scholarly journals Capillary Water Absorption and Micro Pore Connectivity of Concrete with Fractal Analysis

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 892
Author(s):  
Xiangqun Ding ◽  
Xinyu Liang ◽  
Yichao Zhang ◽  
Yanfeng Fang ◽  
Jinghai Zhou ◽  
...  
Keyword(s):  
Pore Structure ◽  
Water Absorption ◽  
Fractal Theory ◽  
Mineral Admixtures ◽  
Capillary Water ◽  
Capillary Water Absorption ◽  
Connectivity Probability ◽  
Fractal Characteristics ◽  
Different Diameters ◽  
The Relationship

This study focuses on the relationship between the complexity of pore structure and capillary water absorption of concrete, as well as the connection behavior of concrete in specific directions. In this paper, the water absorption of concrete with different binders was tested during the curing process, and the pore structure of concrete was investigated by mercury intrusion porosimetry (MIP). The results show that the water absorption of concrete with mineral admixtures is lower, mainly due to the existence of reasonable pore structure. The effect of slag on concrete modification is more remarkable comparing with fly ash. In addition, the analysis shows that the pore with different diameters has different fractal characteristics. The connectivity probability and water absorption of unidirectional chaotic pore are linearly correlated with the pore diameter of 50–550 nm, and the correlation coefficient reaches a very significant level, and detailed analysis was undertaken to interpret these results based on fractal theory.

The Influence of Pore Structure on the Waterproof Performance of Polymer Modified Mortar

2014 ◽  
Vol 584-586 ◽  
pp. 1130-1134 ◽  
Author(s):  
Dao Xun Ma ◽  
Yan Liu ◽  
Yong Lai
Keyword(s):  
Pore Structure ◽  
Water Absorption ◽  
Penetration Depth ◽  
Open Porosity ◽  
Linear Growth ◽  
Capillary Water ◽  
Cement Ratio ◽  
Capillary Water Absorption ◽  
Cement Mortars ◽  
The Relationship

This paper tested the pore structure, capillary water absorption and impermeability of cement mortars modified with three polymers respectively, establishing the relationship between the pore structure and waterproof performance. The results show that with the polymer dosage growing, especially as the polymer/cement ratio (mp/mc) increases from 0% to 5%, the reduction in the capillary water absorption and the penetration depth of water into mortar is significant. In themp/mcrange of 0%~20% the open porosity presents a gradual decrease trend. The capillary water absorption and the penetration depth of water into mortar show linear growth and exponential growth respectively with the open porosity increasing.

scholarly journals Properties of Self-Compacting Mortar Containing Slag with Different Finenesses

2021 ◽  
Vol 7 (5) ◽  
pp. 840-856
Author(s):  
Said Kenai ◽  
Siham Hammat ◽  
Belkacem Menadi ◽  
Jamal Khatib ◽  
El-Hadj Kadri
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Yield Stress ◽  
Autogenous Shrinkage ◽  
The Other ◽  
Mineral Admixtures ◽  
Rheological Parameters ◽  
Capillary Water ◽  
Capillary Water Absorption ◽  
Slump Flow

It is well established that Self-Compacting Concrete (SCC) contains large amounts of fines including mineral admixtures, such as fly ash and slag, in order to avoid segregation and to increase cohesion. The use of these materials in concrete reduces CO2 emissions and contributes towards sustainable construction. To overcome the negative effect of slag on the strength development slag was ground to three finenesses. Therefore, this paper examines the rheological, compressive strength, total and autogenous shrinkage and capillary water absorption of Self-Compacting Mortars (SCM) containing ground granulated blast furnace Slag (S). A total of seven mortar mixes were prepared. The control mix had a proportion of 1 (cement): 1.8 (sand): 0.38 (water). In the other mixes, the cement was partially replaced with 15% and 30% slag of different fineness of 350, 420, and 500 m2/kg. The other constituents remained unchanged. Testing included slump flow, V-funnel flow time, yield stress and viscosity, compressive strength, total and autogenous shrinkage, and capillary water absorption. The presence of slag was found to reduce the plastic viscosity and yield stress of SCM mixtures as the content and the fineness increase. The higher the fineness (specific surface) of the slag the less the rheological parameters (i.e. slump flow and viscosity). The results show also a reduction in compressive strength of SCM at early ages of curing in the presence of slag. However, in the long-term, the compressive strength of SCM mixtures containing slag was higher than that of control mortar. Generally, there is reduction in the total shrinkage and an increase in the autogenous shrinkage of SCM mixtures as the content and fineness increase. Doi: 10.28991/cej-2021-03091694 Full Text: PDF

scholarly journals Effects of Imposed Damage on the Capillary Water Absorption of Recycled Aggregate Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Qi Gao ◽  
Zhiming Ma ◽  
Jianzhuang Xiao ◽  
Fuan Li
Keyword(s):  
Absorption Coefficient ◽  
Water Absorption ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Capillary Absorption ◽  
Capillary Water ◽  
Aggregate Concrete ◽  
Capillary Water Absorption ◽  
Freeze Thaw ◽  
Loading Level

