Fly Ash with Ammonia: Properties and Emission of Ammonia from Cement Composites

Chyliński, Filip; Goljan, Anna; Michalik, Agnieszka

doi:10.3390/ma14040707

Cited by 5 publications

(5 citation statements)

References 18 publications

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“…5. The method of preparing samples for testing and the techniques used during microstructural analyses using scanning microscopy were similar to those described in earlier publications [72,73].…”

Section: Resultsmentioning

confidence: 99%

Characteristic of small-strain stiffness of fine-grained soils based on advanced laboratory tests

2023

Archives of Civil Engineering

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The non-linearity of the modulus in the zone of small deformations has become one of the three basic concepts of modern soil mechanics, together with "effective stresses" or "critical state". It is therefore necessary to obtain suitable parameters to describe these phenomena through the development of modern measuring equipment and new research methods. Limitations in the availability of the research area or research equipment indicate the need to create a data set, in the formula of regional assessments. The article presents a compilation of data on the deformation characteristics of soils covering about 75% of the country's area, which are the most common subsoils for building. Descriptions, images of microstructures, and a record of mechanical parameters are presented for various age-old glacial clays and marginal clays and loesses. Emphasis is placed on parameters obtained from triaxial tests, including the determination of the shear modulus at small deformations obtained from BET measurements. In combination with the patented solution of sample strain measurement, complete deformability curves of the tested samples were obtained, indicating model reference curves developed for the above soil types. The statistically significant amount of data collected allowed the creation of a specific portfolio for selected soils as a starting point for assessing deformability. This corresponds to the current expectations regarding the characteristics of the behaviour of the substrate in the full spectrum of stresses and deformations, obtained from different types of tests, which, as in the case of soil stiffness degradation, together allow the correct determination of the necessary parameters.

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Section: Resultsmentioning

confidence: 99%

Characteristic of small-strain stiffness of fine-grained soils based on advanced laboratory tests

2023

Archives of Civil Engineering

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“…As the results of a spill test confirmed, the addition of fly ash affects the workability and also mortar thickening occurs. During mixture mixing, a reaction of ammonia compounds with alkalis and releasing of NH3 occurs, product [18]. The bulk density of the reference sample was determined around 2.050 kg/m 3 .…”

Section: Alkali Activated Bindermentioning

confidence: 99%

Possibilities of using fly ash after denitrification to various types of building materials

Chromkova

Kubátová²,

Bohm³

et al. 2022

J. Phys.: Conf. Ser.

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The paper summarises information gained within the verification of high-temperature fly ashes after the denitrification process. There was an examination of characteristics of fly ashes from various heat sources as well as possibilities of using these types of fly ashes to various types of building applications. An effect on final properties of a building material produced in laboratory or experimental conditions was observed. Positive results were achieved within the verification of using fly ash to fly ash-cement mixtures. A quality of prepared suspensions was equal to the practically verified one prepared from a fly ash from a powerplant without SNCR. These mixtures after 28 days achieved compressive strengths 8 MPa. Significant increase of strengths in the course of time was recorded. After 90 days compressive strengths achieved values 13-16 MPa and after 1 year even 17-20 MPa. Flexural strengths after 28 days were around 1.5 MPa. This parameter also showed a tendency to increase in time. Fly ash after denitrification was effective within a preparation of repairing materials based on epoxy resin. For these materials, 50% substitution of natural aggregate with fly ash after denitrification process was proven. Final strength characteristics of the new prepared material outperformed a reference mixture, containing only natural fine-grained aggregate/filler. A using of fly ash as a compound of filler of alkali-activated systems was also tested. Fly ash after SNCR in the amount of 20 to 60% in combination with fine-milled blast furnace slag and sodium water glass was tested. These materials achieved compressive strengths 50–75 MPa and flexural strengths 6–10 MPa.

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“…As a result, the problem of the utilization of denitrified fly ash is becoming more and more common in concrete. A large number of studies have shown that NH 4 HSO 4 is a by-product of denitrified fly ash [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

Performance of Cement Paste with Denitrified Fly Ash Containing NH4HSO4

Wang

Qin

et al. 2022

Materials

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The denitrification process was completed in coal-fired power plants, resulting in the fly ash containing NH4HSO4. When this kind of fly ash with ammonia was applied to cement and concrete, there could be phenomena such as a retarded setting time, decreased compressive strength, and volume expansion. This paper mainly investigated the influence of fly ash containing NH4HSO4 on the properties of fly ash cement paste, and pastes with NaHSO4 were set as the control samples. The research on Na+ in cement hydration was studied. The influence of NH4HSO4 content in fly ash on the properties of fly ash cement paste was also investigated. It was found that NH4+ could greatly affect the properties of fly ash cement paste, such as significantly reducing the fluidity, prolonging the setting time, decreasing the compressive strength, increasing the drying shrinkage, decreasing the total heat released during the hydration, and affecting the content of calcium hydroxide hydrate. Increasing the ammonia content of the denitrified fly ash would reduce fluidity, retard its setting time, increase the porosity of the cement stone, and increase the number of pores with large sizes in the fly ash cement paste. The increase of porosity and pores with large sizes in cement decreases the compressive strength and increases the drying shrinkage of the fly ash cement paste.

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Fly Ash with Ammonia: Properties and Emission of Ammonia from Cement Composites

Cited by 5 publications

References 18 publications

Characteristic of small-strain stiffness of fine-grained soils based on advanced laboratory tests

Characteristic of small-strain stiffness of fine-grained soils based on advanced laboratory tests

Possibilities of using fly ash after denitrification to various types of building materials

Performance of Cement Paste with Denitrified Fly Ash Containing NH4HSO4

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