INTRODUCTION The aim of this experimental laboratory study was to evaluate the effect of different mixing and placement techniques on compressive strength (CS) of calcium-enriched mixture (CEM) cement. METHODS AND MATERIALS CEM powder was mixed with its liquid either by hand mixing or amalgamator mixing. The mixture was loaded to cylindrical acrylic molds with 6.0±0.1 mm height and 4.0±1 mm d...

In ultrasonic nondestructive testing (NDT) of materials, pulse-echo measurements are masked by the characteristics of the measuring instruments, the propagation paths taken by the ultrasonic pulses, and noise. This measured pulse-echo signal is modeled by the convolution of the defect impulse response and the measurement system response, added to noise. The deconvolution operation, therefore, s...

Non-destructive testing using ultrasonic measurement is used to ensure the quality of the die-casting products. The quality of a casting depends on the presence of discontinuities such as porosity and on the final metallurgical structure. Discontinuities occurring in the sub-surface of the cast structure mostly have irregular surfaces which scatter the ultrasound waves and make ultrasonic testi...

In ultrasonic defectoscopy it is very difficult to detect flaw in materials with coarse-grain structure. The ultrasonic signals measured on these materials contain echoes which are very similar to fault echo. These echoes arise from grains which are contained in material. For detection of flaw various methods for suppressing of echoes from grains have to be used. In this work we used the method...

Ultrasonic characterization of microstructure evolution during processing" (2007). Many cold-working processes for polycrystalline metals cause alignment of the grains with a single symmetry axis. This type of microstructure is called fiber texture. The existence of a preferred orientation of the grains has a significant influence on the propagation and scattering of ultrasonic waves, which are...

For applications studying fracture mechanical properties of concrete or the in-situ performance of cementitious materials non-destructive testing (NDT) and monitoring techniques (structural health monitoring, SHM) are beneficial. This will be demonstrated for a special application developing concrete exhibiting properties to heal or seal cracks (Jonkers 2011, Van Tittelboom et al. 2011). A deve...