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

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.

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.

Remediation and Improvement of Concrete by Bacterial Mediated Carbonate Deposition

2012 ◽  
Vol 446-449 ◽  
pp. 3373-3376 ◽  
Author(s):  
Pei Hao Li ◽  
Kun Wang ◽  
Zhong Jin Wang
Keyword(s):  
Compressive Strength ◽  
Cementitious Materials ◽  
Strength Test ◽  
Accelerated Carbonation ◽  
Concrete Compressive Strength ◽  
Capillary Water ◽  
Flexural Failure ◽  
Compressive Strength Test ◽  
Carbonate Deposition ◽  
Capillary Water Uptake

Bio-deposition has led to the exploration of remediation and improvement technique in the field of cementitious materials. The aim of this study was to investigate the effects of bio-deposited carbonate on parameters affecting concrete properties and the effects of bio-deposition on the durability of concrete specimens. The remediation efficacy of cracks in concrete was studied through compressive strength test and flexural failure test. Water absorption and the resistance towards carbonation of concrete were analyzed by water absorptivity test and concrete accelerated carbonation test, respectively. Experimental results show that bio-deposition is able to make the improvement in concrete compressive strength and the remediation of cracks. Bacterial deposition of calcite on the surface of the concrete specimens results in a decrease of capillary water uptake and carbonation rate constant, and an increase in resistance towards degradation processes.

scholarly journals Properties of Precast Concrete Using Food Industry-Filtered Recycled Diatoms

2021 ◽  
Vol 13 (6) ◽  
pp. 3137
Author(s):  
Carlos Rodriguez ◽  
Isabel Miñano ◽  
Carlos Parra ◽  
Pedro Pujante ◽  
Francisco Benito
Keyword(s):  
Portland Cement ◽  
Food Industry ◽  
Precast Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Chloride Ingress ◽  
Capillary Water ◽  
Experimental Campaign ◽  
Cast Concrete

The concrete industry is under increasing pressure to reduce greenhouse gas emissions. An immediate solution is to minimize the amount of Portland cement used by partially substituting other supplementary cementitious materials. This article presents the results of an experimental campaign on the influence of replacing Portland cement with both calcined and uncalcined diatomites from the filtration of beer and wine in the production of elements made of vibro-pressed pre-cast concrete, such as pipes. Additionally, a natural diatomite is used. The mechanical properties, capillary water absorption, carbonation, and chloride ingress are tested. The results obtained show the possibility of using natural and recycled diatomites on an industrial scale, which can improve even the long term properties of prepared precast concrete.

Sorption Mechanism of Carbon-14 by Hardened Cement Paste

1995 ◽  
Vol 412 ◽  
Author(s):  
K. Noshita ◽  
T. Nishi ◽  
M. Matsuda ◽  
T. Izumida
Keyword(s):  
Electrostatic Force ◽  
Cementitious Materials ◽  
Hardened Cement ◽  
Sorption Mechanism ◽  
Carbon 14 ◽  
Adsorption Sites ◽  
Radioactive Waste Repositories ◽  
Waste Repositories ◽  
Positively Charged

AbstractCarbon-14 sorption by cementitious materials should be enhanced to ensure the long term safety of radioactive waste repositories. The sorption mechanism of inorganic C- 14 (CO32- was investigated using batch sorption experiments and zeta potential measurements. The results suggested that C-14 was adsorbed onto the cement surface by an electrostatic force, due to the reaction between SiO2 and CaO contained in the cementitious composition. That is, SiO2 was originally negatively charged (SiO-) in cement, but became positively charged through the interaction of Ca2+. These positive sites on the SiO2 surface adsorbed inorganic C-14. Ordinary Portland cement (OPC) did not contain enough SiO2 compared with its CaO content to produce sufficient numbers of C-14 adsorption sites. The C-14 distribution coefficient (Kd) was increased from 2,000 to 7,000 mL/g by adding SiO2 to OPC.

Managing drought-sensitive forests under global change. Low competition enhances long-term growth and water uptake in Abies pinsapo

2017 ◽  
Vol 406 ◽  
pp. 72-82 ◽  
Author(s):  
Victor Lechuga ◽  
Vinicio Carraro ◽  
Benjamín Viñegla ◽  
José Antonio Carreira ◽  
Juan Carlos Linares
Keyword(s):  
Global Change ◽  
Water Uptake ◽  
Abies Pinsapo
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