Their availability, however, varies locally, and several other materials are being researched, based on local availability, such as high calcium fly ash (HCFA), metakaolin, ladle furnace slag (LFS), and rice husk ash . The present research investigates the use of HCFA, a by-product of lignite-fired power plants; LFS, a by-product of the ...
Keywords: geopolymer; high-calcium fly ash; low-calcium fly ash; drying shrinkage; setting time. Abstract. N ew types of binders are b eing d eveloped as an alternative to traditional cement.
For concrete containing high-calcium fly ash (FH, CaO more than 10%), the investigations are relatively insufficient. Due to the problems associated with the FH chemical compositions (high …
In this paper, the performance of MOSC with low-calcium fly ash (L-FA) and high-calcium fly ash (H-FA) was investigated, including the setting times, compressive strengths, shrinkages, compositions and microstructures. The results show that adding FA to MOSC can accelerate the hydration reaction and improve the volume stability of the MOSC paste.
The strength increases with an increase in the curing time. A good strength of 48.5 ... This is rather unexpected as the literatures on the case of low calcium fly ash indicated that the high sodium silicate to NaOH ratio provided a higher compressive strength [4]. The variation in the ratio of sodium silicate to NaOH ratio affects the pH ...
In this paper, we propose a novel mix design methodology for alkali-activated high-calcium fly ash concrete (AAHFAC) in a rational approach. It should be noted that the method is easy to use because it is based on the ACI 211.4R-93 [] with some modification.The parametric studies are composed of different NaOH concentrations, alkaline activator solution- (AAS-) to …
The high strength geopolymer paste could also be obtained with the use of fine fly ash [32]. In this study, the fly ash used was an as-received one and was rather coarse with the Blaine fineness of 2250 cm 2 /g. However, it was illustrated that the rather coarse high-calcium fly ash geopolymer could be used to produce pervious concrete with ...
In this research effort, the role of calcium in geopolymers was investigated through a series of syntheses where a high-calcium fly ash was blended with a low-calcium fly ash. …
The fundamental requirements of high ... the good mix design, inadequate compaction significantly ... Characteristics of Low-Calcium Fly ash-based
Geopolymer concretes have emerged as an alternative to traditional Portland cement concretes with high strength, good durability, well corrosion performance and high-temperature resistance, and being a sustainable and environmentally friendly material. In this study, a comprehensive microstructural analysis of low-calcium fly ash-based geopolymer …
Evaluation of blends of high and low calcium fly ashes for use as supplementary cementing materials ... The fly ash mixtures present good early-age k-values and at 90 days they all exceed the corresponding values of the initial ashes used. It is of special importance to note that the k-value of the blend consisting of equal contributions from ...
For high calcium fly ash, chemical and mineralogical differences have been observed for different size fractions. Compared to low calcium fly ash, optimum moisture content is low and …
The results demonstrated superior performance with high-calcium fly ash compared to low-range alkaline activators [47]. Fashtali et al. (2023) found that clay-fly ash liner activated by 1 M NaOH solution having 20 % fly ash has the best attenuation performance, achieving high removal rates of over 99.71 % for Zn (II) and 94.47 % for Cu (II ...
The influence of calcium compounds (CaO and Ca(OH)(2)) on the mechanical properties of fly ash based geopolymers has been studied. Calcium compounds were substituted in fly ash at 1, 2 and...
Class F or low-calcium fly ash (LCFA) is generally used as a primary aluminosilicate source; however, heat curing is required to complete the reaction and …
The high content of fly ash underwent less geopolymerization and less hydration associated with the calcium as compared to those of less amount of fly ash as indicated by the strength results . Figures 11 and 12 show the density and compressive strength of OPC.
The fly ash used in the study, which has very high-calcium (≈43%), has not good results for 10 M concentration. The compressive strength results and the microstructure images of the pastes support the results.
Transforming MSWI fly ash into low-carbon and high-compatibility composites via designed calcium sulfoaluminate-based binders ... (MSWI FA) is a globally recognized hazardous waste. This study developed a low-carbon and high-compatibility calcium sulfoaluminate-enhanced ternary binders (PCG) composed of calcium sulfoaluminate cement, ordinary ...
