Elaboración de un indicador para la evaluación funcional de pavimentos en terminales portuarias de contenedores

Este trabajo ha tenido como objetivo fundamental definir un indicador para la evaluación funcional de pavimentos de hormigón en terminales portuarias de contenedores. El indicador propuesto se calcula mediante una expresión matemática y permite clasificar los pavimentos de las diferentes zonas de las terminales basándose en dos aspectos: valoración del deterioro y priorización de las zonas. La valoración del deterioro cuantifica su densidad en los pavimentos inspeccionados mientras que la priorización clasifica los pavimentos en función de la importancia de la terminal y del uso de la zona en la que se ubiquen. La primera parte del trabajo ha consistido en definir el modo en que se va realizar la valoración del deterioro del pavimento. Para ello, se ha seleccionado un parámetro de cuantificación de deterioro basándose en el estudio de los deterioros más representativos y en su con-elación con el tráfico y la edad de los pavimentos estudiados. Este parámetro seleccionado es el utilizado para la valoración del deterioro. La segunda parte del trabajo ha consistido en desarrollar la parte del indicador que realiza la priorización de las muestras en función de la importancia de la terminal y del uso de la zona. Se ha valorado la importancia de la terminal mediante el parámetro "Índice de intensidad de uso" tal y como está definido en la ROM 4.1-94. Por otro lado, se ha definido un procedimiento para valorar la importancia de la zona de la terminal teniendo en cuenta su uso principal. Para ello, se ha realizado un estudio Delphi con un panel de expertos constituido por técnicos portuarios. Como resultado de este panel se han obtenido un procedimiento basado en tablas que permiten obtener una valoración de la importancia de cada zona. El método Delphi también ha permitido obtener el valor relativo que los técnicos portuarios otorgan a la importancia de la terminal y de la zona donde se ubican las muestras. Una vez definido el indicador, se ha propuesto una metodología completa para la aplicación del indicador funcional propuesto. Para ello ha sido necesario establecer dos valores umbrales del parámetro de cuantificación de deterioro: de alerta y de actuación. Cuando el indicador alcance estos valores, la actuación sobre el pavimento será recomendable u obligatoria respectivamente. Estos umbrales se han definido mediante un panel de expertos. The principal aim of this thesis is to define an index for concrete pavement functional condition evaluation in port container terminals. The proposed index, calculated through a mathematical equation, enables the classification of different terminal areas based on two factors; distress evaluation and area prioritization. Distress evaluation quantifies its density on surveyed pavements, while area prioritization classifies pavements on the basis of terminal importance and area specific use. Firstly, a method for pavement distress evaluation has been defined. A distress quantification parameter was developed based on analysis of the most representative distresses and their correlation with traffic and age of surveyed pavements. The selected parameter is used for distress evaluation. Subsequently an index factor was developed to prioritize pavement sections taking into consideration terminal importance and area specific use. Terminal importance was evaluated by means of "Port operation index" as defined in ROM 4.1-94. A procedure was also established in order to evaluate terminal area importance taking into consideration its specific use. This procedure was carried out using a Delphi expert opinion panel using port technicians. This study has lead to a table-based assessment procedure for the evaluation of each area of importance. The Delphi method study has also provided the relative value that port technicians attribute to terminal importance and area specific use. Finally, a full methodology is proposed for the application of the new defined index. This has required the establishment of two threshold factors for the distress quantification parameter: warning and action. When the index exceeds these values, maintenance works will be preventive or required respectively. These thresholds were defined also by means of an expert panel

Development of new laboratory equipment for measuring the accelerated polishing of asphalt mixes

The skid resistance of pavements tends to decrease over time, resulting in greater risks for drivers. Currently, skid resistance and macrotexture values can only be determined for existing pavements. It would be of interest to be able to predict the evolution of the skid resistance of an asphalt mixture before its installation as a highway wearing course. This paper summarizes the experience gained and the results obtained during the development of a test procedure which has been applied in the laboratory to measure the evolution of the skid resistance of hot mix asphalts through a modified version of an accelerated polishing machine which is normally used to determine the polished stone value of aggregates

Feasibility of Using Nanosilanes in a New Hybrid Stabilised Soil Solution in Rural and Low-Volume Roads

The application of new materials for soil stabilisation is a growing field of study in recent years. In this work, the effect of two types of silica-based nanomaterials combined with binders (quicklime and cement) are studied to stabilise soils and form structural layers for rural and low volume roads. The physical and chemical properties of the materials have been determined, as well as the mechanical behaviour of the stabilised soil. Three hybrid stabilised soil sections have been designed using a multilayer elastic model, executed at full scale and measuring the evolution of their properties in the medium to short term. The results show that the application of silica-based nanomaterials and two types of binders on the tread layers provide high structural stability and good behaviour of the sections

