Crumbling concrete steps and paths

[damia-b]

Several years ago, I got a local stonemason to repair my steps and cast new concrete paths. They have been OK until this winter. Now the surface is crumbling in places exposing softer stuff underneath. There is no ground heave cracking except on one step. I could now do with some advice please.

I wonder why this has happened this year. Could it be due to the use of dishwasher salt as a de-icing agent instead of the common stuff? (All the local shops had run out of salt during the cold spell.)

What steps should I take to repair the damage? Obviously the cracked step needs broken out and recast, but what about the patches of soft stuff? Some of these are only about the size of your hand.

 

[PrenticeBoyofDerry]

Not just household salt but rock salt can cause problems to concrete.
The freeze thaw action can allow, water moisture to penetrate the concrete, this can cause softening at the surface also as the temperatures go to freezing again, blow concrete at points of ingress.
If the concrete was finished by adding more water to the surface this would also enhance the problem. As the concrete surface will become weaker, as it has been diluted.
My only suggestion would be if you are not replacing the path, is wait till the temperatures rise, as concrete doesn't like the frost. Fill out the dips, with a wet mix of sand and cement(3-1) and waterproof admixture to it, it would be better if you could get some larger aggregates in the mix, but this will depend on the depth of the holes created, but the damage could already be done to the surface and this may continue to crumble.
In future forget the salts as a de-icier and use sand on concrete paths and steps, it will not melt the ice but will allow grip under foot.

 

[damia-b]

Thank you PrenticeBoyofDerry, I will be waiting anyway until that latest dump of snow has cleared and probably a bit longer before I do anything. I'm wondered about the salt as I have used common salt in past years without damage. I thought perhaps there was a sulphate component in the dishwasher stuff that was causing the damage.

Now I will sweep out all the loose stuff and scrub the holes with a stiff brush, but should I apply anything to the surface left before applying the filling? I read in another post that PVA should not be used outside, which was what I was thinking of using.

Final question, I notice that in various replies the small text at the foot "soanso has thanked helpfulperson" and that profiles record how many times a member has been thanked. How do I do this?

 

[PrenticeBoyofDerry]

No don't use PVA outside, just clean the area from loose debris, dirty etc..
It may be worth just dampen the area, not saturating, prior to filling.
To Thank useful post or replies;
If you look at the top of that particular post/reply, at the top right hand side, there are options tabs as follows; wiki, quote, ignore, thank.
Click on the thank tab of the useful post and that it.