Caracterização não destrutiva de blocos estruturais de concreto

Abstract

The systematic work of the structural masonry construction system in the brazilian civil construction market currently demands technical solutions that aim to evaluate the quality of its components in a quick, economic and effective way. Although the compressive strength of masonry walls is represented by the joint action of its components (block, laying mortar and graute), blocks are responsible for the largest share of this resistance. To ensure the quality of the blocks, NBR 6136 establishes requirements. Among them, the blocks must have sharp edges and must not show cracks, fractures or other defects. The most common way to identify such defects is by performing a visual inspection, a time consuming process in the middle of a production line. In this context, the article presented an alternative for the identification of failures in concrete blocks by means of non-destructive tests. After analyzing the spectra of the blocks obtained experimentally by the impulse excitation technique - using microphone and accelerometer - and theoretically by the numerical modal analysis, it was possible to perceive patterns in the acoustic response of the intact blocks of the M-15 and M-20 family (brazilian blocks sizes). Thus, it was established criteria for the quality control of the blocks by using resonant ultrasound spectroscopy. The main objective of this study was to try nondestructive testing methodologies in order to evaluate the conformity of concrete blocks for structural purposes, where a standard spectrum has been established and its efficacy assessed on hollow components.