The Beneficial Effect of the Addition of Fly Ash on Reduction of the Size of Microcracks in the ITZ of Concrete Composites under Dynamic Loading

Golewski, Grzegorz Ludwik

doi:10.3390/en14030668

Cited by 62 publications

(18 citation statements)

References 76 publications

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“…HPC comprises, i.a. microsilica, which reduces porosity and permeability of concrete [23][24][25]. Studies prove [26] that HPC with recycled aggregate achieves similar compressive strength to that of the concretes with natural aggregate.…”

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confidence: 95%

Sustainable Recycling of High-Strength Concrete as an Alternative to Natural Aggregates in Building Structures

Sadowska‐Buraczewska

Grzegorczyk-Frańczak

2021

Sustainability

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The application of recycled coarse aggregates (RCA) in high-performance concrete (HPC) was analyzed in the article. In the paper, the behavior of HPC with coarse recycled aggregate and natural coarse aggregate (NCA) was compared. Short-term experiments were conducted, including concrete deformation, deflection, load bearing capacity, and cracking of beams. The analysis involved reinforced concrete T-beams made in 100% of RCA or NCA. The studies indicated that the beams with recycled aggregate are characterized by greater deflection and 7.6% lower load bearing capacity in comparison to the beams with NCA. Substitution of coarse natural aggregate with RCA reduced the compressive and tensile strengths by 20 and 26 (%), whereas and the modulus of elasticity was decreased by 15%.

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confidence: 95%

Sustainable Recycling of High-Strength Concrete as an Alternative to Natural Aggregates in Building Structures

Sadowska‐Buraczewska

Grzegorczyk-Frańczak

2021

Sustainability

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“…• more effective against negative effects originated from impact and vibrations [26][27][28] as well as dynamic loads, e.g., [29][30][31][32];…”

Section: Introductionmentioning

confidence: 99%

Rheology of Cement Pastes with Siliceous Fly Ash and the CSH Nano-Admixture

Szóstak

Golewski

2021

Materials

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The use of fly ash in cement composites adversely affects its mechanical properties during the first days of mixture curing. Modern technology, in the form of an admixture containing the hydrated calcium silicates, allows to accelerate the hardening and binding process of concrete. In this paper, studies on the influence of the admixture on properties of concretes with the ordinary Portland cements (OPC) containing the addition of siliceous fly ash (FA) have been carried out. As part of the experimental research, the authors conducted a series of studies for cement pastes modified with the addition of FA and the CSH nano-admixture (NA). In order to compare the mixtures, the following tests of cement pastes were carried out: the compressive and flexural strength, heat of hydration, SEM and rheological shrinkage. The mechanical parameters were tested after 4, 8, 12 and 24 h. The hydration heat test and microstructure analysis were carried out during the first 24 h of the concrete curing. All tests were carried out on the standard samples. On the basis of the heat of hydration test, much higher hydration heat was found in mixtures modified with the NA. During the shrinkage test, a positive effect of the NA was observed—the shrinkage during the first 28 days of mixture curing was lower than in the reference samples. The application of the CSH nano-admixture to cement pastes with the addition of FA has brought positive effects. Apart from a significant increase in strength in the first 24 h of mixture curing, a reduction in the rheological shrinkage was observed. The admixture can be successfully used in the ash concretes, in which a higher early strength is required.

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“…Therefore, the confining pressure can effectively limit the propagation speed of micro-cracks in concrete samples, slows down the damage degree of samples, and improves the bearing capacity and deformation capacity of concrete samples. Because the conventional triaxial test is carried out in a closed cavity, it is impossible to directly observe the generation and development process of cracks, but it can be studied by means of SEM technology [13].…”

Section: Analysis Of Test Resultsmentioning

confidence: 99%

“…This is a linear equation with a slope coefficient equal to k and an intercept equal to −k ln m. Therefore, parameters m and k can be easily determined based on a linear regression analysis on a set of triaxial test data of concrete samples, as shown in Table 4. The statistical damage constitutive relation curves of high-strength concrete are obtained by substituting m and k into Equation (13). The results are shown in Figure 8.…”

Section: Verification Of Constitutive Modelmentioning

confidence: 99%

Statistical Damage Constitutive Model for High-Strength Concrete Based on Dissipation Energy Density

et al. 2021

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To study the energy evolution law and damage constitutive behavior of high-strength concrete based on the conventional triaxial compression tests of C60 and C70 high-strength concrete subjected to five different confining pressures, the failure characteristics of high-strength concrete are analyzed at different confining pressures, and the evolution of the input energy density, elastic strain energy density, and dissipation energy density with axial strain and confining pressure are quantified. Combined with a continuous damage theory and non-equilibrium statistical method, the ratio of dissipation energy density of concrete to dissipation energy density corresponding to peak stress is used as the mechanical parameter. Assuming that the mechanical parameter obeys the Weibull distribution laws, the statistical damage variable describing the damage characteristics of concrete were derived. According to the Lemaitre strain equivalent principle, the damage variable is introduced to the generalized Hooke law to establish the statistical damage constitutive model for high-strength concrete. The results show that: (1) the input energy density and dissipation energy density increases with the increase of axial strain, while the elastic strain energy density increases first and then decreases as a function of the axial strain and reaches the maximum value at the peak stress; (2) the input, elastic strain, and dissipated energy densities corresponding to the peak stress of the two high-strength concretes all increase as a function of confining pressure, and the elastic strain energy density corresponding to the peak stress increases linearly as a function of the confining pressure; (3) the statistical damage constitutive model results of C60 and C70 high-strength concrete are in good agreement with the test results, and the average relative standard deviations are only 3.64% and 3.99%. These outcomes verify the rationality and accuracy of the model.

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The Beneficial Effect of the Addition of Fly Ash on Reduction of the Size of Microcracks in the ITZ of Concrete Composites under Dynamic Loading

Cited by 62 publications

References 76 publications

Sustainable Recycling of High-Strength Concrete as an Alternative to Natural Aggregates in Building Structures

Sustainable Recycling of High-Strength Concrete as an Alternative to Natural Aggregates in Building Structures

Rheology of Cement Pastes with Siliceous Fly Ash and the CSH Nano-Admixture

Statistical Damage Constitutive Model for High-Strength Concrete Based on Dissipation Energy Density

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