| Diamond blade performance part 2 Sand is a part of the aggregate mix and determines the abrasiveness of concrete. "Small aggregate" is usually sand. Sand can either be sharp (abrasive) or round (non- abrasive). To determine the sharpness of sand, you need to know where the sand is from. Crushed sand and bank sand are usually sharp; river sand is usually round. Green concrete is more abrasive than cured concrete because when concrete is not fully cured, sand can easily be scraped off the surface being cut. More loose sand means more abrasiveness. Heavy steel reinforcing tends to make a diamond cutting blade cut slower. Less reinforcing steel tends to make a diamond blade cut faster. Light to heavy rebar is a very subjective term.
Heavy rebar can also result from different grades of steel. Typical rebar is grade 40 steel. Grade 60 steel would make the example of #4 rebar, above, into a heavy rebar. Rebar gauges are in eighths of an inch - #4 rebar is 1/2" diameter, #5 is 5/8". Where rebar specifications do not exist on a road, pull a core sample before buying a blade. The drying or cured time of the concrete greatly affects how the material will interact with a diamond cutting blade. Green concrete is freshly poured concrete that has set up but is not yet fully cured. It is softer and more abrasive than cured concrete. You need a harder bonded diamond blade with undercut protectors to cut green concrete. You need a softer bonded diamond blade to cut the same concrete in a cured state. The definition of green concrete can vary widely. Weather, temperature, moisture in the aggregate, time of year and amount of water in the mix all influence curing time. Concrete now has additives which can either shorten or extend curing time. Consult your mix design to find the relative curing time for your job. As soon as wet concrete sets up and does not spall or ravel, green cutting can begin. |
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