Short answers, pulled from the story.
Portland cement is made by heating limestone (calcium carbonate) with materials such as clay to 1,450 degrees Celsius in a kiln. The heat drives off carbon dioxide, producing calcium oxide (quicklime), which reacts with the other materials to form calcium silicates. The resulting clinker is ground with a small amount of gypsum to produce the finished cement powder.
Joseph Aspdin patented Portland cement in 1824, naming it after the Portland stone quarried on the Isle of Portland in Dorset, England. His product was a proto-Portland cement; his son William Aspdin produced the first true alite-based Portland cement in the early 1840s at Northfleet Cement Works in Kent.
The cement industry produces approximately 10% of all human-made carbon dioxide emissions. A 2018 Chatham House study estimated that the roughly 4 billion tonnes of cement produced each year account for 8% of worldwide emissions. Nearly 900 kilograms of carbon dioxide are emitted for every 1,000 kilograms of Portland cement produced.
Yes. Roman engineers used crushed volcanic ash (called pozzolana, named after the town of Pozzuoli west of Naples) mixed with lime and rubble. This mixture set hard even underwater. Structures made from it, including the dome of the Pantheon and the Baths of Caracalla, still stand today.
Hydraulic cement sets through hydration, a series of chemical reactions triggered by water. The mineral hydrates formed during these reactions interlock as they solidify, creating the strength of the hardened cement. Cement does not set by drying out; if it dries prematurely during curing, the hydration reactions stop and the material is significantly weakened.
China is the world's largest producer and user of cement. By 2012, Chinese demand was recorded at 2,160 million tonnes, representing 58% of world consumption. As of a 2021 estimation, approximately half of annual global cement production of about 4.4 billion tonnes is made in China.