DIY Doctor UK DIY Forums

I'm replacing a concrete garage base, after digging up the original concrete, the base under is constructed of red ash. Is red ash a suitable material to lay concrete on or does it react with the concrete and cause cracking ?.

red ash or 'red death' as it has come to be known, is sulphate rich and reacts with concrete causing it to expand and bow away from the ash.

i would dig it up, or at least use a gas dpm if you are going to leave it down.

just lay a dpm