scholarly journals Changes in physical and mechanical properties of soils due to anthropogenic impact on the territory of Chita

2021 ◽  
Vol 34 (04) ◽  
pp. 1499-1514
Author(s):  
Danil D. Shesternev
Keyword(s):  
Mechanical Properties ◽  
Anthropogenic Impact ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Deformation Characteristics ◽  
Laboratory Studies ◽  
Freezing And Thawing ◽  
Construction Sites ◽  
Engineering Structures ◽  
Geological Conditions

When constructing buildings and engineering structures it is necessary to make a pit for the foundation construction. Excavation works, construction of buildings and engineering structures change the deformation-strength properties of soils, which lie under the foundations. To study the changes in engineering-geological conditions during 2016-2018, on one of the construction sites in Chita (Russia), a well was made to take a soil sample and laboratory studies on physical and mechanical properties of soils were performed. As a result of the studies, it was established that the deterioration of the soils’ deformation characteristics under the foundations increased by 2.5 times, from 20 MPa to 8 MPa. The strength characteristics changed almost by 2 times. The soil’s specific cohesion changed from 31 MPa to 16 MPa due to freezing and thawing of the soil on the excavation face of the pit with its subsequent soaking. It is necessary to carry out additional activities to strengthen and stabilize the foundations.

scholarly journals Concrete based on sulfur binder being modified with inorganic additives

2018 ◽  
Vol 212 ◽  
pp. 01013
Author(s):  
Vadim Balabanov ◽  
Victor Baryshok ◽  
Nikita Epishkin
Keyword(s):  
Frost Resistance ◽  
Building Materials ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Strength Properties ◽  
Climatic Conditions ◽  
Freezing And Thawing ◽  
Concrete Mixtures ◽  
Irkutsk Region ◽  
Water Saturated

The sharply continental climate of the Irkutsk region is characterized by wide temperature intervals throughout the year. The repeated cyclicity of freezing and thawing of building materials in the water-saturated state influences the change in technical characteristics and the durability of concrete products and structures. The concrete products’ features in such climatic conditions create the need for the production of concretes with improved indicators of physical and mechanical properties. The effect of modifying additives on the technological characteristics of sulfur concrete is established. The effect of all elements of sulfur concrete on its strength and frost resistance. The composition of sulfuric concrete is obtained, which meets all the requirements and also has high strength and increased frost resistance. Formulations with a certain ratio of structural sulfuric concrete mixtures were developed. As a result of the use of technical sulfur in the composition of concrete products, the problem of utilizing annually accumulating reserves of technical sulfur is partially solved. The strength properties of sulfuric concretes easily compete with high-quality brands of concrete, special types of concretes that have in their composition additives.

scholarly journals CHANGES IN THE COMPOSITION AND PROPERTIES OF THE HOST ROCKS OF COAL DEPOSITS IN YAKUTIA UNDER THE INFLUENCE OF CRYOGENESIS

2020 ◽  
Vol 5 (443) ◽  
pp. 133-140
Author(s):  
Melnikov Andrey E., ◽  
◽  
Ze Zhang, ◽  
Grib Nikolay N., ◽  
Camil Jakub Shabo, ◽  
...  
Keyword(s):  
Ultimate Strength ◽  
Great Influence ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Physicomechanical Properties ◽  
Freezing And Thawing ◽  
Coal Deposits ◽  
Host Rocks ◽  
Transformation Processes ◽  
Cryogenic Processes

The results of laboratory tests carried out on rock samples of the Kharbalakhskoye coalfield located in Central Yakutia revealed significant secondary changes having taken place in the host rocks containing the coal. Evidently, under transformation processes, it is not only the composition of the rocks that had changed, but also the nature of structural bonds that have a great influence on their physical and mechanical properties. Thus, the ultimate strength values of coal-containing sandstone and siltstone samples under uniaxial compression vary from 20 to 30 MPa, while under uniaxial tension, the ultimate strength values range from 6 to 10 MPa. These relatively low numerical values pertaining to the physicomechanical properties of rocks, which are generally atypical for long-flame coal deposits, are almost 50% lower than those of analogous rocks hosting other coal deposits in Russia. It is considered that the mechanical strength properties of the rocks of the Kharbalakhskoye field are due to significant cryogenic processes. A comparative analysis of the properties of core samples obtained from boreholes drilled in 2019 with samples from a quarry obtained several decades ago reveals signs of transformation of rocks in the Kharbalakhskoye field due to phase transitions of freezing and thawing water.

scholarly journals RESEARCH OF PHYSICAL AND MECHANICAL PROPERTIES OF WOOD-FIBER MATERIALS

2020 ◽  
pp. 451-457
Author(s):  
Aleksandr Yur'yevich Vititnev ◽  
Yuriy Davydovich Alashkevich ◽  
Natal'ya Geral'dovna Chistova ◽  
Roman Aleksandrovich Marchenko ◽  
Venera Nurullovna Matygullina
Keyword(s):  
Mechanical Properties ◽  
Wood Fiber ◽  
Experimental Studies ◽  
Physical And Mechanical Properties ◽  
Production Method ◽  
Strength Properties ◽  
Grinding Process ◽  
Technological Parameters ◽  
Fiber Materials ◽  
Traditional Construction

