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. Cement is made by heating limestone with small quantities of other materials to 1450 °C in a kiln, in a process known as calcination to form calcium oxide, or quicklime, which is then blended with the other materials that have been included in the mix. The resulting substance is then ground to make “Portland Cement”. Portland cement is a basic ingredient of concrete, mortar and most non-specialty grout. The most common use for Portland cement is in the production of concrete. In response to a federal court ruling and data from industry, the U.S. Environmental Protection Agency (EPA) is proposing changes to its 2010 air standards for the Portland cement manufacturing industry. The proposal would continue the significant emission reductions from the 2010 standards while providing industry additional compliance flexibilities, including more time to implement the proposed updates by extending the compliance date for existing cement kilns from September 2013 to September 2015.

Go here to read the rest:
Cement Rules

More on SKCEA.org:

• Study links Yellowstone bison fate to genetic flaw
  A congenital defect combined with U.S. government plans to kill bison exposed to an infectious cattle disease could doom America's last wild herd of pure-bred buffalo at Yellowstone National Park, a genetics expert said in a new study. The findings were posted on Monday in Nature...
• Heading Towards a World without Corals
  Every year brings new accounts of coral bleaching in the tropical oceans. Even the largest living structure on Earth, the Great Barrier Reef off the coast of Australia, is under threat. According to marine scientist, J.E.N.Veron, in a couple generations coral reefs will no longer...
• The trouble with urban farming: What if your turkeys are cute?
  by Jess Zimmerman. Kiera Butler is not a farmer. She and her friends have been raising their Thanksgiving turkeys in a backyard for six months, but they're not accustomed to killing animals for food, and they've gotten kind of attached to the little guys. Here's Kier...
• Rivers flowing into the sea offer vast potential as carbon-free energy source
  A new genre of electric power-generating stations could supply electricity for more than a half billion people by tapping just one-tenth of the global potential of a little-known energy source that exists where rivers flow into the ocean, a new analysis has concluded. A report on...
• Global Warming and the Rare Haleakala Silverswords
  One of the most spectacular sights in the Hawaiian Islands is the Haleakalā Volcano. This amazing volcano rises more than 10,000 feet from near sea level at its base. The ecosystems change dramatically as you drive up the twisting road that takes you to the summit. Near the top, ...