This paper investigated the feasibility of replacing cement with fly ash (FA) mass ratios ranging from 40 to 70% to produce high-volume FA (HVFA) concrete. A suite of mechanical tests were conducted over a 180-day time frame. The hydration properties were systematically evaluated using isothermal calorimetry test, X-ray diffraction analysis, thermogravimetric …
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Although fly ash is a valuable mineral admixture for concrete, its low utilization rate raises the interest to replace cement with a high volume of fly ash in cement-based materials . In the 1980s, Malhotra proposed a novel use of fly ash in cement-based materials, i.e., further increasing the cement replacement level to more than 50%, through ...
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Na2SiO3/KOH weight ratio, o n the compressive strength of fly ash-based geopolymer concrete were investigated. T he obtained results showed that using NaOH provided greater 3 - and 7- day
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Fly ash use in concrete improves the workability of plastic concrete, and the strength and durability of hardened concrete. Fly ash use is also cost effective. When fly ash is …
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Concrete cured under water will have its full strength exactly at 90 days. b.) Concrete left in air as early as possible will reach full strength after several years. c.) Concrete left in air after 7 days will have approximately 90 percent of its full strength at 28 days. d.) concrete curing is …
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This is because adding more fly ash to concrete can reduce its cement content and, consequently, its carbon footprint [13]. Studies have also demonstrated that concrete with high fly ash contents, i.e., where fly ash comprises approximately 50 % or more of the binder can possess adequate salt frost scaling [14].
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Influence of fly ash as cement replacement on 28-days compressive strength of composites. FSA: ferrochromium slag aggregate [107,108,109,115].The effect of FA addition has been investigated in self-compacting concrete (SCC).
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observed and found that 20-30% replacement of cement by fly ash can yield acceptable strength at 91 days. As the maximum period of curing was 28 days, therefore, the concrete mixed with fly ash ...
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In comparing the two concretes, fly ash concrete showed about 10% higher compressive strength at 56 days and about 6% higher tensile and flexural strength. Similarly, fly ash concrete showed more than 15% first crack strength and flexural toughness than the cement concrete in post-cracking behavior.
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In this study, the use of recycled concrete aggregate at various replacement amounts (0–100 %) was investigated to be fine or coarse aggregate sources instead of crushed natural aggregate to ...
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Due to the cementitious properties present in these materials, they can be able to reach a good compressive strength. Cement replacement with fly ash, GGBS, and RHA increases strength results on ...
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Fly ash based geopolymer concrete-silica fume is suitable for concrete in hot weather in the absence of external heat. Sodium hydroxide is the dominant factor in 7 days …
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Effect of Fly ash on concrete compressive strength [60] (N/mm2) 7 days Compressive Strength (N/mm2) 28 days Percent Replaced SF by Effect of GGBS on concrete compressive strength[61] Figure 8, 9 ...
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The use of fly ash, a by-product obtained from thermal power plants, for replacement of clinker in blended cement and as cement replacement in concrete production contributes to reduced CO 2 emission and utilization of otherwise industrial waste. Concrete with fly ash has typically improved workability, lower ultimate permeability, and higher ultimate …
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In terms of strength development, rice husk ash concrete is like fly ash/slag concrete. Rice husk ash, on the other hand, is a very active pozzolanic material, and the consequences of the pozzolanic reactions are visible at an early age rather than later as with other replacement cementing materials [14].It is favorable to the strength development of …
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Most of the research work done on replacement of coarse aggregate with recycled aggregates about 25%, 50%, 75% & and class F. fly ash is used to replace ordinary Portland cement by 10% & 20% ...
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Based on Figure-5, it was discovered that increasing the percentage of fly ash in concrete mix tended to reduce the initial compressive strength (3 days) but gradually …
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This paper studied the effect of fly ash (FA) and natural pozzolana (NP) as partial cement substitutes on sustainable concrete permeability and mechanical and microstructural properties. Batches with 10, 20, 30, 40, and 50% FA and NP replacements for cement were prepared and tested for compressive strength after 7, 28, and 56 curing days and for flexural …
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In this paper, a critical review on the strength development of concrete as influenced by the use of FA as a supplement of cement in concrete has been presented on the basis of available …
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Several experimental studies have ... The replacement of cement with fly ash concrete could be up to 20% to produce high strength concrete. ... Concrete compressive strength is 40 MPa and tested ...
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Inclusion of fly in cement or concrete has several benefits. Benefits to concrete vary depending on the type of fly ash, proportion used, other mix ingredients, mixing procedure, field conditions and placement. ... At 120 days, strength of fly ash concrete ranged from 54.8 to 74.6 MPa whereas it was 74.6 MPa of control concrete. Mehta ...
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These results are similar to those of Siddique (2003) who reported that, when fly ash was used as an addition of cement (i.e. 28% by weight of cement) in concrete, there was a 23% gain in strength ...
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The purpose of this study is to find appropriate mixtures for self-leveling mortar that meet the fluidity requirements without displaying segregation by using a combination of two types of cement (Type I Portland cement and sulfoaluminate cement (SAC)) with reactive ultra-fine fly ash (RUFA). Unlike the fly ash, RUFA has a strong strength activity index and exhibits …
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Strength of bagasse ash blended concrete, and rice husk ash blended concrete is higher than the control concrete up to 20% and 15% of cement replacement levels, respectively.
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The concrete mixture with 50 % of fly ash replacement exceeded the target strength at 4 days with a result of 20.8 MPa (3017 psi), however it exhibited a very limited 1-day compressive strength of 0.69 MPa (100 psi).
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The energy requirement and kg-CO 2 eq. emissions depend on the level of cement replacement. The fly ash-based concrete emits less kg-CO 2 eq. and ... and 5 % magnesium sulfate (MgSO 4) for up to 180 days of exposure duration. The specimens' resistance to chemical attack was assessed by visual observation, changes in weight, and the percentage ...
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Naik and Ramme (1989) explored the possibility of addition of up to 60% class C fly ash (CaO = 23.40 to 26.90) as cementitious material in concrete and found that concrete containing 60% class C fly ash were weak at 7 days but at 28 days the mixtures exhibited compressive strength either equal or more than that of concrete with no-fly ash.
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The cement/fly ash paste specimens were prepared and used to monitoring the progress of hydration through SEM observation. These paste specimens were made with water/binder ratio of 30%. 20% of total binder content was replaced with fly ash for cement/fly ash paste specimens. The specimens were demolded after 24 h and cured in water at 20 °C.
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The replacement of Portland cement by GGBS or fly ash usually results in a reduced early strength, often coupled with an increase in late strength. According to the fib Model code [10] the strength of concrete at a certain point in time can be calculated from the strength at 28 days according to the following equation: f cm (t) = cc(t) · f cm ...
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The results publicized that by taking 0% to 25% of Fly ash to the weight of cement that specimen when compared with conventional concrete the compressive strength is increased 32.63% by replacement of cement with 10% of Fly Ash for 28 days. Comparing to normal concrete the compressive strength is increased 29.25% with 10% of Fly ash for 56 days.
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