This paper presents the results of experimental studies of the physical and mechanical properties of wood-fiber boards of the wet production method when regulating the design and technological parameters of the grinding process. This allowed us to determine the influence of the working clearance between the grinding discs and the concentration of fibre mass with the subject to of quality change wood fiber after defibrator using the developed construction of the disc fibrillation action on the physico-mechanical properties of boards. As a result of the experiment, regression models were obtained that adequately describe the studied grinding process and allow predicting the values of physical and mechanical properties of the finished product depending on the established  parameters process. A comparative analysis of the size and quality characteristics of the fiber semi-finished product and its fractional composition when using a developed construction the disc of refiner fibrillation action and a traditional design used in industry is carried out. The preferential efficiency of the grinding process under the fibrillating effect the disc of refiner in comparison with the traditional construction disc of refiner is established. As a result, there is a significant improvement in the quality indicators of the fiber semi-finished product and its composition due to the formation and predominance in the total mass of long and thin, respectively, flexible fibrillated fibers with high tile-forming properties, which allows to increase the strength properties of the product (by 20–25%), without using binding resins.

scholarly journals Effects of nano and micro size of clay particles on the compressive and tensile strength properties of self-consolidating concrete

2018 ◽  
Vol 162 ◽  
pp. 02030 ◽  
Author(s):  
Baydaa Alrashedi ◽  
Maan Hassan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Pozzolanic Activity ◽  
Chemical Compositions ◽  
Particle Sizes ◽  
Self Consolidating Concrete ◽  
Clay Particles

Many past studies concerned about using of nanoclay (nC) particles as an active pozzolan to concrete and their influence on the physical and mechanical properties. In this study, the effects of various nanoclay particle sizes and dosages on the compressive and flexural tensile strengths of SCCs were investigated. Progressive nC percentages of 2%, 5% and 8% were replaced with cements and the produced SCCs were evaluated and compared with similar replacement levels of the metakaolin MK which have comparable chemical compositions. The produced SCCs were tested for compressive, flexural tensile and splitting tensile strengths in 28 and 90 days. Results indicated that nC replacement harmed all the studied mechanical properties at 28 days age. After 90 days, however, both compressive and tensile strengths of nC concretes show superior strengths than control concrete and also exceeded MK concretes made of equivalent replacement levels. This behavior demonstrates the pozzolanic activity of the nC particles at later ages and proved to be significantly more effective than early ages.

scholarly journals Improving the properties of composite materials for civil engineering

2019 ◽  
Vol 91 ◽  
pp. 02015
Author(s):  
Valentina Soloviova ◽  
Irina Stepanova ◽  
Nicholas Ershikov ◽  
Dmitry Soloviov
Keyword(s):  
Mechanical Properties ◽  
Chemical Activation ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Deformation Characteristics ◽  
Energy Effect ◽  
Composite Mixture ◽  
Strength And Deformation ◽  
New Generation ◽  
Hardening System

It is shown that a highly-efficient chemical activation of the cement-containing composite mixture with the help of a new generation nanostructural additive makes it possible to develop high-strength finegrained and heavy-weight concretes with the improved strength and deformation characteristics. The recommended nanostructural additive has an increased triple effect: reactive, catalytic, and plasticizing. The use of the proposed additive many times increases the hydration activity of the hardening system, exerting a double energy effect on it, chemical and thermal, thus making it possible to develop the composite building material of a new level of physical and mechanical properties.

Application of New Soil Consolidator in Road-Construction Engineering

2012 ◽  
Vol 238 ◽  
pp. 466-469
Author(s):  
Hong Zhang ◽  
Dong Liang Xun ◽  
Zhao Yang ◽  
Fu Quan Ji
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Physical And Mechanical Properties ◽  
Road Construction ◽  
Point Of View ◽  
Curing Time ◽  
Construction Engineering ◽  
Geological Conditions ◽  
Silt Layer

This paper contrastively analyses the consolidation instances of silt with HEC and HAS soil consolidators, also emphatically discusses the influence regularities of the compressive strength of solidified soil with the following factors: the dose of consolidators and the curing time. Meanwhile, from the point of view of experiment, this paper studies the physical and mechanical properties of solidified soil. Case study shows that HEC and HAS soil consolidators behave as well as cement and lime in road-construction engineering, and even that filling subgrade independently. Also, this paper proposes the appropriate value 6% of HEC and HAS soil consolidators for solidifying silt layer, which can be used as reference for the similar geological conditions.

scholarly journals STUDY OF RECEIVING WOOD AND PLANT PLASTICS WITHOUT BINDERS IN THE PRESENCE OF CATALYSTS OF POLYOXOMETALLATES TYPE

