NOPR Collection:

Application of three-dimensional optical laser triangulation method for concrete surface morphology measurement

Mon, 01 Dec 2014 00:00:00 GMT

Title: Application of three-dimensional optical laser triangulation method for concrete surface morphology measurement Authors: Sadowski, Lukasz Abstract: The proper preparation of the surface of concrete is an important stage in the construction and renovation of building structures. Before placing a concrete topping it is essential to determine the morphology of the concrete base surface. This paper describes a novel application of three-dimensional (3D) optical laser triangulation method for investigation of the concrete surface morphology. It is demonstrated that the 3D optical laser triangulation method is highly suitable for the fast exploration of large stretches of concrete base. In this paper large size concrete floors specimens with the substrate surface prepared with different roughening techniques are considered. The novel 3D scanner is used to precisely analyze the morphology of a 50 × 50 mm surface for the purposes of the nondestructive identification of the pull-off adhesion of concrete layers in layered building elements. Height parameters are used to describe the concrete surface morphology. Page(s): 692-700

Moisture susceptibility of warm mix asphalt

Mon, 01 Dec 2014 00:00:00 GMT

Title: Moisture susceptibility of warm mix asphalt Authors: Bayazit, Mehmet; Das, Prabir Kumar; Tasdemir, Yuksel Abstract: In this study, moisture susceptibility characteristics of wax modified bitumens and warm mix asphalt (WMA) mixtures are determined. The asphalt mixtures are prepared with 50/70 penetration grade unmodified bitumen and modified bitumens with three different types of additives (Fischer Tropsch wax, montan wax and polyethylene wax) by weight of 6%. The moisture susceptibility characteristic of the four bitumens is determined with Sessile drop method and that for asphalt mixtures is determined with Nicholson stripping test on loose asphalt mixtures and Modified Lottman test on compacted asphalt mixtures. Furthermore, Marshall stability with different blow numbers of WMA mixtures are determined. The findings from all of these tests suggest that due to the Fischer Tropsch wax and montan wax modification the asphalt mixture become more moisture susceptible which correlates with the surface energy characterization. Interestingly, polyethylene wax modification shows positive moisture performance. Page(s): 683-691

Influence of early-age moist curing time on the late-age properties of concretes with different binders

Mon, 01 Dec 2014 00:00:00 GMT

Title: Influence of early-age moist curing time on the late-age properties of concretes with different binders Authors: Jin, Hu; Guohua, Jiang; Qiang, Wang; Haibing, Zhang; Aimin, Tang Abstract: The influence of early-age moist curing time on the late-age properties including compressive strength, permeability to chloride ion, and porosity of concretes with different binders is investigated. Five different binders are adopted: pure cement, 50% fly ash replacement, 50% GGBS replacement, 50% steel slag replacement, and 10% silica fume replacement. Three curing conditions are adopted: moist curing till testing age, moist curing for 3 days, and moist curing for 7 days. The results show that decreasing the early-age moist curing time has negative effects on the late-age properties of most concretes by decreasing the compressive strength, increasing permeability and porosity. The negative effects are smaller at lower W/B. Binders with lower early activity are more sensitive to the early-age moist curing time. The late-age properties of the concrete with 50% fly ash replacement are greatly reduced by decreasing the early-age moist curing time. Page(s): 677-682

Low temperature hydrothermal synthesis of ZnO nanowires for nanogenerator: Effect of gold electrode on the output voltage of nanogenerator

Mon, 01 Dec 2014 00:00:00 GMT

Title: Low temperature hydrothermal synthesis of ZnO nanowires for nanogenerator: Effect of gold electrode on the output voltage of nanogenerator Authors: Ahmad, Mansoor; Iqbal, Muhammad Azhar; Kiely, Janice; Luxton, Richard; Jabeen, Musarrat Abstract: A low temperature hydrothermal technique is developed to grow ZnO (diameter 100 nm) nanowires for high output nanogenerator. Vertically aligned ZnO nanowires are grown on indium tin oxide (ITO) coated poly ethylene terephthalate (PET) substrate. Morphologies and elemental compositions are examined through scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) respectively. X-Ray diffraction peaks have shown growth orientation of these nanowires along (002) direction. We have investigated the effect of sputter coated gold electrode on top of ZnO nanowires. Vertically grown ZnO nanowires under a minute stress have produced a high output voltage of 1.34 V. Page(s): 672-676