Properties of fly ash and metakaolín based geopolymer panels under fire resistance tests

Abstract

This paper presents the results of a study about the effect of fire on geopolymer paste composed of fly ashes, metakaolin and sodium silicate. 2 cm thick, 28 cm high and 18 cm wide panels were filled with the paste obtained. After 28 days of curing at 20 °C and 45% of relative humidity, different tests were carried out in the geopolymers: physico-chemical (density, water absorption, porosity), mechanical (flexural and compressive strength), fire resistance and environmental (leaching and radioactivity). The panels manufactured have been compared with other commercial panels in order to determine the recycling possibilities of fly ashes in manufacturing new fire-insulating geopolymers. The panels obtained can be utilized for the production of interior wall materials, with a good physical, mechanical, fire resistant properties without any environmental problem. RESUMEN: Propiedades de paneles geopoliméricos basados en ceniza volante y metacaolín bajo ensayos de resistencia al fuego.Este documento presenta los resultados de un estudio sobre el efecto del fuego sobre pastas de geopolímeros compuestas de cenizas volantes, metacaolín y silicato sódico. Con la pasta obtenida se han rellenado paneles de dimensiones 2 cm de espesor, 28 cm de altura y 18 cm de ancho. Tras 28 días de curado a 20 °C y un 45% de humedad relativa, diferentes ensayos fueron realizados en los geopolímeros obtenidos: fisicoquímicos (densidad, absorción de agua, porosidad), mecánicos (resistencia a compresión y a flexión), de resistencia al fuego y medioambientales (lixiviación y radioactividad). Los paneles fabricados han sido comparados con paneles comerciales para determinar las posibilidades de reciclaje de las cenizas volantes para la fabricación de nuevos productos geopoliméricos con propiedades aislantes al fuego. Los paneles obtenidos pueden ser utilizados para la producción de paredes interiores, con buenas propiedades físicas, mecánicas y de resistencia al fuego sin ningún problema medioambiental.

Thermal Resistance Variations of Fly Ash Geopolymers: Foaming Responses

“…Even so, the mass loss of geopolymer after exposure to temperature was considered small (9.9–16.4%). According to Luna-Galiano et al 39,. OPC samples had a higher mass loss (20%) than geopolymers and therefore greater degradation with rising temperature.…”

“…Although similar to OPC concrete, geopolymers experienced strength deterioration when subjected to elevated temperature; the strength retention of geopolymer was much greater than that of OPC. The OPC paste was totally damage at elevated temperature232645 due to evaporation of water and decomposition of hydrate products139.…”

“…These pores might have left behind by the escaping water during the temperature exposure or dissolution of remnant fly ash particles. Besides, the porosity increment might probably because of the thermal shrinkage resulted from thermal damage in geopolymers39.…”

Correlation between Compressive Strength and Fire Resistant Performance of Rice Husk Ash-Based Geopolymer Binder for Panel Applications

“…A portion of the water content evaporated when exposed to the fire, and generated pressure in the pores of the material and probably in the microvoids. Since crystallization of the geopolymer surface and intumescent process successfully took place in the sample, the evaporated water molecules were transported to cooler area of the material resulting in very low temperature at the non-exposed area which has been identified previously by Luna-Galiano et al [12].…”

“…Pressure developed simultaneously in the pores of the material vacated by the evaporation. According to LunaGaliano et al [12], evaporated water molecules supposedly travel from the hot fire-exposed surface to the inner part of the material which was cooler. Due to rapid evaporation rate, however, the material pores expanded faster resulting in a weak matrix structure and the release of the evaporated water from the material.…”