2018 ◽  
Vol 8 (1) ◽  
pp. 132-138
Author(s):  
Виктор Бурындин ◽  
Viktor Buryndin ◽  
Лариса Бельчинская ◽  
Larisa Belchinskaya ◽  
Андрей Савиновских ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Functional Groups ◽  
Hot Pressing ◽  
Raw Materials ◽  
Flexural Modulus ◽  
Chemical Activation ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Raw Material ◽  
Plastic Properties

The possibility of obtaining wood and plant plastics without a binder (WP-WB) in the presence of a catalyst of man-ganese-containing sodium vanadomolybdophosphate has been investigated. The use of this catalyst makes it possible to reduce the temperature of hot pressing in closed molds from 1,800°C to 1,600°C. The fractional composition of the initial press raw material influences physical and mechanical properties of WP-WB. Higher values of the plastic properties are obtained by using a 0.7 mm fraction, which is associated with an increased specific surface area of the particles compared to 1.3 mm particles. The results has showed that the samples obtained by using the catalyst have increase in strength properties (flexural strength, flexural modulus, hardness) at lower pressing temperature, but reduction of water resistance performance has been observed . This is explained by the increase in the content of functional groups when using a catalyst. The process of obtaining plastic can be broken down into two successive stages: the first is hydrothermal destruction of lignin-carbohydrate complex (initial moisture of the press raw material is 12%, the temperature of hot pressing in closed molds is 160 ... .180 ° C) and partial chemical activation of lignin as a result of hydrogen peroxide and catalyst application; the second stage - formation of plastic with the formation of a network structure due to the formed functional groups. It is established that the values of physical and mechanical properties of WP-WB are higher than those of plastic obtained on the basis of plant raw materials (PP-WB). This can be explained by the fact that lignin of coniferous species has the guaiacylpropane structure, while plant raw material has a hydroxyphenylpropane structure

scholarly journals Dimensional stability and strength properties of wood plastic composites produced from sawdust of Cordia alliodora (Ruiz and Pav.)

2014 ◽  
Vol 6 (2) ◽  
pp. 338-343 ◽  
Author(s):  
D. N. Izekor ◽  
M. E. Mordi
Keyword(s):  
Mechanical Properties ◽  
Water Immersion ◽  
Physical And Mechanical Properties ◽  
Immersion Test ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Mixing Ratio ◽  
Wood Plastic Composites ◽  
Mean Values ◽  
Plastic Composites

This study evaluates the effects of densities and mixing ratio on the physical and mechanical properties of wood plastic composites boards at mixing ratio of 1:1 to 1:1.4 and nominal densities of 700kg/mm3 and 800kg/mm3. The quantity of High Density Polyethylene (HDPE) and saw dust used in the production of Wood Plastic Composites (WPCs) was weighed to a nominal density of 700kg/mm3 and 800kg/mm3. The materials were thoroughly mixed and fed into a neatly primed oil mould with a dimension of 300 x 300 x 10 mm. Test samples used for physical and mechanical properties determination were collected from each board produced from the mould. The results showed that WPCs board produced from mixing ratio 1:1 had the highest Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) values of 6.52 mm N-2 and 564.95 mm N-2 respectively. Water absorption, thickness swelling and linear expansion of WPCs produced from wood/plastic ratio of 1:1.4 had the lowest mean values of 6.67, 0.83, 0.68% and 21.61, 1.33, 5.35% respectively after 2 hours and 24 hours of water immersion test. Analysis of variance carried out at 0.05% probability level showed that the effect of density and mixing ratio were significant on the physical and mechanical properties of wood plastic composites boards.

scholarly journals POLYMER CONCRETE MIXTURES – APPLICATION IN ENGINEERING INDUSTRY

STED JOURNAL ◽  
2019 ◽  
Vol 1 (2) ◽  
Author(s):  
Robert Poklemba ◽  
Jozef Zajac ◽  
Darina Duplakova ◽  
Peter Cizmar ◽  
David Goldyniak
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Composite Materials ◽  
Material Properties ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Engineering Industry ◽  
Polymer Concrete ◽  
Advantages And Disadvantages ◽  
Concrete Mixtures

This article discusses the properties of concrete composite materials based on their contexture. Systematic and interactive approaches are required in order to achieve optimal material properties in the preparation of composite materials. In order to predict the physical and mechanical properties of each component of the composite material but also as a whole, its optimization, not only the mechanical but also the material properties under different working conditions, requires a combination of different methods and technologies. The advantage of each composite is its specific properties that cannot be achieved by any component of the composite material alone. The strength of the materials based on polymer concrete mixtures can be compared to the strength properties of metals. On the other hand, this material has elastic properties which give the material a high degree of flexibility. When compared to conventional materials, the value of polymer composites is assessed not only in terms of excellent mechanical properties but also in terms of their low weight and cost. The aim of the paper is to describe the advantages and disadvantages of composites based on polymer concrete mixtures.

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