CT-scanning and modelling of the capillary water uptake in aspen, oak and pine

2009 ◽  
Vol 68 (1) ◽  
pp. 77-85 ◽  
Author(s):  
Jimmy Johansson ◽  
Girma Kifetew
Keyword(s):  
Water Uptake ◽  
Ct Scanning ◽  
Capillary Water ◽  
Capillary Water Uptake

Mechanism of long-term capillary water uptake in cementitious materials

2020 ◽  
Vol 106 ◽  
pp. 103448 ◽  
Author(s):  
N.M. Alderete ◽  
Y.A. Villagrán Zaccardi ◽  
N. De Belie
Keyword(s):  
Water Uptake ◽  
Cementitious Materials ◽  
Capillary Water ◽  
Capillary Water Uptake

The influence of dynamic environmental conditions on capillary water uptake of building materials

2018 ◽  
Vol 42 (4) ◽  
pp. 506-526 ◽  
Author(s):  
Nikos Karagiannis ◽  
Maria Karoglou ◽  
Asterios Bakolas ◽  
Magdalini Krokida ◽  
Antonia Moropoulou
Keyword(s):  
Water Uptake ◽  
Environmental Conditions ◽  
Building Materials ◽  
Capillary Rise ◽  
Assessment Tools ◽  
Real Case ◽  
Capillary Absorption ◽  
Capillary Water ◽  
Proposed Model ◽  
Capillary Water Uptake

Water capillary absorption is one of the main water uptake mechanisms in building materials, affecting their overall durability. Thus, the investigation of their capillary rise kinetics can be very useful as regards understanding buildings behavior, contributing to the increase of their durability and their service life. For this reason, a first-order mathematical model was used describing the capillary water uptake under dynamic environmental conditions (different air velocity, air temperature, and relative air humidity) for various natural and artificial building materials. This model successfully fits the experimental data. From the results, it was found that both building materials’ intrinsic characteristics and environmental conditions influence the capillary rise kinetics. In order to assess the validity of the proposed model, a comparison with a similar model was performed. The fitting of the utilized model was more accurate because of the incorporation of the environmental parameters into it. Finally, the proposed model was utilized in order to predict the capillary water uptake under hypothetical extreme weather real-case scenarios. It was found that the proposed model can successfully predict the capillary water uptake under different real-case environmental conditions. The applicability of this semi-empirical model, using parameters with physical meaning, could make it suitable for use in building simulators. This model can contribute to risk assessment tools, dealing with various challenges related to climate change and its effect upon built environment.

scholarly journals The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones

Buildings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 18 ◽  
Author(s):  
Jeanette Orlowsky ◽  
Franziska Braun ◽  
Melanie Groh
Keyword(s):  
Water Absorption ◽  
Water Uptake ◽  
Capillary Water ◽  
Capillary Water Absorption ◽  
Absorption Determination ◽  
Colour Changes ◽  
Uptake Velocity ◽  
Outdoor Weathering

The durability of eleven different water repellents applied on one sandstone type was studied after a long-term weathering at seven different locations in Germany. By measuring colour changes, it could be shown that the formation of black crusts, the deposition of particles and biogenic growth caused a gradual darkening as well as significant changes in total colour over time. Additionally, the water absorption behaviour was investigated with two different methods: applying a low pressure using the pipe method and capillary water absorption measurements from a wet underlay. Afterwards, the test results were analysed with four different evaluation methods: calculation of the protection degree from pipe method and capillary water absorption, determination of the velocity of water uptake during capillary water absorption and calculation of the damaged depth of the stone surface using single-sided NMR technique. The growing damaged depth leads to an increase of the water uptake velocity and to a decrease of the protection degree of the applied hydrophobing agents. Three protective agents based on isobutyltrimethoxysilane showed already after two years of outdoor weathering a clear loss of performance, which significantly increased after 30 years of exposure.

Microbial Carbonate Mineralization as an Improvement Method for Durability of Concrete Structures

2011 ◽  
Vol 365 ◽  
pp. 280-286 ◽  
Author(s):  
Pei Hao Li ◽  
Wen Jun Qu
Keyword(s):  
Laboratory Experiments ◽  
Concrete Structures ◽  
Capillary Water ◽  
Water Penetration ◽  
Mineral Crystal ◽  
Microbial Carbonate ◽  
Improvement Method ◽  
Alternative Techniques ◽  
Capillary Water Uptake ◽  
Durability Of Concrete

Biodeposition treatment had been proposed as alternative techniques for improvement in the durability of concrete structures. Laboratory experiments were conducted by bacterially mediated carbonate precipitation on the surface and subsurface of specimens of concrete. Some properties of specimens and crystal, such as the crystal phase, morphology and growth of the crystal deposited on specimens, water penetration, the resistance towards carbonation of concrete and so on, were analyzed by XRD, SEM, water absorptivity test and concrete accelerated carbonation test. Some efficiencies of biodeposition treatment for were investigated by experiment. Results show that the mineral crystal deposits uniformly on the surface and subsurface of specimens, phases of crystal are calcite and vaterite. Biodeposition effectively reduces capillary water uptake and leading to carbonation rate constant decreased by 25~40%. Bacterially mediated carbonate mineralization can be an ecological and novel alternative for improvement in the durability of concrete structures.

