Service Learning: More than Community Service

Service learning, like apprenticeship and school-to-work, contextualizes student learning. It provides an environment in which students can acquire organizational, team, problem-solving, and other skills, attitudes, and capabilities necessary for future work and learning. This ERIC Digest looks at service learning: what it is and how it supports vocational and career development outcomes

Analysis of KrF excimer laser beam modification resulting from ablation under closed thick film flowing filtered water

The application of closed thick film liquid to immerse the ablation etching mechanism of an excimer laser poses interesting possibilities concerning debris control, modification of machined feature topography and modification of ablation rate. Further more, these parameters have been shown to be dependant on flow velocity; hence offering further user control of machining characteristics. However the impact of this technique requires investigation. This contribution offers comparison of the calculated ablation pressure and the effect on feature surface characteristics given for laser ablation of bisphenol A polycarbonate using KrF excimer laser radiation in ambient air against laser ablation of the same substrate under closed thick film flowing filtered water immersion. Also, the impact of such immersion equipment on the optical performance of the micromachining centre used is quantified and reviewed. The pressure is calculated to have risen some 53% when using the liquid immersed ablation technique. This increase in pressure is proposed to have promoted the frequency of surface Plasmons and asperities with a surface area less than 16 µm2. The focal length of the optical system was accurately predicted to be increased by 2.958 mm when using the equipment composed of a 5 mm thick ultraviolet grade fused silica window covering a 1.5 mm thick film of filtered water flowing at 1.85 m/s. This equipment was predicted to have increased the optical depth of focus via reduction in the angle of convergence of the two defining image rays, yet the perceived focus, measured by mean feature wall angle as a discrete indication, was found to be 25% smaller when using the closed thick film flowing filtered water immersion technique than when laser ablating in ambient air. A compressed plume interaction is proposed as a contributing factor in this change

Graphite–Cement Paste: A New Coating of Reinforced Concrete Structural Elements for the Application of Electrochemical Anti-Corrosion Treatments

This paper reviews research carried out towards the development of a novel conductive coating for reinforced concrete structures in order to enable the application of electrochemical anti-corrosion treatments. The coating is composed of a hardened paste containing graphite powder and cement. The applied techniques were electrochemical chloride extraction (ECE), cathodic protection (CP), and cathodic prevention, as well as combined treatments such as ECE-CP. This research has demonstrated their efficiency when using the new conductive coating as an anode system. The influence of the shape of the structural elements on the performance of the electrochemical treatments was also studied. Several characteristics of the coating have been determined, such as conductivity, durability, adhesion to the concrete surfaces, and ease of application. The results demonstrate the adequacy of using this coating as the anode for anti-corrosion treatments on reinforced concrete structural elements of different shapes, for the purpose of extending service life.This research was funded by the Spanish Ministerio de Economía y Competitividad (and formerly by the Spanish Ministerio de Ciencia e Innovación) and ERDF (European Regional Development Fund) through projects BIA2010-20548 and MAT2009-10866, and also through the project PROMETEO/2013/035 of Generalitat Valenciana (Spain)

Improved Concretes for Corrosion Resistance

DTFH61-93-C-0028A major cause of concrete deterioration on bridge structures is the corrosion of the embedded steel reinforcement. In response to the continued problem of corrosion, the Federal Highway Administration (FHWA) initiated this research aimed at (1) quantifying the corrosive conditions fostering concrete bridge deterioration and (2) identifying concrete materials which consistently provide superior performance when used in bridge applications. The experimental phase of this research project was divided into three tasks: Task A - Corrosive Environment Studies, Task B - Concrete Chemical and Physical Properties, and Task C - Long-Term Corrosion Performance. This Interim Report reviews the results of Tasks A and B and provides recommendations for performing Task C. In Task A, laboratory experiments were conducted to characterize the corrosive environment and to establish boundary conditions for environmental variables of moisture content, chloride concentration, and temperature. Special test specimen design and test procedures were developed to permit uniform chloride diffusion to the steel surface. A full factorial matrix of experiments was performed for three levels each of chloride concentration, relative humidity, and temperature. A regression model was developed to predict corrosion rate and corrosion potential as a function of environment for two different concretes. In Task B, experiments were performed to identify the chemical components of concretes and to determine how they effect corrosion induced deterioration of concrete structures. The dependent variables of interest in examining corrosion induced deterioration of concrete are corrosion rate, corrosion potential, chloride permeability, electrical resistivity, and physical properties. The independent concrete design mix variables examined included: water-cement ratio, air content, coarse aggregate type, fine aggregate type, mineral admixture, and cement type. Because of the large number of independent variables and the number of levels of interest for the variables, an optimized experimental design was developed to permit the estimate of the main-effect terms for each independent variable. Models were developed to predict the effect of the independent variables on corrosion rate and corrosion potential in each of two environments, chloride permeability, resistivity, and compressive strength. The data developed were used to make recommendations for the concretes to be tested in the Task C long-term experiments

Large volume, high-performance applications of fibers in civil engineering

This article presents an overview of fiber applications in cementitious composites. The socio-economic considerations surrounding materials development in civil engineering in general, and fiber reinforced cementitious materials in particular, are described. Current FRC appliations are summarized, and the where, how, and why fibers are used in these applications, are documented. An attempt is made to extract common denominators among the widely varied applications. The R&D and industrial trends of applying fibers in enhancing structural performance are depicted. An actual case study involving a tunnel lining constructed in Japan is given to illustrate how a newly proposed structural design guideline takes into account the load carrying contribution of fibers. Composite properties related to structural performance are described for a number of FRCs targeted for use in load carrying structural members. Structural applications of FRCs are currently under rapid development. In coming years, it is envisioned that the ultra-high performance FRC, with ductility matching that of metals, will be commercially exploited in various applications. Highlights of such a material are presented in this article. Finally, conclusions on market trends are drawn, and favorable fiber characteristics for structural applications are provided. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 660–686, 2002Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34401/1/2263_ftp.pd