I've obviously done something wrong, but I don't understand what, so any suggestions from people with lime experience would be very welcome please.
I laid some sandstone patio slabs about four weeks ago. I made a mix of 4 parts soft sand to 1 part NHL 3.5 lime, and with part of this mix I added water to make mortar and part of the same mix I used dry to grout between the slabs. Once the dry grout was in place I sprayed the slabs and joints lightly with water and also checked for a couple of days that it had got fully damp from spray and ground moisture.
So why is it that now, about four weeks later, the mortar has set nice and hard but the dry grout mix is still so soft that I can stick my finger in it easily? I imagine it's possible that after some of the recent heavy rain that the lime may now have been washed out of the mix leaving just sand. However, before the heavy rain there were several weeks of what appeared to me to be perfect lime setting conditions.
I've used the dry grouting technique before with sand and cement and it worked fine. This time I wanted to use lime for the nicer colour and I thought it would be better if I need to lift some of the slabs again in the future as there are several drain runs under the patio.
Any ideas please?
I laid some sandstone patio slabs about four weeks ago. I made a mix of 4 parts soft sand to 1 part NHL 3.5 lime, and with part of this mix I added water to make mortar and part of the same mix I used dry to grout between the slabs. Once the dry grout was in place I sprayed the slabs and joints lightly with water and also checked for a couple of days that it had got fully damp from spray and ground moisture.
So why is it that now, about four weeks later, the mortar has set nice and hard but the dry grout mix is still so soft that I can stick my finger in it easily? I imagine it's possible that after some of the recent heavy rain that the lime may now have been washed out of the mix leaving just sand. However, before the heavy rain there were several weeks of what appeared to me to be perfect lime setting conditions.
I've used the dry grouting technique before with sand and cement and it worked fine. This time I wanted to use lime for the nicer colour and I thought it would be better if I need to lift some of the slabs again in the future as there are several drain runs under the patio.
Any ideas please?