Pozzolanic Effect on the Hydration Heat of Cements Incorporating Fly Ash, Obsidian, and Slag Additives

Ustabaş, İlker; Erdoğdu, Şakir; Omur, Ihsan; Yilmaz, Erol

doi:10.1155/2021/2342896

Cited by 8 publications

(6 citation statements)

References 20 publications

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“…Findings from the Frattini test imply that the hydration mechanism of the proposed pozzolans varies, unlike OPC hydration, indicating the difference in the saturated lime solution and the pore fluid of OPC [64][65][66]. It is to be noted that the hydration reaction of pozzolans, by the Frattini test, involves alkali metals in the form of sodium (Na + ) and potassium (K + ) ions alongside Ca(OH) 2 [67][68][69]. Contrarily, these ions restrain Ca(OH) 2 solubility in OPC fluids based on the alkali activity [70,71].…”

Section: Discussionmentioning

confidence: 99%

“…Contrarily, these ions restrain Ca(OH) 2 solubility in OPC fluids based on the alkali activity [70,71]. The Frattini test can thereby be associated with a similar methodology as in the case of blended cement (OPC + Pozzolan), where, as the hydration proceeds, initial Ca(OH) 2 present dissolves and aids in the forming of stable compounds [67][68][69].…”

Section: Discussionmentioning

confidence: 99%

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Pozzolanic potential of sustainable precursors for engineered geopolymer composites (EGC)

Subramanian,

Davis,

Thomas

2024

Eng. Res. Express

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Confirming the pozzolanic activity is crucial to ensure their compatibility and performance in geopolymer composite (GC) applications, as it improves the geopolymerization process and optimizes the strength characteristics of GCs. This work evaluates the pozzolanic properties of Fly ash (FA), Basic Oxygen Furnace (BOF) slag, and Iron Ore Tailings (IOT) for their potential use in the development of Engineered Geopolymer Composites (EGC). IOT partially substitutes fine aggregate, while FA and BOF slag are the major precursors. Pozzolanic properties of the aforementioned materials were assessed through the Frattini, saturated lime test (SLT), and strength activity index (SAI). The Frattini test values recorded were 90, 47, and 30 % of CaO removal, denoting their degree of pozzolanicity respectively for BOF Slag, FA, and IOT. In the SLT, the formation of stable calcium silicate hydrates and aluminates are verified by the reaction of the test pozzolans with lime, thereby conforming their pozzolanicity. The results from the Frattini and SAI tests showed a significant correlation, indicating an effective pozzolanicity measure of the test materials. However, the results from the SLT did not align with the outcomes from the Frattini and SAI tests. This contradiction suggests that the SLT is ineffective compared to the other two test methods in measuring the pozzolanic activity of the test materials. The research findings provide valuable insights into the potential usage of these materials (pozzolans) as sustainable building materials in the construction industry.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Pozzolanic potential of sustainable precursors for engineered geopolymer composites (EGC)

Subramanian,

Davis,

Thomas

2024

Eng. Res. Express

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“…Indirect test methods assess the pozzolanic activity of fly ash by measuring a physical property of a test sample that indicates the extent of the activity. Example of physical properties include compressive strength, electrical conductivity [22][23][24][25], or heat evolving from hydration process [26].…”

Section: Fly Ash Pozzolanic Activitymentioning

confidence: 99%

Role of Fly Ash in Concrete Construction Industry

Akhnoukh¹

2023

Preprint

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This paper discusses the use of fly ash in concrete construction industry. Fly ash is incorporated as a supplementary cementitious material (SCM) in ordinary Portland cement (OPC) concrete in partial replacement of cement, and is recently used as a geopolymer cement in the development of geopolymer concrete (GPC) mixes. Class C and Class F fly ash high aluminosilicate content, and fine granular size contributes to concrete improved workability, lower permeability, and reduced heat of cement hydration. Due to its chemical properties, the use of fly ash in producing OPC and GPC results in increased compressive strength, higher tensile strength evaluated by measuring hardened concrete modulus of rupture (MOR), and higher modulus of elasticity (MOE). The fine size of fly ash particles increases the concrete mix packing order, and reduce the ingress of moisture, and mitigates the impact of aggressive environmental attacks through the reduction of sulfates and chlorides rate of concrete penetration. Thus, fly ash improves concrete resistivity to alkali-aggregate reactions (AAR), and reduces the corrosion of reinforcing steel, and prestressing strands. Fly ash as an economic byproduct of coal industry results in reduced material cost, increased durability, and a higher sustainability of concrete construction projects.

