Concrete is the result of a mixture of cement, aggregate and water. Under certain conditions, the concrete mixture can be added with additives and admixture to get the concrete as needed. Cement is the most important material in the manufacture of conventional concrete. When cement is produced, the same amount of CO2 will also be generated as a side effect and pollute the atmosphere. Fly ash as an alternative to cement will be introduced as an alternative concrete material to reduce the use of cement in the concrete mix. In addition to the use of charcoal fly ash as a partial substitute for cement, this study also uses palm oil clinkers as a substitute for fine aggregate as much as 20%. This replacement material is an industrial waste which has the main content of silica and alumina which is similar to the main material for forming concrete. In addition, the use of these two materials also aims to reduce the exploration of the use of natural materials. This research introduces 3 kinds of concrete composition. The grouping is based on the ratio of fly ash and cement used, namely (60%:40%), (70%:30%) and (80%:20%). The test object used is a concrete cylinder with a diameter of 150 mm and a height of 300 mm. Tests were carried out at the age of 28 days of concrete. The compressive strength test showed that the best concrete was produced from the combination of the addition of 60% fly ash of coal aged 28 days, which was 4.21 MPa.
The palm oil clinkers has a high silica content to use in high strength concrete mixtures as additives. In the study to replace silica fume used fly ash which is made from the palm clinkres and mashing then filtered with a No. #200 sieve. The study used a tested beam with 15 × 30 × 220 cm sized with concrete strength design (f’c) 60 MPa and (w/c) is 0.25. The main reinforced used 15.8 mm diameter with yield strength (fy) 446.34 MPa and shear reinforced used 11.9 mm diameter with yield strength (fy) 381.72 MPa. The compressive strength test at 28 days of 3 pieces of control specimens showed average value of 58.77 MPa. The maximum deflection in the middle of reinforced concrete beams is 31,8 mm at the maximum load 260.00 kN. The maximum deflection that happened is bigger than theoretical deflection with with two load points 17,126 mm. While the ductility produced by high quality reinforced concrete blocks with additives of palm oil clinkers is 2.313. Strain that occurs in tensile reinforcement and shear reinforcement under maximum loading conditions is 569,911 μm and 8,967 μm. The palm oil clinkers as a substitute for silica fume in high quality reinforced concrete is effectively used to increase concrete ductility.
This study aims to analyze the flexural capacity of RC without concrete in a tension cross-section using an experimental method. The number of specimens is three pieces, namely a spiral reinforced concrete beam (SBC) and a vertical reinforced concrete beam (CBN); both of these blocks are without concrete in the cross-section of the reinforcement and 60D tensile steel reinforcement in the support area, where D is the primary diameter, and a conventional concrete beam as the control beam (CB). The beam size is 3100×150×200 mm. The beams are supported by simple supports with a span of 3000 mm. The concrete in the structural beam elements, which work optimally to withstand the load, is the outermost fibre part of the side, while the concrete on the tension side does not have a direct role in determining the magnitude of the resisting moment. Therefore, the quality of the concrete in the concrete beam section must be optimized, while the concrete in the tension section must be minimized. Eliminating concrete in tension areas reduces the construction's self-weight and use of concrete-making materials. The main variables in this research are bending behaviour and crack pattern. The beam specimens were tested with two-point loading monotonically. By observing the crack pattern and failure mode, the results showed an increase in the capacity load of SBC by 21.58% CBN but a decrease of 27.57% compared to the CB control beam. Flexural cracks and beam failures resembled under-reinforcing. The flexural capacity was analyzed based on static analysis and then validated by calculating the ratio between the theoretical nominal moment and the experimental moment. This finding shows that changing the conventional shear reinforcement model to spiral can increase the flexural of the beam without concrete in the tension cross-section. Doi: 10.28991/CEJ-2022-08-11-014 Full Text: PDF
Desa Pasie Mesjid merupakan desa yang rawan akan genangan dan banjir ketika musim penghujan, dimana ketinggian banjir bisa mencapai 50-100 cm. Untuk meminimalisir terjadinya kondisi tersebut, maka pengabdian ini dilakkan bertujuan untuk meminimalisir limpasan air permukaan dengan memanfaatkan air hujan yang dipanen melalui atap bangunan. Manfaat lainnya adalah masyarakat memperoleh informasi bahwasanya penerapan pemanenan air hujan dapat menambah jumlah cadangan air tanah, memperoleh sumber air bersih dan dapat mengurangi limpasan permukaan yang dapat menyebabkan genangan dan banjir di kawasan perumahan. Meningkatnya pemahaman masyarakat secara teoritis tentang manfaat pemanenan air hujan melalui atap bangunan sebagai salah satu upaya dalam pemenuhan kebutuhan air bersih. Diharapkan pula nantinya tim mitra mampu menerapkan 1 (satu) sistem pemanenan air hujan untuk 1 (satu) rumah. Selanjutnya kelompok mitra dapat melanjutkan penerapan rainwater harvesting di setiap rumahnya masing-masing untuk memenuhi kebutuhan air domestik maupun non domestik dan dapat membantu pembuatan rainwater harvesting di rumah warga yang lain. Tim mitra dan tim pengabdi juga akan berkolaborasi dalam memberikan pemahaman tentang solusi dari pemanenan air hujan agar dapat diterapkan untuk desa-desa lainnya yang kasusnya sama seperti Desa Pasie Mesjid, Kabupaten Aceh Barat.
The development of research on concrete used natural fibers has been conducted by many previous researchers.Where the fiber added to the concrete mix significantly increases the tensile strength of the concrete. In this study, natural fiber namely bamboo fiber, was used as micro reinforcement to strengthen the tensle strength of concrete. This study was conducted to determine how much strength bamboo is as the reinforcement as compared to steel reinforcement applied to highperformance concrete beams. It had expected that bamboo could be used as an alternative reiforcement to replace steel reinforcement in reinforced concrete bems. The study used four of beam specimen with dimension 150 × 300 × 2200 mm. The strength of Concrete is 60 Mega Pascal. The steel of tensile using four steel bars D16, while the steel of shear using two D12, and bamboo reinforced used 10 x 21 mm. The results shows maximum Deformation in concrete beams (HSC-SR) is 18.470 mm with the maximum loading 254.97 Kilonewtons, with ductility value is 1.713. The beams (HSC-SRBF) obtained Deformation10.260 mm at maximum load 264.78 Kilonewtons, and ductility is 1.832 mm. While the bamboo reinforced concrete beams (HSC-BR) obtained the maximum load is 106.89 Kilonewtons with Deformation is 28.700 mm, and ductility is 1.322, compare to beams (HSC-BRBF) obtained Deformation 24.440 mm at maximum load 158.87 Kilonewtons, with ductility is 1.162. The results give value of capacity beams for (HSC-BR) is 1.104, (HSC-SRBF) is 1.422, (HSC-SR) is 1.331 and (HSC-BRBF) is 0.877. In the beams (HSC-BRBF) use bamboo reinforced give the maximum load 158.87 Kilonewtons compare to (HSC-SRBF) have maximum load 254.97 KN.
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