![]() “And the concrete industry doesn’t want to be the bad guy, so they’re looking for solutions.” “Now it’s recognized that we need to cut net global emissions to zero by 2050,” says Robbie Andrew, a senior researcher at the CICERO Center for International Climate Research in Oslo, Norway. But as the urgency of addressing climate change heightens public scrutiny of cement’s emissions, along with potential government regulatory pressures in both the United States and Europe, it’s become too big to ignore. Granted, that’s nowhere near the fractions attributed to transportation or energy production, both of which are well over 20 percent. Multiply that by gigaton global usage rates, and cement-making turns out to contribute about 8 percent of total CO 2 emissions. The variety of caementum that’s most commonly used to bind today’s concrete, a 19th-century innovation known as Portland cement, is made in energy-intensive kilns that generate more than half a ton of carbon dioxide for every ton of product. Unfortunately, our long love affair with concrete has also added to our climate problem. And as fast-developing nations such as China and India continue their decades-long construction boom, that number is only headed up. Globally, in fact, the human race is now using an estimated 30 billion metric tons of concrete per year - more than any other material except water. ![]() Two millennia later, we’re doing much the same, pouring concrete by the gigaton for roads, bridges, high-rises and all the other big chunks of modern civilization. The Romans used this marvelous stuff throughout their empire - in viaducts, breakwaters, coliseums and even temples like the Pantheon, which still stands in central Rome and still boasts the largest unreinforced concrete dome in the world. ![]() But they had also learned the value of stirring in pumice, pebbles or pot shards along with the water: Get the proportions right, and the cement would eventually bind it all into a strong, durable, rock-like conglomerate called opus caementicium or - in a later term derived from a Latin verb meaning “to bring together” - concretum. They made extensive use of the still-wet slurry as mortar for their brick- and stoneworks. ![]()
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