Chemical Prestressing of Concrete Elements Using Expanding Cements.

Self stressing, produced through the action of an expansive-cement component in concrete, was used to prestress high tensile strength steel in tension, thereby creating designed degrees of precompression in the concrete. The so-called expansive cement consists of a blend of portland cement of high tricalcium silicate and low tricalcium aiuminate content with an expansive component made by grinding a clinlter of calcium alumino sul-fate composition. The concrete elements manufactured and tested, all self stressed by chemical prestressing, include four pressure pipes, three beams, a two-way reinforced slab, a one-way reinforced slab, and a hyperbolic paraboloid thin shell. Only the four pressure pipes and the two slabs are described in detail. The behavior and the strength of pressure pipes and slabs determined by experiment are compared with analytical values based on conventional theory of elasticity and principles of prestressing. It is shown that experimental results obtained with chemical prestressing of pressure pipes and flat slabs agree closely with calculated theoretical values. [ABSTRACT FROM AUTHOR]