A water permeability model of nano-reinforced cement pastes based on GEM theory and multifractals

2021 ◽  
pp. 1-24
Author(s):  
Yuan Gao ◽  
Hongwen Jing ◽  
Zefu Zhou ◽  
Xinshuai Shi ◽  
Zhenlong Zhao
Keyword(s):  
Water Permeability ◽  
Permeability Model ◽  
Cement Pastes ◽  
Reinforced Cement

Glass Fiber Composites Made with a Cement Based on a Hydraulically Active CaO-SiO2-Al2O3 Glass

1990 ◽  
Vol 211 ◽  
Author(s):  
C. Hommertgen ◽  
I. Odler
Keyword(s):  
Glass Fiber ◽  
Fiber Composites ◽  
Fiber Reinforced ◽  
Cement Pastes ◽  
Glass Fiber Composites ◽  
Glass Fiber Reinforced ◽  
Reinforced Cement

AbstractGlass fiber reinforced cement pastes were prepared using a cement based on a hydraulically active glass in the system CaO-SiO2-Al2O3. The properties of such composites were compared with those made with ordinary portland cement.In all the studied materials the MOR and WOF values declined with time, however for different reasons.

Properties of Permeable Concrete Substrate Having Dual Pore Structures

2008 ◽  
Vol 569 ◽  
pp. 233-236
Author(s):  
Z. X. Yang ◽  
Kyu Hong Hwang ◽  
Jeong Bae Yoon ◽  
J.O. Kim ◽  
M.C. Kim
Keyword(s):  
Sodium Bicarbonate ◽  
Physical Properties ◽  
Cement Paste ◽  
Water Permeability ◽  
Vacuum Pressure ◽  
Adsorption Ability ◽  
Cement Pastes ◽  
Porous Concrete ◽  
Digital Microscope

Porous concretes with continuous voids have been gaining more interest as an ecological material because of their useful functions such as water permeability and adsorption ability. Especially, to make porous concrete much more environmentalized, micropores play a role of nest for microorganism and germs to live in. So micropore distribution and the size of micropores especially open pores are the key point . In this study, the size and distribution of micropores of porous concrete were effected by the AE agents to the cement pastes and then by the treating types, treating times, treating temperatures, and the vacuum pressure during the treating. And another group specimens were added sodium bicarbonate and alum. And then physical properties were examined, digital microscope was also used to observe the micropores sizes and distributions. Cracks were observed on the cement-aggregate joint when the amount and vacuum pressure increased. And high treating temperature shows no good on the bonding of cement paste and aggregate.

The Diffusion of Chloride Ions in Fly Ash/Cement Pastes and Mortars

1986 ◽  
Vol 85 ◽  
Author(s):  
R. I. A. Malek ◽  
D. M. Roy ◽  
P. H. Licastro
Keyword(s):  
Fly Ash ◽  
Water Permeability ◽  
Electrical Potential ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Basic Material ◽  
Fly Ashes ◽  
Cement Pastes ◽  
High Calcium ◽  
Class F

ABSTRACTFly ashes having three distinctly different levels of calcium, designated low-calcium (Class F), intermediate-calcium (Class F/C), and high-calcium (Class C), comprised the basic material for the present study. Pastes and mortars were made using cement and one of three types of fly ashes at various levels of replacement and water-solid ratios. Chloride ion diffusion was measured by applying an electrical potential across cured cylindrical samples and measuring the amount of current passed in a certain period of time (proportional to amount of CE” passed in this time). Other supportive measurements were made, e.g. porosity, pore size distribution, water permeability and surface area. The Cl− ion diffusivity was correlated with the chemical composition of fly ash, mix proportion, and water permeability of the hardened paste or mortar.

Cement as a thermoelectric material

2000 ◽  
Vol 15 (12) ◽  
pp. 2844-2848 ◽  
Author(s):  
Sihai Wen ◽  
D. D. L. Chung
Keyword(s):  
Thermoelectric Power ◽  
Cement Paste ◽  
Carbon Fibers ◽  
Cement Matrix ◽  
Electron Conduction ◽  
Cement Pastes ◽  
Hole Conduction ◽  
Reinforced Cement ◽  
The Absolute ◽  
Short Carbon

Cement pastes containing short steel fibers, which contribute to electron conduction, exhibit positive values (up to 68 μV/°C) of the absolute thermoelectric power. Cement pastes containing short carbon fibers, which contribute to hole conduction while the cement matrix contributes to electron conduction, exhibit negative or slightly positive values of the absolute thermoelectric power. The hole and electron contributions in carbon fiber reinforced cement paste are equal at the percolation threshold. Addition of either steel or carbon fibers to cement paste yields more reversibility and linearity in the variation of the Seebeck voltage with temperature difference (up to 65 °C).

