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Strength Enhancement of Geopolymer-Based Concretes by Mixed Alkaline Activators
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In this paper, a new type of construction material with lower CO2 emission and energy consumption, fly ash, waste concrete sludge and metakaolin were used as the main components.Abstract:
As a relatively new material, geopolymer concrete offers benefits as a construction material for sustainable development. It utilizes waste materials such as recycled concrete sludge, fly ash,etc. To reduce CO2 emission, geopolymer concrete is expected to replace the traditional Portland cement based concrete. It’s reported that geopolymer based concrete releases only 1/6 CO2 compared to those of based Ordinary Portland Cement (OPC). In this study, to obtain a new type of construction material with lower CO2 emission and energy consumption, fly ash, waste concrete sludge and metakaolin were used as the main components. Solution of NaOH/KOH and water glass were applied as alkaline activator. The amount of water glass and the ratio of alkaline/water glass were varied to reach an optimal value. Also, silica fume was added as a bonding matrix to enhance the strength, and the specimens were cured in air and oven, then their mechanical properties such as compressive strength and bending strength were measured and their microstructures were investigated.read more
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Preparation and properties of geopolymer from blast furnace slag
Abstract: In this paper, blast furnace slag was investigated as a source of the basic Si–Al ingredient of geopolymer. On the basis of compressive strength, the effects of grinding time on the activity of blast furnace slag and the effects of activator types, compound activator and particle size of blast furnace slag on the compressive strength were studied. The results showed that the optimum parameters were as follows: the grinding time was 12 hours, the granularity of blast furnace slag powders was 0·053–0·075 mm, the incorporation of blast furnace slag was 90 wt-%, the mass ratio of water glass/NaOH was 7:3, the liquid-to-solid mass ratio was 0·25, Additionally, X-ray diffraction, infrared spectroscopy and scanning electron microscope with energy dispersive spectrometer analysis were used to analyse the composition and polymerisation mechanism of the geopolymer. The reaction products of slag-based geopolymer paste was composed of two separate amorphous phases (geopolymeric and CSH gel).
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Geopolymers : inorganic polymeric new materials
TL;DR: In the last few years, technological progress has been made in the development of new materials such as "geopolymers" and new techniques, such as ''sol-gel'' as mentioned in this paper, opening up new applications and procedures and transforming ideas that have been taken for granted in inorganic chemistry.