a little help

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This is not welding but you people on here are always so much help and I am sure some of you do this for a living.  At work we need to cut out a bunch of concrete around our rail road tracks between two buildings.  The thing is that we have a big water cooled saw with a 15 inch diamond blade but the boys were cutting with it last night and took off a bunch of it.  It wore a good 3/8 off all the way around.  The only thing I can think of is they are hitting rebar.  What kind of blade can we use to cut both??  Please give me a bone!!  Thanks Matt
Reply:Those blades are usually designed to cut rebar, since that's a basic part of concrete.  Are they using enough water?  They may have to slow down their cut and use more water.
Reply:Wannabe is correct from my experience in the concrete cutting business.They were either pushing too hard, not using enough water, or the blade speed is wrong.  Diamond blades will basically cut through anything and they should last a lot longer than that if treated properly.  The quality of the blade is also important. Just like any blades, the best blades will cost you.  They usually sell  lower quality matrix and diamond count at the big box stores.Independent contractors who use them everyday actually measure the diamond segement thickness before and after a job, and charge for the amount of diamond used like a welder does for supplies.  I've seen these guys use quality blades for months before they send it out to be re-segmented.Hobart 140 Handler w/ gasHyperTherm Powermax 380 Plasmaoxy/acetylene
Reply:It could also be the wrong diamond. They have different grades for different compositions. Soft rock, hard rock, and so on. Use the hard rock grade on soft rock and it will eat up the blade and vice versa. You just can't get a diamond blade off the shelf and go with it. IT MUST be the right one. Found out that the hard way. Burned up a $5000 blade because someone missed high quartz and flint concentrations in a predominately limestone mix. Then there was the job that had iron aggregate mixed in with the river rock.....don't even get me started on that one. We have several types around here. That is the main reason I quit using diamond blades and went all abrasive. Cutting green concrete, I can get over 1000 inch feet plus out of one 14" blade. Old, cured results vary wildly, but needless to say, it is still cheaper in the long run. FWIW, I use Target Red GC-7A's for most everything. At roughly 20 bucks a blade, it is well worth it. I own a 20", 20hp Dimas FS2000 saw. Not a huge beastie, but it isn't a light weight either.
Reply:If all that doesn't work you can get a 10' Magnesium filled burnning bar and cut it out, most LWS can give you the information needed, if not just ask and I will look it up for you.  JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:Well we got another blade and made sure they know to go slow...  some are not the brightest!!!!  I will look in the the abrasive blades too... I dont think water is a issue... running about 110 psi of water through a 3/4 inch line...Thanks Matt
Reply:Originally Posted by johnsonmoparWell we got another blade and made sure they know to go slow...  some are not the brightest!!!!  I will look in the the abrasive blades too... I dont think water is a issue... running about 110 psi of water through a 3/4 inch line...Thanks Matt
Reply:Sounds like water is not your problem.  60psi through a 3/4" hose is plenty.  Aside from some unique situation/material like DDA52 mentioned, they were probably just pushing it too hard. It's a common problem.  As with all blades, let the blade do the cutting with a consistent, medium pressure. Diamonds can glaze over from not enough pressure and that is not good either.  They are self-sharpening by means of the matrix wearing away and exposing fresh cutting surfaces.Hobart 140 Handler w/ gasHyperTherm Powermax 380 Plasmaoxy/acetylene