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The development of the use of natural fiber as a constituent material for FFP as an external concrete retrofit that is environmentally friendly and affordable price has been quite developed. One plant that grows massively in Indonesia and can be extracted into fiber is water hyacinth. This plant will be extracted into fiber through three variations, namely mechanical, boiling, and natural alkali, by using bio-resin to produce WHBR (Water Hyacinth and Bio-Resin) FRP in the form of rope and weave. The tensile behavior of the obtained WHBR FRP will be investigated against ASTM A931-18 and ASTM D3039 requirements. The results of the investigation are compliance with failure criteria, the impact of the tensile test result on compliance with failure criteria, and the impact of pattern-delignification on tensile strength performance. In this study, it has been found that the boiling treatment-plain woven variation of WHBR FRP has the best properties and it is recommended as an external concrete retrofit material for future studies. [ABSTRACT FROM AUTHOR]

One of the crucial problems caused by the COVID-19 pandemic is the increase in the number of disposable plastic wastes, especially bubble-size plastic straw waste. The use of recycled fiber as a material of fiber-reinforced polymer composites for concrete strengthening can be an alternative to recycling disposable plastic wastes, especially in Indonesia. The use of fiberreinforced polymer made from woven bubble-size plastic straw waste fibers that are bonded with epoxy has been found out to be able to alternate the axial deformability and ultimate compressive strength of confined circular concrete. The axial stress-strain behavior shows a trilinear trend with two ascending parts and one descending part. Adding more FRP layers has also improved significantly the axial deformability and ultimate compressive strength. Based on test results from this study for bubble-size plastic straw waste fiber-reinforced polymer, new models are created to forecast both the ultimate compressive strength and the strain. The results of the experimental analysis have shown that four layers application of bubble-size plastic straw waste fiberreinforced polymer confined circular concrete is effective enough to increase the strength of concrete up to 42.69 % of the initial strength of concrete. [ABSTRACT FROM AUTHOR]

We reported in this study the interrelation between the addition of 0.4, 0.8, 1.2, and 1.6 wt. % reduced graphene oxide (r-GO) into PVA/Alginate and their degradation and biocompatibility properties. The r-GO was synthesized by using the Hummer's method. A crosslinker CaSO 4 was added to prepare Alginate/PVA/r-GO Hydrogel composite. A Field Emission in Lens (FEI)-scanning electron microscopy (SEM), along with X-ray energy dispersive spectroscopy (EDS), was performed, characterizing the morphology of the composite. A compressive test was conducted, determining the mechanical properties of the composite with the highest achieved 0.0571 MPa. Furthermore, in vitro cytotoxicity was conducted to determine the biocompatibility properties of the studied composite. An MTT assay was applied to measure cell viability. In general, the presence of r-GO was found to have no significant effect on the morphology of the hydrogel. Indeed, adding 0.4% r-GO to the PVA/Alginate increased the cell viability up to 122.26 ± 0.93, indicating low toxicity. The studied composites have almost no changes in weight and shape, which proves that low degradation occurred in addition to this after 28 days of immersion in saline phosphate buffer solution. In conclusion, achieving minimal degradation and outstanding biocompatibility lead to PVA/Alginate/r-GO hydrogel composites being the most attractive materials for tissue engineering applications.