Block paving steps - Kerb risers becoming loose

[Jules]

Hi Tony,
without your site where would we all be?? Excellent job, well done! Anyway, I'm near to finishing a 50 foot long block paved path that that ran a 1.8m gradient drop down the length so I've introduced some steps to create a series of "landings" to level it out a bit. One 175mm step every 10ft. I've bedded 190mm high bullnose kerb units onto 125mm wet(ish) concrete allowing a 10mm mortar gap for the steps. My problem is that when I came to mortar jointing the 2nd step 3 of the kerb units came away from the concrete bed in my hand (after leaving for 3 days to cure).

How can I ensure a perfect bond between kerb unit and bedding concrete first time, every time as this problem is proving a bit of a headache as I've now had it on the 3rd step as well!
cheers

[Tony McC]

Use a 'bonding agent' such as Ronafix or SBR, which you should be able to get at any decent BM.

I'm surprised the kerbs have come loose. They normally stick when bedded onto wettish concrete -did you just plop them down onto the concrete or where they tapped down and settled into the concrete?

[Jules]

Thanks Tony I'll give the Ronofix a try. I did tap them down about 10mm to bed them into the concrete but they still came adrift.