Composite Gypsum Binders with Silica-containing Additives

Чернышева, Н. В.; Lesovik, Valery; Drebezgova, Mariya; Shatalova, S.; Аласханов, А.Х.

doi:10.1088/1757-899x/327/3/032015

Cited by 31 publications

(13 citation statements)

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“…Such adverse effects have driven the study and use of industrial waste and by-products from widely varying industries for cement and concrete manufacture. The aims of such practice include achieving the sustainability goals set out in the UN's Agenda 2030 and implementing the guidelines for what is known in the EU as the circular economy [9,10], i.e., to favour more sustainable construction [4,8,9,[11][12][13][14][15][16]. Some of the industrial waste and by-products apt for cement and concrete manufacture are members of the family of so-called NORMs (naturally occurring radioactive materials).…”

Section: Introductionmentioning

confidence: 99%

New Approach for the Determination of Radiological Parameters on Hardened Cement Pastes with Coal Fly Ash

et al. 2021

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Supplementary cementitious materials (SCMs) in industrial waste and by-products are routinely used to mitigate the adverse environmental effects of, and lower the energy consumption associated with, ordinary Portland cement (OPC) manufacture. Many such SCMs, such as type F coal fly ash (FA), are naturally occurring radioactive materials (NORMs). 226Ra, 232Th and 40K radionuclide activity concentration, information needed to determine what is known as the gamma-ray activity concentration index (ACI), is normally collected from ground cement samples. The present study aims to validate a new method for calculating the ACI from measurements made on unground 5 cm cubic specimens. Mechanical, mineralogical and radiological characterisation of 28-day OPC + FA pastes (bearing up to 30 wt % FA) were characterised to determine their mechanical, mineralogical and radiological properties. The activity concentrations found for 226Ra, 212Pb, 232Th and 40K in hardened, intact 5 cm cubic specimens were also statistically equal to the theoretically calculated values and to the same materials when ground to a powder. These findings consequently validated the new method. The possibility of determining the activity concentrations needed to establish the ACI for cement-based materials on unground samples introduces a new field of radiological research on actual cement, mortar and concrete materials.

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Section: Introductionmentioning

confidence: 99%

New Approach for the Determination of Radiological Parameters on Hardened Cement Pastes with Coal Fly Ash

et al. 2021

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“…In addition, it also removes semi cellulose, lignin, and other non-cellulosic substances from the fiber, such as waxes and oils [ 18 , 77 , 82 , 83 ]. These substances, in the fiber, work as binders, and their removal, through alkaline treatment helps to separate fiber agglomerates into elementary fibers [ 18 , 84 ]. The defibrillation of fiber clusters, as well as the reduction in fiber diameter, consequences of mercerization, directly implies an increase in the specific contact area between the fiber and the geopolymer matrix.…”

Section: Surface Treatment Of Natural Fibersmentioning

confidence: 99%

Natural Fibers as an Alternative to Synthetic Fibers in Reinforcement of Geopolymer Matrices: A Comparative Review

Azevedo¹,

Cruz²,

Marvila³

et al. 2021

Polymers

111

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Geopolymer materials have been gaining ground in the civil construction sector not only for having superior physical properties when compared to conventional cement, but also for being less harmful to the environment, since the synthesis of the geopolymer does not release toxic gases or require high energy costs. On the other hand, geopolymer materials like cementitious matrices have low flexural strength and have fragile breakage. To overcome these deficiencies, the insertion of fibers in geopolymeric matrices has been evaluated as a solution. Although most research on this practice focuses on the use of synthetic fibers, the use of natural fibers has been growing and brings as an advantage the possibility of producing an even more ecological material, satisfying the need to create eco-friendly materials that exists today in society. Thus, this paper aimed to, through the evaluation of research available in the literature, understand the behavior of fibers in geopolymer matrices, identify similarities and differences between the performance of geopolymer composites reinforced with natural and synthetic fibers and, understanding that it is possible, point out ways to optimize the performance of these composites.

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“…Although natural rock is subjected to compressive loading in most cases, tensile stress still occurs during excavation unloading of tunnels, roadways, chambers, and slopes, etc. [ 1 , 2 , 3 , 4 , 5 ]. Since rock’s tensile strength is much smaller than its compressive strength [ 6 , 7 ], it plays a key role in controlling the stability of rock engineering, e.g., roof fall and rib spalling [ 8 , 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

A New Flattened Cylinder Specimen for Direct Tensile Test of Rock

Rao

Liu

et al. 2021

Sensors

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In recent decades, researchers have paid more attention to the indirect tensile test than to the direct tensile test (DTT) of rocks, mainly due to difficulties in the alignment and the stress concentration at the end of an intact cylindrical specimen. In this paper, a new flattened cylinder specimen and a clamp device were designed to obtain the true tensile strength of the rock in DTT. Stress distributions of the specimen with different lengths (l) and cutting thicknesses (t) were analyzed, and damage processes of the specimen were monitored by the Digital Image Correlation (DIC), the fractured sections were also scanned. Different mechanical parameters were also obtained by the DTT of the flattened cylinder specimens and the intact cylinder specimens, as well as the Brazilian disc. Research results show that the tensile strength obtained by DTT is smaller than the Brazilian disc and is slightly greater than the intact cylindrical specimen. The flattened cylinder specimen with 0.20 ≤ 2t/D < 0.68 and 0.10 ≤ l/D ≤ 0.20 is recommended to measure the true tensile strength of rock material in DTT. This new shape of the specimen is promising to be extended in the uniaxial or triaxial direct tension test.

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Composite Gypsum Binders with Silica-containing Additives

Cited by 31 publications

References 0 publications

New Approach for the Determination of Radiological Parameters on Hardened Cement Pastes with Coal Fly Ash

New Approach for the Determination of Radiological Parameters on Hardened Cement Pastes with Coal Fly Ash

Natural Fibers as an Alternative to Synthetic Fibers in Reinforcement of Geopolymer Matrices: A Comparative Review

A New Flattened Cylinder Specimen for Direct Tensile Test of Rock

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