Capillary water absorption of concrete is closely related to its pore structure, permeability, and durability. This paper intensively investigates the effects of imposed damage, including freeze-thaw damage and loading damage, on the capillary water absorption of recycled aggregate concrete (RAC). Freeze-thaw cycle test, loading test, and the experiment of capillary water absorption were carried out, respectively. The results demonstrate that the addition of recycled coarse aggregate (RCA) results in the increase in the capillary absorption behavior of RAC without imposed damage, and there exists a linear correlation between the behaviors of capillary water absorption and chloride penetration of RAC. The imposed freeze-thaw damage or load damage of RAC boosts with the increase of RCA replacement percentages after suffering the same freeze-thaw cycles or loading level. The imposed freeze-thaw damage and load damage further lead to the increase in the capillary water absorption of RAC, and the capillary absorption coefficient of RAC increases linearly with the increased RCA replacement percentages, after suffering the same freeze-thaw cycles or loading level. Furthermore, capillary absorption coefficient increases linearly with the growth of imposed freeze-thaw damage or load damage degree, which can be used to estimate the capillary absorption behavior of RAC exposed to the extreme environment.

scholarly journals Effect of Grain Size on Microscopic Pore Structure and Fractal Characteristics of Carbonate-Based Sand and Silicate-Based Sand

2021 ◽  
Vol 5 (4) ◽  
pp. 152
Author(s):  
Shao-Heng He ◽  
Zhi Ding ◽  
Hai-Bo Hu ◽  
Min Gao
Keyword(s):  
Grain Size ◽  
Fractal Dimension ◽  
Pore Structure ◽  
Pore Size ◽  
Quartz Sand ◽  
Glass Bead ◽  
Fractal Theory ◽  
Calcareous Sand ◽  
Wide Range ◽  
Fractal Characteristics

In this study, a series of nuclear magnetic resonance (NMR) tests was conducted on calcareous sand, quartz sand, and glass bead with a wide range of grain sizes, to understand the effect of grain size on the micro-pore structure and fractal characteristics of the carbonate-based sand and silicate-based sand. The pore size distribution (PSD) of the tested materials were obtained from the NMR T2 spectra, and fractal theory was introduced to describe the fractal properties of PSD. Results demonstrate that grain size has a significant effect on the PSD of carbonate-based sand and silicate-based sand. As grain size increases, the PSD of sands evolves from a binary structure with two peaks to a ternary structure with three peaks. The increase in the grain size can cause a remarkable increase in the maximum pore size. It is also found that the more irregular the particle shape, the better the continuity between the large and medium pores. In addition, grain size has a considerable effect on the fractal dimension of the micro-pore structure. The increase of grain size can lead to a significant increase in the heterogeneity and fractal dimension in PSD for calcareous sand, quartz sand and glass bead.

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.

scholarly journals Analysis of the Effect of Nano-SiO2 and Waterproofing Agent on the Water Transportation Process in Mortar Using NMR

2020 ◽  
Vol 10 (21) ◽  
pp. 7867
Author(s):  
Tao Meng ◽  
Huadong Wei ◽  
Kanjun Ying ◽  
Menghua Wang
Keyword(s):  
Water Absorption ◽  
Moisture Diffusion ◽  
Test Results ◽  
Capillary Water ◽  
Process Data ◽  
Capillary Water Absorption ◽  
Nano Sio2 ◽  
Water Transportation ◽  
Cement Based Materials ◽  
Transportation Process

Moisture diffusion in cement-based materials significantly impacts its durability. In this study, we analyzed the effect of adding a waterproofing agent and nano-SiO2 (NS) on the water transportation process in mortar using capillary water absorption tests and nuclear magnetic resonance (NMR) technology. The results indicate that the combined action of the waterproofing agent and nano-SiO2 drastically reduce the capillary water absorption coefficient and have a more significant impact than only adding the waterproofing agent. The moisture diffusion in different sections of the mortar during the water absorption process is obtained from the NMR test results and two function models. Comparative studies indicate that the NMR test results have good correlation with the capillary water absorption test results and provide accurate process data. The NMR analysis results offer a new analytical method to characterize the porosity of cement-based materials by continuously monitoring small-pitch sections.

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