scholarly journals Implementation of innovative technologies for the improvement of concrete properties for freezing and thawing processes

2021 ◽  
pp. 50-62
Author(s):  
Krzysztof FALKOWSKI
Keyword(s):  
Building Material ◽  
Laboratory Tests ◽  
Environmental Influences ◽  
Calculation Model ◽  
Atmospheric Conditions ◽  
Freezing And Thawing ◽  
Porosity Structure ◽  
Bitumen Emulsion ◽  
Original Calculation ◽  
Thawing Processes

For over a hundred years, concrete has been a well-known building material and is widely used in construction. Its properties have convinced construction engineers, architects, contractors and investors, which is why it is currently difficult to find a building completed without the use of this material. However, the influence of atmospheric conditions and other environmental influences means that over time they leave more and more visible signs of progressive destruction even on the best building material of the century. Taking into account the problems related to aeration and surface hydrophobization, the aim of the work was to demonstrate that by using an admixture in the form of an anionic bitumen emulsion and a superplasticizer based on polycarboxylate ethers, it is possible to obtain hard-to-wet concretes with a favorable porosity structure and increased resistance to environmental influences. For static calculations and dimensioning, an original calculation model of the pavement made of concrete with dispersed reinforcement in the form of fibers was used, which made it possible to eliminate the reinforcement in the form of bars. Laboratory tests with the use of concrete samples taken during concreting carried out after 28 days of maturation confirmed the high compressive strength.

scholarly journals Frost heave and thaw settlement of initially saturated-slurried and compacted-saturated materials

2020 ◽  
Vol 195 ◽  
pp. 03036
Author(s):  
Snehasis Tripathy ◽  
Osama Mahdi Al-Hussaini ◽  
Peter John Cleall ◽  
Stephen William Rees ◽  
Han-Lin Wang
Keyword(s):  
Laboratory Tests ◽  
Initial Conditions ◽  
Frost Heave ◽  
Freezing Process ◽  
Cement Kiln ◽  
Freezing And Thawing ◽  
Custom Made ◽  
Thawing Processes ◽  
Thaw Settlement ◽  
Study Laboratory

Soils and industrial waste in various geotechnical engineering applications are expected to experience freezing and thawing processes in various regions of the world where the winter and summer temperatures fluctuate between sub-zero and positive ambient temperatures. In this study laboratory tests were undertaken on three materials (Speswhite kaolin, Pegwell Bay soil and a cement kiln dust). A custom-made test set up was used to carry out the laboratory tests involving freezing and thawing processes. Initially saturated-slurried and compacted-saturated samples of the selected materials were subjected to one cycle of freezing and thawing to study the influence of material type and initial conditions on the one-dimensional frost heave and thaw settlement. The test results showed that the type of material and the initial conditions of the materials prior to the freezing process influenced the frost heave, frost heave rate, velocity of water flow, segregation potential, and thaw settlement. Compacted-saturated materials showed a tendency to exhibit a greater magnitude of frost heave as compared to their saturated-slurried counterparts.

scholarly journals FREEZING AND THAWING | Processes

2005 ◽  
pp. 104-110 ◽  
Author(s):  
G.N. Flerchinger ◽  
G.A. Lehrsch ◽  
D.K. McCool
Keyword(s):  
Freezing And Thawing ◽  
Thawing Processes

scholarly journals Cryopreservation: The secret of modern preservation of brewer’s yeasts – minireview

2021 ◽  
Vol 67 (1) ◽  
pp. 403-408
Author(s):  
Katarína Hanzalíková ◽  
Petra Kubizniakova ◽  
Lucie Kyselová ◽  
Dagmar Matoulková
Keyword(s):  
Cell Damage ◽  
Cellular Structures ◽  
Biological Functions ◽  
Freezing And Thawing ◽  
Thawing Processes ◽  
Thawing Rate ◽  
Brewer’S Yeasts ◽  
Long Term Preservation ◽  
Stress Accumulation

The aim of the long-term preservation of cells, tissues and organs is to maintain their cellular structures and biological functions for as long as possible. Cryopreservation is a process where biological material is stored and preserved at very low temperatures. However, freezing and thawing processes can cause irreversible cell damage, which is related to formation of ice crystals, osmotic stress, accumulation of reactive forms of oxygen, etc. Therefore the cell viability depends mainly on the freezing rate, the composition of the cryoprotective medium as well as on the thawing rate. Using a suitable cryoprotective medium can increase the viability rate of the yeasts after “revitalization“. Appropriate pre-cultivation before freezing also plays an important role. These facts show that cell freezing and thawing processes must be controlled to avoid cell damage.

Аpplication of the mathematical model of human torso for modeling abbreval influence in wound ballistics

2020 ◽  
Vol 22 (3) ◽  
pp. 132-139
Author(s):  
A. V. Denisov ◽  
M. D. Stepanov ◽  
N. A. Haraldin ◽  
A. V. Stepanov ◽  
A. I. Borovkov ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Element Model ◽  
Mechanical Action ◽  
Calculation Model ◽  
Calculation Results ◽  
Automated Processing ◽  
Original Calculation ◽  
Using Data ◽  
The Mathematical Model ◽  
Selection Of

Abstract. In the work, a review of scientific articles on the behavior of tissues and organs of the human body under local mechanical effects on it, as well as a description of the physico-mechanical properties of biological materials. The selection of mechanical behavior for each biological material as part of a mathematical model of the human torso was carried out, its finite element model was created, validation experiments were modeled using data presented in the literature. An original calculation model of a human torso with a tuned interaction of organs with each other was developed. Contact interaction parameters are determined. The developed computational model of a human torso was verified based on data from open sources for an experiment with mechanical action by a cylindrical impactor. An algorithm for processing pressure and acceleration graphs has been implemented in order to obtain tolerance curves. A specialized modular program has been created for the automated processing of calculation results and the output of the main results. 42 numerical tests were carried out simulating the entry of a steel ball into each of 21 zones for power engineers of 40 and 80 J. According to the results of the tests for each organ, pressure and acceleration tolerance curves were obtained, animations of the behavior of organs under shock were created, visualization of the pressure field propagation in organs was obtained torso.

scholarly journals Non-growing-season soil respiration is controlled by freezing and thawing processes in the summer monsoon-dominated Tibetan alpine grassland

2014 ◽  
Vol 28 (10) ◽  
pp. 1081-1095 ◽  
Author(s):  
Yonghui Wang ◽  
Huiying Liu ◽  
Haegeun Chung ◽  
Lingfei Yu ◽  
Zhaorong Mi ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Summer Monsoon ◽  
Growing Season ◽  
Alpine Grassland ◽  
Freezing And Thawing ◽  
Thawing Processes
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