Lean construction is one method that may reduce waste on construction projects. Waste is something that is non-value adding activities in the construction site. Implementing lean concepts into the construction industry is expected to increase the company's productivity. In this study, we have reviewed any causes that make much waste in the construction industry in Indonesia and how the effects of the application of lean construction to reduce waste in a construction site. The results show that there is much waste in construction projects. Some of the most common cases are design changes when the project is being implemented, workers who are still not qualified, complicated bureaucratic systems, and always late in making decisions, and materials always do not on time to the construction site. The above causes a work effect that is not following the plan, and the project becomes a delay from the schedule. Implementing the lean concept in construction companies shows that it takes a long time to change the mind-set and work culture in Indonesia. The lean concept is a strategic concept to be implemented in developing countries like Indonesia.
Abstract. Castellated steel beams are made from normal steel beams cut into half with certain pattern and re-jointed to increase its height. This action results in many shapes of openings in its web, one of them being circular. Circular openings of castellated beams can also be implemented with single fix supported structures, but if uniform shape is used, it will reduce its effectiveness. In this paper, adoption of tapered shape on castellated beams with circular openings as cantilever structures will be discussed. This study uses 150x75x5x7 and 200x100x5.5x8 IWF sections with variations of opening diameters, opening spaces, and span lengths. The steel has a yield strength of 400 MPa and the analysis runs with solid element 10-node tetrahedron using the finite element method, by observing Von Mises stress and displacement. Free-licenced software such as LISAFEA 8.0 and FreeCAD are utilized for analysing and drawing solid elements. The result shows that the optimum height of IWF section for 150x75x5x7 is 230 mm and for 200x100x5.5x8 is 318 mm between span lengths of 2 m to 3.5 m. It can be concluded that each of the span lengths has various optimum diameters and opening spaces to acquire the smallest stress and displacement.
This study discusses the use of zeolite waste and nylon fiber which are used as added material in making concrete. The type of concrete used is self fiber compacting concrete (SFCC). Self-Compacting Concrete (SCC) is a type of concrete that emphasizes a high enough workability value so that the concrete can flow and solidify itself during the casting process. In this study, fresh and hardened properties will be tested. The fresh properties tested consisted of slump flow, T50, V-Funnel and L-Box while the hardened test of concrete consisted of compressive strength, splitting tensile strength and flexural strength. Nylon fiber is used as much as 1% of the weight of cement with length of 50 mm, while zeolite ash is used as a substitute for cement with variations of 5%, 10% and 15%. The purpose of this study was to determine the effect of nylon and zeolite ash variations on fresh and hardened properties of self fiber compacting concrete. The results show that using these two additional materials can be applied to self-compacting concrete because it meets predetermined standards for the fresh properties of concrete. In the hardened properties of the mixture of 5% zeolite produces higher compressive strength, splitting tensile strength and flexural strength than other variations. It can be concluded that the content of 1% fiber and 5% zeolite ash instead of cement is the optimum level and suitable for self-fiber compacting concrete.
Concrete is considered one of the construction materials that contribute the most significant carbon dioxide in the world. Meanwhile, according to various studies, concrete production will continue to rise through 2050, especially in developing countries. According to several reports, cement manufacture is one of the largest sources of carbon dioxide in the concrete sector. In addition, overexploitation of aggregates due to concrete production also causes unavoidable natural damage. Bottom ash waste was used as a replacement for cement and fine aggregate as sustainable construction materials. It is envisaged that this research would allow industrial waste to be utilized to its full potential, resulting in a concrete that is more environmentally friendly and minimizes carbon dioxide emissions during the manufacturing process. This study is divided into bottom ash as a cement substitute and bottom ash as a fine aggregate substitute. The engineering properties of the concrete were checked during the experiments in this study when it was fresh and hardened states. The slump test is used to determine the workability of fresh concrete. While for the hardened properties tests consist of compressive strength, splitting tensile strength, flexural strength, and mass density. The usage of bottom ash as a cement replacement demonstrates that as the composition of bottom ash increases, the performance of the hardened properties of concrete decreases. While using bottom ash as a fine aggregate replacement reveals that the performance of hardened properties has improved as the proportion of bottom ash utilized has increased. Doi: 10.28991/CEJ-2022-08-01-014 Full Text: PDF
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