scholarly journals How effective is kaolin clay for the creation of a perfect hydraulic interface contact between materials?

2020 ◽  
Vol 172 ◽  
pp. 14002
Author(s):  
Evy Vereecken ◽  
Petra Schůtová ◽  
Staf Roels
Keyword(s):  
Water Uptake ◽  
Moisture Transfer ◽  
Kaolin Clay ◽  
Contact Interface ◽  
Uptake Curve ◽  
Interface Resistance ◽  
Interface Phenomena ◽  
Interface Contact ◽  
Perfect Contact ◽  
Composite Samples

Due to interface phenomena such as compaction pores, a mismatch of the pore structure, etc., moisture transfer in multi-layered building elements can deviate from the moisture transfer observed for the combination of the separate materials. Several studies on interface phenomena make use of kaolin clay to provide – as a reference – a perfect hydraulic contact between materials. This paper investigates, based on a series of imbibition experiments, whether kaolin clay truly creates this perfect contact, and thus, whether the hydraulic interface resistance between materials can be nullified by use of kaolin clay. For a low absorptive material or a large distance between the contact interface and the water surface, composite samples put together with kaolin clay show an identical water uptake curve as observed for homogeneous samples. For a material with a high absorptivity and a contact interface closer to the water plain, however, even with kaolin clay a hydraulic interface resistance is observed and estimated to be in the order of 6 000 m/s till 12 000 m/s. If present, such an interface resistance is furthermore shown to have no impact on the water uptake curve for samples composed of low absorptive bricks or with a contact interface further away from the water plain.

Water Absorption Curves versus Gamma-Ray Attenuation Profiles: A Comparative Analysis of Hygric Permeance Results

2020 ◽  
Vol 400 ◽  
pp. 32-37
Author(s):  
A.S. Guimarães ◽  
I.M. Ribeiro ◽  
A.C. Azevedo ◽  
João M.P.Q. Delgado
Keyword(s):  
Comparative Analysis ◽  
Water Absorption ◽  
Building Materials ◽  
Gamma Ray ◽  
Moisture Transfer ◽  
Contact Interface ◽  
Perfect Contact ◽  
Gamma Ray Attenuation ◽  
Attenuation Profiles ◽  
Experimental Values

The knowledge of moisture transfer in multi-layered building materials and components using numerical simulations is fundamental to predict the behaviour of that building materials and components when in contact with moisture and to avoid some possible future pathology guarantying a correct performance.This paper describes a comparative analysis of experimental values of Hygric Permeance (HP) obtained by water absorption curves and gamma-ray attenuation profiles, for perfect contact interface.

scholarly journals Measurement of the Hygric Resistance of Concrete Blocks with Perfect Contact Interface: Influence of the Contact Area

2021 ◽  
Vol 15 (1) ◽  
pp. 29-37
Author(s):  
António C. Azevedo ◽  
João M.P.Q. Delgado ◽  
Klayne.K.S. Silva ◽  
André L.M.S. Leal ◽  
Ana S. Guimarães ◽  
...  
Keyword(s):  
Contact Area ◽  
Water Resistance ◽  
Capillary Absorption ◽  
Radial Compression ◽  
Contact Interface ◽  
Knee Point ◽  
Concrete Blocks ◽  
Interface Contact ◽  
Building Components ◽  
Perfect Contact

Introduction: Concrete sealing blocks are not only used in Brazil but worldwide. T he knowledge of the material properties in the presence of moisture becomes necessary to study the durability of buildings. Methods: An experimental study was carried out in order to analyse the effect of contact area on the capillary absorption coefficient of concrete samples used in sealing blocks, according to several standards: NBR 9779 (2012), EN 1015-18 (2002), ISO 15148 (2002) and ASTM C1794 (2015). Two types of specimens were analysed; monolithic samples and samples with a perfect contact interface. The monolithic samples were also subjected to axial and radial compression in order to enhance the capacity of masonry. Results: The experimental results for the samples with perfect contact interface indicate that the water absorption before the interface presents similar behaviour to the monolithic samples. However, it is possible to observe a reduction of the absorption rate when water reaches the interface due to the hygric resistance. In other words, the moisture transport is significantly retarded by the existence of an interface, i.e., the discontinuity of moisture content across the interface indicated that there was a difference in capillary pressure across the interface. Also, the interface contact area does not greatly influence the water-resistance values. Conclusion: Finally, the Hygric Resistance values (HR), in multilayer building components, with perfect contact interface are calculated using the “knee point” methodology.

scholarly journals Does kaolin clay really create a perfect hydraulic interface contact between materials?

