scholarly journals EFFECT OF DOSAGE OF REDISPUTABLE POWDERS AND THE TYPE OF LOW-MODULAR INCLUSIONS ON THE PROPERTIES OF FINE-AGGREGATE CONCRETE

2019 ◽  
Vol 46 (2) ◽  
pp. 167-175 ◽  
Author(s):  
A. V. Dolgova ◽  
G. V. Nesvetaev
Keyword(s):  
Fine Aggregate ◽  
Fine Grained ◽  
Deformation Properties ◽  
Low Modulus ◽  
Strength And Deformation ◽  
Properties Of Materials ◽  
Materials Used ◽  
Entrained Air ◽  
Polymer Powders

Objectives Reliability and durability of structures using materials with various properties (plaster coatings, cement glue, new concrete during repair and restoration of structures, etc.) largely depends on the adhesion of the layers and the deformation properties of the coatings. To obtain the required properties of materials used for coatings, modifiers based on polymers and low-modulus inclusions are introduced into the composition of new concretes, for example, entrained air. The aim of the work is to identify some patterns of change in the properties of concrete with the joint introduction of these modifiers.Method Experimental determination of the tensile strength in bending, compression, E-modulus, adhesion to the concrete base by standard methods.Result The influence of separate and joint introduction of dispersible polymer powders and various low-modulus inclusions into the composition of fine-grained concrete has been established.Conclusion The joint introduction to the composition of fine-grained concrete of various low-modulus inclusions and redispersible polymer powders provides a reduction in the stress level during forced deformations due to the different effects additives on the strength and deformation properties and contributes to increased adhesion to the concrete. 

scholarly journals DETERMINATION OF CREEP PARAMETERS IN LAYERS OF BUILDING COMPOSITES/SLUOKSNIUOTŲJŲ STATYBINIŲ KOMPOZITŲ VALKŠNUMO PARAMETRŲ NUSTATYMAS

1998 ◽  
Vol 4 (2) ◽  
pp. 101-108 ◽  
Author(s):  
Gediminas Marčiukaitis
Keyword(s):  
Force Action ◽  
Building Product ◽  
Creep Coefficient ◽  
Deformation Properties ◽  
Linear Creep ◽  
Modulus Of Deformation ◽  
Composite Product ◽  
Properties Of Materials ◽  
Creep Deformations

Various composite building products consisting of layers of different physical-mechanical properties being tied rigidly together are manufactured and used in construction. In many cases such products curve, become flaky, crack and their thermo-insulating capability suffers. It occurs because deformation properties are not adjusted, different layers of such products deform differently under the load. And the deformation effects the behaviour of the whole structure. A correct adjustment of deformations can be achieved with allowance for creep of different layers and of the whole composite. Determination of creep parameters—creep coefficient and specific creep—depends on the orientation of layers in respect of the direction of force action. When layers are situated transverselly in respect of the direction of action of forces (stresses), creep parameters of composite depend on creep parameters of materials of separate layers and on relative volumes of these layers. Creep deformations of a composite can be described by equations describing creep of individual layers. Appropriate equations and formulas ((17)-(25)) are presented for determining such deformations. When layers are parallel to the direction of stresses, redistribution of these stresses between layers takes place. Compression stresses increase in a layer with higher modulus of deformation and decrease in that with lower modules. Proposed equations (37)-(42) enable to determine redistribution of stresses between layers, the main creep parameters of composite, their modulus of deformations and creep deformations themselves when strength of a composite product is reached, E(t0)=E(t)=const and stresses produce linear creep. Such loading of a composite product is the most common in practice. Presented formulas ((46), (52)) and diagrams show that it is possible to design a composite building product or material with creep parameters given in advance by means of appropriate distribution of product layers, selecting ratios between layers and properties of materials.

Development of Methodological Support for the Study of Materials’ Air Permeability

2019 ◽  
Vol 945 ◽  
pp. 938-943
Author(s):  
I.A. Sheromova ◽  
A.S. Zheleznyakov
Keyword(s):  
Air Permeability ◽  
Control Procedure ◽  
Fibrous Materials ◽  
Additional Advantage ◽  
Textile Materials ◽  
The Subject ◽  
Properties Of Materials ◽  
Materials Used ◽  
Different Levels

The object of research of the article is the methodological and technical support for the process of studying the characteristics of ergonomic properties of materials used in the manufacture of garments, and the subject – the method for the determination of textile materials’ air permeability. The aim of the work is to simplify the method for determination of fibrous materials’ air permeability and to expand the technological capabilities of its instrument base while increasing the flexibility of the control procedure. To achieve this goal, the tasks related to the analysis of existing methods and technical means, and the development of a new method for determining the air permeability of textile materials were solved. The principal difference in the developed method is the possibility to conduct studies on the air permeability of textile materials at different levels of pressure drop on both sides of the sample, and not only in accordance with the standardized requirements. An additional advantage of the method is the possibility to create an online electronic database on the properties of materials. In comparison with analogues, the proposed method for the determination of air permeability ensures the accuracy and reliability of the data obtained, as well as facilitates the testing process by automation.

