Giwangkara Giwangkara - Academia.edu (original) (raw)
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Papers by Giwangkara Giwangkara
IOP Conference Series: Earth and Environmental Science, 2020
Coal ash is generated as a raw product during combustion in thermal power plants. These industria... more Coal ash is generated as a raw product during combustion in thermal power plants. These industrial wastes include fly ash and bottom ash, which has been deemed as a source materials for geopolymer. Bottom ash is used in soil columns for stabilizing foundation soil. In the present study bottom ash from Tanjung bin power station was used as a substitute materials for making geopolymers. The effect of alkali activator to bottom ash ratio on the undrained shear strength of bottom ash based geopolymer was studied. The molarity of sodium silicate solution was kept as 14, Na2SiO3/NaOH of ratio 2.5, mass ratio of alkali activator to bottom ash 0.40, 0.50 and 0.60, and steam curing at 65°C were attempted for the samples. The experimental results of UU triaxial test indicate that alkali-activator to bottom ash ratio of 0.50 gives higher undrained shear strength.
IOP Conference Series: Materials Science and Engineering, 2020
Road base layer has a unique way to distribute the stresses. Unlike a concrete layer which relies... more Road base layer has a unique way to distribute the stresses. Unlike a concrete layer which relies on its flexural strength, the road base layer transmit its working load by grain-tograin contact. Many aspects will affect this load transfer system, for example, the aggregate type, shape, and strength. In this research, the fibre optic sensing was used to obtain the strains of the load under the road base layer. By knowing the strains under the road base layer, then the load distribution characteristic on the road base layer can be obtained. Two samples were tested in this research. Sample A was a road base layer constructed from natural crushed aggregate (NCA), and sample B was constructed from recycled concrete aggregate (RCA). The dimensions of the samples are 1 m x 1 m with 200 mm of thickness. A gradual static load was applied on the road base layer surface and the fibre optic sensing will measure the strains at the bottom of the road base layer. A software simulation also conducted as a comparison for the mechanical test. The result shows that the distribution area of road base layer from RCA is smaller than road base layer from NCA which means it distributes less stress than road base layer from NCA. It means that NCA has a better grain-to-grain action compare to RCA.
IOP Conference Series: Materials Science and Engineering, 2019
This paper presents the findings on the improvement of California Bearing Ratio (CBR) value of so... more This paper presents the findings on the improvement of California Bearing Ratio (CBR) value of soil subgrade using garnet waste. Soil subgrade are very important in construction of roadways and need more attention in strength. Many researchers found that soil subgrade in Malaysia need an improvement technique for the road constructions. One of the techniques is using garnet waste which is an industrial waste that is getting bulkier, and thus create opportunity to reduce and reuse the waste. The research aims to determine the properties of soil subgrade and garnet waste, to determine the CBR value of soil subgrade and to determine CBR value of soil subgrade mixed with garnet waste. Material properties testing for soil subgrade are sieve analysis and Atterberg limit; and garnet waste used sieve analysis and chemical composition. Compaction test in the mixed proportion are used to obtain the Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) and CBR test was done using CBR-Ma...
IOP Conference Series: Materials Science and Engineering, 2019
Natural crushed aggregate (NCA) is the most common material for aggregate throughout the world. T... more Natural crushed aggregate (NCA) is the most common material for aggregate throughout the world. The consumption of the NCA itself is rising up through the years. Concrete structures and road construction are some of the most consuming aggregate material, especially NCA. Therefore, aggregate such as recycled concrete aggregate (RCA) has become an alternative material for some particular civil construction. The implementation of RCA as road construction material has been raised for a long time ago especially in road base layer. Road base layer as foundation for road pavement must provide an adequate strength to hold the working load on the pavement surface. RCA is more heterogeneous material compared to NCA as the RCA contain many substances, such as aggregate, cement, sand, and some additive substances. Hence, it effects the strength of the RCA as construction material. In this paper, the properties of the RCA are investigated to get the characteristic of the aggregate. Density, wate...
![Research paper thumbnail of Nilai Ekonomi Tanaman Kelapa Sawit (Elaeis guinensis jack) Untuk Rakyat Indonesia [Economic Value of Palm Oil (Elaeis guinensis) for Indonesian People]](https://attachments.academia-assets.com/100285625/thumbnails/1.jpg)
](Palm oil provides the highest economic income to the country's economy. Based on the results ... more Palm oil provides the highest economic income to the country's economy. Based on the results of studies obtained from various sources it can be concluded that the Palm Oil Plant (Elaeis guineensis Jacq.) Originates from Nigeria, West Africa. Oil palm is a superior plantation commodity and Indonesia. Plants whose main products consist of palm oil (CPO) and palm kernel oil (PKO) have high economic value and are one of the biggest contributors to foreign exchange compared to other plantation commodities. Indonesia and Malaysia are major exporters of palm oil, which each have an export of 15.7 and 15.1 million tons. The main importing countries of palm oil are India, China and the European Union, which each import 6.7 million, 6 , 3 million and 4.6 million tons. It is alleged that there is a lack of flexibility in the management of oil palm plantations in particular so that oil palm development needs to prioritize the national economic interests of the Indonesian people. .
Penelitian ini merupakan penelitian eksperimental within subject yang melihat pengaruh dari pembe... more Penelitian ini merupakan penelitian eksperimental within subject yang melihat pengaruh dari pembelajaran dengan menggunakan sarana panggung boneka (sebagai IV) terhadap perilaku peduli pada anak-anak (sebagai DV). Pengumpulan data dalam penelitian ini menggunakan metode observasi terstruktur. Kemudian teori yang digunakan sebagai landasan pemikiran peneliti adalah teori perkembangan kognitif oleh Piaget dan teori pembelajaran observasional oleh Bandura.
