Q.: My company mainly does outdoor residential work. Our finishing procedure for drives and walks is to straightedge, bull float, hand float, hand trowel and broom. We are thinking of speeding up production by using a large trowel with a handle commonly called a Fresno trowel. I'm hesitant because the ACI 302-69 "Recommended Practice for Concrete Floor and Slab Construction," Section 7.2.9 states, "Troweling is done immediately following floating, and no troweling should ever be done to a surface which has not been floated by power or by hand." My question is this: If I use this kind of trowel following straightedging and bull-floating, eliminating hand floating, will this reduce the wear resistance and the resistance to freeze-thaw damage?
A.: The concern you raise--about not using the trowel on a surface that has not been floated--is a real one. The basic question is whether bleed water has begun to rise to the surface. If you can complete the bull-floating and Fresno troweling before bleed water comes to the surface there should be no problem. The trick would be to work fast enough, and then to be prepared to go back to your usual procedure if bleed water does appear before the Fresno troweling can be completed.