Measurement System for Determination of Supercapacitor Equivalent Parameters

2013 ◽  
Vol 20 (4) ◽  
pp. 581-590 ◽  
Author(s):  
Ryszard Kopka ◽  
Wiesław Tarczyński
Keyword(s):  
Measurement System ◽  
Properties Of Materials ◽  
Materials Used ◽  
Measurement Capabilities

Abstract In this paper a measurement system for determination of supercapacitor equivalent parameters is proposed. Specific properties of materials used for supercapacitor construction require some advanced tools and measurement procedures to be applied during tests. The measurement system allows to measure values of equivalent parameters by both the DC and AC method whilst keeping appropriate time criteria required by this type of devices. Furthermore, in this paper the most relevant properties and measurement capabilities of the proposed system are described as well as some exemplary values of the supercapacitor equivalent parameters measured experimentally are presented.

scholarly journals Determination of mechanical properties of materials used for 3D printing

2020 ◽  
Vol 20 (2) ◽  
pp. 190-194
Author(s):  
Josef Sedlak ◽  
Josef Chladil ◽  
Martin Cerny ◽  
Ales Polzer ◽  
Matus Varhanik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Mechanical Properties Of Materials ◽  
Properties Of Materials ◽  
Materials Used

Express-Method for Determination the Fibrous Materials Resistance to Bending

2019 ◽  
Vol 945 ◽  
pp. 407-411 ◽  
Author(s):  
I.A. Sheromova ◽  
G.P. Starkova ◽  
A.S. Zheleznyakov
Keyword(s):  
Universal Method ◽  
Fibrous Materials ◽  
Electronic Database ◽  
Natural Oscillations ◽  
The Subject ◽  
Properties Of Materials ◽  
Methodological Approaches ◽  
Materials Used ◽  
Express Methods

The object of research of the article is the characteristics of mechanical properties of fibrous systems under the bending deformation, and the subject is the method of determination of the resistance to bending. The aim of the work is to develop a new universal method for evaluating the resistance of fibrous materials to bending, including, among other things, the possibility of forming an electronic database on the characteristic properties of materials. To achieve this goal, a set of problems related to the analysis of existing methodological approaches and technical means, the rationale for possible solutions to the problem posed, and the development of a new patentable method for evaluating the materials’ resistance to bending, have been solved in the research. In the course of the project, a study was developed of the required characteristics for textile and leather-fur materials used for the manufacture of garments. The method is based on the use of natural oscillations frequencies of the material as an informative parameter of their resistance to bending. The method belongs to the class of express methods and provides an opportunity to create an electronic database on the properties of materials online. The approbation of the proposed solution by comparing the estimates obtained with the results of studies obtained on the basis of a standardized method (the method of the console), showed sufficient accuracy and the possibility of practical application of the developed method.

The Residual Stress in Thawing Soils

1973 ◽  
Vol 10 (4) ◽  
pp. 571-580 ◽  
Author(s):  
J. F. Nixon ◽  
N. R. Morgenstern
Keyword(s):  
Residual Stress ◽  
Effective Stress ◽  
Simple Procedure ◽  
Frozen Soil ◽  
Fine Grained ◽  
Deformation Properties ◽  
Fine Grained Soil ◽  
Soil Skeleton ◽  
Strength And Deformation ◽  
Undrained Strength

If a fine grained soil is thawed under undrained conditions, in general an effective stress exists in the soil skeleton. This effective stress is termed the residual stress. In ice-rich soil the residual stress may be zero, but various combinations of stress and thermal histories can result in significant residual stresses being generated upon thawing.A simple procedure for measuring the residual stress is described and the method is employed to obtain values for the residual stress in natural and reconstituted samples of frozen soil. The residual stress is found to be dependent on the void ratio in the thawed undrained condition. A profile of the residual stress with depth is given for the natural permafrost samples that have been tested.Some implications of the residual stress in practice are discussed, with particular emphasis on the undrained strength and deformation properties of thawed permafrost.

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