Impact of silica fume, fly ash, and metakaolin on the thickness and strength of the ITZ in concrete

Nežerka, Václav; Bílý, Petr; Hrbek, Vladimír; Fládr, Josef

doi:10.1016/j.cemconcomp.2019.05.012

Cited by 171 publications

(57 citation statements)

References 91 publications

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“…An ITZ with low strength and high porosity is formed between aggregates and the cement paste matrix due to the low packing efficiency of cement particles near aggregates. It was experimentally confirmed that addition of fly ash results in a denser and stronger ITZ, possibly due to the filling effect of small fly ash particles [30,31]. However, the chloride diffusivity of ITZ is still much larger than that of fly ash cement paste [31].…”

Section: Chloride Diffusivity Of Fly Ash Concretementioning

confidence: 86%

“…It was experimentally confirmed that addition of fly ash results in a denser and stronger ITZ, possibly due to the filling effect of small fly ash particles [30,31]. However, the chloride diffusivity of ITZ is still much larger than that of fly ash cement paste [31]. Therefore, it is appropriate to model the ITZ as an independent phase.…”

Section: Chloride Diffusivity Of Fly Ash Concretementioning

confidence: 99%

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Experimental Investigation and Analytical Modeling of Chloride Diffusivity of Fly Ash Concrete

et al. 2020

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Owing to its importance in the assessment of reinforced concrete structures, it is essential to determine the chloride diffusivity of fly ash concrete. This paper presents an investigation into the diffusion characteristics of chloride ions in fly ash concrete. Through experiment, the relationship between chloride diffusivity and curing age up to 1800 days is measured and the effects of curing age, water/binder ratio, aggregate volume fraction, and fly ash content (i.e., percentage of total cementitious material by mass) on chloride diffusivity are evaluated. It is found that the chloride diffusivity decreases with the increase of curing age, aggregate volume fraction, and fly ash content, but increases with the increase of water/binder ratio. In analytical modeling, an equivalent aggregate model is constructed and the equivalent interfacial transition zone (ITZ) thickness is derived analytically. With the equivalent aggregate model, three-phase fly ash concrete reduces to a two-phase composite material. By extending the Maxwell method, the chloride diffusivity of fly ash concrete is formulated. Finally, the validity of the analytical method is verified by experimental results.

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Section: Chloride Diffusivity Of Fly Ash Concretementioning

confidence: 86%

Section: Chloride Diffusivity Of Fly Ash Concretementioning

confidence: 99%

Experimental Investigation and Analytical Modeling of Chloride Diffusivity of Fly Ash Concrete

et al. 2020

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“…Lee et al [36] demonstrated that the fracture energy shows a rapid increase during earlier and then starts to converge to a certain extent of 173.1 N•m −1 at 28 d. The main reason for the increase of concrete G F and K IC with age was the strengthening of the ITZ between the paste and aggregate. ITZ is the most sensitive area inside the concrete, where the largest number of micro-cracks are formed [37]. In other words, the failure of concrete usually depends on the strength of its weakest area.…”

Section: Discussionmentioning

confidence: 99%

Fracture Properties of Concrete in Dry Environments with Different Curing Temperatures

et al. 2020

Applied Sciences

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This paper investigated the fracture properties of concrete in dry environments with different curing temperatures (5, 20, 40, and 60 °C). For each curing condition, the key fracture parameters of concrete were tested using wedge splitting specimens at five different ages (3, 7, 14, 28, and 60 d). The results show that in dry environments, the effective fracture toughness and fracture energy of concrete exposed to elevated temperatures increased at a relatively high growth rate at an early age. Nevertheless, the growth speed of effective fracture toughness and fracture energy decreased more quickly at elevated temperatures in the later stages. As a result, the concrete cured at higher temperature exhibited lower ultimate values of fracture parameters, and vice-versa. Namely, a temperature crossover effect was found in the effective fracture toughness and fracture energy of concrete under dry environments. Considering the early growth rate and ultimate values of fracture parameters, the optimum temperature suitable for concrete fracture properties development under dry condition was around 40 °C.

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“…The microstructures of 4% SF PCPC are given in Figure 12. The addition of SF can enhance the interfacial transition zone by reducing its thickness and increasing its strength [58]. In addition, SF increases Si/Ca ratio in the matrix, which refines the pore structures and improves the microstructures and the durability of hydrated cement paste [10,40].…”

Section: Microstructuresmentioning

confidence: 99%

Deterioration of Portland Cement Pervious Concrete in Sponge Cities Subjected to Acid Rain

Gao

Lai²,

Pramanic

et al. 2021

Materials

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The deterioration of Portland cement pervious concrete (PCPC) subjected to wet-dry cycles in the simulated acid rain solution was investigated; 4% silica fume (SF) and 8% fine aggregate (FAG) were used to replace part of cement and the coarse aggregates (weight by weight), respectively. The wear resistance, the compressive, and flexural strength of PCPC were measured. The results show that after 12 wet-dry cycles in acid rain solution the compressive strength and the flexural strength of control PCPC are decreased by 30.7% and 40.8%. The final compressive strength of PCPC with 4% SF and PCPC with 8% FAG is increased by 6.9% and 30.3%, and the final flexural strength is increased by 25.4% and 72.3%, respectively. The wear loss of PCPC is decreased by 58.8% and 81.9% when 4% SF and 8% FAG is added to PCPC, respectively. The microstructures of PCPC with wet-dry cycles are also discussed.

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Impact of silica fume, fly ash, and metakaolin on the thickness and strength of the ITZ in concrete

Cited by 171 publications

References 91 publications

Experimental Investigation and Analytical Modeling of Chloride Diffusivity of Fly Ash Concrete

Experimental Investigation and Analytical Modeling of Chloride Diffusivity of Fly Ash Concrete

Fracture Properties of Concrete in Dry Environments with Different Curing Temperatures

Deterioration of Portland Cement Pervious Concrete in Sponge Cities Subjected to Acid Rain

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