Quiz on Cement and Manufacture of Cement
Portland cement was named for the Isle of Portland, a peninsula in the English Channel where it was first produced in the 1800’s. Since that time, a number of developments and improvements have been made in the production process and cement properties. The production process for portland cement first involves grinding limestone or chalk and alumina and silica from shale or clay. The raw materials are proportioned, mixed, and then burned in large rotary kilns at approximately 2500°F until partially fused into marble-sized masses known as clinker. After the clinker cools, gypsum is added, and both materials are ground into a fine powder which is portland cement.
Portland cement concrete is a composite material made by combining cement, supplementary cementing materials, aggregates, water, and chemical admixtures in suitable proportions and allowing the resulting mixture to set and harden over time. Because hardened concrete is a relatively brittle material with a low tensile strength, steel reinforcing bars and sometimes discontinuous fibers are used in structural concrete to provide some tensile load-bearing capacity and to increase the toughness of the material.