scholarly journals INFLUENCE OF LIGHTWEIGHT FILLERS ON THE PERFORMANCE OF CEMENT-BASED SKIM COAT

2020 ◽  
Vol 12 (1) ◽  
pp. 5-11
Author(s):  
MARCIN KUPIŃSKI ◽  
KAROLINA STOBIENIECKA ◽  
KAROL SKOWERA
Keyword(s):  
Thermal Conductivity ◽  
Thermal Conductivity Coefficient ◽  
Pozzolanic Reaction ◽  
Vapor Condensation ◽  
Cement Matrix ◽  
Capillary Absorption ◽  
Mold Growth ◽  
Expanded Perlite ◽  
Water Vapor Condensation ◽  
Effective Additive

Lightweight fillers are used in dry-mixed building mortars in order to improve thermal insulation properties, yield, and workability. In the case of thin layer products, used as a finishing layer, reduced thermal conductivity coefficient enables to restrain of water vapor condensation on walls – which inhibits mold growth. The aim of the study was to determine the influence of 4 types of lightweight fillers on the performance of cement-based skim coat – with emphasis on the economic aspect. Formulas reflecting typical commercial products were used. The dosage of different components -such as expanded perlite, glass and polymeric bubbles or expanded glass – was optimized for sufficient yield and workability, keeping the constant price of 1 kg of the final product. Mechanical parameters, capillary absorption coefficient, and thermal conductivity coefficient were determined. Observations by Scanning Electron Microscope revealed poor incorporation of polymer microspheres in the cement matrix, leading to loss of mechanical strength. With the addition of expanded glass, an increase of flexural and compressive strength thanks to the pozzolanic reaction was observed. Glass bubbles were found the most effective additive.

scholarly journals Methods for Determining Mold Development and Condensation on the Surface of Building Barriers

Buildings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 4 ◽  
Author(s):  
Aleksander Starakiewicz ◽  
Przemysław Miąsik ◽  
Joanna Krasoń ◽  
Lech Lichołai
Keyword(s):  
Water Vapor ◽  
Vapor Condensation ◽  
Mold Growth ◽  
Vapor Pressures ◽  
Climate Conditions ◽  
Outdoor Climate ◽  
Surface Condensation ◽  
Water Vapor Condensation ◽  
Calculation Results ◽  
Temperature Factors

The article presents four equivalent methods for checking mold growth on the surface of building barriers and checking water vapor condensation on their surface. Each method applies to two parallel phenomena that may occur on a building barrier. The first method is to calculate and compare temperature factors. In the second method, the characteristic humidity in the room is calculated and compared. The third method is to calculate and compare the characteristic temperatures in the room. The fourth method is based on the calculation and comparison of characteristic water vapor pressures. Three boundary conditions are presented for each method and phenomenon: when a given phenomenon can occur, when it begins or ends, and when it does not occur. The presented methods systematize the approach to the problem of mold development and surface condensation. The presented calculation results relate to the selected building barrier functioning in specific indoor and outdoor climate conditions. The calculation results confirm the compliance of the presented methods in identifying the phenomenon of mold growth or condensation on the surface of the barrier. A graphical interpretation of the results for each method with periods of occurrence or absence of a given phenomenon is also presented.

Mold Growth Risk Analysis on the Surfaces of an Organic Building Structure Based on In Situ Monitoring

2016 ◽  
Vol 824 ◽  
pp. 235-242 ◽  
Author(s):  
David Bečkovský ◽  
František Vlach ◽  
Jan Vitík ◽  
Eva Šuhajdová
Keyword(s):  
Water Vapor ◽  
Risk Analysis ◽  
Vapor Condensation ◽  
In Situ Monitoring ◽  
Mold Growth ◽  
Building Structure ◽  
Hygrothermal Behavior ◽  
Monitoring Process ◽  
Water Vapor Condensation

