scholarly journals Accumulation of moisture of cellular concrete wall structures in the annual cycle

2021 ◽  
pp. 55-67
Author(s):  
Veronika Aleksandrovna Shakirova
Keyword(s):  
Annual Cycle ◽  
Construction Materials ◽  
Mineral Wool ◽  
Climatic Conditions ◽  
Wall Structure ◽  
Concrete Wall ◽  
Outdoor Climate ◽  
Wall Structures ◽  
One Year ◽  
Cellular Concrete

This article delivers the calculation of moisture accumulation of the wall structure in the annual cycle for the climatic conditions of Krasnoyarsk. Analysis is conducted on the multilayer wall structure made of cellular concrete, with the plaster based on cement-sand mortar as top layer and use of thermal insulation in the form of mineral wool board. The subject of this research is the typical corner unit made of cellular concrete in combination with monolithic belt and an inter-floor overlap used in low-rise construction. The author acquires the results of moisture accumulation in layers of the structure for each month within one year, depending on the climatic parameters. The novelty lies in the fact that the outdoor climate and sorption moisture influences the accumulation of moisture in construction materials, creating a large seasonal increase in moisture. Consideration of these factors in the design process, allows making the structures more durable and energy-efficient. The conclusion is made that the distribution of moisture structural layers under climatic conditions. Krasnoyarsk is uneven throughout the year; however, meet the regulations. It is recommended to conducted regulation in the design in order to maintain the level of moisture in construction materials

scholarly journals Heat flow redistribution in wall structure during diurnal cycle in summer

2021 ◽  
Vol 23 (2) ◽  
pp. 96-104
Author(s):  
A. N. Belous ◽  
O. E. Belous ◽  
S. V. Krakhin
Keyword(s):  
Heat Flow ◽  
Flow Distribution ◽  
Climatic Conditions ◽  
Wall Structure ◽  
Main Role ◽  
Summer Period ◽  
Transfer Resistance ◽  
Wall Structures ◽  
Calculation Results ◽  
Main Factor

The standardized indicator is the heat transfer resistance as the main factor that plays the main role in assessing the energy efficiency of the thermal envelope of a building. During the last decades, the climatic conditions change toward the increase in average daily temperature in the summer period. Thus, the thermal resistance of external wall structures becomes more and more urgent. This problem is reduced to an assumption that the heat flow in the wall structure is directed from the external surface to the internal. This paper analyzes the heat flow distribution and redistribution in time in the wall structure. The paper presents a comparative analysis of the modelling and calculation results of the nonstationary heat flow for solving the thermal stability problem.

Utilization of Granite powder and Glass Powder in Reactive Powder Concrete: Assessment of Strength and Long Term Durability Properties

2021 ◽  
Author(s):  
Venkatesan B ◽  
Kannan V ◽  
Sophia M
Keyword(s):  
Electrical Resistivity ◽  
Glass Powder ◽  
Construction Materials ◽  
Reactive Powder Concrete ◽  
Waste Glass Powder ◽  
Chloride Migration ◽  
One Year ◽  
Granite Powder ◽  
Reactive Powder

This paper aims to assess the mechanical and long-term durability performance of Reactive Powder Concrete (RPC) containing Granite Powder (GrP) as cement replacement and waste Glass Powder (GP) as quartz sand replacement. The workability and mechanical behaviour of RPC containing various proportions of GrP and GP are assessed for different w/b ratios (0.3, 0.35, 0.4 and 0.45). The water resistance and tightness of RPC are measured by monitoring the electrical resistivity, water absorption, sorptivity and chloride migration over a one year period. Results reveal that substitution of GrP and GP at optimum levels of 15% and 30% respectively enhances the performance of RPC with the achievement of satisfiable workability at a 0.35 w/b ratio. A significant increase in the resistance towards chloride penetration and electrical resistivity was also observed with increasing ages. Thus, glass powder and granite powder can be considered as alternative construction materials providing economical and ecological efficiency.

Study on the shear wall structure with combined form of replaceable devices

2017 ◽  
Vol 21 (9) ◽  
pp. 1327-1348
Author(s):  
Cong Chen ◽  
Renjie Xiao ◽  
Xilin Lu ◽  
Yun Chen
Keyword(s):  
Shear Walls ◽  
Shear Wall ◽  
Performance Comparison ◽  
Wall Structure ◽  
Structural Part ◽  
Coupled Shear Wall ◽  
Wall Structures ◽  
Strength And Stiffness ◽  
Energy Dissipated ◽  
Resilient Structure

