ABSTRACT
Archaeological evidence attests to the longevity of terra cotta. Durability is a function of clay vitrification and dependent on kilns reaching higher firing temperatures. Terra cotta emerged in Babylon, Greece and Rome as roof tiles because that is the most extreme exposure of the building envelope. Usage grew as a workable, cost-efficient alternative to stone. In eighteenth-century England, Eleanor Coade marketed artificial stone using secret formulas that made it more durable than the original. The formula proved to be terra cotta with the addition of ground glass from industrial waste. Terra cotta is known for its resistance to moisture and freeze/thaw cycles. It was revived in the Victorian era because of superior performance in the harsh atmosphere of new industrial cities. Perhaps most important is the resistance to fire. Terra cotta played a critical role on the development of “skyscrapers,” protecting iron and steel frames both inside and out. The contributions were technical and aesthetic as architects searched for new expressions of curtain wall construction. The chapter concludes with an overview of the testing protocols used for contemporary products, including compressive strength, modulus of rupture, absorption, freeze/thaw resistance and dimensional stability.
