Physical evidence of swelling as the cause of anomalous capillary water uptake by cementitious materials

2019 ◽  
Vol 120 ◽  
pp. 256-266 ◽  
Author(s):  
N.M. Alderete ◽  
Y.A. Villagrán Zaccardi ◽  
N. De Belie
Keyword(s):  
Water Uptake ◽  
Cementitious Materials ◽  
Capillary Water ◽  
Physical Evidence ◽  
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.

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 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 Influence of Crystalline Admixtures on the Short-Term Behaviour of Mortars Exposed to Sulphuric Acid

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 82 ◽  
Author(s):  
Victoria García-Vera ◽  
Antonio Tenza-Abril ◽  
José Saval ◽  
Marcos Lanzón
Keyword(s):  
Compressive Strength ◽  
Absorption Coefficient ◽  
Water Absorption ◽  
Sulphuric Acid ◽  
Cementitious Materials ◽  
Pulse Velocity ◽  
Capillary Water ◽  
Short Term ◽  
Water Absorption Coefficient ◽  
Capillary Water Absorption

Using durable materials is a sustainable solution for extending the lifetime of constructions. The use of crystalline admixtures makes cementitious materials more durable. They plug pores, capillary tracts and microcracks, blocking the entrance of water due to the formation of crystals that prevent the penetration of liquids. The literature has covered the performance of these admixtures on concrete, but studies on mortars are still scarce. The aim of this study is to investigate the effect of an aggressive environment (sulphuric acid solution—3 wt%) on mortars produced with different percentages of a crystalline admixture (1%, 1.5% and 2% by weight of cement content). Physical and mechanical properties were studied after immersing the mortars in a H2SO4 solution for 90 days. It was found that, after a 90-day sulphuric acid exposure, mortars with the crystalline admixture showed greater compressive strength than the control mortar, besides exhibiting lower mass loss. However, the crystalline admixture did not produce any significant effect on the capillary water absorption coefficient. In a nonaggressive environment, and in the short term, the crystalline admixture did not have a significant effect on the compressive strength, the capillary water absorption coefficient or the ultrasonic pulse velocity.

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