expensive.

use expose on the surface of the concrete, cover with 6 mill plastic and wash off with water, use floor broom that will expose the surface easy. Ask the cement supplier if the have type i or type iii cement , that concrete is usually white, but type iii goes very fast (astm c 150). The gray or tan color of ordinary portland cements depends mosty on the amount of iron in the cement. White portland cement is made with selected raw materials containing very little iron or manganese oxides-the substances that give the typical gray color. Hope this helps

 

[Tscarborough]

I was in Marble Falls today and got a (crappy) phone pic of the granite I was trying to emulate:

 

[Tscarborough]

The sample:

 

[Ohio Mason]

advise

hi I do terrazzo for a living, and what your trying to do is making a piece of precast terrazzo. With that being said you can only come close to looking like granite, because granite doesn't have a binder like cement or epoxy your not going to get it as tight looking, you can come close by using a range of sizes in your pour. Smaller chips fill voids between larger chips making it look tighter. Also matching cement color to the chips will make it look tighter. If you want to match the color above, I would add some black color to the terra cotta, a little black goes far, be careful. The mix should be 1.5 to 1.75 parts chips to 1 part cement, you can add acryl but you don't need it. after you pour it in your form let it get firm but not hard, you need to sprinkle more chips on top, an even thin layer. Punch the chips into the cement and trowel smooth. you need be sure the top is flat, no dips. Let it set til it gets a little harder, take a wet sponge and dab off the cement on top, and close it back up with your trowel. any dips in the top means more grinding so the better the job you do the easier it is later. Cover with plastic for a day, uncover, wet it and wait one more day to grind. You really need to give cement 2 days to cure to grind. Adding calcium isn't going to give you a better job so why do it. for the face I would cut it on a saw to give a clean straight square front. grout the pin holes with straight cement and acryl polish the next day an seal with a solvent based sealer. Good luck

 

[jgray152]

Wow Thanks for the information folks! :thumbup:

Once the warmer weather comes around I will start up on this again.