The drying or curing time of concrete greatly affects how the material will interact with a diamond blade. Green concrete is freshly poured concrete that has set up but not yet fully cured. It is softer and more abrasive than cured concrete. You need a harder-bonded blade with undercut protectors to cut green concrete. You need a softer-bonded blade to cut the same concrete in a cured state.
As it applied to diamond blade sawing, concrete defined as "green" is less than 24 hours from pour or younger, the actual time can vary widely. Weather, temperature, moisture in the aggregate, time of year, and the amount of water in the mix all influence curing time. Also, much of the concrete poured today 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 should begin. Spalling or raveling is a condition where the edges of a saw cut are ragged and very rough because of aggregate pull out. This condition is a result of the concrete surface not having enough cure time to achieve enough strength to hang on to the surface aggregate. The best method to determine when concrete if ready to be "green sawn" is when surface aggregate and sand particles are not torn free by scratching the surface with a knife or other hard metal object. Currently a more promising and exact technique is emerging utilizing a maturity meter to determine when a concrete slab is ready for green cutting.