Ya es sabido que incorporar cenizas volcánicas a los morteros de cal les confiere propiedades hidráulicas. De hecho, morteros y hormigones hidráulicos aditivados con cenizas se conocen desde la época de los romanos (cenizas del Vesubio). Pero en la mayoría de estudios actuales que proponen dosificaciones de estos componentes, no se menciona el origen de las cenizas volcánicas, ni el coste de la materia prima. En determinadas zonas volcánicas (tanto en la zona mediterránea –Cerdeña, NE peninsular-, Canarias, como en el W de Centro y sur de América –Guatemala, El Salvador, Colombia, Ecuador, Perú, Chile) hay acumulaciones naturales de material volcánico “lapilli” (fragmentos piroclásticos, expulsados por un volcán durante una erupción y con un diámetro variable de 2 a 64 mm). La composición química, velocidad de reacción puzolánica, así como el color, son diferentes. En este proyecto se pretende diseñar morteros de cal con áridos volcánicos de algunas de estas zonas.El criterio que suscita esta discriminación inicial es por una parte económico (no se buscan productos que requieran costos de machaqueo y molienda importantes) como técnico, ya que el volcanismo explosivo se produce por la expansión de los fluidos contenidos en el seno del magma en el tramo final del conducto eruptivo de un volcán, lo que conduce a la fragmentación del líquido en innumerables gotas de reducidas dimensiones, y también a un importantísimo aumento de la superficie libre reactiva del líquido (luego vidrio) mediante la generación de vesículas gaseosas en el seno de ese líquido. Hecho que también permite el rápido enfriamiento de éste al acceder violentamente a la atmósfera e impide su cristalización generalizada, resultando todo esto en la formación de piroclastos, fragmentos vítreos de magma muy vesiculados o celulares. Actualmente, este hecho se reproduce artificialmente durante la expansión térmica de vidrios naturales hidratados de tipo perlita. Se propone optimizar dosificaciones de morteros de cal aérea con diferentes tipos de áridos volcánicos, tanto física como mecánicamente, y determinar su envejecimiento artificial acelerado frente a agentes agresivos (sales solubles, hielo-deshielo).
Is well known that if you add volcanic ashes to limestone mortars it actually adds up hydraulic properties. In fact, mortars and hydraulic concrete with additives and ashes are known since roman century. Actual studies of the behavior of mortars that were utilized in the past in some ancient buildings doesn’t have a clue of were theses arid comes from, that is something that is not going to be happening in this work because all the arid we have is already known were it is from and all the aspects we need to know in order to work with it. Eternity is a word that is not appropriate to use it in a building, but being able to make them last thru eternity is out job, that is why in this project we are trying to make mortars which could be used in this type of jobs. Utilizing the aerial lime which is the raw material we know is most present in those type of projects. The eruption is produced by the expansion of the fluids contained in magma, in the final conduit of the volcano. For the development of the thesis, we have selected two main situations which are Tenerife (TE) and GC (Gran Canarias), from the Mediterranean. This aggregates were taken from the different eruption in volcanos located near this areas. In certain volcanic zones (Mediterranean Zone, Cerdeña, NE peninsular. Canarias, middle and south America, Guatemala, El Salvador, Colombia, Ecuador, Peru, Chile) they are natural deposits of volcanic ashes “lapilli” (pyroclastic fragments, expulsed by a Vulcan during an eruption and with a variable diameter in between 2 – 64 mm). Chemical Composition, speed of pozzolanic reaction, the color, they are different. Economic factor is going to be very present in the characteristics of the mortars. All the mortars worked in the project are easily found in their natural ambient like we are going to be using them. There is no need of smashing them or make them pass thru a process which involves money. Another fact that we have to bring is the liquid fragmentation of innumerable drops of ashes in reduced dimensions, also a very important surface growth (after glass) generating gas in this liquid, this air bubbles produced in this paste which make the dry process easier to accomplish. This fact also enables rapid cooling. Making a violently access to the atmosphere and preventing it from their widespread crystallization, all this resulting in the formation of pyroclastic, very glassy vesicular fragments or cell magma. Currently, this fact artificially propagated during thermal expansion of perlite hydrated natural glass type. It is proposed to optimize dosages of air lime mortars with different types of volcanic aggregates, both physically and mechanically, and determine its artificial accelerated aging to aggressive agents (soluble salts, freeze-thaw). Special attention will be done on the study of pozzolanic behavior, both in terms of known compounds are formed, and in terms of determining the reaction rate. This process which involves the formation of the rock is the responsible for the higher porosity found in these type of stones.
