Old paving jointing damp and crumbling.

[utterlydiy]

I've spent the last week or so cleaning the old grouting and muck from the gaps between the 3 x 2 slabs. Surprisingly the old grouting laid by the house builder against the house and first row of slabs some 30 years ago was damp and crumbly where we've had no rain for some 3 weeks.

So now I'm ready to start to refill the gaps with fresh cement and was going for a 3 to 1 mix. But now worried whether if this would dry in 24/48 hrs as it seems the sub base is still holds alot of damp from the winter.

Any advice ???

Thanks

 

[r896neo]

the water will only do it good. make sure its compacted well into the joint with a trowel or jointing iron.

 

[utterlydiy]

Thanks,

OK, so the water would be absorbed to help the curing process.

But would the new mix remain damp and crumbly like the old, not drying out. Also would the mix ratio be ok or should another be used.

thanks again.

 

[utterlydiy]

Would this damp and crumbling jointing be due to an original weak mix. IE: 10 to 1.

As it appears so sandy.

 

[r896neo]

yes possibly.

3:1 will give a very hard mortar and will certainly not be crumbly unless you put it in too dry.

Make sure its well packed in and not too dry. Too wet and it will stain the paving badly. general guide is that you should be able to squeeze it in your hand but no water comes out but wet enough that it holds together in a lump and doesn't crumble

 

[utterlydiy]

Thanks,

In other words, made up like Groundbait for fishing.

As I want to power wash after every winter as they are blackened and slimey, would a 4:1 or 5:1 be OK or stay with 3:1.

thanks again

 

[r896neo]

Use 3:1, it will be very hard.

Powerwashing regularly will deteriorate pointing gradually. Can you begin to use chemical treatments for cleaning? they are more effective anyway in my experience.