Proceedings of the International Conference on Road and Rail Infrastructure CETRA, May 1, 2012
Road structural materials should have satisfactory behaviour that enables a proper load carrying ... more Road structural materials should have satisfactory behaviour that enables a proper load carrying capacity. Asphalt mixtures used in road construction, must have properties that prevent formation of permanent deformations and cracking caused by temperature changes and fatigue. Road damages caused by the impact of different factors don't have equal impact on all sections of carriageway and have manifested in various forms. To determine resistance to permanent deformations at high temperatures of asphalt specimens, triaxial cyclic compression and wheel tracking tests are used. We have made wheel tracking tests according to standard SIST EN 12697-22and triaxial cyclic compression test according to standard SIST EN 12697-25 methodB. Experiments were done for all principal asphalt mixtures: AC, SMA, MA and PA to obtain an extensive model of asphalt behaviour for mixtures which contain the most and the least air voids. Mastic asphalt dictated the use of bitumen B20/30 in all mixtures with the intention to compare results of wheel tracking test and cyclic compression test for four asphalt mixtures. The cylindrical specimen in triaxial test is subjected to a confining stress and a cyclic axial stress at elevated conditioning temperature and vertical plastic deformation is measured. The results will be interpreted with a statistical model.
This report documents the results of the first part of "Combigrade"project. 100 pieces... more This report documents the results of the first part of "Combigrade"project. 100 pieces of both spruce (Picea abies) logs and pine (Pinus sylvestris) logs were sampled and sawn timber produced. Nondestructive measurements of logs and sawn timber were made by 15 organisations producing 40 different measured quantities for each test piece. Finally, test material was loaded to failure in bending, and grade determining properties (modulus of elasticity, bending strength and density) were measured. Coefficients of determination were calculated between nondestructively measured indicators and grade determining properties. Also strength grading procedure determined by prEN 14081 was simulated numerically, and effectiveness of some potential grading methods was analysed. Part 1 of the project is planned to be followed by a larger testing programme enabling the determination of settings for new and combined grading methods in accordance with the upcoming European standard.
Monitoring displacements of the object can be performed using geodetic methods by selecting refer... more Monitoring displacements of the object can be performed using geodetic methods by selecting reference points on the surrounding terrain and points on the object that discretely describe the object’s behavior. The measurements are repeated in several epochs. By analyzing the geodetic network we can determine the status of a single point, i.e., whether the point has moved or not. The article discusses the testing of congruence, the testing of transformation of a single triangle, and the calculation of other deformation parameters in 2D networks resulting from the changes of points coordinates between two epochs. This is essentially the content of the Munich deformation method presented by W.M. Welsch, which includes the X- and L-method. The article also proposes some corrections to the original Munich approach. Finally, the applicability of the method is shown on a well-known practical example.
Many heat-transfer problems involve a change of phase of material due to solidification or meltin... more Many heat-transfer problems involve a change of phase of material due to solidification or melting. Applications include: the safety studies of nuclear reactors (molten core concrete interaction), the drilling of high ice-content soil, the storage of thermal energy, etc. These problems are often called Stefan's or moving boundary value problems. Mathematically, the interface motion is expressed implicitly in an equation for the conservation of thermal energy at the interface (Stefan's conditions). This introduces a non-linear character to the system which treats each problem somewhat uniquely. The exact solution of phase change problems is limited exclusively to the cases in which e.g. the heat transfer regions are infinite or semiinfinite one dimensional-space. Therefore, solution is obtained either by approximate analytical solution or by numerical methods. Finite-difference methods and finite-element techniques have been used extensively for numerical solution of moving...
Proceedings of the International Conference on Road and Rail Infrastructure CETRA, May 1, 2012
Road structural materials should have satisfactory behaviour that enables a proper load carrying ... more Road structural materials should have satisfactory behaviour that enables a proper load carrying capacity. Asphalt mixtures used in road construction, must have properties that prevent formation of permanent deformations and cracking caused by temperature changes and fatigue. Road damages caused by the impact of different factors don't have equal impact on all sections of carriageway and have manifested in various forms. To determine resistance to permanent deformations at high temperatures of asphalt specimens, triaxial cyclic compression and wheel tracking tests are used. We have made wheel tracking tests according to standard SIST EN 12697-22and triaxial cyclic compression test according to standard SIST EN 12697-25 methodB. Experiments were done for all principal asphalt mixtures: AC, SMA, MA and PA to obtain an extensive model of asphalt behaviour for mixtures which contain the most and the least air voids. Mastic asphalt dictated the use of bitumen B20/30 in all mixtures with the intention to compare results of wheel tracking test and cyclic compression test for four asphalt mixtures. The cylindrical specimen in triaxial test is subjected to a confining stress and a cyclic axial stress at elevated conditioning temperature and vertical plastic deformation is measured. The results will be interpreted with a statistical model.
This report documents the results of the first part of "Combigrade"project. 100 pieces... more This report documents the results of the first part of "Combigrade"project. 100 pieces of both spruce (Picea abies) logs and pine (Pinus sylvestris) logs were sampled and sawn timber produced. Nondestructive measurements of logs and sawn timber were made by 15 organisations producing 40 different measured quantities for each test piece. Finally, test material was loaded to failure in bending, and grade determining properties (modulus of elasticity, bending strength and density) were measured. Coefficients of determination were calculated between nondestructively measured indicators and grade determining properties. Also strength grading procedure determined by prEN 14081 was simulated numerically, and effectiveness of some potential grading methods was analysed. Part 1 of the project is planned to be followed by a larger testing programme enabling the determination of settings for new and combined grading methods in accordance with the upcoming European standard.
Monitoring displacements of the object can be performed using geodetic methods by selecting refer... more Monitoring displacements of the object can be performed using geodetic methods by selecting reference points on the surrounding terrain and points on the object that discretely describe the object’s behavior. The measurements are repeated in several epochs. By analyzing the geodetic network we can determine the status of a single point, i.e., whether the point has moved or not. The article discusses the testing of congruence, the testing of transformation of a single triangle, and the calculation of other deformation parameters in 2D networks resulting from the changes of points coordinates between two epochs. This is essentially the content of the Munich deformation method presented by W.M. Welsch, which includes the X- and L-method. The article also proposes some corrections to the original Munich approach. Finally, the applicability of the method is shown on a well-known practical example.
Many heat-transfer problems involve a change of phase of material due to solidification or meltin... more Many heat-transfer problems involve a change of phase of material due to solidification or melting. Applications include: the safety studies of nuclear reactors (molten core concrete interaction), the drilling of high ice-content soil, the storage of thermal energy, etc. These problems are often called Stefan's or moving boundary value problems. Mathematically, the interface motion is expressed implicitly in an equation for the conservation of thermal energy at the interface (Stefan's conditions). This introduces a non-linear character to the system which treats each problem somewhat uniquely. The exact solution of phase change problems is limited exclusively to the cases in which e.g. the heat transfer regions are infinite or semiinfinite one dimensional-space. Therefore, solution is obtained either by approximate analytical solution or by numerical methods. Finite-difference methods and finite-element techniques have been used extensively for numerical solution of moving...
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