This article deals with the assessment of methodologies for water vapor condensation determination and mold growth risk analysis on the surfaces of an organic building structure based on in-situ monitoring, carried out on the structural elements of renovated roof truss above the greenhouse “Květná zahrada” in Kroměříž. The garden including the building is signed on the UNESCO Word Heritage List for its historical and architectonical value. The monitoring was focused on hygrothermal behavior of a particular attic area during winter term 2014 - 2015. The risks of water vapor condensation and mold growth were then analyzed on the basis of data obtained by the monitoring process. These also include measurement and output data accuracy is included as well. The Results were used as recommendation for a control system of forced ventilation in the monitored attic area.

scholarly journals Compressive Strength and Microstructure Analysis of Treated Rice Husk Ash (TRHA) Incorporated Mortar

2018 ◽  
Vol 7 (4.35) ◽  
pp. 388
Author(s):  
Siti Asmahani Saad ◽  
Nasir Shafiq ◽  
Mariana Mohamed Osman ◽  
Siti Aliyyah Masjuki
Keyword(s):  
Compressive Strength ◽  
Rice Husk ◽  
Treatment Process ◽  
Rice Husk Ash ◽  
Concrete Strength ◽  
Pozzolanic Reaction ◽  
Cement Matrix ◽  
Curing Period ◽  
Strength Increment ◽  
Effective Additive

High amount of reactive silica is ubiquitous in pozzolanic reaction for concrete strength increment. Rice husk ash (RHA) is proven contains high content of amorphous silica that is essential in the pozzolanic reaction of effective additive in concrete. Nevertheless, incorporation of RHA as cement replacement material (CRM) or additive is very minimal in current concrete industry. Therefore, improvement on the RHA properties by introduction of thermal and chemical pretreatment prior to incineration process is considered as a promising way in order to achieve the goal. This treatment process has been reported widely in literature. In this paper, the effect of treated rice husk ash (TRHA) and non-treated rice husk ash (NTRHA) incorporated mortar in terms of its compressive strength and microstructure properties are examine subsequently. The strength activity of TRHA from the optimum treatment process was measured by testing the compressive strength of mortars. The highest compression value obtained was 50.73MPa with 3% UFTRHA replacement at 28 days. At a longer curing period i.e. 90 days, it was recorded that 3% of UFTRHA mortar had the highest compression value at 53.87MPa. As for microstructure properties, a denser microstructure with excellent aggregate bonding and cement matrix in the interfacial transition zone (ITZ) was observed.

scholarly journals Lightweight Cement Mortars with Granulated Foam Glass and Waste Perlite Addition

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Waldemar Pichór ◽  
Adrian Kamiński ◽  
Paulina Szołdra ◽  
Maksymilian Frąc
Keyword(s):  
Thermal Conductivity ◽  
Water Absorption ◽  
Thermal Insulation ◽  
Quartz Sand ◽  
Thermal Conductivity Coefficient ◽  
Foam Glass ◽  
Expanded Perlite ◽  
Water Absorption Coefficient ◽  
Cement Mortars ◽  
Lightweight Filler

This article presents the influence of granulated foam glass (GFG) on thermal insulation and mechanical properties of lightweight cement mortars. The mortars were additionally modified with addition of ground perlite dust. Ground expanded perlite waste was introduced into the cement matrix in the amounts of 10%, 20%, and 30% of cement mass. The results show that application of this waste increases the strength of the mortars as well as decreases their thermal conductivity coefficient. A series of mortars were prepared with introduction of granulated foam glass with mass per unit filler/cement ratio equal to 0.6, 0.9, and 1.2. The aggregate composition of GFG was combined from different monofractions in the range 0–2 mm so that it filled the mortar volume to the maximum. Additionally, mortars were made, in which 20% of 0–0.25 mm GFG volume was replaced with quartz sand with the same granulation. Each mortar series was modified with addition of ground perlite waste in the amount of 20% of cement mass. The results indicate an improvement of thermal insulation properties along with greater participation of perlite in the mortars. The increase of the thermal conductivity coefficient was observed in the mortars, where the GFG was replaced with quartz sand. Greater amount of GFG results in decrease of compressive strength, but it can be improved by replacing part of the lightweight filler with sand or by introducing the addition of ground expanded perlite to the matrix. This also results in lower water absorption of mortars. Research proved that in most cases, the addition of ground expanded perlite decreased the capillary sorption of mortars, as well as the water absorption coefficient by capillary action, with growing proportion of the lightweight filler.