Proyecto LCweb. Respaldo documental para prácticas de laboratorio [LCweb Project. Documental support for laboratory practices]

Las prácticas de laboratorio en enseñanza universitaria están siendo sustituidas en muchos casos por laboratorios virtuales o entornos Web que permiten trabajar a distancia. Sin embargo, parece ser que el mejor modelo docente en este ámbito está constituido por una combinación de las tradicionales prácticas presenciales en el laboratorio y laboratorios virtuales o entornos Web que complementen las prácticas reales. Esta comunicación técnica presenta el Proyecto LCweb. Se trata de un entorno Web que no sustituye sino complementa las prácticas de laboratorio de materiales de construcción de la asignatura de Firmes y Pavimentos de la Universidad Politécnica de Madrid. Su contenido está compuesto por los diferentes ensayos de laboratorio de materiales para carreteras, casos prácticos a partir de datos del laboratorio, tests de autoevaluación y normativa técnica actualizada que se utiliza en la resolución de los casos prácticos. Aunque su implantación es muy reciente, en el curso 2016/2017, todo parece indicar que los alumnos efectivamente la utilizan como complemento de las visitas al laboratorio. Proyectos de este tipo suponen un fuerte trabajo inicial, pero una vez en marcha precisan poco esfuerzo por parte del profesor y suponen un recurso importante para el alumno. [Laboratory practices in the university education are being replaced for virtual laboratories or web-based applications which allow the students to work offsite. Nevertheless, it appears that the best model for this purpose is a combination of traditional hands-up laboratory work and virtual or web-based applications. This technical communication presents the LCweb Project. It is a web-based application which does not replace the hands-up work in the laboratory but complements it for the students of Pavements in the Universidad Politécnica de Madrid. The web site offers several road materials standard trials, practical examples, self-evaluation tests and the in force specifications for materials, useful to solve the practical examples. Although it has been implemented during 2016/2017 it appears that the students make use of this resource as a complement of the hands-up laboratory work rather than a substitute. This kind of projects demands a strong initial effort by the professor but when it is ongoing a small effort is required even though it gives an important support to the student.

Use of Nanomaterials in the Stabilization of Expansive Soils into a Road Real-Scale Application

Stabilization is a traditional strategy used to improve soils with the main objective of ensuring that this base is compliant with the technical specifications required for the subsequent development of different infrastructures. This study proposes the use of commercial nanomaterials, based on a solution of silicates, to improve the technical characteristics and bearing capacity of the expansive soil. A physical–chemical property study was carried out on the additive nanomaterial. Subsequently, different mixtures of expansive soil, selected soil and artificial gravel with quicklime and commercial nanomaterials were developed to evaluate the improvement obtained by the use of nanomaterials in the technical characteristics of the soil. Compressive strength and the Californian Bearing Ratio index were considerably increased. A full-scale study was carried out in which the nanomaterial product was applied to two different sections of stabilized road compared to a control section. The results obtained showed that the use of nanomaterial led to the possibility of reducing the control section by 30 cm, thus achieving less use of quicklime and a mechanical means for preparing the road section. The use of commercial nanomaterial improved the behavior of the stabilized sub-base layer. Through life cycle assessment, this study has shown that the use of nanomaterials reduces the environmental impact associated with soil stabilization.FEDER/Ministerio de Ciencia, Innovacion y Universidades-Agencia Estatal de Investigacion/Ecaryse RCT-2017-6202-

Laboratory Compaction Study and Mechanical Performance Assessment of Half-Warm Mix Recycled Asphalt Mixtures Containing 100% RAP

The use of low-carbon and energy-efficient paving technologies is gaining worldwide acceptance in recent years as a means to encourage commitment towards more sustainable pavement management practices. However, there still remain some technical gaps regarding mix design procedures for the half-warm mix asphalt (HWMA) mixtures' preparation and characterization in the laboratory. To this end, three different laboratory compaction methods (e.g., static load, Marshall impactor, and gyratory compactor) were selected and put into assessment to define the most suitable compaction test method for half-warm mix recycled asphalt (HWMRA) mixtures with 100% reclaimed asphalt pavement (RAP). Posteriorly, the effect of four-accelerated curing treatments (0, 24, 48, and 72 h) on the mixtures' mechanical performance was investigated. Then, advanced mechanical characterization of the mixture performance was conducted to quantify the indirect tensile strength (ITS), stiffness modulus, rutting, and four-point bending (4PB) fatigue test. Thus, based on the authors? findings, the HWMRA mixtures with 100% RAP and emulsified bitumen exhibited proper volumetric (e.g., air voids and density) and mechanical behavior in terms of moisture damage, ITS, stiffness modulus, rutting, and fatigue cracking. These findings encourage greater confidence in promoting the use of these sustainable asphalt mixes for their use in road pavements or urban streets