Analysis of the occurrence of damage to concrete surfaces through the cavitation phenomenon – cavitation machine type-ventury

ABSTRACT Under natural conditions of occurrence, the phenomenon of cavitation becomes difficult to measure due, essentially, to the characteristics in which the flow is found, that is, high-speed flows and local pressures below the vaporization pressures of the liquid. Studies using type -Ventury cavitation devices, which provide the analysis of this phenomenon in conditions closer to those to which concrete surface coating materials are subjected. Thus, the present research, using cavitation device, with a flow of velocity (V) of 30 m/s and a discharge flow of 60 l/s, analyzed the damage caused to the surfaces of concrete blocks with a water/cement ratio (w/c) of 0.35; 0.45; 0.50 and 0.65. The tests were carried out in the experimental installation of the Laboratório de Obras Hidráulicas of the Universidade Federal do Rio Grande do Sul (LOH/UFRGS). The results of maximum damage depth (hmáx.) were correlated to the characteristic parameters of the concrete and the cavitation phenomenon through the application of already well-founded studies by Peterka (1953); Gal’perin et al. (1971) and Kudriashov (1983). Finally, new graphical tools for analyzing damage arising from cavitating flow on concrete surfaces were obtained according to the average compressive strength in the concretes tested.