Materials Science Forum Vol. 1007

Abstract: Membrane technology has attracted significant attention from the researchers, especially in gas separation process due to their simple process design and low capital cost compared to conventional techniques. In this work, oil palm frond (OPF) waste was used as nanoadsorbent embodied in polyether block amide (Pebax 1657) nanocomposite membrane to improve the CO₂/CH₄ separation. The effectiveness of the nanoadsorbent derived from OPF was evaluated by varying the nanoadsorbent concentration (2–8 wt %) and controlling the Pebax 1657 concentration (5 wt %), dipping time (5 s), and number of sequential coatings (3 layers). The pore characteristics of the nanoadsorbent was analyzed using Brunauer–Emmett–Teller (BET) analysis. The morphology and the existence of active groups in the newly synthesized nanoadsorbent and nanocomposite membranes were investigated using field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The single gas permeation process was carried out at constant pressure (2 bar) and room temperature (25 ± 5 °C). The optimum condition with 5 wt % nanoadsorbent made the nanocomposite membrane exceeded the trade-off limit of the Robeson plot with a CO₂ permeability and CO₂/CH₄ selectivity of 1475.09 Barrer and 40.48, respectively.

Abstract: Crystalline ZnO nanoparticles were synthesized by a mechanochemical method using zinc acetate dihydrate and sodium hydroxide as starting materials, and cetyl trimethylammonium bromide (CTAB) as a protective agent. Mechanochemical activation of the solid-state reaction was achieved at low temperatures in a rapid laboratory ball mill. A three-level full factorial experimental design was used to investigate the effect of milling time and surfactant ratio on ZnO crystallite size. The product powders were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The crystallite size of ZnO samples estimated from XRD is consistent with the SEM images and found to be less than 40 nm. The crystallite size of the ZnO decreased as the surfactant ratio increased. There is an optimal milling time of 60 minutes in order to obtain ZnO nanoparticles with the smallest average grain size. The antibacterial activity of the obtained products against Escherichia coli (E. coli) was examined, and the minimum inhibitory concentration value was 5 mg/mL. ZnO synthesized by this simple method can be considered potentially as an effective bactericidal agent.

Abstract: Conventional cement production process emits tons of carbon dioxide gas which is one of the greenhouse gases that influence the environment across the world. Discovering the alternative construction material with the eco-friendly process and the performance similar to or greater than ordinary Portland cement has been attractive to find out. This research presented green construction materials or so-called geopolymers from metakaolin substituted by high calcium fly ash by 20, 40, 60, 80 and 100 wt%. Some researches reported that geopolymer produced from metakaolin and fly ash with alkali solution gave a great result, but usually, they used fly ash containing very low calcium component. Compressive strength at 3, 7 and 28 curing days and flowability were conducted. The compressive strength of geopolymers blended with high calcium fly ash was still developed as the curing day increased and revealed the highest at 28 days especially on MK40 (high calcium fly ash 60 wt%). Geopolymer pastes prepared with a higher amount of high calcium fly ash exhibited less viscous. It was proved that the high amount of high calcium fly ash could be applied and gave extraordinary compressive strength. Furthermore, X-ray diffraction and X-ray fluorescence were used to investigate chemical properties as well as microstructure by a scanning electron microscope. For phase analysis, the existence of oxides of calcium and sulfur in high calcium fly ash resulted in the formation of thenardite, calcite, portlandite and C-S-H phase associating with geopolymeric phase. Therefore, this research proposed the opportunity for geopolymer production by using abundant high calcium fly ash to raise the value of the industrial waste products and green alternative construction material compared with OPC.

Abstract: Metals removal from wastewater has become a major concern over the years due to the adverse effects of metals on organisms and environment. Adsorption is one of the safest, simplest, and most cost-effective methods for metals removal. The primary purpose of this study was to develop a magnetically separable activated carbon from pineapple crown leaf for zinc removal. Magnetic activated carbon (MAC) were characterized by SEM-EDX and FTIR. The ability of MAC to adsorb zinc ion was studied through variation of initial solution pH, concentration, and contact time. The optimum pH for zinc removal was four, while the equilibrium was reached after 180 min. In this condition, the percentage removal of zinc was 70.5%.

Abstract: Sustainability in concrete structure has been developed rapidly for ensuring the requested for a new thinking about construction by concrete elements. This paper deals with using buddle using polyethylene terephthalate PET bottles and steel meshes for fabricating and modeling one way RC voided slab. That is very useful to reduce the weight of slab, also reduced the wastes in same time. For both the voided and solid ones, the load-displacement curves were almost identical from beginning until the load reaches ultimate stages, where the increasing in depth of voided slab showed higher strengths and lower displacement at same load level.

