Modeling of the link between microstructure and effective diffusivity of cement pastes using a simplified composite model

Béjaoui, S.; Bary, Benoı̂t

doi:10.1016/j.cemconres.2006.06.004

Cited by 95 publications

(49 citation statements)

References 34 publications

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“…Figure 9 illustrates the percolation function of the more permeable phase, i.e. the dependence of the percolating fraction on the total volume fraction, in hardened cement paste [19].…”

Section: Combination Of Hp Uc and Poresmentioning

confidence: 99%

“…The more permeable phase must enable transport through a connected path, and the tortuosity coefficient thus reflects the length of the diffusion path or the formation difficulty of the diffusion path, as shown in Figure 7. Thus the effective diffusion coefficient of the composite material depends on the tortuosity coefficients, the phase diffusion coefficients and the phase volume fractions, as expressed in Equation 5 [19]. (5) In Equation 5, D e is the effective diffusion coefficient of the composite material, d i are the phase diffusion coefficients (of solid and pore phase), ϕ i are the volume fractions of (solid and pore phase) and T i (ϕ i ) are the tortuosity coefficients (of solid and pore phase) as a function of the respective volume fractions ϕ i .…”

Section: Combination Of Hp Uc and Poresmentioning

confidence: 99%

“…When the volume fraction of the percolating part of the pore phase is y, the effective diffusivity of the combination of the two phases (solid and pore phase) can be calculated by Equation 7 [19].…”

Section: Combination Of Hp Uc and Poresmentioning

confidence: 99%

See 2 more Smart Citations

Microstructure-Based Prediction Model for Chloride Ion Diffusivity in Hydrated Cement Paste

Ma¹,

Zhang²

2017

Ceramics - Silikaty

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“…Figure 9 illustrates the percolation function of the more permeable phase, i.e. the dependence of the percolating fraction on the total volume fraction, in hardened cement paste [19].…”

Section: Combination Of Hp Uc and Poresmentioning

confidence: 99%

Section: Combination Of Hp Uc and Poresmentioning

confidence: 99%

See 1 more Smart Citation

Microstructure-Based Prediction Model for Chloride Ion Diffusivity in Hydrated Cement Paste

Ma¹,

Zhang²

2017

Ceramics - Silikaty

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“…Indeed Chapelle tests, which allow the quantification of the amount of lime fixed by a material, carried out on BAs and NP have shown that BA fixes 352 mg of calcium oxide per gram of material and NP absorbs 290 mg of calcium oxide per gram of materials. 29 BAs will react with more calcium hydroxide than NP; so the amount of calcium hydroxide will be lower in the presence of the ternary matrix than in the presence of commercial cement, the degradation of raw fibers will slow down and the quantity of formed calcium silicate hydrates responsible for the high compressive strength of cement will also be reduced. 30 CSHs are produced by the hydration of mineralogical phases of cement (2 calcium oxide), silicon dioxide) as dicalcium silicate (C 2 S) and (3(calcium oxide), silicon dioxide) as tricalcium silicate (C 3 S)).…”

Section: Specific Heatmentioning

confidence: 99%

“…On one hand, the thermal conductivity varies as a function of the matrix, the amount and the treatment of the fibers as shown in section 3.2.1.1, and on the other hand, the specific heat is quasi-constant, that is to say that diffusivity × density changes with those parameters. Indeed Bejaoui and Bary, 29 in a modeling study of the link between microstructure and effective diffusivity of cement paste, proposed that the diffusivity of calcium silicate hydrates ((CaO) x (SiO 4 ) y (H 2 O) z or CSHs) produced during the cementitious matrix hydration depends on the density of these products.…”

Section: Specific Heatmentioning

confidence: 99%

Thermal and flexural properties of bagasse/cement composites

et al. 2015

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Enhancing the sustainability, circular economy and use of by-products and renewable resources concerns a great number of researchers. Adding value to tropical vegetable resources and proposing a replacement for asbestos are challenges for chemists. Sugar cane bagasse is evaluated both as a mineral replacement and as a reinforcement in cementitious paste. In this matrix, ordinary Portland cement is partly replaced by natural pozzolan and bagasse ashes; a ternary binder is obtained. The pastes reinforced with vegetable fibers are prepared by the incorporation of untreated and pyrolyzed bagasse fibers (2-6 wt%) in this modified matrix. The thermal conductivity and the bending strength of the composite pastes, placed in various environments (curing chamber and water), are evaluated and compared to those of composite pastes made with commercial cement and bagasse fibers, exposed to identical aging conditions. The more relevant results are obtained in the curing chamber: the composite pastes prepared with the ternary matrix conduct less heat than the commercial binder composites at 28 d, and better bending strengths are obtained with the ternary binder composites at 28 and 90 d, particularly with the untreated bagasse fibers. . IntroductionGuadeloupe is a French Caribbean island with a tropical climate (latitude 16°59¢45″ north, longitude 62°04¢03″ west) and where seismicity is high and hurricanes occur frequently, so the choice of construction materials takes an essential place in structure design. As the durability of construction materials is strongly related to the exposure conditions, metallic structure degradation by corrosion is one of the preoccupations of researchers.As shown by various authors, 1-3 a way to prevent structure corrosion is the use of pozzolanic materials during the preparation of pastes, mortars or concretes. These silico-aluminous materials, when they are finely crushed, 4 react with the calcium hydroxide (Ca(OH) 2 ) released during cement hydration, to form products of the same chemical nature as the hydration products of cement. In Guadeloupe, cement is widely used for construction. A way to prevent the corrosion of steel framework in concrete is the partial replacement of cement by natural local pozzolan or ashes prepared from agro-industrial by-products. As indicated by Malhotra and Metha, 5 using pozzolanic materials coming from vegetable, mineral or agro-industrial by-products leads to (a) mechanical and physical-chemical benefits: improved mechanical strength, low permeability and strength against aggressive chemicals and thermal cracking; (b) economic benefits: reduced cost of buildings with the replacement of 20-60% by mass of cement by pozzolanic materials; and (c) ecological benefits: reduction of greenhouse gas (GHG) emission because of the partial replacement of cement in concrete and contribution to sustainability.Moreover, French thermal and acoustic regulations 6 expect autosufficiency and use of 50% renewable power in energy consumption by 2020. These regulations are essentia...

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Modeling of the link between microstructure and effective diffusivity of cement pastes using a simplified composite model

Cited by 95 publications

References 34 publications

Microstructure-Based Prediction Model for Chloride Ion Diffusivity in Hydrated Cement Paste

Microstructure-Based Prediction Model for Chloride Ion Diffusivity in Hydrated Cement Paste

Thermal and flexural properties of bagasse/cement composites

Attack of Cementitious Materials by Organic Acids in Agricultural and Agrofood Effluents

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