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Effects of mixture design parameters and compaction methods on the properties of roller compacted concrete pavements

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2019
Şengün, Emin
The aim of the thesis is to develop laboratory compaction methodology suitable for simulating field compaction procedures used for creating roller compacted concrete (RCC) mixtures. Based on this methodology, mechanical performance and fracture properties of RCC mixtures of different strength classes were determined and long-term fatigue performance of RCC mixtures with different strength levels was investigated. In this context, a three-phase experimental study was designed. First, mixtures with different binder content and water amounts were prepared, and samples were made using different compaction procedures. A compaction methodology using a double drum vibratory hand roller was also implemented to represent field compaction procedures in the laboratory and was used to prepare RCC specimens in the later stages of the study. Second, the effects of RCC mixture parameters on RCC properties, especially fracture parameters, were determined for different binder contents and maximum aggregate sizes. Finally, for three RCC mixes of different performance categories, the flexural fatigue performance was determined and expressed as S-N curves. The experimental results show that ideal RCC mixtures can be achieved with water amounts of 5-6%, Vebe times in the range of 30 ±10 sec, and a compaction ratio higher than 96%. It was also observed that fracture toughness was enhanced with increasing binder dosage and maximum aggregate size, although the increase in binder dosage or maximum aggregate size did not significantly change the fracture energy. Moreover, the average fatigue strength of the RCC mixture, corresponding to 2 million load cycles, was found to be about 62.5% of the ultimate static strength. Above all, compaction ratio, which is influenced by not only compaction methodologies but also mixture designs, is found to be the most important parameters affecting RCC properties.