Influence of Oxygen Plasma Surface Treatment of PET Micro Fibers on Flexural Strength of Reinforced Cement Pastes

2016 ◽  
Vol 825 ◽  
pp. 73-76
Author(s):  
Jan Trejbal ◽  
Jan Bartoš ◽  
Lubomír Kopecký ◽  
Pavla Ryparová ◽  
Štěpán Potocký
Keyword(s):  
Surface Treatment ◽  
Oxygen Plasma ◽  
Fiber Surface ◽  
Cement Matrix ◽  
Cement Pastes ◽  
Softening Behavior ◽  
Plasma Surface Treatment ◽  
Water To Cement Ratio ◽  
Reinforced Cement ◽  
Fiber Surface Treatment

Presented work deals with PET (polyethylene terephthalate) fiber-reinforced cement pastes and cool oxygen plasma fiber surface treatment used to attain the better adhesion between fibers surface and the cement matrix. Three sets of cement paste samples were made with the same matrix (CEM I 42.5R with water to cement ratio equal to 0.4). The two sample sets contained micro fiber reinforcement varying in surface properties. One set was reinforced with unmodified fibers, while in to the other set plasma treated fibers were used. As a comparative indicator to bending response of the composite materials, four-point destructive tests were carried out. The samples reinforced with unmodified fibers exhibited deflection-softening behavior during the post-cracking phase, while samples with plasma treated fibers exhibited deflection-hardening behavior.

Nanofibrillated cellulose as nanoreinforcement in Portland cement: Thermal, mechanical and microstructural properties

2016 ◽  
Vol 51 (17) ◽  
pp. 2491-2503 ◽  
Author(s):  
Roukaya Mejdoub ◽  
Halim Hammi ◽  
Joan Josep Suñol ◽  
Mohamed Khitouni ◽  
Adel M‘nif ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Cement Hydration ◽  
Coefficient Of Thermal Expansion ◽  
Nanofibrillated Cellulose ◽  
Partial Replacement ◽  
Cellulose Content ◽  
Cement Pastes ◽  
Eucalyptus Pulp ◽  
Reinforced Cement ◽  
Mechanical And Microstructural Properties

Nanofibrillated cellulose from eucalyptus pulp, produced by high-pressure homogenization, was used as cement partial replacement for cement paste at a content ranging from 0% to 0.5% by weight of cement. The effect of the content of nanofibrillated cellulose on porosity, thermal properties, compressive strength and degree of cement hydration was investigated. Results have shown an improvement in the compressive strength by more than 50% with 0.3 wt% of added nanofibrillated cellulose. The porosity was reduced by nanofibrillated cellulose addition, and the greatest result was achieved with mixture incorporating 0.3 wt% nanofibrillated cellulose. The coefficient of thermal expansion and the thermal conductivity measurements, relative to nanofibrillated cellulose-reinforced cement pastes, have pointed out the reinforcement effectiveness of nanofibrillated cellulose. The degree of cement hydration has increased with nanofibrillated cellulose content. This trend was confirmed by X-ray diffraction and Fourier Transform Infrared spectroscopy. These analyses have revealed that the presence of nanofibrillated cellulose promoted the hydration of cement, by producing more portlandite and calcium silicate gel, which is likely the main reason accounting for the strong enhancement in the compressive strength.

Distribution and Shape of the Pores in Water Permeable Concrete

2007 ◽  
Vol 544-545 ◽  
pp. 227-230
Author(s):  
Z. X. Yang ◽  
Jeong Bae Yoon ◽  
J.O. Kim ◽  
Kyu Hong Hwang ◽  
B.S. Jun ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Water Permeability ◽  
Type I ◽  
Adsorption Ability ◽  
Cement Pastes ◽  
Size And Shape ◽  
Crushed Aggregate ◽  
Type C

Porous concretes with continuous voids have been gaining more interest as an ecological material because of their useful functions such as water permeability and adsorption ability. So pore size distribution and the shape of especially open pores are the key point to permeability. In this study, the size and shape of pores of water permeable concrete were primary controlled by the size and shape of aggregates and secondly by the expanding agents to the cement pastes. 2 types of raw coase aggregate, type I and type C which mean fabricated by impact crusher and concrusher, were taken into uses and 3 sizes of aggregate were used, namely 3 to 5mm, 5 to 13 mm, and 13 to 20 mm. The compressive strength was found to be higher when using impact crushed aggregate. And the smaller size of aggregate was used, the higher compressive strength was achieved.

Compressive Strength and Microstructure of Multi-Wall Carbon Nanotubes Reinforced Cement Composites

2012 ◽  
Vol 450-451 ◽  
pp. 594-599
Author(s):  
Jin Tao Liu ◽  
Dong Ming Yan ◽  
Shi Lang Xu
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Carbon Nanotube ◽  
Microscopic Analysis ◽  
Cement Composites ◽  
Cement Pastes ◽  
Multi Wall Carbon Nanotubes ◽  
Multi Walled Carbon Nanotubes ◽  
Reinforced Cement ◽  
Walled Carbon Nanotubes

Advancement in the study of carbon nanotube has enabled its application in civil engineering as constitutive materials or additives. In this study, the availability of applying multi-walled carbon nanotube to improve the characteristics of cement composites was investigated with experiments on more than 30 specimens. The multi-walled carbon nanotubes (MWCNTs) were effectively dispersed in the water with surfactant, which can keep stable for over 3 months. Specimens with MWCNTs of 0.025%, 0.05% and 0.1% of cement (by weight) were tested with a loading machine and then analyzed with a SEM. It was found that the compressive strength of the samples increased with the increasing MWCNTs, it can improve the 7-day compressive strength by 22% . Microscopic analysis (SEM) revealed that carbon nanotubes were surrounded with hydration products. The bridging and debonding of carbon nanotubes in cement pastes was observed as well.

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