Durability performance of alkali-activated concrete with pre-treated coarse recycled aggregates for pavements.

This study examines the effect of coarse recycled aggregates (CRAs) and processed coarse recycled aggregates (PCRAs) on the behaviour of alkali-activated concrete (AAC) before and after exposure to marine seawater and acidic environments (5% HCl and 5% H2SO4 solutions). Measurements of compressive strength and the microstructure changes were conducted over periods of 56 and 90 days to assess these effects. The experimental design included varying the replacement levels of NAs with CRAs and PCRAs from (0-100%) and using ground-granulated blast furnace slag and fly ash as constant components. In addition to durability tests, sorptivity assessments were conducted to gauge the material's porosity and water absorption capabilities. Advanced microstructure techniques, such as scanning electron microscopy (SEM) and X-ray diffraction (XRD), were employed to detail the pre and post-exposure mineralogical and microstructural transformations within the AAC blends. The AAC mixtures incorporating PCRAs emerged as durable, showcasing better strength and a denser, more compact matrix facilitated by the synergistic formation of NASH and CASH gels after exposure to aggressive agents compared to untreated CRAs. In addition, the results show that the samples exposed to marine seawater exhibited improved mechanical performance compared to those exposed to acidic environments. The novelty of this study lies in its exploration of the effects of recycling plant-based CRAs and PCRAs on AAC for marine and acid exposure.

Simulation of Wood Polymer Composites with Finite Element Analysis.

Wood is a cellulosic material that is most abundantly available in nature. Wood has been extensively used as reinforcement in polymer composite materials. Wood polymer composite (WPC) is an environmentally friendly and sustainable material exploited in building and construction within the marine, packaging, housewares, aerospace, and automotive industries. However, the precision of testing equipment for finding the properties of WPCs becomes less feasible compared to experimental analysis due to a high degree of differences in the measurement of properties such as stress, strain and deformation. Thus, evaluating the mechanical properties of WPCs using finite element analysis (FEA) can aid in overcoming the inadequacies in measuring physical properties prior to experimental analyses. Furthermore, the prediction of mechanical properties using simulation tools has evolved to analyze novel material performance under various conditions. The current study aimed to examine the mechanical properties of saw dust-reinforced recycled polypropylene (rPP) through experimentation and FEA. A model was developed using SolidWorks, and simulation was performed in ANSYS to predict the mechanical properties of the WPCs. To validate the obtained results, the simulated static tension test results were confirmed with experimental tension tests, and both assessments were well in accordance with each other. Using FEA to predict material properties could be a cost-effective technique in studying new materials under varied load conditions.

Development of Biodegradable Composites Using Polycaprolactone and Bamboo Powder.

The use of biodegradable polymers in daily life is increasing to reduce environmental hazards. In line with this, the present study aimed to develop a fully biodegradable polymer composite that was environmentally friendly and exhibited promising mechanical and thermal properties. Bamboo powder (BP)-reinforced polycaprolactone (PCL) composites were prepared using the solvent casting method. The influence of BP content on the morphology, wettability, and mechanical and thermal properties of the neat matrix was evaluated. In addition, the degradation properties of the composites were analysed through soil burial and acidic degradation tests. It was revealed that BP contents had an evident influence on the properties of the composites. The increase in the BP content has significantly improved the tensile strength of the PCL matrix. A similar trend is observed for thermal stability. Scanning electron micrographs demonstrated uniform dispersion of the BP in the PCL matrix. The degradation tests revealed that the biocomposites with 40 wt·% of BP degraded by more than 20% within 4 weeks in the acidic degradation test and more than 5% in the soil burial degradation test. It was noticed that there was a considerable difference in the degradation between the PCL matrix and the biocomposites of PCL and BP. These results suggest that biodegradable composites could be a promising alternative material to the existing synthetic polymer composites.