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Plastic production has risen steadily, but recycling rates lag. Researchers are increasingly investigating the use of plastics in road construction, especially in terms of modifying asphalt with waste plastics. The dry process, which involves incorporating plastics into hot aggregates, is increasingly gaining traction as an alternative to the wet process, where plastics are added to hot bitumen. Past studies indicate enhanced asphalt mixture properties with the dry process, but there is debate about the role of waste plastics—whether they should be used as aggregates, fillers, or binder modifiers. This study explores the extent to which dry-added waste plastic modified the binder of the asphalt mixtures. Fluorescent microscopy and scanning electron microscopy revealed the impact of plastic on the binder, while image analysis quantified polymer swelling and dispersion in the binder matrix. It was concluded that when plastics are added to hot aggregates, they will act as binder modifiers. Lower plastic content and reduced polymer crystallinity led to increased polymer swelling and better dispersion in the mixture. This study recommends plastic inclusion of less than 2.5% (by volume) in the dry-added method since high plastic content leads to polymer agglomeration, especially for highly crystalline polymers. Additionally, mixes modified with amorphous plastics exhibited superior workability and performance compared to those modified with crystalline plastics. This study also suggests that using plastics to replace both bitumen and filler can improve cost efficiency, reduce the carbon footprint, and enhance the overall performance of the asphalt mixture. [ABSTRACT FROM AUTHOR]

This study examines the applicability of an unknown composition waste plastic bag sample as bitumen modifier. The waste components were initially characterized to identify the type of plastics and the level of impurity. Asphalt binder performance was examined for rutting, thermal, and age resistance. The results revealed that the waste plastic bags, predominantly consisted of Low-Density Polyethylene (LDPE) and Linear Low-Density Polyethylene (LLDPE) and contained 6.1% impurities. The binder tests indicated that the waste plastic bags enhanced the rutting resistance of bitumen by one grade, with its modification more similar to LLDPE, rather than LDPE. The thermal degradation and aging properties of the modified binders demonstrated that the bitumen modified by the waste plastic bags exhibited slightly lower resistance to temperature and aging compared to virgin LDPE and LLDPE. This was attributed to the impurities contained in the waste plastic. In conclusion, the analyzed waste plastic bags proved to be suitable for use in binder modification, presenting a viable alternative to virgin LLDPE. [ABSTRACT FROM AUTHOR]

Fibers are added to foam concrete to improve its mechanical properties. Despite several studies about the performance of fiber-reinforced foam concretes, the mechanism of fiber reinforcement in foam concretes is not understood. In this research, the microstructural properties of Polyvinyl alcohol (PVA) fiber-reinforced foam concretes were quantitatively analyzed with different fiber sizes and fiber contents. The relationship between different parameters was investigated to understand how and why fibers influence the microstructural properties of foam concrete. In addition, a regression model was developed to analyze how fibers influence the compressive strength and which parameters have the highest impact on the compressive strength. The results show that the mechanism of reinforcement is different in high-density and low-density foam concretes. In high-density foam concrete, fiber distribution had a dominant impact on the compressive strength, but the pore structure did not show much influence on the strength. However, in low-density foam concrete, fiber distribution significantly influenced pore structure, and an improved pore structure provided higher compressive strength. The size of fibers significantly affects fiber reinforcement efficiency. The large-diameter fibers outperformed small-diameter fibers in improving the compressive strength of high-density foam concrete. In contrast, the small-diameter fibers showed better reinforcement efficiency in low-density foam concrete. By optimizing the PVA fiber size and content, the compressive strength of low-density and high-density foam concretes can be improved by 45.3% and 15.5%, respectively. [ABSTRACT FROM AUTHOR]

Geopolymers, as a potentially environmentally friendly alternative to Portland cement, are increasingly attracting attention in the construction industry. Various methods have been applied for customizing the properties of geopolymers and improving their commercial viability. One of the promising methods for refining the properties of geopolymers such as their toughness is the use of short fibers. The effectiveness of a high‐strength short fiber in the geopolymer matrix is largely dependent on the interfacial bonding between the fiber and its surrounding matrix. While the importance of this interfacial chemistry is highlighted in the literature, the characteristics of this bonding structure have not been fully understood. In this paper, we aim to investigate the bonding mechanism between the carbon fiber and metakaolin‐based geopolymer matrix. For the first time, the existence and nature of the chemical bonding at the interfacial region (interphase) between carbon fiber and geopolymer matrix has been revealed. X‐ray pair distribution function computed tomography (PDF‐CT), field emission‐scanning electron microscopy imaging, and nanoindentation techniques are employed to discern the chemo‐mechanical properties of the interphase. PDF‐CT results show the emergence of a new atom–atom correlation at the interfacial region (around 1.82 Å). This correlation is a characteristic of interfacial bonding between the fiber and its surrounding matrix, where the existence of chemical linkages (potentially VAl‐O‐C) between fibers and the matrix contributes to the adhesion between the two constituents making up the composite. Due to such chemical bonding, the nanomechanical properties of the interfacial region fall between that of the carbon fiber and geopolymer. The combination of advanced techniques is proved useful for enhancing our understanding of the interfacial chemistry between fibers and the binding matrix. This level of knowledge facilitates the engineering of composite systems through the manipulation of their nanostructure. [ABSTRACT FROM AUTHOR]