Structure with replaceable devices is a type of earthquake resilient structure developed to restore the structure immediately after strong earthquakes. Current researches focus on one type of the replaceable device located in the structural part that is most likely to be damaged; however, plastic deformation would not be limited in a specific part but expand to other parts. To concentrate possible damage in shear wall structures, combined form of replaceable devices was introduced in this article. Based on previous studies, combined form of replaceable coupling beam and replaceable wall foot was used in a coupled shear wall. Influences of the dimension and location of the replaceable devices to the strength and stiffness of the shear wall were investigated through numerical modeling, which was verified by experimental data. Performance comparison between the shear walls with one type and combined form of replaceable devices and the conventional coupled shear wall was performed. In general, the shear wall with combined form of replaceable devices is shown to be better energy dissipated, and proper dimensions and locations of the replaceable devices should be determined.

scholarly journals Methacholine responsiveness of proximal and distal airways of monkeys and rats using videomicrometry

2002 ◽  
Vol 92 (3) ◽  
pp. 989-996 ◽  
Author(s):  
Kayleen S. Kott ◽  
Kent E. Pinkerton ◽  
John M. Bric ◽  
Charles G. Plopper ◽  
Krishna P. Avadhanam ◽  
...  
Keyword(s):  
Airway Hyperresponsiveness ◽  
Airway Responsiveness ◽  
Wall Structure ◽  
Airway Closure ◽  
Airway Wall ◽  
Human Airway ◽  
Wall Structures ◽  
Distal Airway ◽  
Luminal Area ◽  
Young Rat

Rat and monkey are species that are used in models of human airway hyperresponsiveness. However, the wall structures of rat and monkey airways are different from each other, with that of the monkey more closely resembling that of humans. We hypothesized that differences in wall structure would explain differences in airway responsiveness. Using videomicrometry, we measured airway luminal area in lung slices to compare proximal and distal airway responsiveness to methacholine in the rat and monkey. The airway type was then histologically identified. Proximal airways of the young rat and monkey were equally responsive to methacholine. In contrast, respiratory bronchioles of monkeys were less responsive than were their proximal bronchi, whereas the distal bronchioles of rats were more responsive than their proximal bronchioles. Both proximal and distal airways of younger monkeys were more responsive than those of older monkeys. Airway heterogeneity in young monkeys was greatest with regard to degree of airway closure of respiratory bronchioles. We conclude that responsiveness to methacholine varies with airway wall structure and location.

scholarly journals A 1D Model for Predicting Heat and Moisture Transfer through a Hemp-Concrete Wall Using the Finite-Element Method

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6903
Author(s):  
Maroua Benkhaled ◽  
Salah-Eddine Ouldboukhitine ◽  
Amer Bakkour ◽  
Sofiane Amziane
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Moisture Transfer ◽  
Construction Material ◽  
Climatic Conditions ◽  
Vapor Permeability ◽  
Transfer Model ◽  
The Finite Element Method ◽  
Concrete Wall ◽  
Element Method

Plant-based concrete is a construction material which, in addition to having a very low environmental impact, exhibits excellent hygrothermal comfort properties. It is a material which is, as yet, relatively unknown to engineers in the field. Therefore, an important step is to implement reliable mass-transfer simulation methods. This will make the material easy to model, and facilitate project design to deliver suitable climatic conditions. In recent decades, numerous studies have been carried out to develop models of the coupled transfers of heat, air and moisture in porous building envelopes. Most previous models are based on Luikov’s theory, considering mass accumulation, air and total pressure gradient. This theory considers the porous medium to be homogeneous, and therefore allows for hygrothermal transfer equations on the basis of the fundamental principles of thermodynamics. This study presents a methodology for solving the classical 1D (one-dimensional) HAM (heat, air, and moisture) hygrothermal transfer model with an implementation in MATLAB. The resolution uses a discretization of the problem according to the finite-element method. The detailed solution has been tested on a plant-based concrete. The energy and mass balances are expressed using measurable transfer quantities (temperature, water content, vapor pressure, etc.) and coefficients expressly related to the macroscopic properties of the plant-based concrete (thermal conductivity, specific heat, water vapor permeability, etc.), determined experimentally. To ensure this approach is effective, the methodology is validated on a test case. The results show that the methodology is robust in handling a rationalization of the model whose parameters are not ranked and not studied by their degree of importance.

scholarly journals Application of physical theory of cavity in the construction of double skin facades

2021 ◽  
Vol 9 (1) ◽  
pp. 40-53
Author(s):  
Boris Bielek ◽  
Daniel Szabó ◽  
Josip Klem ◽  
Kristína Kaniková
Keyword(s):  
Flow Line ◽  
Aerodynamic Resistance ◽  
Climatic Conditions ◽  
Operating Modes ◽  
Outdoor Climate ◽  
Energy Needs ◽  
In Situ Experiments ◽  
Correct Function ◽  
Double Skin ◽  
Double Skin Facades

