La generación de residuos sólidos de concreto hidráulico, considerados como desecho, está convirtiéndose en un problema medioambiental. El material de construcción mayormente fabricado es el cemento Portland (CP), pero un problema es su alta temperatura de fabricación, que genera contaminantes. El uso de agregados triturados provenientes de demolición de concreto hidráulico se aprovecha para generar Concreto Hidráulico Reciclado, un material que puede abatir costos, disminuir la contaminación y abaratar la edificación. Sin embargo,  la elaboración de concreto reciclado se enfrenta a la búsqueda de diseños óptimos para lograr el mayor desempeño mecánico bajo solicitaciones estáticas y dinámicas. En este trabajo se hace una revisión de los avances internacionales en esta temática.

This paper summarizes the research study conducted to develop and implement a methodological framework, using an economic analysis technique, to evaluate the cost effectiveness of the three different preventive maintenance treatments applied to roadways in Texas: chip seals, microsurfacing, and thin overlays. The analysis is based on a stochastic evaluation of the effective life and cost of more than 14,000 maintenance and rehabilitation projects undertaken from 1994 to 2015. The effect of traffic loads, traffic volume, and roadway type was also evaluated. The life-cycle cost of the preventive maintenance techniques was obtained using a Monte Carlo simulation. Among the principal results, it was found that chip seals are the most cost-effective treatment and present the lowest life-cycle cost variability. The effective life of all three treatments was found to be quite similar. Additionally, it was found that the chip seals and microsurfacing tend to present comparable life-cycle costs when used on heavy traffic roadways.

Learning-centered models, which rely on active methodologies such as Project-Based Learning (PBL), should be adopted in undergraduate programs to potentiate the development of collaboration skills within future industry professionals like civil engineers. Thus, this study reports the implementation of PBL in two successive Virtual Design and Construction (VDC) courses from an undergraduate civil engineering program: 1) VDC I, in which the VDC methodology implementation was applied theoretically in an already-built project, and 2) VDC II, in which the VDC methodology implementation was applied in a currently-under-construction project. The study's objective is to identify students' perceptions of PBL influence on their learning experience, degree of acquisition of generic competencies, and project development under the VDC methodology. To assess the PBL and VDC implementation, a survey was applied to measure students' perceptions of the three mentioned variables. Results show an increase in their perceptions about the benefits of implementing VDC and PBL for the generic competencies acquisition process by more than a third, compared to other studies which implemented Building Information Modelling (BIM) with PBL. This is due to the theoretical background of the VDC methodology in terms of collaboration, processes, and tools. Besides, VDC II students' perceptions of the generic competencies' development process, degree of learning, and project development improved by 6.13%, 7.15%, and 3.44%, respectively, compared to VDC I students' perceptions, which is owed to the natural interaction between students and stakeholders of the projects adopted.

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