The second industrial age also saw the reemergence of concrete and higher-strength artificial cements.
Lime mortar—made of lime, sand, and water—had been known since ancient times. It was improved in the late 18th century by the British engineer John Smeaton, who added powdered brick to the mix and made the first modern concrete, known as Hydraulic Concrete.
William Aspdin patented the first true artificial cement, which he called Portland Cement, in 1824. The name implied that it was of the same high quality as Portland stone.
To make portland cement, Aspdin burned limestone and clay together in a kiln; the clay provided silicon compounds, which when combined with water formed stronger bonds than the calcium compounds of limestone.
Nowdays a Portland cement clinder is made by heating, in a cement kiln, a mixture of raw materials to a calcining temperature of above 600 °C (1,112 °F) and then a fusion temperature, which is about 1,450 °C (2,640 °F) for modern cements, to sinter the materials into clinker.
This compound is obtained from unprocessed common natural materials. Consequently, the characteristics of Portland cement clinker may vary from
one cement plant to another. To limit the variations of the technological properties of Portland cement, acceptance standards have now been developed.
image source: https://www.cement.org/apparent-use-reports