The most efficient way of putting in a large number of fasteners on a current job seems to be to use a powder-actuated tool. However, this method has caused a lot of spalling and so we either have to relocate many fasteners or be satisfied with a smaller amount of holding power. What can be done to minimize spalling?
Possibly you should use a powder-actuated tool that is equipped with an anti-spalling device. This may be a device that applies a substantial load on the surrounding surface while the fastener is being driven to counter the tensile stresses from the entry of the fastener. Concrete made with a high proportion of coarse aggregate, incidentally, is more likely to spall when powder-actuated fasteners are driven than concrete made with a high proportion of sand. Also, long fasteners are more likely to cause spalling than short ones.