Abstract:Abstract. There are more than four decades since the last 1970s where geopolymers concrete was first introduced and developed to use as a replacement to conventional concrete material which uses cement as a binder. And since the last two decades, geopolymers which utilized fly ash as aluminosilicate source material, i.e. fly ash based geopolymers, have been investigated. Many researchers present how to produce the best fly ash based geopolymer with a various source of constituent material as well as mixing for… Show more
“…It means that silica tetrahedral units become available for the polycondensation reactions. SiO4and AlO4units are able to form a new network where the negative charge of IV-fold coordinated Al 3+ is balanced by the positive charges of Na + ions from the alkaline solution [47,11]. The reaction process leads to the formation of a geopolymer gel that acts as the matrix phase, which bind unreacted particles, forming a composite geopolymer material.…”
This paper aims to develop a low-cost, green construction material for low-income house builders. A series of geopolymer samples were prepared by partially substituting the Cameroonian lateritic soil (LS) with different quantities of heat-treated laterite (20~50 wt. %). The chemical composition of the LS was determined through inductively coupled plasma spectroscopy (ICP). The specimens were subjected to thermogravimetric and differential thermal analyses (TGA/DTA), X-ray diffractometry (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). In addition, the compressive strength of dry and wet specimens was measured with a hydroelectric device. The results show that the geo-polymerization and properties like setting time and mechanical strength of the samples were improved through the combined action of the raw LS and the laterite treated at 500-600°C; the crystallized particles from non-clayed minerals and from aggregates of kaolinite also contribute to strength of the samples; crystalline phases formed a tridimensional skeleton in the microstructure of the geopolymer. The research provides a promising composite that can serve as a low-cost construction material with reduced environmental impact.
“…It means that silica tetrahedral units become available for the polycondensation reactions. SiO4and AlO4units are able to form a new network where the negative charge of IV-fold coordinated Al 3+ is balanced by the positive charges of Na + ions from the alkaline solution [47,11]. The reaction process leads to the formation of a geopolymer gel that acts as the matrix phase, which bind unreacted particles, forming a composite geopolymer material.…”
This paper aims to develop a low-cost, green construction material for low-income house builders. A series of geopolymer samples were prepared by partially substituting the Cameroonian lateritic soil (LS) with different quantities of heat-treated laterite (20~50 wt. %). The chemical composition of the LS was determined through inductively coupled plasma spectroscopy (ICP). The specimens were subjected to thermogravimetric and differential thermal analyses (TGA/DTA), X-ray diffractometry (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). In addition, the compressive strength of dry and wet specimens was measured with a hydroelectric device. The results show that the geo-polymerization and properties like setting time and mechanical strength of the samples were improved through the combined action of the raw LS and the laterite treated at 500-600°C; the crystallized particles from non-clayed minerals and from aggregates of kaolinite also contribute to strength of the samples; crystalline phases formed a tridimensional skeleton in the microstructure of the geopolymer. The research provides a promising composite that can serve as a low-cost construction material with reduced environmental impact.
“…Fly ash, either with low calcium (class F) or high calcium (class C) content, is a material rich in silica and alumina, and can be used as a precursor in making geopolymer. The activation of the source material occurs in the presence of a highly alkaline solution, commonly a combination of sodium hydroxide and sodium silicate (Wattimena et al 2017;Yildirim et al 2011). The ratio and content of the two alkalis determine the characteristics of the geopolymer concrete (Arioz et al 2012;Hardjito et al 2004;Mustafa et al 2011;Rangan 2010;Rattanasak and Chindaprasirt 2009;Thunuguntla and Gunneswara Rao 2018).…”
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AbstractGeopolymer is synthesized by mixing material rich in alumina and silica, such as fly ash, with a highly alkaline solution to form a hardened matrix. However, when using high calcium fly ash as a precursor, a flash set frequently occurs, i.e., the mixture hardens very rapidly before casting can be completed. The use of borax as an additive has been reported due to its potential to prolong the setting time. In this study, the use of a significantly higher dosage of borax is explored. The results show that the addition of borax up to 20% of fly ash, by mass, into the alkaline solution prolongs the setting time by up to 90 min. Conversely, the addition of higher amounts of borax tends to decrease the compressive strength of the geopolymer, whereas adding a small amount of calcium oxide into the mixture increases the strength marginally, especially when the borax content is small. However, the amount of calcium oxide should be limited because at higher content, the effectiveness of borax to prolong the setting time is reduced.
“…Therefore, it was necessary to make reasonable use to eliminate solid waste. Research suggested that FA with large specific surface area and porosity can be used to adsorb PCM; besides, FA is also a commonly used concrete mineral admixture; thus, it is feasible to use FA as a carrier to adsorb Na 2 SO 4 ·10H 2 O.…”
Section: Introductionmentioning
confidence: 99%
“…Therefore, it was necessary to make reasonable use to eliminate solid waste. Research suggested that FA with large specific surface area and porosity can be used to adsorb PCM; besides, FA is also a commonly used concrete mineral admixture 27,28 ; thus, it is feasible to use FA as a carrier to adsorb Na 2 SO 4 ·10H 2 O. Therefore, in this paper, porous solid waste FA was chosen as an adsorption carrier of Na 2 SO 4 ·10H 2 O to form the Na 2 SO 4 ·10H 2 O/FA composite PCM (FAPCM).…”
Summary
In this work, a novel Na2SO4·10H2O/fly ash shape‐stabilized phase change material mortar (PCM mortar) was prepared for building energy efficiency, in the context of energy conservation and environmental protection. The working, mechanical, and thermal properties of this proposed PCM mortar were investigated. The experiment results showed that the incorporation of PCMs greatly increased the thermal inertia of the mortar, while corresponding compressive strength was little affected. Specifically, when the blending amount of PCMs reached 15%, the thermal storage capacity of mortar sample (PCM‐15) was 6.18 × 104 kJ/m3, which is 2.4 times of that for mortar sample without PCM (OPC) evaluated by theoretical calculations, while the corresponding compressive strength of mortar sample (PCM‐15) still remained above 31 MPa. Furthermore, the effects of PCM mortar on thermal comfort and energy use of buildings were studied by using experiment and simulation methods, respectively. The control experiments showed that PCM mortar can effectively alleviate the influence of outdoor temperature on indoor temperature compared with OPC. Temperature difference between PCM‐15 and OPC board can reach 4.6°C (inner surface) and 8.6°C (outer surface), respectively. Meanwhile, temperature difference of internal space reached 1.2°C. The simulation results showed that the energy consumption per unit building area was reduced by 4.4 and 18.7 kg/m2 in Guangzhou and Harbin, respectively, with PCM mortar as the envelope structure. Hence, the proposed PCM mortar showed significant thermal and mechanical properties and had broad application prospects in regulating indoor temperature and constructing energy‐efficient buildings.
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