IOP Conference Series: Earth and Environmental Science, 2020
Coal ash is generated as a raw product during combustion in thermal power plants. These industria... more Coal ash is generated as a raw product during combustion in thermal power plants. These industrial wastes include fly ash and bottom ash, which has been deemed as a source materials for geopolymer. Bottom ash is used in soil columns for stabilizing foundation soil. In the present study bottom ash from Tanjung bin power station was used as a substitute materials for making geopolymers. The effect of alkali activator to bottom ash ratio on the undrained shear strength of bottom ash based geopolymer was studied. The molarity of sodium silicate solution was kept as 14, Na2SiO3/NaOH of ratio 2.5, mass ratio of alkali activator to bottom ash 0.40, 0.50 and 0.60, and steam curing at 65°C were attempted for the samples. The experimental results of UU triaxial test indicate that alkali-activator to bottom ash ratio of 0.50 gives higher undrained shear strength.
IOP Conference Series: Materials Science and Engineering, 2020
Road base layer has a unique way to distribute the stresses. Unlike a concrete layer which relies... more Road base layer has a unique way to distribute the stresses. Unlike a concrete layer which relies on its flexural strength, the road base layer transmit its working load by grain-tograin contact. Many aspects will affect this load transfer system, for example, the aggregate type, shape, and strength. In this research, the fibre optic sensing was used to obtain the strains of the load under the road base layer. By knowing the strains under the road base layer, then the load distribution characteristic on the road base layer can be obtained. Two samples were tested in this research. Sample A was a road base layer constructed from natural crushed aggregate (NCA), and sample B was constructed from recycled concrete aggregate (RCA). The dimensions of the samples are 1 m x 1 m with 200 mm of thickness. A gradual static load was applied on the road base layer surface and the fibre optic sensing will measure the strains at the bottom of the road base layer. A software simulation also conducted as a comparison for the mechanical test. The result shows that the distribution area of road base layer from RCA is smaller than road base layer from NCA which means it distributes less stress than road base layer from NCA. It means that NCA has a better grain-to-grain action compare to RCA.
IOP Conference Series: Materials Science and Engineering, 2019
This paper presents the findings on the improvement of California Bearing Ratio (CBR) value of so... more This paper presents the findings on the improvement of California Bearing Ratio (CBR) value of soil subgrade using garnet waste. Soil subgrade are very important in construction of roadways and need more attention in strength. Many researchers found that soil subgrade in Malaysia need an improvement technique for the road constructions. One of the techniques is using garnet waste which is an industrial waste that is getting bulkier, and thus create opportunity to reduce and reuse the waste. The research aims to determine the properties of soil subgrade and garnet waste, to determine the CBR value of soil subgrade and to determine CBR value of soil subgrade mixed with garnet waste. Material properties testing for soil subgrade are sieve analysis and Atterberg limit; and garnet waste used sieve analysis and chemical composition. Compaction test in the mixed proportion are used to obtain the Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) and CBR test was done using CBR-Ma...
IOP Conference Series: Materials Science and Engineering, 2019
Natural crushed aggregate (NCA) is the most common material for aggregate throughout the world. T... more Natural crushed aggregate (NCA) is the most common material for aggregate throughout the world. The consumption of the NCA itself is rising up through the years. Concrete structures and road construction are some of the most consuming aggregate material, especially NCA. Therefore, aggregate such as recycled concrete aggregate (RCA) has become an alternative material for some particular civil construction. The implementation of RCA as road construction material has been raised for a long time ago especially in road base layer. Road base layer as foundation for road pavement must provide an adequate strength to hold the working load on the pavement surface. RCA is more heterogeneous material compared to NCA as the RCA contain many substances, such as aggregate, cement, sand, and some additive substances. Hence, it effects the strength of the RCA as construction material. In this paper, the properties of the RCA are investigated to get the characteristic of the aggregate. Density, wate...
Palm oil provides the highest economic income to the country's economy. Based on the results ... more Palm oil provides the highest economic income to the country's economy. Based on the results of studies obtained from various sources it can be concluded that the Palm Oil Plant (Elaeis guineensis Jacq.) Originates from Nigeria, West Africa. Oil palm is a superior plantation commodity and Indonesia. Plants whose main products consist of palm oil (CPO) and palm kernel oil (PKO) have high economic value and are one of the biggest contributors to foreign exchange compared to other plantation commodities. Indonesia and Malaysia are major exporters of palm oil, which each have an export of 15.7 and 15.1 million tons. The main importing countries of palm oil are India, China and the European Union, which each import 6.7 million, 6 , 3 million and 4.6 million tons. It is alleged that there is a lack of flexibility in the management of oil palm plantations in particular so that oil palm development needs to prioritize the national economic interests of the Indonesian people. .
Penelitian ini merupakan penelitian eksperimental within subject yang melihat pengaruh dari pembe... more Penelitian ini merupakan penelitian eksperimental within subject yang melihat pengaruh dari pembelajaran dengan menggunakan sarana panggung boneka (sebagai IV) terhadap perilaku peduli pada anak-anak (sebagai DV). Pengumpulan data dalam penelitian ini menggunakan metode observasi terstruktur. Kemudian teori yang digunakan sebagai landasan pemikiran peneliti adalah teori perkembangan kognitif oleh Piaget dan teori pembelajaran observasional oleh Bandura.