Search Results (6)

The construction sector faces growing pressure to adopt sustainable alternatives amid the global plastic-waste crisis. This study presents a novel use of mechanically recycled high-density polyethylene (HDPE) and polypropylene (PP) to manufacture full-scale plastic rebars for mortar-free, light-load construction applications. A total of 48 samples, plain and ribbed, across three diameters (12 mm, 19 mm, and 25 mm) were fabricated and tested. Due to the absence of standardized protocols for recycled plastic rebars, tensile testing was conducted in reference to ASTM A615. Characterization techniques such as X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM) confirmed the material’s structural features and polymer integrity. XRD confirmed the crystalline phases of HDPE and PP, while SEM revealed ductile fracture in HDPE and brittle failure in PP. The 25 mm ribbed PP rebars demonstrated superior performance, achieving a maximum load capacity of 12.2 ± 0.6 kN, a toughness index of 19.3 ± 1.0, and energy absorption of 101.6 ± 5.0 N-m × 10. These results affirm their suitability for lightweight structural components such as boundary walls, partition panels, and mortar-free interlocking systems. Unlike prior studies that confined recycled plastics to filler roles in composites, this work validates their direct application as full-section, load-bearing members. Additionally, a polynomial-based empirical model was formulated to predict the tensile behavior of the recycled rebars. The findings underscore the potential of mechanical extrusion as a low-emission, scalable solution to convert plastic waste into durable construction materials that support circular economic principles. Full article

Pavement systems in wet-freeze regions are prone to cracking, rutting, and moisture damage, making it challenging to incorporate recycled materials into asphalt mixtures in a way that enhances sustainability while maintaining performance and constructability. This study investigates and demonstrates the combined benefits of using processed waste glass in a leveling course and high-content crumb rubber in a surface course, focusing on both laboratory and full-scale field assessments in a wet-freeze region of northern Michigan. A leveling course containing 10% waste glass aggregate and a surface course using 16% crumb rubber (by binder weight) modified asphalt were designed with low air voids (3.0–3.5%) to promote thicker asphalt binder films for improved crack resistance. Laboratory results demonstrated that the combination of a 10% glass aggregate leveling course and a 16% rubber-modified surface course significantly enhanced low-temperature fracture energy while maintaining robust rut resistance and moisture durability. Full-scale construction in northern Michigan corroborated these findings; field cores from rubber and glass sections surpassed performance thresholds for rutting, cracking, and noise reduction. This study demonstrates that integrating crumb rubber and waste glass into asphalt pavements offers both environmental and performance benefits. The approach presents a scalable solution for enhancing pavement durability in wet-freeze regions. Full article

Parallelepipeds specimens were made to further investigate the rockburst occurrence mechanism of ore pillars in underground mining units. The investigation was carried out with uniaxial compression systems and real-time testing systems, such as stress, video, and acoustic emission, combined with digital image correlation (DIC) and SEM electron microscope scanning technology, to systematically analyze the evolution of rockburst of ore pillars, strain field characteristics, acoustic emission characteristics, mesoscopic characteristics of the rockburst fracture, morphology of the bursting crater, and debris characteristics. The findings demonstrate that the pillar’s rockburst process went through four stages, including the calm period, the particle ejection period, the block spalling period, and the full collapse period. According to DIC digital image correlation technology, the development of cracks in the rock is not obvious during the calm period, but during the small particle ejection and block spalling periods, the microcracks started to form and expand more quickly and eventually reached the critical surface of the rock, resulting in the formation of a complete macro-rockburst rupture zone. During stage I of the test, the rate of acoustic emission events and energy was relatively low; from stages II to IV, the rate gradually increased; and in stage V, the rate of acoustic emission events and energy reached its maximum value at the precise moment the rock exploded, releasing all of its stored energy. The specimen pit section primarily exhibits shear damage and the fracture exhibits shear fracture morphology, while the ejecta body primarily exhibits tensile damage and the fracture exhibits tensile fracture morphology. The location of the explosion pit is distributed on the left and right sides of the middle pillar of the specimen, and the shape is a deep “V”. The majority of the rockburst debris is greater than 5 mm, and it mostly takes the shape of thin plates, which is comparable to the field rockburst debris’s shape features. Full article