Abstract: The influence of volumetric hydrophobization of cement stone samples on mass transfer processes during hardening has been studied. It was found that the introduction of a hydrophobizing additive at the stage of sample production reduces the amount of water evaporating during drying. With increasing concentration of the hydrophobizer mass transfer processes are slowed down during the hardening of cement concretes, which affects their structural and phase composition, strength characteristics and durability.

Abstract: Cement is the most utilized construction material. The energy-intensive processes that are involved in its production contribute up to 10% of total global CO₂ emissions, with potentially adverse environmental implications. It is however possible, that energy and cost efficiency can be achieved by reducing on the amount of clinker, and in its place utilising supplementary cementitious materials (SCMs) or pozzolans that require less process heating and emit fewer levels of CO₂. Currently, most sustainable concrete uses either GGBS (slag) or PFA (fly ash) to reduce the quantity of cement used in construction and highways applications. GGBS and PFA come from industries (steel and coal waste respectively) which are in decline that should not be relied upon in the long term. This report shows that cement in concrete can also be replaced with rice husk ash (RHA) which actually enhances the mechanical properties. RHA comes from the food production industry and is vital for the growing global population. It is thus a socially responsible objective to use a pozzolan in civil engineering applications that is sourced from an environmentally friendly and sustainable industry. This study investigated the potential of RHA to be used as a SCM by evaluating mechanical properties. Experiments were carried out by supplementing cement in concrete mixes with RHA at up to 10% replacement by mass. Results were compared with a control specimen (100% cement), with a water/binder (w/b) ratio of 0.4 and C32/40 design mix using CEM I. The results show excellent early age strengths with all RHA mixes surpassing 40 MPa strength within 7 days which is contrary to general trends in SCM concrete where strength development is slow in the initial stages in comparsion to 100% cement concrete. All RHA specimens exhibited impressive flexural and tensile strengths.

Abstract: The Simple Performance Test (SPT) can be used to characterize the strength and load resistance of asphalt mixtures. The objectives of this study are to determine the effect of temperature on the phase angle and dynamic complex modulus of the asphalt mixtures tested at 30°C, 35°C, 40°C, 45°C and 50°C at 25Hz, 20Hz, 10Hz, 5Hz, 1Hz and 0.5Hz frequencies. The asphalt mixtures of NMAS 12.5mm are prepared using asphalt binder PEN 80/100 and PEN 60/70. The asphalt mixtures are designed using the Superpave system and compacted using the Superpave Gyratory Compactor (SGC). The dynamic modulus test results showed that at a higher temperature, the stiffness of the asphalt mixtures is affected. The dynamic modulus of the mixtures is highest at 30°C and gradually decrease at 35°C, 40°C, 45°C and 50°C respectively. The dynamic modulus values for asphalt mixtures with bitumen grade PEN 60/70 are also higher compared to the asphalt mixtures with bitumen grade PEN 80/100. Results also showed that the low phase angle values indicate low viscosity of the asphalt binder due to increase in temperature. The present study is meaningful in understanding the asphalt mixture behaviour at different temperature and loading frequencies.

Abstract: In this paper, a new ultrasonic phased array full focus imaging method based on oblique incidence is proposed to solve the problem of the non-destructive testing of the internal defects in the GIS (gas insulated switchgear) shell welds. By using wedge coupling, the measured weld is far away from the near-field range of the transducer, and the detection angle range can be increased by changing the propagation direction of the acoustic beam. Based on Snell's law, the propagation characteristics of the ultrasonic wave in the interface are studied. On the basis of the conventional ultrasonic array matrix and the full focus imaging algorithm, by introducing the energy attenuation calibration coefficient of the acoustic wave propagation through the wedge, the correction amplitude of the specific focus point p(x, z) is obtained, The non-destructive testing of weld defects of GIS shell in the spot is carried out, and the test results show that the qualitative and quantitative detection of the weld defects can be well realized by using this method.

Abstract: The development of alkaline activated materials has enabled the production of eco-friendly alternatives for the construction industry. In the present article, the mechanical characterization of a new structural masonry system composed of fiber-reinforced lightweight pozzolana-based blocks and cement-lime mortar was performed. The mechanical characterization involved uniaxial compression tests in prisms and diagonal compression in wallets. The results indicate that the compressive and shear strength of the masonry system is up to 3.24 MPa and 0.38, respectively. The results obtained indicate that the evaluated system is structurally efficient and that can be used as both non-load and load-bearing walls.