1. Too much water weakens concrete
If you mix too much water with concrete, cement crystals form farther apart, leaving concrete weak and porous. That can cause trouble later as pores and pockets fill with water, freeze and break up the concrete’s surface. With the right amount of water, cement crystals grow tightly together and interweave to form strong, watertight concrete.
2. Floating too soon leads to trouble
As concrete sets, water rises to the surface. Left alone, this “bleed water” is reabsorbed into the concrete. But if you float the watery surface, you’ll force the aggregate and cement down, leaving a watery mix of sand and too little cement on top. Wait for the bleed to disappear before floating. Also, don’t overwork it. Too much floating (or troweling) will…