Abstract
As a first part of the research, systematic experimental series were conducted in order to develop an appropriate fly ash-based geopolymer binder focusing on the workability of the paste. In these series, the NaOH molar ratio and water glass/NaOH ratio were investigated and the fineness of the fly ash was optimized presented in a recent paper. Based on these results the effect of metakaolin on the mechanical properties was studied. After developing the appropriate binder, experimental series were carried out using ground polystyrene as light aggregate in various concentration (from 30 V/V% up to 98 V/V%) and geopolymer as a binder in order to develop a heat insulating material. Compressive and flexural strength, specimen density, flammability, freeze-thaw resistance were determined in order to characterize the composite product. As a result of the experimental investigation, it was found that the flexural strength of the composite was found to be ~400 kPa which is as high as the original polystyrene heat insulating panel. Additionally, the flammability was much better than the original pure PS product, the sample was not ignited even at higher PS content (90%). Furthermore, the freeze-thaw resistance of the composite improved compared with the neat geopolymer.
Highlights
Geopolymers are inorganic polymers prepared by the reaction of alumino-silicate bulk material and alkali activator solution at high pH
The main objective of the project reported in this paper is to develop a new environmentally friendly heat insulating material, polystyrene-geopolymer composite, using secondary raw materials
Strength of geopolymer and composite Based on our present and previous results [4, 5, 6], it was found that the following factors influenced significantly strength of the geopolymer binder: origin of the fly ash, its activation type, composition and quantity of the activating solution, origin quantity of the added metakaolin, and age)
Summary
Geopolymers are inorganic polymers prepared by the reaction of alumino-silicate bulk material and alkali activator solution at high pH. Geopolymers can be used as a binder of lightweight aggregate for producing heat insulating composite [3], especially for organic compounds to improve its flame resistance. It was proved in recent papers that geopolymer properties are controllable by mechanical activation (grinding) of the secondary raw materials [4,5,6]. These secondary material based geopolymers with engineered properties might be appropriate to use as a binder for lightweight aggregate. The main objective of the project reported in this paper is to develop a new environmentally friendly heat insulating material, polystyrene-geopolymer composite, using secondary raw materials. The starting material of the polystyrene (PS) was waste from a construction site and package material
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