Evaluation of Mode II Fracture Toughness of Hybrid Fibrous Geopolymer Composites

Abid, Sallal R.; Murali, G.; Amran, Mugahed; Vatin, Nikolai; Fediuk, Roman; Karelina, M. Yu.

doi:10.3390/ma14020349

Cited by 59 publications

(29 citation statements)

References 52 publications

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“…Pictures for the disc specimens at room ambient temperature (R) and after exposure to 100, 200, 300, 400, 500 and 600 • C are shown in Figure 14a-g, both before and after impact testing. The fracture and failure of the reference unheated specimens align with what has been reported in previous studies [84][85][86][87][88] for plain concrete, where after a number of repeated blows, a small-diameter central fracture zone was created under the concentrated compression impacts via the top surface's steel ball. After a few more blows, the internal cracks propagated to the surface, forming a surface cracking of two or three radial cracks from the central fracture zone, which formed the failure shape that occurred after a few additional blows, as shown in Figure 14a.…”

Section: Failure Patternssupporting

confidence: 82%

Residual Repeated Impact Strength of Concrete Exposed to Elevated Temperatures

et al. 2021

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Portland cement concrete is known to have good fire resistance; however, its strength would be degraded after exposure to the temperatures of fire. Repeated low-velocity impacts are a type of probable accidental load in many types of structures. Although there is a rich body of literature on the residual mechanical properties of concrete after high temperature exposure, the residual repeated impact performance of concrete has still not been well explored. For this purpose, an experimental study was conducted in this work to evaluate the effect of high temperatures on the repeated impact strength of normal strength concrete. Seven identical concrete patches with six disc specimens each were cast and tested using the ACI 544-2R repeated impact setup at ambient temperature and after exposure to 100, 200, 300, 400, 500 and 500 °C. Similarly, six cubes and six prisms from each patch were used to evaluate the residual compressive and flexural strengths at the same conditions. Additionally, the scattering of the impact strength results was examined using three methods of the Weibull distribution, and the results are presented in terms of reliability. The test results show that the cracking and failure impact numbers of specimens heated to 100 °C reduced slightly by only 2.4 and 3.5%, respectively, while heating to higher temperatures deteriorated the impact resistance much faster than the compressive and flexural strengths. The percentage reduction in impact resistance at 600 °C was generally higher than 96%. It was also found that the deduction trend of the impact strength with temperature is more related to that of the flexural strength than the compressive strength. The test results also show that, within the limits of the adopted concrete type and conducted tests, the strength reduction after high temperature exposure is related to the percentage weight loss.

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Section: Failure Patternssupporting

confidence: 82%

Residual Repeated Impact Strength of Concrete Exposed to Elevated Temperatures

et al. 2021

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“…The mixture of NaOH with Na 2 SiO 3 exhibits a higher concrete compressive strength than that of KOH with K 2 SiO 3 . FAs with a higher amount of CaO produce a higher compressive strength, particularly in the early ages [ 40 , 224 ]. According to an experimental study that involved the geopolymerization of 16 natural Si-Al minerals, the percentage of potassium oxide and calcium oxide in the raw material, as well as the molar ratio of Si-to-Al, the liquid alkali form, the degree of Si dissolution, and the molar ratio of Si-to-Al in a solution, have a significant impact on the compressive strength of AAMs [ 225 , 226 ].…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Fly Ash-Based Eco-Efficient Concretes: A Comprehensive Review of the Short-Term Properties

et al. 2021

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Development of sustainable concrete as an alternative to conventional concrete helps in reducing carbon dioxide footprint associated with the use of cement and disposal of waste materials in landfill. One way to achieve that is the use of fly ash (FA) as an alternative to ordinary Portland cement (OPC) because FA is a pozzolanic material and has a high amount of alumina and silica content. Because of its excellent mechanical properties, several studies have been conducted to investigate the use of alkali-activated FA-based concrete as an alternative to conventional concrete. FA, as an industrial by-product, occupies land, thereby causing environmental pollution and health problems. FA-based concrete has numerous advantages, such as it has early strength gaining, it uses low natural resources, and it can be configurated into different structural elements. This study initially presents a review of the classifications, sources, chemical composition, curing regimes and clean production of FA. Then, physical, fresh, and mechanical properties of FA-based concretes are studied. This review helps in better understanding of the behavior of FA-based concrete as a sustainable and eco-friendly material used in construction and building industries.

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“…Haist and Ferrara investigated the rheological properties of high-performance FRC during the mixing process and studied the influence of steel fibers on the rheological properties and concluded that thixotropic behaviors increase with the addition of steel fibers [47]. The distribution and orientation of the steel fibers also have an impact on the rheological behavior [25,[48][49][50][51][52][53][54].…”

Section: Introductionmentioning

confidence: 99%

Rheological Behavior and Strength Characteristics of Cement Paste and Mortar with Fly Ash and GGBS Admixtures

et al. 2021

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A cement paste or mortar is composed of a mineral skeleton with micron to millimeter-sized grains, surrounded by water filaments. The cohesion or shear resistance in the cement paste and mortar is caused by capillary forces of action. In the case of mortar mixes, there is friction between the particles. Therefore, the mortar mixture shows both friction between particles and cohesion, while the paste shows only cohesion, and the friction between particles is negligible. The property of the cement paste is greatly influenced by the rheological characteristics like cohesion and internal angle friction. It is also interesting that when studying the rheology of fresh concrete, the rheological behavior of cement paste and mortar has direct applicability. In this paper, the rheological characteristics of cement paste and mortar with and without mineral admixtures, that is, fly ash and ground granulated blast-furnace slag (GGBS), were studied. A cement mortar mix with a cement-to-sand ratio of 1:3 was investigated, including fly ash replacement from 10% to 40%, and GGBS from 10% to 70% of the weight of the cement. A suitable blend of fly ash, GGBS, and ordinary Portland cement (OPC) was also selected to determine rheological parameters. For mortar mixtures, the flow table was conducted for workability studies. The flexural and split tensile strength tests were conducted on various mortar mixtures for different curing times. The results indicate that in the presence of a mineral mixture of fly ash and GGBS, the rheological behavior of paste and mortar is similar. Compared with OPC-GGBS-based mixtures, both cement with fly ash and ternary mixtures show less shear resistance or impact resistance. The rheological behavior of the mortar also matches the rheological behavior in the flow table test. Therefore, it is easy to use the vane shear test equipment to conduct cohesion studies to understand the properties of cement paste and mortar using mineral admixtures. The strength results show that the long-term strength of GGBS-based mixtures and ternary mixed mixtures is better than that of fly-ash-based mixtures. For all mixtures, the strength characteristics are greatest at a w/b ratio of 0.6.

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Evaluation of Mode II Fracture Toughness of Hybrid Fibrous Geopolymer Composites

Cited by 59 publications

References 52 publications

Residual Repeated Impact Strength of Concrete Exposed to Elevated Temperatures

Residual Repeated Impact Strength of Concrete Exposed to Elevated Temperatures

Fly Ash-Based Eco-Efficient Concretes: A Comprehensive Review of the Short-Term Properties

Rheological Behavior and Strength Characteristics of Cement Paste and Mortar with Fly Ash and GGBS Admixtures

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