In
order to get a good bonding between old and new concrete :
§ Clean
the surface of all loose particles and moisten with water.
§ Apply
Polyalk EP & Cement in the proportion of 1:1 (by weight) by brush.
§ Provide
a thin layer (chat coat) of 1:2 cement and mortar.
§ Immediately
place a new concrete over it and carry on with the rest of the work as usual.
Note:
Provide a thin layer of 1:2
cement sand mortar.
It is advisable for the mortar
mix to match the proportion of cement sand part of the concrete e.g. if mix of
new concrete is 1:1 ½:3 then the thin mortar layer should preferably be 1:1 ½.
Sometimes longish aggregates
are left protruding above the lower concrete and this would be helpful to
increase intergrity.
