Adding new concrete on top of old - bonding agent needed?

Reply

  #1  
Old 10-30-19, 09:19 AM
B
Member
Thread Starter
Join Date: Sep 2019
Posts: 18
Received 0 Votes on 0 Posts
Adding new concrete on top of old - bonding agent needed?

Hi there. Need some advice on adding new concrete on top of old. In this case ďoldĒ is about 3 weeks and has never been exposed to any elements. And itís not a flat surface...itís a round concrete ball. Want to know what Prep and products to use to make sure it adheres

I was trying to make a concrete garden feature for my wifeís birthday. Itís a sphere and I used a plastic light globe as the mold. Got the idea from the atlas stones that strong men and CrossFit folks use. Itís cored (3/4Ē hole) it and it will be a bubbling water feature

Being my first try the sphere is pretty much perfectly round but has some rough spots and voids. I read (again on a strongman site) that you can repair damaged atlas stones with concrete patch product. Smear it into the voids and smooth it out. Buff/sand when dry (24 hours). But as to the steps and products...opinions vary. Some sites say to add a fortifier to the concrete. And others say to paint on a concrete bonding agent/primer. While still others say to make a slurry of primer and sand/concrete as a first layer. Or do all that. Again, most of these are for repairs to stones that are being (potentially) dropped repeatedly and have been exposed, may have cracks etc. Mine is new and undamaged and will be installed and never lifted again....itís just imperfect. Some imperfection is fine and gives character but I want to fill those voids

Will try to attach some photos in a bit. Advice appreciated!

Thanks!
 
  #2  
Old 12-13-19, 02:34 PM
S
Member
Join Date: Dec 2013
Location: usa
Posts: 1,348
Received 1 Vote on 1 Post
rapid set cements - quikrete - yellow bucket - apron/vest stores
 
  #3  
Old 12-14-19, 06:00 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 24,738
Received 787 Votes on 724 Posts
Since it's going to be a fountain and visible I would put extra effort into making the ball perfect from the beginning and do less worrying about fixing blemishes. Any patches for "filling" you do will likely always be visible (and ugly) in your final ball. So do everything you can to make it come out perfect and without needing filling. If the mold is bad your ball will be bad so take the time to smooth any bumps in the mold and fill any voids. Also, make sure your mold is strong enough to retain it's shape when filled.

Before pouring spray or coat the mold with a release to make it easier to remove from the mold. When pouring your concrete vibrate the mold to insure there are no air pockets or voids but don't do so much that you separate the cream from the aggregate.
 
  #4  
Old 01-01-20, 10:08 AM
S
Member
Join Date: Dec 2013
Location: usa
Posts: 1,348
Received 1 Vote on 1 Post
ever see the balls around target stores ? they're cast then patched,,, final step's an overlay w/polymer-modified cements
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: