Date

2021-2-15

Author

MAHYAR, MAHDİ

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The use of concrete instead of traditional asphalt in road construction has been a challenge in the last century for road owners looking for a safe and sustainable solution. Very heavy expenditures of asphalt pavement rehabilitation during its lifetime, have made concrete the best choice for substitution. However, it is generally accepted that the initial construction costs of conventional concrete pavements are high. In concrete pavement construction, a competitive method for decreasing initial cost of construction is the application of roller compacted concrete (RCC) paving technology which carries the advantages of both methods in terms of costs; low construction costs similar to asphalt pavement and low rehabilitation costs similar to conventional concrete pavements. RCC is a zero-slump concrete consisting of densely graded aggregates. Because of its poor workability, it is usually placed with an asphalt paver, and compacted by a vibrating roller. The most common disadvantages of RCC pavements are due to the uncertainties in the unevenness and the skid resistance which are both related to its surface texture. Hence, it is commonly recommended for heavy load carrying lots and urban streets with lower traffic speeds. However, unlike mechanical properties of RCC pavements, which is almost well-understood in literature, there is not any adequate evidence of its surface texture characteristics. Within the framework of this study, a high accuracy 3D laser beam scanner is developed at the METU Materials of Construction Laboratory. It has a capacity of scanning 500x500 mm samples with a 0.010 mm accuracy in depth and MATLAB is used for the surface texture analysis using the ISO 25178-2 international standard. The standard defines various roughness parameters as quantitative parameters computed from the measured 3D surface textures. This study intended to investigate the roughness parameters of various RCC samples prepared using different compaction methods. Superpave gyratory compactor, and a double drum a double drum vibratory hand roller (DDVHR) to better simulate the field compaction procedures of RCC were the two compaction procedures utilized. Besides RCC, hot mix asphalt (HMA) specimens were also utilized. It was shown that, super-pave gyratory compacter cannot represent the vibratory rollers in terms of surface texture. Furthermore, it was observed that the generated texture of RCC and HMA surface, utilizing identical aggregate gradation, type and content, is not identical as demonstrated with 3D scanning of textures and comparing computed roughness parameters based on ISO 25178-2. It is found that HMA texture provides higher degree of contact with 4 to 7 times more contact points compared to RCC texture. Shape of the contact points for the asphalt samples are 3 times pointier than the RCC samples. As a summary, RCC suffers from producing a uniform texture and it is prone to get waviness from compaction. However, comparisons also showed that RCC can provide equal and greater macro-texture to HMA. Additionally, potential correlations between micro-texture and skid resistance of the surfaces and the surface-scaling durability of the RCC pavement samples subjected to chemical deicers under freeze and thaw cycling was determined. Finally, two texture modification techniques were applied on the RCC pavements and their influence on macro-texture and micro-texture were also determined.

Subject Keywords

Roller Compacted Concrete Pavement, Micro- and Macro-Texture Parameters, Skid Resistance, Optical Surface Profiler

URI

https://hdl.handle.net/11511/90239

Collections

Graduate School of Natural and Applied Sciences, Thesis