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Portland cement concrete (PCC) has been the most widely used concrete in the construction industry. However, PCC has a short service life under some aggressive environments, leading to the need of costly repairs. The purpose of this research was to implement local materials to produce a modified sulfur concrete (MSC) with better performance in industrial applications. Several modified sulfur concrete mixtures were prepared using natural aggregates from the northern region of Colombia, and sulfur cement by combination of sulfur with a modifier, with the objective of achieving the best performance based on mechanical strength and chemical resistance. To achieve this purpose, an experimental program based on a k-factorial design was used to determine the optimal mix design based on the results of the compressive strength. The mixture presenting the best results was then examined further with standardized tests to determine its physical, mechanical, and chemical properties (compressive strength, abrasion resistance, bulk density, absorption, and chemical resistance). Final results showed that the sulfur concrete mixture is very resistant to chemical attack and an outstanding substitute for PCC. The results indicated that there is no significant loss in weight and no relevant variation in compressive strength after the specimens were immersed in sulfuric acid and sulfate solutions. In addition, similar results were obtained for the slabs located in chemicals plants whose conditions were assessed during a 60-day period of exposure.

A new methodology that describes relevant aspects of microstructure characterization and mechanical properties analysis of aluminum alloys, which may be used in other metals, is presented here. The methodology is based on qualitative and quantitative techniques of analysis, and it is substantiated on the weldability concept, which is constructed by means of literature information, experimental methods, modeling, simulation and validation of the results. The proposed methodology helps ensuring the quality of welding, selection of process parameters windows, working conditions and in-depth studies of weldability on welded constructions. This work generates a useful document to support research and learning processes of welding, which could be used as reference for professionals of welding engineering and materials science.

This paper describes the design and implementation of a system composed by a low cost camera, a database of images of call numbers taken from the spine of on shelf books, and image processing and search algorithms. The system is intended to be implemented and applied for rapid inventory of books on library shelves.

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