Chapter 2 - Concrete Materials

Abstract

This chapter presents an overview of Portland cement and concrete. Portland cement is a general term used to describe a variety of cements. Because they are hydraulic cements, they will set and harden by reacting chemically with water through hydration. Hydraulic cements are the binding agents in concretes and most mortars and are thus common and critically important construction materials. Hydraulic cements are of two broad types: those that are inherently hydraulic, and those that are pozzolanic. Portland cement is the most commonly manufactured and used hydraulic cement in the United States and the world. It is manufactured through the blending of mineral raw materials at high temperatures in cement rotary kilns. Rotary kilns produce an intermediate product called “clinker.” Clinker is ground to produce cement. Portland cement manufacturing is a two-step process beginning with the manufacture of clinker followed by the fine grinding of the clinker with gypsum and other additives to make the finished cement product. Grinding can occur on site or at offsite grinding plants. The U.S. Geological Survey (USGS) estimated that in 2005 approximately 97.5 million metric tons (Mt) of Portland plus masonry cement was produced at 113 plants in 37 states in the United States.