Improvement of Concrete Materials by Bacterial-Mediated Precipitation

2011 ◽  
Vol 306-307 ◽  
pp. 455-458 ◽  
Author(s):  
Pei Hao Li ◽  
Wen Jun Qu
Keyword(s):  
Laboratory Experiments ◽  
Carbonate Precipitation ◽  
Accelerated Carbonation ◽  
X Ray Diffraction ◽  
Capillary Water ◽  
X Ray ◽  
Microbial Carbonate ◽  
Microbial Carbonate Precipitation ◽  
Concrete Materials ◽  
Capillary Water Uptake

Microbial carbonate precipitation had been proposed as alternative technique for improvement in concrete materials. Laboratory experiments were conducted by bacterially mediated carbonate deposition on the surface and subsurface of concrete specimens. The crystal phase, morphology and growth of the crystal deposited on specimens as well as the efficiency of bonding and protection were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM), and ultrasonic test. Water absorption and the resistance of carbonation of concrete were analyzed by water absorptivity test and concrete accelerated carbonation test, respectively. Results show that phases of crystal are calcite and vaterite. The crystals are deposited uniformly on the surface of specimens. Biodeposotion effectively reduces capillary water uptake and carbonation rate constant.

scholarly journals Einfluss von Rissen in hydrophobiertem Beton auf den kapillaren Wassertransport / Influence of cracks in water repellent concrete on capillary water movement

1999 ◽  
Vol 5 (1) ◽  
pp. 41-56
Author(s):  
P. Limit ◽  
F.H. Wittmann
Keyword(s):  
Penetration Depth ◽  
Water Uptake ◽  
Crack Width ◽  
Water Movement ◽  
Water Repellent ◽  
Capillary Water ◽  
Effective Surface ◽  
Critical Crack ◽  
Surface Protection ◽  
Penetration Behaviour

Abstract In practice, hydrophobing impregnation has been established as an effective surface protection system against water and de-icing salt attack. Cracks in concrete, whether impregnated by a hydrophobing treatment or not, are unavoidable and can therefore lead to damage. In absorption tests on laboratory samples, the significant influences of cracks on the penetration behaviour of capillary water have been determined and quantified. The experimental results show that the water uptake depends on the craclc width and the penetration depth of the hydrophobing agent. There exists a 'critical' crack width depending on the penetration depth of the hydrophobing agent which can maintain the hydrophobing behaviour. Finally practical conclusions of the present work are drawn.

Effect of glutaraldehyde on water related properties of solid wood

Holzforschung ◽  
2010 ◽  
Vol 64 (4) ◽  
Author(s):  
Zefang Xiao ◽  
Yanjun Xie ◽  
Holger Militz ◽  
Carsten Mai
Keyword(s):  
Cell Wall ◽  
Magnesium Chloride ◽  
Weight Percent ◽  
Tangential Direction ◽  
Solid Wood ◽  
Equal Weight ◽  
Capillary Water ◽  
Weight Losses ◽  
Cell Wall Polymers ◽  
Capillary Water Uptake

Abstract Scots pine sapwood was treated with various concentrations of glutaraldehyde (GA) and magnesium chloride as a catalyst in aqueous solutions. The weight percent gains (WPGs) attained after leaching were 1.0%, 8.6%, 13.7%, and 21.9%, respectively. The treatments reduced the equilibrium moisture content at 90% RH up to 30% compared with the untreated controls. Capillary water uptake of wood was also restrained by GA treatment (8.6% WPG) resulting in water reduction effectiveness of approximately 50% in both radial and tangential direction after 244 h. Wood blocks treated to the highest WPG (22%) attained 70% anti-swelling efficiency (ASE). High ASE values were caused by cell wall bulking through incorporation of GA in the cell wall and as a result of reduction of the maximum degree of swelling in water, i.e., through crosslinking of cell wall polymers. During 10 water submersion and drying cycles, untreated and GA treated specimens displayed equal weight losses indicating that mainly wood constituents were washed out. These cyclic water submersion tests also caused approximately 10% reduction in ASE in samples treated to higher WPG. Magnesium chloride as a catalyst for the reaction of GA imparts wood similar water related properties as sulphur dioxide catalysis of GA treatment, but the application of MgCl2 is much easier to perform in practice.

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