This study investigates the relationship between transferred shear force and relative displacement of the shear connector in steel-concrete sandwich beam. The models, which can consider the effects of the height, thickness and shape of the shear connector, concrete strength, and thickness of the base steel plate where the shear connectors were attached, were proposed. The predicted relationship between transferred shear force and relative displacement as well as the curvature distribution along the vertical part of the shear connector are found to agree with the experimental results. Finite element analysis with the proposed model indicates its applicability as a constitutive model for shear connector.

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The majority of catches by fishermen in Aceh, Indonesia are sold raw, directly to consumers, and in the local market. This contributes to the low price of fish and low income for the fishermen, and the COVID-19 outbreak has made this situation even worse. One solution could be the establishment of a cold storage business in the area. This study assessed the financial feasibility of a 200-ton cold storage business in Banda Aceh, the capital of Aceh province. Using secondary data collected from online sources, we applied the most common financial indicators used in feasibility studies, namely Net Present Value (NPV), Internal Rate of Return (IRR), and Benefit-Cost Ratio (BCR). A sensitivity test was also performed to predict the feasibility of the cold storage business if the basic assumptions are changed. We found that cold storage in Banda Aceh is financially feasible as the NPV was positive, the IRR was higher than the interest rate (i.e., the discount rate), and the BCR was higher than 1. Besides, the sensitivity test also suggested that cold storage would still be feasible even if there were a 20% increase or decrease in storage capacity and project costs.

The cement industry has contributed large amounts of CO2 emissions and is responsible for the consumption of non-renewable natural resources. Geopolymer based cement has emerged as an environmentally friendly alternative to construction materials because it can be produced from industrial waste. Similar to ordinary portland cement, geopolymer cement can be strengthened with nanomaterials. This paper presents a review of nanosilica and cellulose nanocrystals in geopolymer cement. The addition of nanosilica can improve the properties of pozolan which is able to bind calcium-hydroxide so that the resistance to sulfate corrosion will also be better and nanosilica can also increase chemical reactions due to its surface area. Nano-sized cellulose-based particles can fill the smallest gaps in cement paste that cannot be treated by other micro or macro sized materials. This paper also presents an overview of the latest advances in the production of geopolymer cement that reinforced by nanosilica and cellulose nanocrystals as promising sustainable construction materials.

Nanosilica produced from physically-processed white rice husk ash agricultural waste can be incorporated into geopolymer cement-based materials to improve the mechanical and micro performance. This study aimed to investigate the effect of natural nanosilica on the mechanical properties and microstructure of geopolymer cement. It examined the mechanical behavior of geopolymer paste reinforced with 2, 3, and 4 wt% nanosilica. The tests of compressive strength, direct tensile strength, three bending tests, Scanning Electron Microscope-Energy Dispersive X-ray (SEM/EDX), X-ray Diffraction (XRD), and Fourier-transform Infrared Spectroscopy (FTIR) were undertaken to evaluate the effect of nanosilica addition to the geopolymer paste. The addition of 2 wt% nanosilica in the geopolymer paste increased the compressive strength by 22%, flexural strength by 82%, and fracture toughness by 82% but decreased the direct tensile strength by 31%. The microstructure analysis using SEM, XRD, and FTIR showed the formation of calcium alumina-silicate hydrate (C–A–S–H) gel. The SEM images also revealed a compact and cohesive geopolymer matrix, indicating that the mechanical properties of geopolymers with 2 wt% nanosilica were improved. Thus, it is feasible for nanosilica to be used as a binder.

In this paper, an experimental study was carried out to evaluate the number of layer effect of abaca fiber composite as natural reinforced polymer (NFRP) material for shear-strengthened reinforced concrete (RC) beams. Two externally bonded shear-strengthened beams with a different number of NFRP layers and a sound beam as a control beam were prepared. The test was conducted by applying two axial loads on the beam. The results showed that the use of one-layer and two-layer of abaca fiber composite as NFRP material for the shear-strengthened beam increased 9.78% and 9.92% of maximum load compared to sound beam respectively. Abaca fiber composite NFRP material contributed 11% and 18.57% of the total maximum shear load for one-layer and two-layer laminates respectively. In addition, externally bonded shear-strengthened beams affected the crack pattern and deflection value. However, debonding failure of NFRP laminates occurred in two-layer of the NFRP shear strengthened beam. It caused the beam did not work optimally.

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