Microtomography is a powerful non-destructive method that allows the visualization of the internal structure of the object and makes possible to generate internal graphic models of the object. Concrete is a mixture widely used in the construction industry due to the union between its mechanical properties with the low cost for its production. The application of X-ray microtomography in lightweight concrete structures allows the visualization of the layout and formation of existing internal structures. In this work, it was possible to identify the presence of ethyl vinyl acetate (EVA) and piaçava fibers in the internal structure of the samples and to classify the high-density aggregates according to the ASTM C125-18 standard, as well as to evaluate the influence of the light aggregates in the increasing of the total porosity.

The X-ray computed tomography (XCT) technique is a widely applicable and powerful non-destructive inspection modality for evaluation and analysis of geometrical and physical characteristics of materials, especially internal structures and features. XCT is applicable to metals, ceramics, plastics, and polymer and mixed composites, as well as components and materiel. The Army Research Laboratory (ARL) and its partners are currently investigating the use of cast iron-manganese-aluminum (FeMnAl) steel alloy material in support of weight reduction initiatives in Army Development Programs. Steel alloy FeMnAl has been identified as a key enabling material technology to reduce the weight in ground combat vehicle systems. A set of FeMnAl blocks each approximately 50.8 mm (2 in.) thick by 76.2 mm (3 in.) wide by 76.2 mm (3 in.) long, which had been sectioned from an industrially cast ingot (∼12,000 lbs.), were individually scanned by XCT using a conventional 450 kV X-ray source and a solid-state flat panel detector. Mainly due to the thickness of the blocks, as well as a desire to keep geometric unsharpness relatively small which affected overall scan geometry (set up), the scans had a very low response at the detector through the FeMnAl blocks. With the calibrated detector response through air (i.e., around a block) at 85–90% the response through the block was only 5–10%. The XCT scanning parameters and overall protocol used to mitigate the very low-intensity throughput and achieve acceptable scan image results will be discussed. Image processing (IP) methods used to segment porosity features in the FeMnAl blocks will also be discussed.

The feasibility of utilizing focused ultrasonic waves for the nondestructive evaluation of porosity content in curved corner sections of carbon fiber reinforced plastic (CFRP) laminate structures is investigated numerically as well as experimentally. For this purpose, two-dimensional (2D) finite element simulations are carried out to clarify the wave propagation behavior and the reflection characteristics when the nonfocused or focused ultrasonic wave impinges on the corner section of unidirectional and quasi-isotropic CFRP laminates from the inner side via water. The corresponding reflection measurements are carried out for the CFRP corner specimens in the pulse-echo mode using nonfocusing, point-focusing, and line-focusing transducers. The numerical simulations and the experiments show that the use of focused ultrasonic waves is effective in obtaining clearly distinguishable surface and bottom echoes from the curved corner section of CFRP laminates. The influence of the porosity content on the reflection waveforms obtained with different types of transducers is demonstrated experimentally. The experimental results indicate that the porosity content of the CFRP corner section can be evaluated based on the amplitude ratio of the surface and bottom echoes obtained with focusing transducers, if the calibration relation is appropriately established for different ply stacking sequences.