Q.: We're saw cutting a road that consists of 6 inches of concrete overlaid with 1 inch of asphaltic concrete. In most places there's only 1/2 inch of asphalt left. The cut is 3 inches deep and our saw blades are lasting for only 500 lineal feet of cutting. Isn't that low? We're using a 14-inch-diameter asphalt/concrete blade with a 26-hp saw. Cooling water is gravity fed from a flatbed truck through a 3/4-inch-diameter hose.

A.: We asked several concrete saw manufacturers and concrete sawing contractors for their suggestions. They said blade life depends a lot on the concrete you're cutting. Hard aggregates such as river gravels wear out blades faster than soft aggregates such as crushed limestone. Thus it's hard to say whether or not the 500 lineal feet is exceptionally low. Also, there are as many as five different qualities of blades, with top-of-the-line blades lasting much longer than lower-priced blades. Buy the best blade available. It might cost 30% more but can give you as much as twice the cutting life.

It's better to cool the saw blade with pumped water. You need 2 1/2 to 5 gallons per minute, and it's tough to get that much water with gravity feed through a 3/4-inch-diameter hose. If smoke or steam is coming from the saw cut you're not getting enough water to the blade and blade life will be reduced.

Also, try using an 18-inch-diameter blade if the saw will take the bigger blade.