Induced Anisotropic Gas Permeability of Concrete due to Coupled Effect of Drying and Temperature

An experimental campaign is carried out to study the effect of drying shrinkage and temperature on multi-directional gas permeability of dry concrete. Thermal loadings up to 250°C are applied on concrete samples in cylinder (11×22) and dog-bone forms (total length of 61 cm). Samples are sliced for permeability measurements. Permeabilities in longitudinal and radial directions are addressed. The cylinder samples are first sliced then dried or heated whilst the dog-bone samples are first dried or heated then sliced. The average of initial intrinsic permeability for the slices (5 cm height, 11 cm diameter) obtained from the (11×22) samples is found isotropic and equal to 2.93×10-17 m2. In this case, drying shrinkage is isotropic. Furthermore, it is shown that for the dog-bone samples, drying shrinkage may induce micro-cracks preferentially in a certain direction which induces permeability anisotropy. Finally, the evolution of the normalized intrinsic permeability with respect to initial permeability versus temperature is found isotropic. An exponential fitting of intrinsic permeability versus temperature is found based on experimental measurements.

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Influence of mineral additions on the microstructure of concrete in chloride environment

Academic Perspective Procedia ◽

10.33793/acperpro.01.01.54 ◽

2018 ◽

Vol 1 (1) ◽

pp. 283-292

Author(s):

Walid Fouad Edris ◽

Safwat Abdelkader ◽

Encarnacion Reyes Pozo ◽

Amparo Moragues Terrades

Keyword(s):

Portland Cement ◽

Blast Furnace Slag ◽

Mercury Intrusion Porosimetry ◽

Gas Permeability ◽

Chloride Diffusion ◽

Mercury Intrusion ◽

Experimental Campaign ◽

Mineral Additions ◽

Chloride Environment ◽

Furnace Slag

In this work we have designed an experimental campaign with four different dosages of concrete to study the influence of the principal additions used in marine environments. The effect of material composition [Sulfate Resistant Portland Cement (SRPC), Blast Furnace Slag Portland Cement (BFSPC), Silica Fume (SF) and Fly Ash (FA) with four different mix designs] was performed by means of differential thermal analysis (DTA), mercury intrusion porosimetry (MIP), gas permeability, chloride diffusion and mechanical properties of concrete. In order to simulate the aggressiveness of the marine environment the concretes were immersed in a sodium chloride solution with a concentration of 1 molar during different times of 182, 365 and 546 days. According to the results obtained, the SRPC and SRPC+FA samples suffered the highest rise in permeability, porosity and chloride diffusion, and the greatest loss in compressive strength

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Durability and Shrinkage Characteristics of Self-Compacting Concretes Containing Recycled Coarse and/or Fine Aggregates

Advances in Materials Science and Engineering ◽

10.1155/2015/278296 ◽

2015 ◽

Vol 2015 ◽

pp. 1-18 ◽

Cited By ~ 9

Author(s):

Mehmet Gesoglu ◽

Erhan Güneyisi ◽

Hatice Öznur Öz ◽

Mehmet Taner Yasemin ◽

Ihsan Taha

Keyword(s):

Coarse Aggregate ◽

Gas Permeability ◽

Drying Shrinkage ◽

Recycled Aggregate ◽

Fine Aggregate ◽

Restrained Shrinkage ◽

Durability Properties ◽

Recycled Fine Aggregate ◽

Restrained Shrinkage Cracking ◽

Fine Aggregates

This paper addresses durability and shrinkage performance of the self-compacting concretes (SCCs) in which natural coarse aggregate (NCA) and/or natural fine aggregate (NFA) were replaced by recycled coarse aggregate (RCA) and/or recycled fine aggregate (RFA), respectively. A total of 16 SCCs were produced and classified into four series, each of which included four mixes designed with two water to binder (w/b) ratios of 0.3 and 0.43 and two silica fume replacement levels of 0 and 10%. Durability properties of SCCs were tested for rapid chloride penetration, water sorptivity, gas permeability, and water permeability at 56 days. Also, drying shrinkage accompanied by the water loss and restrained shrinkage of SCCs were monitored over 56 days of drying period. Test results revealed that incorporating recycled coarse and/or fine aggregates aggravated the durability properties of SCCs tested in this study. The drying shrinkage and restrained shrinkage cracking of recycled aggregate (RA) concretes had significantly poorer performance than natural aggregate (NA) concretes. The time of cracking greatly prolonged as the RAs were used along with the increase in water/binder ratio.

