This morning, we went around air blasting the 89 holes we drilled yesterday to clear out the rubbish. We undid all the concrete screws and lifted off the timber plank and using the compressed air and the long thin probe, we blasted the bits and pieces out. Then we replaced the plank and redid the screws again.
The impact driver was successful half the time to drive the whole screw down, and when it couldn’t, we used a manual ratchet to finish winding the screws down onto the wood. The heads are countersunk so it formed a smooth finish.
But we did have some trouble with one or two holes where the screws wouldn’t go down pass a certain point and we believe that there was a larger harder granite stone which the concrete screw wasn’t able to bite its way through.
Tomorrow, we will go and buy a slightly larger masonry SDS bit, a 6.5mm diameter, and drill these holes again to reduce the amount of work these concrete screws need to do.
The next job is to mix a load of 4:1 sand cement mortar and push it under all the planks and set the top surface of the timber to exactly a fixed height all the way around.