Resumen de Morteros aligerados con residuos de espumas rígidas de poliuretano: obtención, caracterización y puesta en obra
- español
La utilización de residuos de espumas rígidas de poliuretano generados en la industria, como sustitutivo de la arena en los morteros para albañilería, tiene un doble efecto beneficioso para la preservación del medio ambiente. Por un lado se reciclan unos desechos que generalmente acaban en vertederos y por otro se disminuye el consumo de áridos que se extraen de la naturaleza. La caracterización física y química de los morteros confeccionados con los residuos de espuma de poliuretano, nos muestra que las mezclas obtenidas tienen propiedades que los pueden hacer aptos para su utilización en obras de construcción. Por ello se han diseñado distintas mezclas con varias clases de cemento, arena y dos tipos de espuma, empleando diferentes dosificaciones con el objeto de comprobar la viabilidad de los morteros. Para la fase experimental del estudio de las propiedades de los morteros se han seguido las normas UNE-EN aplicables a los morteros para albañilería, y a falta de normativa concreta, se han utilizado aquéllas que se refieren a materiales similares como la piedra natural. La consistencia, densidad y aire ocluido en estado fresco y la densidad y resistencias mecánicas a flexión y compresión en estado endurecido han indicado que la mayoría de los morteros estudiados cumplen con las especificaciones de la normativa de aplicación. El principal inconveniente encontrado ha sido la elevada cantidad de cemento por metro cúbico de mortero en las mezclas con resistencias mecánicas altas, lo que ha obligado a seleccionar las dosificaciones con mejor ratio de resistencia por cantidad de cemento, primando especialmente los morteros con mayor contenido de espuma. Se han estudiado las modificaciones que producen el empleo de dos tipos de aditivos en los morteros seleccionados y además se ha profundizado en el conocimiento de otras propiedades tales como la trabajabilidad y retención de agua, resistencia a la adhesión y a la abrasión, realizando por último, ensayos de envejecimiento acelerado para comprobar la durabilidad. Los resultados obtenidos en la fase de experimentación han sido similares a los de los morteros de uso habitual en albañilería, destacando fundamentalmente la mejor trabajabilidad, menor densidad del mortero endurecido, mayor elasticidad y un importante incremento de la permeabilidad al vapor en todas las dosificaciones estudiadas.
- English
The use of rigid polyurethane foam waste, from industrial production, as a substitute for sand in masonry mortars has two beneficial consequences for environmental conservation. On the one hand, waste that is often dumped in landfill sites may be recycled and, on the other hand, the use of fines extracted from the natural environment is reduced.
The physical and chemical characterization of mortars manufactured with polyurethane foam waste suggests that the properties of their mixtures could be suitable for use in construction work.
Different mixtures were therefore designed with various types of cement, sand and two types of foam, at different dosages, with the aim of testing the viability of such mortars.
At the experimental stage, the UNE-EN norms applicable to masonry mortars were followed in the study of mortar properties and in the absence of specific regulations, those referring to similar materials such as natural stone were used.
Consistency, density and level of occluded air in the fresh state and the flexural and compressive mechanical strengths and density in the hardened state all indicate that the majority of mortars in the study comply with the normative specifications for their application. The main drawback was the large amount of cement by cubic meter in the mixtures of high mechanical strength, which obliged us to select mixtures with higher strength ratios by percentage of cement, giving special priority to mortars with larger amounts of foam.
The modifications arising from the use of the two types of additives in the selected mortars were studied, as were other properties such as workability and water retention, adherence resistance, and abrasion, followed last of all by accelerated ageing to test durability.
The results obtained in the experimental phase were similar to those of mortars of habitual use in masonry, fundamentally highlighting better workability, lower density of hardened mortar, greater elasticity and an important increase in water vapor permeability for all the dosages under study.
Various small constructions were built at the ¿Cúpula de la Energía¿ complex, at Garray, in the province of Soria, in order to determine the viability of the mortars manufactured in this investigation. These tests formed part of the ¿CONPOL¿ CDTI-MEC research project, conducted by the University of Burgos research team and the company VIAS S.A. Different dosages were used in work units such as brick masonry, interior and exterior renderings, and basement floor screed. Their adaptability was tested through the execution of ceramic and epoxy-resin renderings with plastic paint finishes, confirming in all cases the suitability of the products to support traditional renderings.
The low density of the mixtures has a direct impact on the evaluation of the structural loads of the buildings, which was confirmed by a study on a residential building, in which it was calculated that the use of lightweight mortars could reduce the total weight of the building by up to 7.7%.
The final evaluation of the mortars was completed with an economic study that specified the distance from the source of waste generation to the site, highlighting preparatory costs of some mixtures that were on a par with or even less than traditional mortars.
