what is quicklime
How to Make Quicklime. Quicklime, also known as calcium oxide (CaO), is a caustic alkaline substance. It has been used by humans for centuries for many things such as mortar, flux, treating corn, and in mixtures to waterproof boats.Today, quicklime is used in many industrial processes.Ad.uicklime, also known as calcium oxide (CaO), is a caustic alkaline substance. It has been used by humans for centuries for many things such as mortar, flux, treating corn, and in mixtures to waterproof boats. Today, quicklime is used in many industrial processes. Ad.