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. Thanks Toom