On Monday, 13 November 2017 13:33:10 UTC, wrote:
Original (20 yeasr ago) garage floor was not power floated so has a rough dusty surface. Is there an easy answer to this problem ? Would self levelling compound be effective ? It woiuld have to be able to withstand irregular movement of heavy machines on castors,

There really isn't anything that will withstand wheeled traffic for long.
Esp. meatal/hard plastic tyres.