Assessment of Polymer Concrete Sample Geometry Effect on Ultrasonic Wave Velocity and Spectral Characteristics

In this paper an analysis of the influence of polymer concrete sample shape and dimensions on ultrasonic wave propagation is carried out. Compositions of tested fly ash polymer concretes were determined using a material optimization approach. The tests were carried out on the samples of three shapes: cubes, beams, and plates. The ultrasonic testing was done by a direct method (transmission method) using a digital ultrasonic flow detector and piezoelectric transducers of 100 kHz central frequency. Propagation of the ultrasonic wave was characterized by pulse velocity. Frequency spectra and time-frequency spectrograms obtained using Fourier transform and Fourier-based synchrosqueezing transform were also presented. The correlation analysis showed that neither the path length nor the lateral dimension to the direction of wave propagation are not statistically significant for the UPV variability. However, a general trend of decrease in the UPV with increasing the path length was noticed. The analysis of the signal in time-frequency domain seemed to be useful in the analysis of particulate composites properties, especially when UPV changes are not clear enough, since it revealed greater differences in relation to changes in sample geometry than frequency spectra analysis.

Effect of sample geometry and aggregate type on expansion due to alkali-silica reaction

Late expansions due to alkali-silica reaction were observed in field samples for some aggregates and supplementary cementing materials (SCM) combinations despite meeting the 2-year expansion criterion of the concrete prism test. This fosters a research into the effect of sample geometry and aggregate reactivity on alkali leaching and expansion of lab samples. Larger samples showed less leaching compared to standard prisms. Cylinders of 100 mm-diameter showed higher expansion than 75 mm-standard prisms; however, both sample shapes showed similar expansions for one tested aggregate when used with SCM. Alkali leaching from concrete samples and alkali release from some aggregates could lead to cylindrical samples having higher expansion and better correlation to field samples compared to standard concrete prisms.

Effect of sample geometry and aggregate type on expansion due to alkali-silica reaction

Late expansions due to alkali-silica reaction were observed in field samples for some aggregates and supplementary cementing materials (SCM) combinations despite meeting the 2-year expansion criterion of the concrete prism test. This fosters a research into the effect of sample geometry and aggregate reactivity on alkali leaching and expansion of lab samples. Larger samples showed less leaching compared to standard prisms. Cylinders of 100 mm-diameter showed higher expansion than 75 mm-standard prisms; however, both sample shapes showed similar expansions for one tested aggregate when used with SCM. Alkali leaching from concrete samples and alkali release from some aggregates could lead to cylindrical samples having higher expansion and better correlation to field samples compared to standard concrete prisms.

Effect of sample geometry and aggregate type on expansion due to alkali-silica reaction

Late expansions due to alkali-silica reaction were observed in field samples for some aggregates and supplementary cementing materials (SCM) combinations despite meeting the 2-year expansion criterion of the concrete prism test. This fosters a research into the effect of sample geometry and aggregate reactivity on alkali leaching and expansion of lab samples. Larger samples showed less leaching compared to standard prisms. Cylinders of 100 mm-diameter showed higher expansion than 75 mm-standard prisms; however, both sample shapes showed similar expansions for one tested aggregate when used with SCM. Alkali leaching from concrete samples and alkali release from some aggregates could lead to cylindrical samples having higher expansion and better correlation to field samples compared to standard concrete prisms.

A hybrid open-top light-sheet microscope for multi-scale imaging of cleared tissues

Light-sheet microscopy has emerged as the preferred means for high-throughput volumetric imaging of cleared tissues. However, there is a need for a user-friendly system that can address imaging applications with varied requirements in terms of resolution (mesoscopic to sub-micrometer), sample geometry (size, shape, and number), and compatibility with tissue-clearing protocols and sample holders of various refractive indices. We present a ‘hybrid’ system that combines a novel non-orthogonal dual-objective and conventional (orthogonal) open-top light-sheet architecture for versatile multi-scale volumetric imaging.

Salt Scaling of Pervious Concrete: Optimizing a Test Method and The Effects of Different Deicers

There is currently no standard test method for evaluating the resistance of pervious concrete to salt scaling. In this study, a number of test methods were evaluated to determine an effective test method. A number of parameters were varied, including sample geometry, cycle length, level of submersion, and the effects of various deicers. The optimum cycle length was found to be 24 hours with the submersion of the bottom 10 mm of the pervious concrete samples made with 14 mm aggregate. Cylinder samples with a diameter of 100 mm and height of 150 mm are recommended as they provide consistent results. Using these samples, a mass loss failure criterion of 3 to 5% is proposed. The deicers that caused the most damage are NaCl, CaCl2, and urea, followed by MgCl2, K acetate, Na acetate, and CMA. More testing is needed to validate the effects of different deicers. i

Salt Scaling of Pervious Concrete: Optimizing a Test Method and The Effects of Different Deicers

There is currently no standard test method for evaluating the resistance of pervious concrete to salt scaling. In this study, a number of test methods were evaluated to determine an effective test method. A number of parameters were varied, including sample geometry, cycle length, level of submersion, and the effects of various deicers. The optimum cycle length was found to be 24 hours with the submersion of the bottom 10 mm of the pervious concrete samples made with 14 mm aggregate. Cylinder samples with a diameter of 100 mm and height of 150 mm are recommended as they provide consistent results. Using these samples, a mass loss failure criterion of 3 to 5% is proposed. The deicers that caused the most damage are NaCl, CaCl2, and urea, followed by MgCl2, K acetate, Na acetate, and CMA. More testing is needed to validate the effects of different deicers. i