Once it has been through the heating process, you can mix this with water and aggregate to make concrete. To change the speed of how fast the concrete sets, you can add admixtures to slow down or speed up the process, but as resources are limited, such things are not necessary. The aggregate can be a number of different things: rocks, sand, etc. These components do not make any sort of chemical reaction, they are just there to add strength and bulk to the concrete.
figure 3: Photograph of setting cement
When
adding water back into the cement, some of its properties change. Any
chemicals that were formed during the heating process change into other
chemicals when met with water. For example, the main chemical which does
this in Portland cement is tricalcium silicate, which forms calcium hydroxide
when mixed with water. During this process heat is released, and can be
written as:
Tricalcium silicate + Water Calcium Silicate hydrate + calcium Hydroxide
+ heat.
Or in chemical symbols:
2ca3SiO5 + 7H2O 3CaO 2SiO2 4H2O + 3Ca(OH)2 + Heat (about
174 kJ)
figure 4: Diagram for the process of making cement