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PERFORMANCE OF STEEL MICRO FIBER REINFORCED MORTAR MIXTURES CONTAINING PLAIN, BINARY AND TERNARY CEMENTITIOUS SYSTEMS

Journal of Green Building ◽

10.3992/jgb.11.4.109.1 ◽

2016 ◽

Vol 11 (4) ◽

pp. 109-130 ◽

Cited By ~ 2

Author(s):

Ali Mardani-Aghabaglou ◽

Cihat Yüksel ◽

Hojjat Hosseinnezhad ◽

Kambiz Ramyar

Keyword(s):

Total Mass ◽

Drying Shrinkage ◽

Chloride Ion ◽

Mineral Admixtures ◽

Impact Loads ◽

Test Results ◽

Chloride Ion Penetration ◽

Micro Cracks ◽

The Matrix ◽

Cementitious Systems

Steel micro fibers provide strengthening, toughening and durability improvement mechanisms in cementitious composites. However, there is not much data in the literature regarding how the extent of their effectiveness changes depending on the type of matrix being reinforced. For clarifying this point, the influence of a constant volumetric ratio (1%) of 6 mm long steel micro fibers on the performance of 5 mortar mixtures was investigated and were prepared using plain, binary and ternary cementitious systems. A total of 10 mixtures were cast. The mineral admixtures used in the study include silica fume (SF), metakaolin (MK) and a Class C fly ash (FA). While the replacement levels of SF and MK were 10% by weight of the total mass of the binder, this ratio was chosen as 30% for FA. In addition to the behavior of the mixtures under compressive, flexural and impact loads, abrasion, water absorption, chloride ion penetration, freezing-thawing resistance and drying shrinkage characteristics of the mixtures were determined. Test results indicate that generally the refinement in the pore structure of the matrix provided by mineral admixtures and the increase in resistance against growth and coalescence of micro-cracks provided by fibers produce a synergistic effect and improve the investigated performances of the mixtures.

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Drying Shrinkage of Fly Ash Mortar Mixed with Seawater

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.802.118 ◽

2015 ◽

Vol 802 ◽

pp. 118-123 ◽

Cited By ~ 1

Author(s):

John Wilmer Bautista ◽

John Benedict Crockett ◽

Beatrice Ann Liu ◽

Timothy John Obra ◽

Cheryl Lyne Roxas

Keyword(s):

Carbon Dioxide ◽

Compressive Strength ◽

Fly Ash ◽

Carbon Dioxide Emissions ◽

Drying Shrinkage ◽

Water Shortage ◽

Ash Content ◽

Partial Substitution ◽

Partial Replacement ◽

Micro Cracks

Drying shrinkage in mortar produces cracks and micro-cracks which affect the durability of a structure. The effects of seawater as a substitute to freshwater and fly ash as a partial replacement for cement were investigated in this study in order to address the predicted water shortage by 2025 and the increasing carbon footprint from carbon dioxide emissions worldwide. Moreover, these materials are also more economical alternatives to freshwater and cement. Rectangular prism specimens with varying fly ash content (10%, 15%, 20%, 25%, and 30%) were cast to measure the drying shrinkage in mortar while 50-mm cube mortar specimens were prepared to determine the compressive strength. This study investigated whether the addition of fly ash and seawater reduced the drying shrinkage of mortar. From the results, it was found that mortar specimens with 20% fly ash replacement achieved the highest early and late strengths. Partial substitution of fly ash would result to shrinkage in mortar while substitution of seawater to freshwater counteracts the effects of fly ash, thus producing less shrinkage. Fly ash content between 20%-25% combined with seawater produces the least shrinkage value without compromising the minimum required compressive strength.

