Effect of cooling rates on mineralization in Portland cement clinker

The rate at which cement clinker is cooled as it exits the kiln has long been known to be an important factor in cement quality. Cooling rate is one of the variables that has a significant impact on the minerals produced during the cement making process. The goal of the industry has been to produce cement clinker containing minerals that are highly reactive with water. Highly reactive clinker minerals will equate to improved mortar strength and faster set times than clinker with minerals that have a lower level of reactivity.;This study analyzed five cooling rates of Portland cement clinker produced in a laboratory. Characteristics of clinker minerals were then analyzed with an emphasis on silicate minerals, alite and belite. The fastest cooled sample was determined to be the best quality sample in terms of hydraulic reactivity. Alites and belites in this sample exhibited good crystal form. The belite minerals from this sample had higher levels of foreign ions which yielded more highly reactive belite polymorphs. This sample had less periclase than other samples and small, more amorphous aluminate and ferrite crystals.;With progressively slower cooling rates, less hydraulically reactive silicate minerals with increasingly poor crystal form were observed. Periclase content increased in slower cooled samples and aluminate and ferrite crystals were progressively larger.