"Conditional co-operation is like adulterated cement which does not bind…”
Mahatma Gandhi
Joseph Aspdin (1778-1855) invented the first Portland cement, named after the gray Portland stone it resembled, in 1824. However, his cement set too quickly and had poor early strength. Joseph's son William then noticed that when the constituent clay and limestone are burned together to combine the minerals, increased burning temperatures (exceeding 2,282°F/1,250°C) and greater proportions of limestone resulted in much stronger cements suitable for concrete, and hence construction.
The difference in strength was largely due to the calcium silicates present. The strength of Joseph's cement was derived from its belite (dicalcium silicate) content, which could take weeks to develop. For early strength, cement has to contain alite (tricalcium silicate), which is precisely what William had produced by using higher burning temperatures. Despite having a different composition than his father's invention, William neither patented his idea nor changed its name. By not applying for a patent, claiming it was covered by his father's, he was able to keep his invention a secret from his competitors.
Due to the large amounts of carbon dioxide released during cement production, there are calls to find alternatives. However, our love affair with cement is unlikely to be extinguished any time soon as the alternatives are expensive and not as versatile.