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Intrinsic permeability of refractories from gas permeability measurements: Comparison of results

Ceramics International ◽

10.1016/j.ceramint.2017.11.038 ◽

2018 ◽

Vol 44 (3) ◽

pp. 2900-2910 ◽

Cited By ~ 5

Author(s):

Emmanuel de Bilbao ◽

Lise Loison ◽

Yassine Hbiriq ◽

Cédric Orgeur ◽

Séverine Brassamin ◽

...

Keyword(s):

Gas Permeability ◽

Intrinsic Permeability ◽

Comparison Of Results

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Transport Properties of CVI Preforms and Composites

MRS Proceedings ◽

10.1557/proc-168-49 ◽

1989 ◽

Vol 168 ◽

Cited By ~ 2

Author(s):

G. B. Freeman ◽

T. L. Starr ◽

T. C. Elston

Keyword(s):

Simple Model ◽

Transport Properties ◽

Material Properties ◽

Gas Permeability ◽

Layer Structure ◽

Transport Coefficients ◽

Experimental Measurements ◽

Model Calculations ◽

Component Material ◽

Anisotropic Transport

AbstractA simple model, based on physical microstructure, that predicts the anisotropic transport properties of cloth lay-up composites is discussed. This anisotropic material is modeled as a layer structure consisting of two, or more, isotropic components. Composite transport coefficients perpendicular and parallel to the layers are given by “series” and “parallel” combining laws involving the isotropic coefficients of these component materials and their volume fractions. These component material properties are determined using microstructural information and fundamental material properties. Model calculations are compared to experimental measurements for gas permeability.

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Investigation of Flexural Behavior of Engineered Cementitious Composites

Asian Journal of Engineering and Applied Technology ◽

10.51983/ajeat-2018.7.1.855 ◽

2018 ◽

Vol 7 (1) ◽

pp. 84-87

Author(s):

V. Selvapriya .

Keyword(s):

Construction Industry ◽

Drying Shrinkage ◽

Fiber Reinforced Concrete ◽

Flexural Behavior ◽

Cementitious Composites ◽

Volume Changes ◽

Engineered Cementitious Composites ◽

New Class ◽

Micro Cracks ◽

New Material

Traditional concrete is brittle, rigid and less durable. The search for the new material in construction industry results in the development of new class of Fiber Reinforced Concrete (FRC), known as Engineered Cementitious Composites (ECC). They impart ductility and durability to the structure. In concrete structural cracks develop even before loading, particularly due to drying shrinkage or other causes of volume changes. When loaded, the micro cracks propagate and open up, and owing to the effect of stress concentration, additional cracks form in places of minor defects. The development of micro cracks is the main cause of inelastic deformation in concrete. This paper deals with flexural behavior of ECC.

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External sulfate attack in structural concrete made with Portland-limestone cement: an experimental study

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2019-0354 ◽

2020 ◽

Author(s):

Nicola Cefis ◽

Cristina Tedeschi ◽

Claudia Comi

Keyword(s):

Experimental Study ◽

Sulfate Attack ◽

Compression Tests ◽

Structural Concrete ◽

Outer Skin ◽

Experimental Campaign ◽

Portland Limestone Cement ◽

Micro Cracks ◽

Ultrasonic Measurements ◽

Limestone Cement

This experimental study aims to assess the effect of external sulfate attack on structural concrete made with a common Portland-limestone cement. The experimental campaign, lasted about three years, has been performed on standard-sized cylinders (<i>Φ</i>15×30 cm) subject to different exposure conditions. The overall swelling of the specimens due to chemical reactions was monitored in time. SEM-EDS observations and XRD tests were also carried out. Results showed the presence of secondary ettringite causing swelling and micro-cracks formation. The porosity increase due to sulfate attack of the outer skin of the specimens was measured. Ultrasonic measurements and compression tests on cores drilled from the cylinders immersed in different solutions allowed to confirm and quantify the consequent degradation of macroscopic elastic properties.

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