2.1. Materials. High calcium fly ash was used as the primary binder in this investigation. The chemical components of the high calcium fly ash used were detected by X-Ray fluorescence (XRF) and presented in Table 1.The fly ash was acquired from the Manjung Power Plant in Perak, Malaysia as a source of aluminosilicate materials for the production of one-part …
Optimization of surface modification parameters of fly ash with high calcium oxide (CaO) content to use as a filling material ... modification time (min.). The low and high levels of the six design parameters in this ... and 0.8390, respectively. The model fit is very good for the response associated with the R 2, R adj 2, and R pre 2. Then, a ...
Hwang and Shahsavari (2019) investigated the optimization of a high calcium cementless fly ash (FA) binder with a low environmental footprint. Their optimized composition comprising of FA and ...
fly ash or high-calcium fly ash, as it typically contains more than 20 percent of C aO. On the other hand, fly ash from the bituminous a nd anthracite c o als is referred a s ASTM Class F fly ash ...
In this paper, a comparative study has been made for physical and engineering properties of low calcium and high calcium Indian fly ash. The grain size distribution of fly ash is independent of lime content. Fly ash particles of size >75 μm are mostly irregular in shape whereas finer fractions are spherical for low calcium fly ash. For high calcium fly ash, chemical and mineralogical ...
The higher compressive strength achieved by OPG synthesised in this study is because of the lower water content in this mix system and the high CaO content in the fly ash used that was able to yield calcium-containing hydrate gel, which was compact and contributed to a better mechanical properties [27]. The finding of this study suggests that ...
High-calcium fly ash (HCFA) from the lignite PCC process of the Mae Moh power plant complied with Class C coal ash specifications and was used for comparison. The minimum combined content of SiO 2, Al 2 O 3, and Fe 2 O 3 of 50% was detected for the Class C fly ash, with a high calcium content of 31.0 wt%.
To enhance its utilization, the treatment of low-calcium fly ash to convert it into high-calcium fly ash would involve additional economic costs. ... Under CHCS activation, the geopolymer sample strength exhibits good activation effects compared to single activators. Furthermore, the optimal activation effect is achieved at a calcium hydroxide ...
cal differences have been observed for different size fractions. Compared to low calcium fly ash, optimum moisture content. is low and maximum dry density is high for high calcium fly ash. …
The results of the XRF test are reported in Table 3.Both fly ash samples were found to be high calcium fly ash (class C), with total content of SiO 2 + Al 2 O 3 + Fe 2 O 3 of 67.8% and 66.29% for FA1 and FA2, respectively, and the CaO level of more than 10% and with a very low loss on ignition (LOI) value. FA2 has higher CaO content than FA1.
Fly ash integrates well with cement, demonstrating favorable qualities in concrete such as good workability, high ultimate strength, and durability. ... The pozzolanic reaction of low-calcium fly ash in mixtures activated at 20 °C and 60 °C using 0.14 M NaOH leads to a significant increase in compressive strength at an early age, ...
shows a high early strength (Xie and Kayali, 2016). Fly ash is an aluminosilicate material that is widely used for the preparation of geopolymer composites, especially low-calcium fly ash (LCF)(NathandSarker,2017).Infact,oneofthemostimportantbenefits of using fly ash forgeopolymersynthesisis itseasyavailabilitycompared
A high-calcium fly ash (FH, 23% total CaO–5% free CaO), with high SO3 content (4.3%), was studied as additive in mortar, replacing part of the volume either of Portland cement or aggregate.
The micromorphology of low-calcium fly ash and blast furnace slag is presented in Fig. 18. Low-calcium fly ash shows a complete spherical structure under SEM (Fig. 18 a), so fly ash can be used as an additive to improve the fluidity of concrete materials when preparing concrete. However, the spherical structure has a negative impact on concrete ...
High-calcium or low-calcium wood ash Generally, according to the content of calcium oxide, coal fly ash can be divided into high-calcium (CaO > 10%) and low-calcium ash (CaO < 10%) [4,5, 119 ...
215 phase in the high calcium class C fly ash is considerably more reactive than that in the low calcium fly 216 ash. [57] Such amorphous form of calcium compound is usually the main constituent ...
Table 6 has shown that mullite, an essential mineral in low calcium fly ash, is not available in three ashes investigated in this study. Anhydrite content in three ashes is considerably high, more than 2 wt%, which is less than 0.34 wt%, in the case of …
