scholarly journals The Thermal Parameters of Mortars Based on Different Cement Type and W/C Ratios

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4258
Author(s):  
Agata Stolarska ◽  
Jarosław Strzałkowski
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Surface ◽  
Surface Area ◽  
Point Of View ◽  
Thermal Parameters ◽  
Cement Type ◽  
Water Absorbability ◽  
The Relationship ◽  
Total Specific Surface Area

This study examines the thermal parameters of mortars based on different cement type and water-cement W/C ratios. The presented relationships are important from the point of view of thermal insulation of the entire building component, of which the mortar is a part. The thermal properties of the mortar, and in particular its dependence on the degree of moisture, is important information from the point of view of hygrothermal simulations of building components. The moisture effect on the thermal properties was tested using nine mortar types. The study consisted of producing nine types of mortar on the basis of three cements (CEM I 42.5R, CEM II A-S 52.5N, CEM III A 42.5N). For each cement type, three variants of specimens were prepared which differed according to their water/cement ratio (0.50, 0.55 and 0.60). The main research of thermal parameters was carried out using a non-stationary method based on the analysis of changing heat flux readings. The thermal conductivity, volume-specific heat and thermal diffusivity values were analyzed. The tests performed allowed for determination of the density of specimens, water absorbability and thermal parameters in three water saturation states: dry, natural and wet. Additional microstructural tests were performed using mercury intrusion porosimetry. The obtained parameters were used to determine the relationship between the measured properties. An adverse effect of dampness on the thermal insulation of the studied materials was confirmed. In extreme cases, the increase in thermal conductivity due to material high moisture was 93%. The cement used affects the relationship between the total specific surface area and the W/C ratio. As expected, the total porosity of specimens was higher for mortars with higher W/C ratios. A strong correlation has been demonstrated between the total surface area and thermal conductivity. The opposite results were obtained when assessing the relationship between the total specific surface area and water absorbability. In case of specimens CEM II A-S 52.5N, the relation was the proportional, and in specimens CEM III A 42.5N, the relationship was inversely proportional to the W/C ratio.

scholarly journals Tuning the Mechanical and Thermal Properties of Hydroxypropyl Methylcellulose Cryogels with the Aid of Surfactants

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 118
Author(s):  
Rafael S. Dezotti ◽  
Laíse M. Furtado ◽  
Márcio Yee ◽  
Ticiane S. Valera ◽  
Krishnasamy Balaji ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Surface ◽  
Interaction Energy ◽  
Surface Area ◽  
Specific Surface Area ◽  
Hydroxypropyl Methylcellulose ◽  
Hydroxyl Group ◽  
Sulfonate Group ◽  
Mechanical And Thermal Properties

The mechanical and thermal properties of cryogels depend on their microstructure. In this study, the microstructure of hydroxypropyl methylcellulose (HPMC) cryogels was modified by the addition of ionic (bis (2-ethylhexyl) sodium sulfosuccinate, AOT) and non-ionic (Kolliphor® EL) surfactants to the precursor hydrogels (30 g/L). The surfactant concentrations varied from 0.2 mmol/L to 3.0 mmol/L. All of the hydrogels presented viscous behavior (G″ > G′). Hydrogels containing AOT (c > 2.0 mmol/L) led to cryogels with the lowest compressive modulus (13 ± 1 kPa), the highest specific surface area (2.31 m2/g), the lowest thermal conductivity (0.030 W/(m·°C)), and less hygroscopic walls. The addition of Kolliphor® EL to the hydrogels yielded the stiffest cryogels (320 ± 32 kPa) with the lowest specific surface area (1.11 m2/g) and the highest thermal conductivity (0.055 W/(m·°C)). Density functional theory (DFT) calculations indicated an interaction energy of −31.8 kcal/mol due to the interaction between the AOT sulfonate group and the HPMC hydroxyl group and the hydrogen bond between the AOT carbonyl group and the HPMC hydroxyl group. The interaction energy between the HPMC hydroxyl group and the Kolliphor®EL hydroxyl group was calculated as −7.91 kcal/mol. A model was proposed to describe the effects of AOT or Kolliphor®EL on the microstructures and the mechanical/thermal properties of HPMC cryogels.

scholarly journals Structure, specific surface area and thermal conductivity of the snowpack around Barrow, Alaska

