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Sodium and potassium are the common alkalis present in fly ash. Excessive amounts of fly ash alkalis can cause efflorescence problems in concrete products and raise …
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In addition, stress–strain behavior and brittleness index of alkali-activated fly ash class C and slag mortars were considered as a function of strain. ... In this study, 400 kg/m 3 of fly ash content was used in all concrete mixtures. The liquid to fly ash ratio was set at a constant value of 0.7. Superplasticizer type F was used to control ...
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Fly ash (FA) is the principal industrial waste byproduct from the burning of solid fuels. FA is a powdery solid that is constituted mostly of unburned carbon (UC), metal oxides (Si, Fe, Ca, and Al ...
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For this purpose, the standard guide for ASR mitigation, ASTM C1778 [23], recommends the use of fly ash with alkali content (Na 2 O eq) less than 4.0% and prefers fly …
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Fig. 5.12: % of Fly Ash Content versus MDD (gm/cm^3) Fig. 5.13: % of Fly Ash Content versus OMC (%) From Fig 5.12 and Fig 5.13, it can be shown that increasing the varying percentage of fly ash content with 2Molal of Alkali Activator solution, the maximum dry density decreases and optimum moisture content increases.
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The [available] alkali content of fly ash shall not exceed X.X% In an NRMCA review of more than 100 specifications for private work, these types of restrictions were noted
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Alkali-activated materials (AAMs) are one of the viable alternatives to replace Portland cement due to their lower CO2 emissions. This study investigated the evolution of rheological parameters of alkali-activated fly …
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Workability, rheology, and geopolymerization of fly ash geopolymer: Role of alkali content, modulus, and water–binder ratio. February 2023; Construction and Building Materials 367(1-3):130357;
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Sodium and potassium are the common alkalis present in fly ash. Excessive amounts of fly ash alkalis can cause efflorescence problems in concrete products and raise concern about the effectiveness of the fly ash to mitigate alkali-silica reaction (ASR).
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Expansive Soil Stabilization Using Alkali-Activated Fly Ash Huan Wang 1, *, T engjiao Liu 1, Chao Yan 1 and Jianqi W ang 2 1 School of Civil Architecture, Henan University, Kaifeng 475004, China
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Production of sustainable green mortar by ultrahigh utilization of fly ash: Technical, economic and environmental assessment. ... thermogravimetric analysis and strength activity index. Then mortar was prepared by replacing cement with FA up to and the targeted compressive strengths were obtained through cementing and by alkali activation ...
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Reducing the water-cement ratio (w/c value) decreases the porosity and thus increases the sulfate resistance [25]. Adding concrete admixtures such as silica fume, blast furnace slag or fly ash ...
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The activity index on Day 28 of fly ash A was only 117%, and the amorphous form was the lowest among the three raw materials, indicating the activity index and amorphous content are not in absolute relation to AAM strength. ... The optimum alkali-equivalent content in fly ash A was AE% = 7%, with the best compressive strength 38.58 MPa at 20% ...
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While extensive work has been conducted on fly ash-based geopolymers incorporating slag (slag-to-fly ash ratio between 0 and 1), limited work has been performed on alkali-activated slag concretes ...
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In alkali-activated class F fly ash concrete, the solution to binder ratio and the concentration of the alkali solution play an important role in determining the tensile strength. A lower s/b ratio and higher alkali concentration improve the geopolymerization of fly ash and result in a higher splitting tensile strength [ 20, 21 ].
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After years of decline, coal consumption has risen significantly in the last year (2021), driven mainly by the ever-increasing demand in fast-growing Asian countries and fostered by rising gas prices in Europe and the United States. Coal is both the largest electricity production source and the largest source of carbon dioxide emission. Coal-fired plants produce electricity …
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In order to efficiently utilize industrial solid waste while minimizing the preparation cost of engineering materials and the technical difficulty of construction, this paper prepared a high fly ash content alkali-activated fly ash slag composite system at normal temperatures and conducted an in-depth investigation on it. A systematic study was conducted on the …
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The F values of fly ash content and water glass solid content were significantly higher than those of the other two factors. This means that the fly ash content and water glass solid content has a greater impact on the early flexural strength than the other two parameters. 3.4. The Influence of Each Parameter on the Compressive Strength
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The effects of type of fly ash, alkali-equivalent content, GGBFs replace percentage, and ages on the compressive strengths and shrinkage of fly ash-based AAM were investigated.
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The study conducted axial tensile strength tests on concrete samples that replaced conventional aggregates with recycled aggregates. In Series I, using FNG instead of FNA resulted in a reduction ...
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Abstract. It is well chronicled that coal fly ash can mitigate the risk of alkali-silica reaction (ASR) in concrete structures. However, the efficacy of individual fly ashes is highly dependent on their chemical composition. Prescriptive requirements for ASR mitigation have largely focused on whether the fly ash is classified as Class F or Class C per ASTM C618, …
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Figure 1 shows the variation in initial and final setting times of alkali-activated slag/fly ash mixtures with variation in fly ash content and chemical admixture. The setting time of the BFS sample was an initial time of 9.8 h and a final time of 11.8 h, while those of the other samples were delayed: 10 h and 13.7 h for 85% BFS and 19 h ...
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Sodium and potassium are the common alkalis present in fly ash. Excessive amounts of fly ash alkalis can cause efflorescence problems in concrete products and raise concern about the effectiveness of the fly ash to mitigate alkali-silica reaction (ASR). The available alkali test, which is commonly used to measure fly ash alkali, takes approximately 35 days for execution and …
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Relationship between total alkali and available alkali for fly ash High-alkali fly ash from Ottumwa Generating Station was not conclusively linked to ASR problems at any field site. It was used in pavements that had both good and poor performance. Sites 2, 5 and 9 all contained OGS fly ash but did not exhibit significant
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Additionally, the alkali content in fly ash, including compounds like sodium oxide (Na 2 O) and ... The refractive index of wollastonite varies based on its composition, typically ranging from 1.61 to 1.64. ... the fly ash content and the activator solution to fly ash ratio were chosen based on the needed strength and by maintaining a ...
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The UCS of the soil increased with the addition of alkali activators, fly ash content, and the curing time. The highest UCS result was found with 25% fly ash content, M+ of 16% and SM of 1.25 at 28 days of curing which can improve the …
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The main technical index of fly ash (%). Alkali content SO 3 f-CaO CaO Activity index Loss of burning Water demand ratio Fineness; 0.45: 0.2: 0.03: 4.43: 84: 1.01: 94: 7.6: Table 2. ... fly ash content (C), and amount of air-entraining admixtures (D) were regarded as variables. The orthogonal experiment was designed according to the orthogonal ...
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Results showed that decrease in fly ash content irrespective of % of alkali activators and alkali modulus (Ms), the compressive strength was increasing and setting time was getting shorter.
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Various factors influencing the strength development of alkali-activated fly ash-based geopolymer mortar are discussed, such as activator composition, curing conditions, curing duration, and fly ...
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Effect of alkali activated fly ash (AAFA) on Index properties, swelling and compaction behavior Property Liquid Limit (%) Plastic Limit (%) Plasticity Index (%) Free Swell Index (%) Optimum Moisture Content (%) Maximum Dry Density (kN/m3) 0% 45 19 26 66.67 16.8 1.768 CONCLUSIONS The following conclusions can be drawn from this experimental study.
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