Hi
I used a mix of 1prt cement to 4prt builders sand and a drop (unmeasured) of
plasticizer to repoint some damaged areas of pointing. However, the mortar
has remained crumbly, I can rub it away with my finger.

What do you think has gone wrong? I did wet the wall (concrete blocks) with
a paint brush but could the water have soaked into the wall too quickly? I
was a hot day and that wall does get the sun on it in the afternoon.

Thanks
Roger