The vast majority of deterioration mechanisms in concrete revolve around the development of some form of internal expansive stress that causes cracking within the hydrated cement paste. Whether this expansive stress is due to the expansion of water during freezing, the expansion of alkali-silicate gel during an alkali silica reaction, or the formation of ettringite during sulfate attack, the mechanical effect is the same. Even the corrosion of reinforcing steel results in a volume increase of the steel that induces tensile stress in the surrounding concrete. Cracking in a brittle material like concrete is a tensile phenomenon, and thus the evaluation of mechanical properties induced by such deterioration should intuitively rely on tensile strength evaluation. However, measuring the tensile strength of a brittle material, particularly concrete, is not easy. Gripping specimens without inducing additional stresses and localized failure at the contact points is difficult. This paper describes the development of an alternative technique that induces an internal pore pressure using a non-contact gas pressure loading approach. This test is capable of generating a true tensile failure from the inside, using the diphase concept of load application. Though the fundamental form of this method for static tensile strength determination has been used for quite some time, recent developments to the apparatus have now expanded its capabilities to include long-term sustained loading (creep), cyclic loading, or any combination of loading/unloading the researcher requires. Results from testing various forms of deterioration have shown that the pressure tension test is capable of detecting damage at much lower levels, or at significantly earlier stages, than other destructive testing techniques currently in use.

concrete, tensile strength, durability, deterioration, cracking