2020 ◽  
Vol 262 ◽  
pp. 120700
Author(s):  
Evy Vereecken ◽  
Petra Schůtová ◽  
Staf Roels
Keyword(s):  
Kaolin Clay ◽  
Interface Contact

Mechanical, degradation and cytocompatibility properties of magnesium coated phosphate glass fibre reinforced polycaprolactone composites

2014 ◽  
Vol 29 (5) ◽  
pp. 675-687 ◽  
Author(s):  
Xiaoling Liu ◽  
Muhammad S Hasan ◽  
David M Grant ◽  
Lee T Harper ◽  
Andrew J Parsons ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mass Loss ◽  
Water Uptake ◽  
Phosphate Glass ◽  
Glass Fibre ◽  
Mechanical Degradation ◽  
Osteosarcoma Cell ◽  
Ph Change ◽  
Glass Fibre Reinforced ◽  
Composite Samples

Retention of mechanical properties of phosphate glass fibre reinforced degradable polyesters such as polycaprolactone and polylactic acid in aqueous media has been shown to be strongly influenced by the integrity of the fibre/polymer interface. A previous study utilising ‘single fibre’ fragmentation tests found that coating with magnesium improved the fibre and matrix interfacial shear strength. Therefore, the aim of this study was to investigate the effects of a magnesium coating on the manufacture and characterisation of a random chopped fibre reinforced polycaprolactone composite. Short chopped strand non-woven phosphate glass fibre mats were sputter coated with degradable magnesium to manufacture phosphate glass fibre/polycaprolactone composites. The degradation behaviour (water uptake, mass loss and pH change of the media) of these polycaprolactone composites as well as of pure polycaprolactone was investigated in phosphate buffered saline. The Mg coated fibre reinforced composites revealed less water uptake and mass loss during degradation compared to the non-coated composites. The cations released were also explored and a lower ion release profile for all three cations investigated (namely Na+, Mg2+ and Ca2+) was seen for the Mg coated composite samples. An increase of 17% in tensile strength and 47% in tensile modulus was obtained for the Mg coated composite samples. Both flexural and tensile properties were investigated and a higher retention of mechanical properties was obtained for the Mg coated fibre reinforced composite samples up to 10 days immersion in PBS. Cytocompatibility study showed both composite samples (coated and non-coated) had good cytocompatibility with human osteosarcoma cell line.

A Critique on “Measurement of the Hygric Resistance of Concrete Blocks with Perfect Contact Interface: Influence of the Contact Area”

2021 ◽  
Vol 15 (1) ◽  
pp. 330-338
Author(s):  
Hans Janssen
Keyword(s):  
Contact Area ◽  
Moisture Absorption ◽  
Capillary Absorption ◽  
Identification Algorithm ◽  
Contact Interface ◽  
Knee Point ◽  
Concrete Blocks ◽  
Perfect Contact ◽  
The Impact ◽  
Absorption Measurements

Background: In March 2021, this journal published the article “Measurement of the hygric resistance of concrete blocks with perfect contact interface: influence of the contact area”. That article reports on a study on the impact of ‘perfect contact’ between concrete blocks on moisture absorption, with a focus on the impact of the sample cross-section. Objective: This critique aims at formulating several essential concerns on the hygric aspects of that article, thus expressing the discusser’s reservations on the reliability of the presented outcomes in particular and the published article in general. Methods: The data, as provided in the graphs of the critiqued article, are digitally extracted and further analysed by the discusser. Results: That analysis results in serious concerns with regard to 1) the magnitude of the quantified post-interface flows, 2) the distinguishability of the moisture absorption in the monolithic and perfect contact samples, 3) the robustness of the knee-point identification algorithm, 4) the dependability of the capillary absorption measurements, and 5) the consistency of the capillary absorption processing. These are finally translated into 8 concrete questions to be addressed by the authors of the critiqued article in order to placate these doubts and establish the reliability of their work. Conclusion: This critique formulates appreciable apprehension with respect to an earlier publication in the journal and invites its authors to respond to that via answering the 8 concrete questions. If not satisfactory, then the critiqued article’s findings cannot be considered reliable, and the journal should reconsider its prior publication.