2012 ◽  
Vol 117 (D14) ◽  
pp. n/a-n/a ◽  
Author(s):  
Florent Domine ◽  
Jean-Charles Gallet ◽  
Josué Bock ◽  
Samuel Morin
Keyword(s):  
Thermal Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area

Effect of ACF Properties on the Electric Adsorption Performance of the ACF Electrode

2012 ◽  
Vol 209-211 ◽  
pp. 1990-1994 ◽  
Author(s):  
Qin Zhang ◽  
Zhao Hui Zhang ◽  
Liang Wang ◽  
Zi Long Zhang ◽  
Xing Fei Guo
Keyword(s):  
Activated Carbon ◽  
Carbon Fiber ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Activated Carbon Fiber ◽  
Adsorption Performance ◽  
Carbon Fiber Cloth ◽  
Activated Carbon Fiber Cloth ◽  
The Relationship

The properties of four different activated carbon fiber cloth (ACF), such as specific surface area, pore volumes and pore size distribution, were evaluated. The relationship between ACF properties and its electrosorption performance was analyzed. The experimental results show that pore structure has more influence on the performance of ACF electrode than that of specific surface area for ACF material. More abundant mesopores and shallower pore channels for ACF is favorable to improve the specific capacitance and electrosorption capacity of ions.

Influence of Surface Area on the Flowability Behaviour of Self-Flow Refractory Castables

2010 ◽  
Vol 636-637 ◽  
pp. 124-129 ◽  
Author(s):  
D.G. Pinto ◽  
Abílio P. Silva ◽  
A.M. Segadaes ◽  
T.C. Devezas
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Raw Materials ◽  
High Hardness ◽  
Size Composition ◽  
High Melting Point ◽  
Refractory Castables ◽  
Materials Used ◽  
The Relationship

Alumina, with high melting point (2050°C), high hardness and mechanical strength, and excellent abrasion resistance, is one of the most common raw materials used in self-flow refractory castables (SFRC) for monolithic linings and is commercially available in various fine to coarse size classes. However, the performance of the refractory lining depends not only on the properties of its ingredients but also on its easy installation (good flowability). The aim of this work was to evaluate the relationship between the flowability index (FI) of fresh castable and the specific surface area (SSA) of its particles, which is mostly determined by the finer particles content. The results obtained showed that, by controlling the proportion between matrix and aggregate, it is possible to control the SSA of the refractory castable and find a mathematical relationship between the specific surface area and the minimum flowability index required to obtain a self-flow refractory castable. It is, thus, possible to optimize the refractory castable size composition and obtain an estimate for FI as a function of SSA. Using a minimum 45 wt.% matrix content in the castable mixture, a SSA value above 2.215 m2/g is obtained, which leads to FI ≥ 80%, the recommended value for self-flow.

Temperature Gradient of Concrete Pavement Slab Overlaid with Asphalt Surface Course

2000 ◽  
Vol 1730 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Tatsuo Nishizawa ◽  
Shigeru Shimeno ◽  
Akinori Komatsubara ◽  
Masashi Koyanagawa
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Stress ◽  
Temperature Gradient ◽  
Numerical Simulations ◽  
Structural Design ◽  
Concrete Slab ◽  
Concrete Pavement ◽  
Reduction Effect ◽  
The Relationship

In the structural design of composite pavement with a concrete pavement slab overlaid with an asphalt surface course, it is very important to estimate the temperature gradient in the concrete slab. An asphalt surface course reduces the temperature gradient in an underlaid concrete slab, resulting in the reduction of thermal stress of the concrete slab. This effect was investigated by temperature measurement in model pavements and by thermal conductivity analysis. Thermal properties were estimated by a backanalysis by using measured temperatures over 1 year. From the numerical simulations varying the thickness of asphalt surface and concrete slab, the relationship between the reduction effect and the asphalt thickness was derived as a function of the thickness of asphalt surface course, which can be used in the structural design of the composite pavement.

