New concrete on old

[jps71]

Hi Guys

I need to lay some concrete over an old concrete step and along the edge of a pathe thats broken away and cracked in places.

Can any one please advise me as to if the new concrete will bond with the old or is there something that I can do to make them bond.

Unfortunately I cant remove the old step and path and start from scratch so any tips are greatly appreciated.

the old concrete on the step has allowed moisture to penetrate in to the wall behind it if I add a waterproofer to the new concrete will it stop the moisture penetrating.

thanks Jim

 

[noseall]

the thicker the new concrete the better as the weight and thickness will make bonding to old irrelevant.

you will get a better bond however, if you thoroughly wet the old concrete first.

a well mixed, slow cured and properly trowelled concrete surface should be impervious to water.

 

[jps71]

Thanks for the info noseall

 

[Static]

You can scabble the concrete surface to roughen it up and allow the new to bond a little.

 

[canny177]

i've done a similar job, with regard to the chipped edge i fixed screw in wall ties, a bit like half a wall tie with a thread at one end. You drill and fix a raw plug then screw in the tie ( Also known as starter ties) into the original edge, fix your shuttering and fill with concrete and cover. This holds the new concrete to the original