A tack coat is a thin layer that ensures the bonding between an asphalt overlay and existing pavement. Adequate tack coat bonding is required for the composite pavement structure to behave as a single layer. The adhesion between the layers is significantly reduced at high temperatures, given that tack coat is characterized as a temperature-dependent material. This implies that debonding frequently occurs at elevated temperature during summer season. However, the distresses or failures related to debonding may not be occurred due to the bond strength recovery effects of the tack coat material in the early-age of the composite pavement. This study intended to investigate the bond strength recovery effect of the tack coat at the interface between the asphalt overlay and existing concrete layer based on the pull-off tests. The bond strengths measured between 18 to 20°C were 0.75 MPa and 0.81 MPa for the cationic rapid setting emulsified asphalt and modified rubberized asphalt, respectively. However, the measured bond strengths of all the specimens were 0.08 MPa or less at a high temperature of 38 to 42°C. As a result of testing the possibility of recovering the bond strength to the debonded specimens at high temperature, the bond strength of 75% or more could be recovered at the interface.

Coal bottom ash (CBA) is a by-product generated in the coal furnaces of thermal power plants. It has adverse effects on the environment and requires additional landfill storage. However, the physical appearance of CBA is similar to that of sand, with particle sizes ranging from fine to coarse aggregates. Hence, many previous studies have focused on its application instead of sand for conventional concrete and structural fill materials considering natural sand depletion. Roller compacted concrete (RCC) is a zero-slump concrete with better compressive strength than conventional concrete because of the aggregate interlock achieved due to the compactness. It uses a low cement content but requires a large amount of sand. However, the applicability of CBA to RCC is limited. The properties of CBA may vary depending on the location. Therefore, this study aims to evaluate the effect of CBA as a sand replacement in RCC in terms of strength and long-term performance by conducting an empirical experiment under given conditions. Initially, a comprehensive literature review of various concrete strengths using CBA as sand replacement is provided. Thereafter, details related to the experiments on the strength and durability of the given CBA are presented. The results show that the RCC strength improves when CBA increases owing to the good gradation and low percentage of calcium oxide. Furthermore, the samples displayed acceptable freeze–thaw resistance values, but the scaling resistance values were small, owing to the high-water absorption. Therefore, CBA can be used in RCC as sand for improved structural performance, while additional research should be conducted to improve its long-term performance.

Roller-Compacted Concrete (RCC) has been used widely for construction of pavements. The strength of RCC Pavement (RCCP) can be obtained from not only hydration of binder but also the aggregate interlock resulting from roller compaction. For this reason, RCCP normally achieves strengths greater than conventional concrete pavement with similar cement content. Even though RCCP can provide good structural performance, it has been difficult to verify its long-term performance through actual field construction. Therefore, this study evaluated the fatigue behavior using 1 by 1-m dimensional RCC slab specimens obtained in the field in order to take into consideration field variability. A set of numerical analyses indicated that the failure modes of the specimens for a given loading condition appeared to be four-directional bottom-up cracks. A fatigue equation was developed based on the relationship between the stress level and the number of load repetitions.

In Korea, the transverse tining method has been applied to the surface texture of concrete pavements as it provides excellent skid resistance that improves road safety. However, transverse tining produces higher noise levels of about 4–5 dB(A) compared to asphalt pavements. Accordingly, exposed aggregate concrete pavement (EACP) is introduced since the low tyre-pavement noise and long-term skid resistance can be obtained. Surface texture of this pavement consists of coarse aggregates that are exposed after the removal of the cement mortar. Tyre-pavement noise in EACP resembles that in asphalt pavement due to the similar surface texture that is characterised by wavelength. This parameter is the distance between aggregate particles; thus, it is significantly related to the size and amount of coarse aggregate in the mixture proportion. In addition, short wavelength tends to produce low tyre-pavement noise and this can be a criterion to minimise the noise level in pavement design. Therefore, this study aims to optimise the mixture proportion of low-noise EACP based on the requirement of surface texture and structural capacity. As a result, concrete mixture with 8-mm size and 27% amount of coarse aggregate provided as short-wavelength as asphalt pavement and adequate structural strength was also achieved.