10.1 INTRODUCTION TO CEMENT, CONCRETE, AND MASONRY UNITS

Materials have evolved tremendously over the millennia, and the rate of evolution seems to be ever accelerating. And, yet, as exciting and life-improving as the developments of steel, plastics, synthetic reinforced composites, and nanomaterials are, the most widely used engineering material in the world is concrete. In fact, no other material comes close by any measure: volume or value. It is used everywhere for constructing roads, dams, bridges, buildings, and other civil structures, in huge quantities. And, while not officially recognized as part of ceramics by the American Ceramic Society, it is a ceramic by its nature and a masterpiece of materials engineering by its structure and properties. Together with cement and so-called masonry units, concrete is so important that it not only deserves to be included in a book like this, it merits its own chapter.

As used in this treatment, and generally elsewhere, "cement" refers to a mixture of lime, CaO (obtained by roasting or "calcining" limestone, CaCO ₃), and various other naturally-occurring oxides including alumina (Al ₂O ₃), silica (SiO ₂), iron oxide (Fe ₂O ₃), and magnesia (MgO). ^[1] Known as "hydraulic cement," construction cements or masonry cements achieve their strength in cast and cured solid entities from the formation of hydrogen bonds by water molecules between fine particles of these oxides or more complex silicates and aluminates with calcium. "Masonry units" refer to any ceramic or glass-based building block or shape intended...