Effect of the Composition of Mixed Recycled Aggregates on Physical–Mechanical Properties

Recycled aggregates (RA) from construction and demolition waste are an alternative to natural aggregates in the construction sector. They are usually classified according to their composition. The main constituent materials are separated into the following categories: unbound natural aggregates, ceramic particles, cementitious particles, bituminous materials, and other materials considered impurities, such as glass, plastic, wood, or gypsum. In this research, a large number of samples of RA were collected from three different recycling plants and their properties were studied. After that, 35 samples were selected randomly, and their RA constituents were separated under laboratory conditions. Cementitious particles were differentiated into two subcategories: masonry mortar and concrete particles. Subsequently, their physical–mechanical properties were measured. The statistical analysis carried out exhibited that the constituents had a statistically significant influence on the physical–mechanical properties studied. Specifically, masonry mortar particles had higher water absorption and worse mechanical properties than concrete and ceramic particles. Secondly, multiple regression models were performed to predict the physical–mechanical properties of RA from their composition since mean absolute percentage error (MAPE) ranged between 0.9% and 8.6%. The differentiation in the subcategories of concrete and masonry mortar particles in compositional testing is useful for predicting the physical–mechanical properties of RA.

Application of Steel Fibre to Improve the Self-Healing Mechanism of Bituminous Mixtures: A Review

The self-healing mechanism of bituminous mixtures was demonstrated through several studies and was recognised for developing sustainable road pavement. This paper presents a comprehensive summary of various studies related to steel fibre as a self-healing mechanism of bituminous materials. Based on the extensive literature, it was found that steel fibre was likely to be used in the asphalt industry due to several benefits. First, the idea of using steel fibre in pavement engineering materials gives great attention to their utilisation in asphalt. It helps increase the self-healing mechanism and contribute to reducing the problem related to potholes, ravelling, slipping during raining while driving and many more. Second, this study identifies the gap of research for future research in pavement engineering. Finally, some proposals were made for the possible construction of self-healing asphalt.

Effects of Alkylamines-Based and Polyalkylene Glycol-Based Bonding Enhancers on the Performance of Asphalt Binders

The premature deterioration of asphalt pavements usually occurs due to different moisture damage mechanisms resulting in stripping, ravelling, potholes, and disintegration without proper treatment. Numerous efforts have been taken into consideration to improve the bonding between materials, hence prolonging the pavement life. This study evaluates the performance of asphalt binders incorporating Alkylamines-based (ALM) and Polyalkylene Glycol-based (PLG) bonding enhancers. Each bonding enhancer at 0.5% and 1.0% based on the weight of asphalt binder was separately blended with the conventional asphalt binder 60/70 penetration grade using a high shear mixer at 1000 rpm for 30 minutes at 160°C. The physical and rheological properties of modified binders were evaluated through penetration value, softening point, ductility, elastic recovery, rotational viscosity (RV), and dynamic shear rheometer (DSR) tests. Overall, additions of ALM and PLG show identical penetration grade compared to the control sample. Both ALM and PLG showcase a higher ductility and elastic recovery than the neat binder. The DSR test indicates the incorporation of bonding enhancers improves the modified binders’ rutting performance. While the application of ALM at 0.5% dosage increased the binder failure temperature out of all the tested samples, where the failure temperature is at 70°C, compared to others at 64°C. Studies at mastics and mixture levels should be conducted to appropriately understand the effect of bonding enhancer on the bituminous materials.