Cement Masons

Cement has been used for thousands of years as a hard building material. It is made by mixing such elements as powdered alumina, silica, and limestone with water to make a solid mass. One could say that the ancient Egyptians and Greeks were cement masons—both groups made cements. The most effective masons were perhaps the Romans, for they developed a kind of cement made from slaked lime and volcanic ash and used it throughout Europe in building roads, aqueducts, bridges, and other structures. After the collapse of the Roman Empire, however, the art of making cement practically disappeared.

In the 18th century, an English engineer named John Smeaton developed a cement that set even under water. Smeaton successfully used this cement in building the famous Eddystone Lighthouse in Devon, England. Later it was used in some parts of the Erie Canal, the waterway built to connect the Great Lakes and New York City.

Joseph Aspdin, an English stonemason, developed the first portland cement mixture in 1824 by burning and grinding together limestone and clay. He called his product "portland" cement because it resembled the limestone quarried on the Isle of Portland. It soon became the most widely used cement because of its strength and resistance to water. The first American portland cement plant was built in 1871. Cement manufactured today is essentially made of the same material as Aspdin's portland cement.

Masons seldom use cement by itself in large quantities. More often, they mix it with another material, like sand, to form a mortar to be used in structures such as brick walls and buildings. When they mix it with gravel or crushed rock, it forms concrete, a cheap, versatile, durable structural material. Today concrete is one of the most widely used building materials in the world. With the development of ways to reinforce concrete with metal and the appropriate machinery for handling it, concrete has become useful in building many structures, including fence posts, swimming pools, sculptures, roofs, bridges, highways, dams, helicopter pads, and missile launching sites.