The eighty-year old steps on the path to my front door seem to be made
of some sort of composite cement casing over a much softer crushed red
shale brick-like core. Over the last twenty years years some cracks in
the vertical facing resulted in frost damage and some sections of the
outer casing falling off the facing. I've repaired them as they
happened, with mortar, sometimes with a bit more cement added, and
sometimes padded out by mixing with small gravel to fill the deeper
sections. Occasionally frost has caused a repaired bit to fall out
again, and I've patched it up again. We're typically talking about
sections up to 8 inches long and 4 high. though one is now about 15
inches long ( and up to about one inch deep)
In the recent severe weather, it's ALL fallen out again.
I'd appreciate any advice on whether and how more effective and longer-
lasting patching could be done - e.g any special mortar or cement/
concrete mix? Any hints on how to stop water penetration and frost
damage at the seams between the repair and the original material,
which I assume is what causes the weakness after a few years?
Temperature here is supposed to be max of 4 or 5 celsius over the next
few days, with no frost. Is that too low to attempt repairs now? I'd
like to fix it to prevent further frost damage to exposed soft core
material and edges of the damaged sections.