Design of SAW Specific Gas Sensor with High Sensitivity

2013 ◽  
Vol 303-306 ◽  
pp. 137-142
Author(s):  
Jin Yi Ma ◽  
Jing Yang ◽  
Bo Du ◽  
Lu Wang ◽  
Hong Min Jiang ◽  
...  
Keyword(s):  
High Temperature ◽  
Acoustic Wave ◽  
Specific Surface ◽  
Surface Area ◽  
Gas Sensor ◽  
Temperature Stability ◽  
High Sensitivity ◽  
Response Speed ◽  
High Temperature Stability ◽  
The Relationship

To improve the temperature stability, response speed and sensitivity of surface acoustic wave (SAW) gas sensor, the relationship between the sensing region of the resonator for SAW gas sensor and the sensitivity of sensor is studied, a specific resonator with big space topology structure is proposed. A SAW resonator with high temperature stability is investigated from the viewpoint of piezoelectric material, cut type and fabrication process. A nano-wire bundle based SAW gas sensor with big specific-surface-area is proposed.

Research on the Relationship between Thermal Conductivity and Porosity during Carbonation of Cement Materials

2014 ◽  
Vol 1065-1069 ◽  
pp. 1838-1841
Author(s):  
Son Tung Pham
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Cement Mortar ◽  
Total Porosity ◽  
Accelerated Carbonation ◽  
Experimental Campaign ◽  
Hydrostatic Weighing ◽  
Specific Material ◽  
The Relationship ◽  
Microstructural Studies

The objective of this work was to examine the relationships that may exist between porosity and thermal conductivity with particular reference to normalized cement mortar which is most commonly found in civil engineering. Samples were prepared and subjected to accelerated carbonation at 20°C, 65% relative humidity and 20% CO2 concentration. We investigated the evolution of the total porosity measured by hydrostatic weighing and of the thermal properties measured by Hotdisk method. This experimental campaign allowed relating the total porosity and the thermal conductivity before and during carbonation. These results can be used for further studies which can propose models predicting the thermal conductivity if changes in porosity are known. Moreover, the results indicated that the thermal conductivity of a cement material is directly related to the density and inversely related to porosity. Finally, this study showed that a characteristic coefficient can be deduced for two states of material: non-carbonated and carbonated. This coefficient is therefore proper to a specific material and can be used not only for modeling the relationship between porosity and thermal properties but also for other microstructural studies of cement materials.

TiO2 mesocrystals built of nanocrystals with exposed {001} facets: facile synthesis and superior photocatalytic ability

2014 ◽  
Vol 2 (46) ◽  
pp. 19589-19593 ◽  
Author(s):  
Yanna Guo ◽  
Hui Li ◽  
Jin Chen ◽  
Xuejing Wu ◽  
Lei Zhou
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Crystallite Size ◽  
Surface Area ◽  
Crystallographic Orientation ◽  
Low Cost ◽  
Facile Synthesis ◽  
Photocatalytic Ability ◽  
Similar Crystallographic Orientation ◽  
The Relationship

A totally novel, extremely easy, much greener and low-cost method has been developed to synthesize TiO2 mesocrystals. These materials are built of TiO2 nanocrystals with similar crystallographic orientation and largely exposed {001} facets. Their unique structure optimizes the relationship between specific surface area, crystallite size and active facets, and therefore leads to superior photocatalytic activity.

scholarly journals The Brandon mathematical model describing the effect of calcination and reduction parameters on specific surface area of ex-ADU UO₂ powders

2016 ◽  
Vol 6 (3) ◽  
pp. 54-59
Author(s):  
Trong Hung Nguyen ◽  
Ba Thuan Le
Keyword(s):  
Mathematical Model ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Uranyl Carbonate ◽  
Proposed Model ◽  
And Control ◽  
The Relationship ◽  
Fabrication Parameters ◽  
Good Agreement

The report “Brandon mathematical model describing the effect of calcination and reduction parameters on specific surface area of UO2 powders” [14] has built up a mathematical model describing the effect of the fabrication parameters on SSA (Specific Surface Area) of ex-AUC (Ammonium Uranyl Carbonate) UO2 powders. In the paper, the Brandon mathematical model that describe the relationship between the essential fabrication parameters [reduction temperature (TR), calcination temperature (TC), calcination time (tC) and reduction time (tR)] and SSA of the obtained ex-ADU (Ammonium Di-Uranate) UO2 powder product has established. The proposed model was tested with Wilcoxon’s rank sum test, showing a good agreement with the experimental parameters. The proposed model can be used to predict and control the SSA of ex-ADU UO2 powders

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