Estudos de caso nas aplicações de ensaios não destrutivos na avaliação da resistência mecânica a compressão e detecção de corrosão no concreto armado da construção civil

Abstract

This thesis has in its general scope evaluate the performance of materials and techniques for measurement of mechanical properties and corrosion address degradation of buildings especially in aggressive environments with subliminal aim to evaluate the use of non-destructive techniques (NDT) in diagnostic engineering construction. For corrosion studies the techniques of ultrasound, concrete resistivity, corrosion potential measurements and micromagnetic in specimens of reinforced concrete and steel plates subjected to accelerated electrolytic corrosion process were used, if aiming to obtain reliable correlations between properties and corrosion degradation of steel. Only with the combined micromagnetic techniques excellent correlations and small deviations in the detection of corrosion of steel plates were obtained, demonstrating high potential of this new methodology. With ultrasound and resistivity no correlations were found. In assessing the compressive strength correlations between ultrasounds speeds and hammer impacts indices were studied with this mechanical property through one ousand and one hundred of specimens ruptured at ages 3, 7, 14, 21 and 28 days. The specimens were cast during the construction of the superstructure (columns, beams and slabs) from 3rd to 13th floors of a residential building in Aracaju / Se. There were no correlations in any of the ages of healing, both with the results of the work at 28 days as the laboratory referred to in ages. Reliable correlations with time were obtained in monitoring the hardening of concrete (cement hydration kinetics) by ultrasound techniques, rebound hammer resistivity and compressive strength. The study also addressed the importance of the statistical technique of analysis of the uncertainties in the experimental measurements.