In this paper, harmless municipal solid waste incineration fly ash (H-MSWIFA) was used to replace part of the mineral powder in asphalt mastic prepared with different ratios of filler to asphalt (F/A). Cone penetration (CPT), rotational viscosity, low-temperature bending, and full section fracture energy(FSFET) tests on the prepared H-MSWIFA asphalt mastic were carried out to evaluate the viscosity at room temperature, viscosity at high temperature, tensile property at low temperature, and crack resistance at room temperature of the asphalt mastic with different F/A and different H-MSWIFA content. An asphalt concrete mixture with a nominal maximum particle size of 13 mm (AC-13) with different F/A and H-MSWIFA replacement ratios was prepared. The effects of F/A and H-MSWIFA content on the high-temperature stability, water stability, and low-temperature cracking resistance of the asphalt mixture were studied. The results showed that the shear strength and viscosity of the asphalt mastic increased after H-MSWIFA replaced part of the mineral powder; and the greater the F/A, the greater the shear strength and viscosity of the asphalt mastic. H-MSWIFA can greatly improve the viscosity of asphalt mastic at high temperatures, and with the increase in H-MSWIFA content, the improvement effect becomes more obvious. The high-temperature stability of the asphalt mixture is not related to H-MSWIFA content but mainly depends on the F/A. Both the F/A and the H-MSWIFA replacement ratio can significantly affect the water stability of the asphalt mixture, specifically, the water stability reaches the best value when the F/A is around 1.0, and the addition of H-MSWIFA harms water stability. Both the F/A and the H-MSWIFA replacement ratio can significantly affect the low-temperature cracking resistance of the asphalt mixture. The higher the F/A, the worse the low-temperature crack resistance. At the same time, the addition of H-MSWIFA harms low-temperature cracking resistance. From the point of view of water stability and low-temperature crack resistance of the asphalt mixture, the H-MSWIFA replacement ratio should not be too high. Full article

As an asphalt modifier, waste battery powder (WBP) has been proven to be possible. This paper studies the modification effect of WBP on asphalt. The Flight Test Instrumentation Requirements (FITR) of WBP, Dynamic Shear Rheology (DSR) test, and Full Section Fracture Energy Test (FSFET) of asphalt are carried out. The high-temperature rheological properties and low-temperature properties of WBP modified asphalt are analyzed. The high-temperature stability, low-temperature crack resistance and water stability of WBP modified asphalt mixture are tested. The research results show that the modification of asphalt by WBP is essentially physical modification but the mixing of WBP has a certain enhancement effect on the bond energy of the methylene group, which is helpful to improve the technical performance of modified asphalt. The proportion of elastic components in asphalt can be significantly increased by adding WBP, thus enhancing the deformation resistance of asphalt under high-temperature conditions. The dynamic shear modulus of 10% waste battery powder is about 1.5–2.0 times that of 0% waste battery powder. The mixing of WBP reduces the proportion of viscous components in asphalt which is unfavorable to the crack resistance under low temperatures. The greater the amount of WBP, the smaller the fracture energy density, the content of WBP is 6% and 10%, the fracture energy density is about 60–80% and 40–60% of the original asphalt, and the low temperature cracking resistance of asphalt decreases. The modification effect of WBP on asphalt is much lower than that of SBS. Full article

In the last few decades, increasing efforts have been devoted to the development of beam-to-column connections able to accommodate the local ductility demand dissipating, contemporaneously, the seismic input energy. Among the typologies proposed, the so-called RBS (Reduced Beam Section) has gained wide acceptance in the construction market, leading to easy-to-construct and cost-effective solutions. As an alternative, new proposals based on the inclusion of friction devices in beam-to-column joints have recently been made. Such a practice has the merit, in case of destructive events, of exhibiting wide and stable hysteretic cycles concentrating damage in elements that undergo only minor yielding. Both RBS and friction joints have been widely studied, carrying out experimental tests on sub-assemblies investigating their cyclic rotational response. Nevertheless, the available experimental results on full-scale structures equipped with these connections are still quite limited. This is the reason why two experimental campaigns aimed at performing pseudo-dynamic testing of a full-scale two-storey steel building equipped with RBS and friction connections have been planned at the STRENGTH (STRuctural ENGineering Test Hall) Laboratory of the University of Salerno. The first experimental campaign with the structure equipped with RBSs has already been performed; the connections showed higher resistance than expected, and exhibited brittle fracture due to cyclic fatigue. The second campaign has not yet been carried out, but in this paper the blind analysis of the supposed behavior is reported. It is expected that the friction joints allow to dissipate the seismic input energy without any structural damage in the members, but only through the friction pads of the devices, which can be easily replaced at the end of a severe seismic event. Full article