Poured these at 7am, is 5pm too early to start the saw?

If you're under direct sun and it's hitting high temperatures, that concrete is cooking from the bottom up. Waiting til tomorrow morning on a 31-foot wide slab is asking for trouble. You’ll likely wake up to a hairline crack right down the center or coming off a corner before you even get the saw off the truck. With spans that big, the internal tension builds up fast as the moisture leaves the surface and the slab begins to shrink. Ten hours is generally plenty of time for a standard mix to set up enought for a clean cut in these conditions. The best way to tell is to just do a small test score where a secondary joint will be. If the blade is throwing **slurry** and the edges of the cut stay sharp, you're good to go. If it’s pulling out chunks of aggregate—what we call raveling—then back off for an hour and try again. But in this heat, the window for cutting opens alot faster than people realize.

I'd definatly jump on it tonight. Get your lines snapped and get moving. On a 31-foot width, you really need to split that into at least three bays, so you're looking at two long longitudinal cuts. If you leave those out overnight, the slab is going to decide where it wants to break, and it won't be in a straight line. Those spider cracks aren't random at all; they're just the concrete reacting to the heat and the sheer mass of the pour.

Make sure you're using a good diamond blade and keep an eye on your depth. One-quarter of the slab thickness is the standard for effective joints. If you're running a **Soff-Cut** saw, you could have started hours ago, but for a standard walk-behind, 5 PM sounds like a solid window. Better to have a tiny bit of minor raveling you can rub out later than a wild crack that ruins the look of a massive driveway.

I'm curious if the type of aggregate affects that raveling window. Like, does a round pea gravel pop out easier than crushed stone when you're doing those test cuts? I'm also wondering about the cleanup part—if the edges do get a little chewed up, do you just use a rubbing stone once it's fully cured, or is there a trick to smoothing it over while it's still relatively fresh? This heat makes everthing feel like a race.

In this heat, watch out for 'crusting.' The top skin might look hard but the middle is still mushy. If you're getting some raveling with crushed stone, try walking the saw a bit slower to let the blade work without yanking the rock. Most importantly, blow that dust off the slab imediately. If that dust bakes into the broom finish under this sun, it’s a nightmare to clean later. You definatly want those joints in tonight. If one driveway cracks, you’ve got three unhappy sisters comparing notes. Better to have a few slightly rough edges than a wild crack running trough the middle of that 31-foot span.

Make sure you've got a fresh blade ready to go before you start. Those 76-foot runs will dull a diamond edge faster than a standard driveway, and a dull blade is what realy causes that nasty raveling. Also, if you’re wet cutting, keep an eye on your water levels. In high heat, you don't want the blade overheating and warping halfway thru a 31-foot span. Once you're done, give it a quick misting with some water or cure-and-seal. Those sisters won't be happy if the slab turns white and chalky from drying out too fast tonight.