Kvantifiering av kornformsförändring vid materialkvalitetstestning av ballast
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Roads and railroads are important and essential transport systems for our everyday life. It is important to continue the development to create greater understanding of how these constructions are affected by degradation to not build long life constructions that are not fulfilling tomorrow’s changed demands. In constructions consisting of aggregates degradation caused by external loads is described by effects like changed properties of the soil mass. One step in the right direction when it comes to better understanding degradation is to describe the grain shape changes that occur. A number of grain shape describing variables are presented: soliditycircularity, aspect ratio, roundness and . These are measured with two dimensional digital image processing (DIP).The degradation is simulated by the material quality tests Los Angeles and micro Deval tests. A great number of grains from their samples are analyzed before and after the tests to compare the change of the grain shape. The results are analyzed to find the change of the grain shape and differences of the grain shape change of the two tests. The Los Angeles samples show a significant decrease in size indicating that fragmentation is the degradation mode. The samples also to some extent show more circular grains after testing. The micro Deval samples show smaller grains, but not to the same extent as for the Los Angeles samples. The micro Deval samples also show that the grains are more even and circular indicating the grains are exposed to wearing. These results verify the degradation modes for the micro Deval and Los Angeles tests. The data is also analyzed with factor analysis to identify connections between the measured variables’ results. A clear connection can be seen for Los Angeles and micro Deval tests both before and after testing. Circularity and solidity are varying alike and represents a shape factor, measuring a grain’s shape in two scales. Another analysis was completed for flakiness index to explore if there is a way to perform a similar grain shape test with two dimensional digital image processing. There is a great difference between the results from the laboratory test and the DIP. This is because of the fact that only two dimensions are identified with the DIP, and the data collected from the DIP does not represent the data from the flakiness index test. That one dimension is not identified with the two dimensional DIP can also affect the grain shape results. Despite this, it is possible that the great number of analyzed grains can counter this effect. Further investigation is necessary to verify this.
Place, publisher, year, edition, pages
2014. , 352 p.
Teknik, friktionsjord, Los Angelestest, micro Devaltest, flisighetsindex, bildanalys, nedbrytning, kornform, cirkularitet, aspect ratio, rundhet, soliditet
IdentifiersURN: urn:nbn:se:ltu:diva-43085Local ID: 0fdf7131-cca4-467d-8bbf-2d561d876542OAI: oai:DiVA.org:ltu-43085DiVA: diva2:1016313
Subject / course
Student thesis, at least 30 credits
Civil Engineering, master's level
Validerat; 20140612 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved