Recycled Polyethylene Modified Asphalt Binders and Mixtures: Performance Characteristics and Environmental Impact

This study addresses the effects of recycled polyethylene (RPE) on the performances of both asphalt binders and asphalt mixtures. Whether using RPE in an asphalt mixture might leach harmful chemicals into rainwater or melted snow was also determined. Two processes, wet and dry, were used to formulate the RPE modified asphalt binders and mixtures. In the wet process, RPE was added to asphalt binder. In the dry process, it was added to heated aggregates. RPE from two sources and PG 64-22 virgin asphalt binders from two sources were used in this study. In conclusion, RPE improved the rutting resistance of the asphalt binders and asphalt mixtures. However, it had adverse effects on their resistance to intermediate-temperature and non-load associated cracking. The dry process could produce a mixture with a higher RPE dosage compared with the wet process using one virgin asphalt binder but not the other; thus, the virgin asphalt binder source was a significant factor for the dry process. Based on an embryotoxicity test, it was found that RPE can be used by the asphalt paving industry without creating any significant environmental risks.

Identification of antioxidant components of Gayo Arabica Coffee Cascara using the GC-MS method

Approximately half of the coffee will become by-product in coffee processing. This by-product needs a special focus because of its content can be pollutant for nature. One of the coffee by product that underutilized is cascara, composed by pulp and husk. The major by-product of dry process is husk whereas pulp is the major by-product from wet process. Nowadays, there are various ways to utilize coffee by-product. Previous studies have shown that coffee has a potent antioxidant activity which can be a solution in dermatology problem. This research aims to identify the antioxidant component of coffee arabica husk and pulp of Gayo, Aceh Tengah, Aceh using GC-MS method. One of the compounds that identified in both coffee husk and pulp is caffeine. Caffeine is a potential natural antioxidant and it also has anticellulite effect to skin. The other compounds found in coffee husk and pulp also have benefit in dermatology. We conclude that coffee arabica husk and pulp can be a potential natural source to eradicate dermatologic problem.

Controlling Factors of the Particle Size of Spherical Silica Synthesized by Wet and Dry Processes

We clarified the controlling factors of the particle size of the amorphous silica synthesized by wet and dry processes. In the wet process using methyl-trimethoxy-silane as a starting monomer, the obtained particle size can be easily controlled by changing the reaction time appropriately. However, to obtain larger particles, a relatively long time is needed. After the condensation reaction was conducted for 50h, the silica particles (D50: 3μm) were synthesized by calcination at 550oC in air. To synthesize larger silica particles, we used silica-seed particles (8μm) to obtain very large spherical silica particles (D50: 20μm). Thus, although the wet process needs a relatively long reaction time, it is very useful for synthesizing spherical silica particles with a wide range of particle size. In the dry process, we used methyl-trimethoxy-silane (MTMS), tetra-ethoxy-silane (TEOS), and octamethyl-cyclotetrasiloxane (OMCTSO) as the starting materials. In this process, the size of the silica particles was dominated by the molecular structure of the monomer, in particular, the number of silicon atoms contained in the monomer and the bulkiness of the substituent group. The largest silica particles were synthesized from OMCTSO, which contains the largest number of silicon atoms.

Protonic Ceramic Fuel Cell with Bi-Layered Structure of BaZr0.1Ce0.7Y0.1Yb0.1O3–δ Functional Interlayer and BaZr0.8Yb0.2O3–δ Electrolyte

Widespread application of PCFCs will require higher performance even at lower temperatures (<600 °C). This paper reports development of a protonic ceramic fuel cell (PCFC) with a bi-layered proton-conducting phase structure consisting of a BaZr0.1Ce0.7Y0.1Yb0.1O3–δ (BZCYYb1711) functional interlayer and BaZr0.8Yb0.2O3–δ (BZYb20) electrolyte. In this PCFC, a zirconate-based oxide with high durability against CO2, BZYb20, is selected as the electrolyte material, and a BZCYYb1711 functional interlayer is applied between the dense BZYb20 electrolyte and a cathode to achieve higher power density and higher open-circuit voltage (OCV) of the PCFC. In cell fabrication via conventional wet process and co-sintering, although Ni diffusion occurs from NiO-BZYb20 anode into the approximately 8-µm-thick BZYb20 electrolyte, almost no Ni diffuses into the BZCYYb1711 functional interlayer. Compared to a PCFC without this functional interlayer, the proposed PCFC exhibits higher electrochemical performance. Results showed that the BZCYYb1711 functional interlayer reduces cathode polarization resistance and increase power density of the PCFC. Moreover, the OCV increases because the BZCYYb1711 functional interlayer suppresses the current leakage caused by hole conduction of the BZYb20 electrolyte. In conclusion, this bi-layered structure effectively improves both the power density and OCV of PCFCs.

Production and Physical–Mechanical Characterization of Peat Moss (Sphagnum) Insulation Panels

Peat moss (sphagnum) is a commonly used sealant, fill, and insulation material in the past. During the efforts to rewet drained moors due to ecological considerations, the technical use of peat moss (sphagnum farming) again became the focus of attention. In the framework of this investigation, insulation panels consisting of peat moss, bound with urea formaldehyde, were produced. Panels manufactured in a wet process and mats bound with textiles were also fabricated. The specimens’ thermal conductivity, water vapor diffusion resistance, modulus of rupture, modulus of elasticity, internal bond, compression resistance, water absorption, and thickness swelling were measured. Physical–mechanical properties were adequate with the resin-bound panels, but not with wet process panels. Moss mats had good characteristics for cavity insulation purposes. The thermal conductivity of the moss panels and mats was found to be lowest with a density of 50 kg/m³, accounting for 0.04 W/m·K. The results show that peat moss is a promising resource for production insulation panels, because their thermal conductivity and mechanical stability are comparable to other insulation materials.

Influence of Additives on the Fatigue Life and Stiffness of Asphalt Concrete

Implementation of additives to the asphalt binder can enhance the overall physical properties of the modified asphalt concrete. In the present assessment, an attempt has been made to use 2 % of silica fumes and 4 % of fly ash class F for modification of asphalt binder in wet process. Asphalt concrete wearing course mixtures have been prepared and compacted by roller in the laboratory. The beam specimens of 400 mm length and 50 mm height and 63 mm width were extracted from the slab samples. The specimens were subjected to the four-point repeated flexural bending beam test. The flexural stiffness was calculated under three constant micro strain levels of (250, 400, and 750). The fatigue life was monitored in terms the number of load repetitions to reach the required reduction in stiffness. It was concluded that the flexural stiffness increases by (11, and 15) %, (17.7, and 63.6) %, (57.2, and 65) % when 2% of silica fumes or 4 % of fly ash are implemented and the specimen’s practices 750, 400, and 250 microstrain levels respectively. However, the fatigue life of asphalt concrete beam specimens increases by (40, and 72.8) %, (115, and 220.6) %, (46, and 94.6) % when 2% of silica fumes or 4 % of fly ash are implemented and the specimen’s practices 750, 400, and 250 microstrain levels respectively. It is recommended to use modified binder with fly ash and silica fumes in asphalt concrete to enhance the fatigue life and stiffness.