The effects of reclaimed asphalt pavement aggregates on the behavior of cement-based mortars

Reclaimed Asphalt Pavement (RAP) is generally considered as one of the components in bituminous hot mixtures. The presence of bitumen in RAP is particularly one of the main factors for this preference. One of the research efforts to explore the alternative use of this material is the investigation of mixtures prepared with finely crushed RAP and cement mortar. In this thesis, six different mixtures were created by varying the RAP content while keeping the cement content constant (400 kg/m3) and the water-to-cement ratio constant (0.60). RAP with particle sizes of 0-4 mm were substituted for natural sand of the same size in proportions of 0%, 20%, 40%, 60%, 80%, and 100%. Tests were conducted to evaluate the workability (spread), flexural strength, compressive strength, unit weight, water absorption, capillarity, drying shrinkage, ultrasonic pulse velocity (UPV), and energy absorption capacity (toughness) of the mixtures. According to the experimental findings, it was determined that there was no significant loss of workability in the mixtures, and the flexural and compressive strengths increased with curing time, but increasing RAP content had a negative effect on both strength developments. While the unit weight showed a continuous decrease with increasing RAP content, the water absorption increased up to 80% RAP content and then started to decline. The capillary properties of all specimens were found to be similar to their water absorption behavior. The development of drying shrinkage generally increased as the RAP content increased. The control specimens without RAP showed a shrinkage of 0.075% at the end of 112 days, while specimens with 100% RAP recorded an approximately fourfold increase to 0.288%. Increased RAP content resulted in drying shrinkage ranging from 0.200% to 0.288% in all specimens. According to the UPV test results, it was concluded that specimens with 80% and 100% RAP content could be classified as "medium," while the other specimen groups could be classified as "good" concrete class. In the control mixtures without RAP, the fracture energy was 0.0444 N/mm, while with 60% and 80% RAP utilization, an improvement in fracture energy level was calculated to be approximately 12% with values of 0.0500 N/mm and 0.0496 N/mm, respectively. When the ratio of fracture energy to flexural strength was evaluated as a ductility parameter, it was observed that the use of RAP could have a positive contribution ranging from 5.5% to 60% in all scenarios. The results of all the experiments indicate that RAP, despite causing a decrease in important properties such as flexural and compressive strength, can be an alternative material in the production of concrete with certain quality. The significant contribution of RAP in energy absorption capacity is at a level that would make this material be considered as an enhancing material rather than being treated as waste. In particular, structures with high energy dissipation requirements such as concrete barriers, surface coatings where flexibility is desired in rigid pavements, seismic isolators, and structural elements where lightweight, ductility, and toughness are desired rather than strength, it is concluded that RAP can be used in cement mortar content based on controlled experiments.