Cement, the gray and fine powder, is the most used construction material on the world. However, how many people do they know what cement is? the answer for this question from Wikipedia is as follows,
In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word “cement” traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed rock with burnt lime as binder.
The reason why cement can sets and hardens independently is its hydraulic property. When cement is mixed with water, the chemical reaction occurs and produces hydration products, such as C-S-H gel, calcium hydroxide, ettringite and monosulfoaluminate. The C-S-H gel is the main material to bind different particles and resulting in the engineering strength which is needed as a construction material.Since the set and hardening process of cement is chemical reaction, so we can get cement set under water.
As for the chemical composition of cement, there are four essential elements in cement, which are Calcium, Silicon, Aluminum and Iron. The four elements form four clinkers, namely,
- Tricalcium silicate (3CaO.SiO2), (50-70%)
- Dicalcium silicate (2CaO.SiO2), (15-30%)
- Tricalcium aluminate (3CaO.Al2O3), (5-10%)
- Tetracalcium aluminoferrite (4CaO.Al2O3.Fe2O3), (5-15%)
If you would like to know the production process how cement is made, refer to this web page or the video below.
It is common to see another name of cement that is Portland cement, because concrete made with cement resembled natural stone from the Isle of Portland. It worthy to note that first cement is produced by early Greeks and Romans from volcanic ash mixed with slaked lime. Unfortunately, this art was lost during the Middle Ages. The modern cement, Portland cement, is developed in England by bricklayer Joseph Aspdin in early 1800’s.