MOISTURE TRANSPORT ACROSS PERFECT CONTACT INTERFACE OF CERAMIC BLOCKS

2020 ◽  
Vol 23 (2) ◽  
pp. 101-119
Author(s):  
J.M.P.Q. Delgado ◽  
A. C. Azevedo ◽  
Ana Sofia Guimarães
Keyword(s):  
Moisture Transport ◽  
Contact Interface ◽  
Ceramic Blocks ◽  
Perfect Contact

scholarly journals Integrated modeling of canopy photosynthesis, fluorescence, and the transfer of energy, mass, and momentum in the soil–plant–atmosphere continuum (STEMMUS–SCOPE v1.0.0)

2021 ◽  
Vol 14 (3) ◽  
pp. 1379-1407
Author(s):  
Yunfei Wang ◽  
Yijian Zeng ◽  
Lianyu Yu ◽  
Peiqi Yang ◽  
Christiaan Van der Tol ◽  
...  
Keyword(s):  
Root Growth ◽  
Water Uptake ◽  
Land Surface ◽  
Moisture Transfer ◽  
Fluorescence Emission ◽  
Coupled Model ◽  
Field Measurements ◽  
Root Water Uptake ◽  
Surface Fluxes ◽  
Canopy Photosynthesis

Abstract. Root water uptake by plants is a vital process that influences terrestrial energy, water, and carbon exchanges. At the soil, vegetation, and atmosphere interfaces, root water uptake and solar radiation predominantly regulate the dynamics and health of vegetation growth, which can be remotely monitored by satellites, using the soil–plant relationship proxy – solar-induced chlorophyll fluorescence. However, most current canopy photosynthesis and fluorescence models do not account for root water uptake, which compromises their applications under water-stressed conditions. To address this limitation, this study integrated photosynthesis, fluorescence emission, and transfer of energy, mass, and momentum in the soil–plant–atmosphere continuum system, via a simplified 1D root growth model and a resistance scheme linking soil, roots, leaves, and the atmosphere. The coupled model was evaluated with field measurements of maize and grass canopies. The results indicated that the simulation of land surface fluxes was significantly improved by the coupled model, especially when the canopy experienced moderate water stress. This finding highlights the importance of enhanced soil heat and moisture transfer, as well as dynamic root growth, on simulating ecosystem functioning.

The effects of the Mo–Sn contact interface on the oxidation reaction of dimethyl ether to methyl formate at a low reaction temperature

2016 ◽  
Vol 6 (15) ◽  
pp. 6109-6117 ◽  
Author(s):  
Zhenzhou Zhang ◽  
Qingde Zhang ◽  
Lingyu Jia ◽  
Wenfeng Wang ◽  
Shao Peng Tian ◽  
...  
Keyword(s):  
Dimethyl Ether ◽  
Reaction Temperature ◽  
Oxidation Reaction ◽  
Methyl Formate ◽  
Molar Ratio ◽  
Contact Interface ◽  
Low Reaction Temperature ◽  
Interface Contact

With increasing degrees of Mo–Sn interface contact, the molar ratio of methyl formate (MF) to methanol (MeOH) and formaldehyde (FA) was found to linearly increase simultaneously.

scholarly journals Integrated Modeling of Photosynthesis and Transfer of Energy, Mass and Momentum in the Soil-Plant-Atmosphere Continuum System

2020 ◽  
Author(s):  
Yunfei Wang ◽  
Yijian Zeng ◽  
Lianyu Yu ◽  
Peiqi Yang ◽  
Christiaan Van de Tol ◽  
...  
Keyword(s):  
Water Uptake ◽  
Land Surface ◽  
Moisture Transfer ◽  
Coupled Model ◽  
Critical Factor ◽  
Root Water Uptake ◽  
Surface Fluxes ◽  
Root Zones ◽  
Terrestrial Water ◽  
Heat And Moisture

Abstract. Root water uptake is an important component of the terrestrial water balance and a critical factor that influences energy, water vapor, and carbon exchange among soil, vegetation and atmosphere interfaces. However, most of the current vegetation photosynthesis models do not account for root water uptake, which compromises their applications under water stressed conditions. To address this limitation, this study integrates photosynthesis and transfer of energy, mass and momentum in the soil-plant-atmosphere continuum system, via a simplified 1D root growth model and a resistance scheme (from soil, through root zones and plants, to atmosphere). The coupled model was evaluated with field measurement of a maize canopy. The results indicated that the simulation of land surface fluxes was significantly improved due to considering the root water uptake, especially when vegetation is experiencing sever water stress. This finding highlights the importance of enhanced soil heat and moisture transfer, as well as dynamic root distribution, on simulating ecosystem functioning.

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