It’s made by heating limestone, iron, alumina, and silica to 2,700ºF, which changes the ingredients into calcium silicates, aluminate, and aluminoferrite. The minerals are then ground into a dust that’s just waiting to be mixed with H2O. (Contrary to what you might think, the water doesn’t evaporate out as the concrete hardens; it reacts with the minerals, lending its Hs and Os to create new compounds that form a rigid matrix.)

 

Calcium sulfoaluminate
The “quik” in this version of Quikrete, CSA reacts with water much faster than the minerals in portland cement, so putting this in the bag speeds things up. Where Quikrete’s basic product might take eight hours to solidify, Quikrete Fast-Setting Concrete Mix can harden in as little as 40 minutes—meaning fewer handprints in your new driveway!

 

Alumina and amorphous silica
The ancient Romans discovered that adding volcanic ash from Mt. Vesuvius made their concrete stronger. The 20th century saw the widespread use of fly ash—particles of alumina, amorphous silica, and other substances from coal-burning smokestacks—to accomplish the same thing.