Effect of Calcareous Fly-ash Processing Methods on Rheological Properties of Mortars

Gołaszewski, Jacek; Giergiczny, Z.; Ponikiewski, Tomasz; Kostrzanowska–Siedlarz, Aleksandra; Miera, Patrycja

doi:10.3311/ppci.11038

Cited by 6 publications

(15 citation statements)

References 10 publications

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“…Such grains physically bind a large amount of water. In the case of processing by grinding, large grains are broken down and destroyed, which results in the decrease of water demand of CFA [14].…”

Section: Methodsmentioning

confidence: 99%

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Influence of the Variability of Calcareous Fly Ash Properties on Rheological Properties of Fresh Mortar with Its Addition

Nowoświat

Gołaszewski

2019

Materials

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One of the main by-products of brown coal burning is calcareous fly ash (CFA). Apart from other applications, it is used as a main component of cement, or as an active mineral additive to concrete. The present study involves the impact of the raw and processed calcareous fly ash (CFA) on the changes of rheological properties of mortars. The said impact was determined by using the coefficient of variation (CV) given in percentage. CFA samples collected from various sources were subjected to testing. The samples were collected from two electrofilters of blocks with boilers of different combustion parameters and from the retention tanks of the CFA sales department (CFA T) in which CFAs from various boilers are mixed. It has been demonstrated that the degree of the impact of CFA addition on the rheological properties of mortars depends on the source of this addition and on bulk density. The present work demonstrates the negative impact of raw CFA on mortar workability, and hence it is questionable to support its use in concrete technology.

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Section: Methodsmentioning

confidence: 99%

“…Yet, even then it remains higher than the water demand of cement [1,5]. High water demand of CFA makes it difficult to obtain fresh concrete with the required and stable workability in the long term [5,11,12,13,14,15,16,17,18]. This problem can be largely resolved by using effective plasticizers and superplasticizers [5,19,20,21,22,23,24].…”

Section: Introductionmentioning

confidence: 99%

Influence of the Variability of Calcareous Fly Ash Properties on Rheological Properties of Fresh Mortar with Its Addition

Nowoświat

Gołaszewski

2019

Materials

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“…mixture. There is also some research on how specific surface area (SSA) influences flow time [14], plastic viscosity, and yield stress [15] of mortars containing various dosages of limestone powder.…”

Section: Introductionmentioning

confidence: 99%

“…Fine fillers affect not only the hydration of the mortars but also rheological properties [7,14,15] which are another key parameter when it comes to using construction chemicals.…”

Section: Introductionmentioning

confidence: 99%

Influence of Calcium Carbonate Flour on Hydration, Strength, and Rheology of fast setting CSA based mortars

Crcoroska,

Kupiński,

Stobieniecka

et al. 2023

ce papers

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Calcium Sulfoaluminate cements (CSA) are a more sustainable alternative to Portland Cement (PC). On top of that, they can outperform PC in mortars application. The addition of calcium carbonate to such a system is beneficial as it improves workability, accelerates the setting time, and stabilizes the ettringite in the hardened mortar. In this paper, we are investigating the influence of fine calcium carbonate flour on CSA‐C$‐based mortars. The hydration course was traced by the means of isothermal microcalorimetry. It was observed that with the addition of fine calcium carbonates the heat release due to the hydration of CSA started earlier and resulted in the higher hydration peak. Higher hydration degree was able to partially compensate for additional water used to maintain workability. The rheological properties were measured with the rotational viscometer. The results were compared to the mortars of the same composition where fine calcium carbonate was replaced with the ground quartz sand of similar particle size distribution. Surprisingly, no differences in rheology and mechanical parameters between these flours were found.

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“…Unfortunately, the use of CFA as a concrete additive is significantly hindered by problems related to fresh concrete's workability. In a raw state, CFA is characterized by very high water demands, much higher than those of cement [5,14]. These demands can be reduced by processing, preferably by grinding [2,14].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Calcareous Fly Ash on the Effectiveness of Plasticizers and Superplasticizers

Gołaszewski

Ponikiewski

Kostrzanowska–Siedlarz

et al. 2020

Materials

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Due to the rational shaping of the environment and the management of environmental resources in accordance with the principle of sustainable development, calcareous fly ash (CFA)—high-calcium as a by-product of lignite combustion—is a valuable addition to concrete. This additive, however, due to its high-water demand lowers the workability of the concrete mix, which is a problem, especially in the first 90 min after mixing the components of the mix. In order to meet this challenge, plasticizers (P) and superplasticizers (SP) for concrete are used with various effects which are designed to reduce the yield value and plastic viscosity. To check the technical efficiency of admixtures P and SP with different chemical bases, the main objective of this research was to investigate the influence of raw and ground CFA on the rheological properties and other side effects of admixtures, such as the amount of air in the mixture and the amount of heat of hydration. The use of P, particularly SP, effectively improves the workability of the mortar containing CFA, especially ground CFA. With these admixtures, it is possible to obtain mortars containing ground CFA with similar rheological properties to mortars without its addition. To obtain a specific workability of mortar with CFA, it is usually necessary to introduce a higher dose of P or SP than used for mortars without CFA. The presence of raw CFA does not alter the effectiveness of P and strongly reduces the effectiveness of SP. The reduced effectiveness of SP manifests primarily as a high workability lost. The presence of ground CFA does not change the effectiveness of P (or is higher). The effectiveness of the superplasticizer SNF (with a chemical base of naphthalene sulfonate) and PE (with a chemical base of polycarboxylate ether) is slightly lower or does not change. The effectiveness of the superplasticizer SMF (with a chemical base of melamine sulfonates) is significantly lower. We found that the presence of ash affects the efficiency of P and SP, while processing via the grinding of ash makes the effect negligible. These results are novel in both their cognitive and practical aspects.

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Effect of Calcareous Fly-ash Processing Methods on Rheological Properties of Mortars

Abstract: Abstract

Cited by 6 publications

References 10 publications

Influence of the Variability of Calcareous Fly Ash Properties on Rheological Properties of Fresh Mortar with Its Addition

Influence of the Variability of Calcareous Fly Ash Properties on Rheological Properties of Fresh Mortar with Its Addition

Influence of Calcium Carbonate Flour on Hydration, Strength, and Rheology of fast setting CSA based mortars

The Influence of Calcareous Fly Ash on the Effectiveness of Plasticizers and Superplasticizers

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