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“…One of the most effective methods to mitigate the issue of peak core temperature is the use of SCMs as they react relatively slower than ordinary Portland cement (OPC) 16–18 . Various SCMs such as silica fume (SF), fly ash (FA), ground granulated blast furnace slag (GGBS), and metakaolin (MK), are abundantly available in the market 19–23 .…”

Section: Introductionmentioning

confidence: 99%

“…One of the most effective methods to mitigate the issue of peak core temperature is the use of SCMs as they react relatively slower than ordinary Portland cement (OPC). [16][17][18] Various SCMs such as silica fume (SF), fly ash (FA), ground granulated blast furnace slag (GGBS), and metakaolin (MK), are abundantly available in the market. [19][20][21][22][23] Among them, SF and MK are very fine and highly reactive pozzolanic materials, which increase the hydration rate in concrete and are not suitable to reduce the peak core temperature.…”

Section: Introductionmentioning

confidence: 99%

Impact of slag‐fly ash cementitious system on thermal controls and durability of high‐strength mass concrete

Mokal,

Mandal,

Nayak

et al. 2023

Structural Concrete

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The rise in temperature due to the heat of hydration in the high‐strength mass concrete poses serious issues such as thermal cracking and delayed ettringite formation. The present experimental investigation is to optimize the proportions of SCMs like fly ash (FA) and ground granulated blast‐furnace slag (GGBS) for the same grade of high‐strength mass concrete with a focus on controlling the peak temperature rise and improving sustainability. For this purpose, one 100% ordinary Portland cement (OPC)‐based sample (T1) and five SCMs‐based samples viz. T2, T3, T4, T5, and T6 in which OPC was replaced by 20% FA, 35% FA, 50% GGBS, 70% GGBS, and 33%FA + 33% GGBS, respectively, were cast in the insulated blocks having one cubic meter volume. Analyzing critically, it is observed that for the same grade of concrete, the right blend of SCMs greatly reduces the peak core temperature (~33.2% and ~ 39.4% for T5 and T6 samples, respectively) than the sample prepared with 100% OPC. This is due to the reduction in the total heat of hydration in the SCMs‐based system than that of the OPC‐based system at early age. The amount of hydration products formed at early age varies for different percentages of SCMs, which is investigated by X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), and Field emission scanning electron microscopy (FESEM) analyses. Additionally, compressive strength analysis reveals that all the samples achieved almost similar strength (71.4, 74.6, 73.5, 71.5, 69.2, and 68.2 MPa, respectively, for T1 to T6 samples) at 56 days. Moreover, the rapid chloride permeability test (RCPT) values of the T2 to T5 samples are measured to be 597, 461, 672, 584, and 621 coulombs; while, the same is measured to be 2637, coulombs for the T1 sample, indicating higher durability of SCMs‐based samples. Finally, based on the analyses, a plausible model has been presented to explain the phenomenon, and industrial viability analysis is done to adjudge its suitability for an onsite application.

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Pozzolanic Effect on the Hydration Heat of Cements Incorporating Fly Ash, Obsidian, and Slag Additives

Cited by 8 publications

References 20 publications

Pozzolanic potential of sustainable precursors for engineered geopolymer composites (EGC)

Pozzolanic potential of sustainable precursors for engineered geopolymer composites (EGC)

Role of Fly Ash in Concrete Construction Industry

Impact of slag‐fly ash cementitious system on thermal controls and durability of high‐strength mass concrete

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