Chris, good job on the hard surface thread . Get it on your site . Ed
Does not matter what goes in it ...it won't last as the joints are not wide enough. The joints will be weak.
I have done more of these jobs than you can shake a stick at and the Geo Fix is superb. I am not talking about the deal in the Blue Bucket I mean the Geo Fix Pro and Sika Jointing Sand is Setting sand that sets rock hard and it is designed for narrow joints It is not a loose kiln dried sand. We sell at least 50 buckets a month of Geo Fix and it is fantastic stuff. Kev MartinMarblelife Ltd
That's not Sandstone, it is precast concrete rivened slabs.Needs deep cleaning and a total clean-out & re-point of the joins and not using the Geo-Fix S**T as that will fail.