What chemistry makes cement set?
Cement is a very fine powder made from limestone and clay, heated in a kiln to form binding compounds such as tricalcium silicate.
The terms cement and concrete are often used interchangeably, but they are not the same; cement is the binding ingredient used to make concrete. Tricalcium silicate in cement reacts with water, in a process called hydration, releasing calcium and hydroxide ions and a great deal of heat.
The less water-to-cement ratio, the stronger the concrete will be.