scholarly journals An Experimental Investigation of Water Vapor Condensation from Biofuel Flue Gas in a Model of Condenser, (1) Base Case: Local Heat Transfer without Water Injection

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 844
Author(s):  
Robertas Poškas ◽  
Arūnas Sirvydas ◽  
Vladislavas Kulkovas ◽  
Povilas Poškas
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Flue Gas ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Water Injection ◽  
Vapor Condensation ◽  
Base Case ◽  
Water Vapor Condensation ◽  
Condensing Heat Exchanger

Waste heat recovery from flue gas based on water vapor condensation is an important issue as the waste heat recovery significantly increases the efficiency of the thermal power units. General principles for designing of this type of heat exchangers are known rather well; however, investigations of the local characteristics necessary for the optimization of those heat exchangers are very limited. Investigations of water vapor condensation from biofuel flue gas in the model of a vertical condensing heat exchanger were performed without and with water injection into a calorimetric tube. During the base-case investigations, no water was injected into the calorimetric tube. The results showed that the humidity and the temperature of inlet flue gas have a significant effect on the local and average heat transfer. For some regimes, the initial part of the condensing heat exchanger was not effective in terms of heat transfer because there the flue gas was cooled by convection until its temperature reached the dew point temperature. The results also showed that, at higher Reynolds numbers, there was an increase in the length of the convection prevailing region. After that region, a sudden increase was observed in heat transfer due to water vapor condensation.

Thermal conductivity and extinction coefficient of opacified expanded perlite for vacuum super insulation up to 1073 K

2021 ◽  
Vol 163 ◽  
pp. 106813
Author(s):  
Matthias Rottmann ◽  
Thomas Beikircher ◽  
Hans-Peter Ebert ◽  
Frank Hemberger ◽  
Jochen Manara
Keyword(s):  
Thermal Conductivity ◽  
Extinction Coefficient ◽  
Expanded Perlite

The effect of variable properties and rotation in a visco-thermoelastic orthotropic annular cylinder under the Moore–Gibson–Thompson heat conduction model

2021 ◽  
pp. 146442072098589
Author(s):  
Ahmed E Aboueregal ◽  
Hamid M Sedighi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stresses ◽  
Thermal Conductivity Coefficient ◽  
Variable Properties ◽  
Transformation Technique ◽  
Present Contribution ◽  
Conduction Model ◽  
Thermoelastic Model ◽  
Shock Heating ◽  
Physical Fields

The present contribution aims to address a problem of thermoviscoelasticity for the analysis of the transition temperature and thermal stresses in an infinitely circular annular cylinder. The inner surface is traction-free and subjected to thermal shock heating, while the outer surface is thermally insulated and free of traction. In this work, in contrast to the various problems in which the thermal conductivity coefficient is considered to be fixed, this parameter is assumed to be variable depending on the temperature change. The problem is studied by presenting a new generalized thermoelastic model of thermal conductivity described by the Moore–Gibson–Thompson equation. The new model can be constructed by incorporating the relaxation time thermal model with the Green–Naghdi type III model. The Laplace transformation technique is used to obtain the exact expressions for the radial displacement, temperature and the distributions of thermal stresses. The effects of angular velocity, viscous parameter, and variance in thermal properties are also displayed to explain the comparisons of the physical fields.

Sign in / Sign up

Export Citation Format

Share Document