Abstract The article deals with the issue of double skin transparent facades as a new technological-operational system of transparent exterior walls. Especially of high-rise buildings, which with its operating modes ingeniously uses a renewable source of solar energy to reduce the energy needs of the building. The basic precondition for the correct function of the double skin facade is its functional aerodynamics in any climatic conditions of the outdoor climate. In the critical state of windlessness, the aerodynamic quantification of a double skin facade is the total aerodynamic resistance of the cavity, which consists of the aerodynamic frictional resistances along the length of the air flow line and local aerodynamic resistances of the cavity. The article analyses the functional aerodynamics on two frequented types of double skin facades with a narrow type and corridor type cavity. At the end it confronts functional aerodynamics with the results of their temperature, aerodynamic and energy regime obtained from in-situ experiments.

scholarly journals The Analysis of Outdoor Climate, Moist Air Enthalpy and their Relation to Cooling Energy Consumption in the Tropics

2018 ◽  
Vol 7 (4.35) ◽  
pp. 254
Author(s):  
Waraporn Rattanongphisat ◽  
Anantachai Suwannakom
Keyword(s):  
Energy Consumption ◽  
Correlation Coefficient ◽  
Energy Demand ◽  
Climate Data ◽  
Outdoor Temperature ◽  
Indoor Climate ◽  
Outdoor Climate ◽  
Enthalpy Difference ◽  
One Year ◽  
The Tropics

The air conditioned auditorium classroom was monitored for energy consumption by a monitoring platform. One year collected data from energy consumption and indoor climate monitoring systems and outdoor climate data in Phitsanulok province, Thailand, where its climate classified as the tropics, was employed to determine their relation by regression analysis. The analysis of climate data showed that the outdoor temperature above 26 oC was accounted for 70% of the year this emphasizes on cooling requirement. Furthermore, the hourly cooling energy consumption ranged from 8.1 to 10.3 kWh for indoor air temperature between 20 oC and 32 oC.  The higher outdoor temperature causes the greater cooling energy consumption. The correlation between outdoor temperature and cooling energy consumption with linear regression showed the correlation coefficient of 0.38 while the correlation between temperature difference and enthalpy difference of the outdoor and indoor found the correlation coefficient of 0.71. This pointed out that the outdoor tropical climate highly affected to the cooling energy demand.

scholarly journals Flat Glass or Crystal Dome Aperture? A Year-Long Comparative Analysis of the Performance of Light Pipes in Real Residential Settings and Climatic Conditions

2020 ◽  
Vol 12 (9) ◽  
pp. 3858 ◽  
Author(s):  
Magda Sibley ◽  
Antonio Peña-García
Keyword(s):  
Comparative Analysis ◽  
Flat Glass ◽  
Climatic Conditions ◽  
Long Term Effect ◽  
Different Types ◽  
The Difference ◽  
The Aesthetic ◽  
One Year ◽  
The One

This paper presents the first comparative study of its type of the performance of light pipes with different types of apertures: a flat glass versus a bohemian crystal dome. Measurements were taken at 20-minute intervals over a period of one year in the bathrooms of two newly built identical houses of the same orientation located in Manchester, UK. The comparative analysis of the data collected for both light pipes types reveals that the crystal domed aperture consistently outperforms the flat glass one. Furthermore, the difference in the recorded horizontal illuminance is most marked during the winter months and at the end of the one-year experiment, indicating that the crystal dome has better performance for low incident winter light and higher resistance for the long term effect of weathering and pollution. This study provides strong evidence based on long term real measurements. Such evidence informs architects’ decisions when weighing up the aesthetic considerations of a flat glass aperture versus the higher illumination levels afforded by a crystal dome aperture with higher resistance to weathering and pollution.

Mechanical Properties of Mortars Prepared by Alkali Activated Fly Ash Coming from Different Production Batches

2015 ◽  
Vol 244 ◽  
pp. 140-145 ◽  
Author(s):  
Matej Špak ◽  
Pavel Raschman
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Construction Materials ◽  
Chemical Properties ◽  
Raw Material ◽  
Fly Ashes ◽  
Coal Burning ◽  
Alkali Solutions ◽  
One Year ◽  
Alkali Activated

Fly ash is a well utilizable secondary raw material for the production of alkali activated construction materials. It is a significant alumina-silicates source suitable for the chemical reaction resulting in hardened composites. Physical and chemical properties of fly ashes as a co-product of coal burning mainly depend on characteristics of coal, burning temperature and combustion conditions. High variability of the properties of fly ash causes an uncertainty in the properties of alkali activated mortars. Time behaviour of the composition of the fly ash produced in a heating plant located in Košice, Slovakia as well as leaching behaviour of both alumina and silica from particular batches during one-year period was documented. Leaching tests were carried out using the distilled water and alkali solutions with three different concentrations. Both compressive and tensile strengths of alkali activated mortars were measured, and the correlation between the mechanical properties of hardened mortars and the chemical composition of fly ashes as well as their leaching characteristics was investigated.

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