Analisis Kuat Beton Geopolimer Menggunakan Fly Ash dan Abu Sekam Padi

One of concrete construction development is the use of geopolymer concrete which is environmentally friendly and efficient in regard to energy utilization. In this study, four combinations of fly ash (FA) and rice husk ash (RHA) was used, namely: i) 100% FA and 0% RHA, ii) 75% FA and 25% RHA, iii) 50% FA and 50% RHA, and iv) 25% FA and 75% RHA, with addition of alkaline solution mix of Na2SiO3 and NaOH with a ratio of 5:1 at 7 days, 14 days, and 28 days of concrete age, with cube samples and will be done a compressive strength test of 225 kg/cm2 (28 days of concrete age). This study aims to determine the optimum variation and analyze the compressive strength of geopolymer concrete using FA and RHA with the addition of an alkaline solution of Na2SiO3: NaOH = 5: 1. Results found that the optimum variation was in the geopolymer concrete mix of 100% FA and 0% RHA with a compressive strength value of 395.643 kg/cm2 (28 days of concrete age), whereas other variations have shown a decrease of compressive strength compare to the normal concrete. Therefore, the geopolymer concrete variation of 100% FA and 0% RHA has a higher compressive strength because the cement substitute used (100% fly ash) contains the right chemical composition in which it can react with alkaline solutions properly. Meanwhile, rice husk ash contains a composition that is not appropriate to be reacted with alkaline solutions. This shows that fly ash is a suitable substitute for cement for geopolymer concrete. In the other hand, rice husk ash is not suitable for use as a substitute for cement in geopolymer concrete.

BEARING CAPACITY OF FOLDED PLATE FOUNDATIONS IN CLAY SOIL

The design of a foundation is inseparable from the type and strength of the soil, for example, clay soils have poor properties for structures due to their low bearing capacity. Therefore, it is necessary to modify the model of a foundation to increase its bearing capacity and one of the popular methods is the application of folded plate on a flat foundation with angles and flange lengths on both sides. Therefore, this research presented its application at different flange lengths of 0.5B, 0.75B, 1B, 1.25B, and 1.5B where B is the width of the flat plate and the results showed the bearing capacity of the folded plate was higher than the flat foundation. Moreover, an increment in the folded length led to a bigger ultimate load and smaller settlement but the ultimate load and settlement were observed to be almost constant at over 1B. This means the optimum variation where the flange length is equal to the foundation width is 1B and it was observed to have increased by 129.52 % using the Tangent Method and 148.4 7% with Butler Hoy Method. Meanwhile, the lowest settlement factor for the folded plate foundation was 0.22 with the highest bearing capacity of 61.19 kN/m2

Effect of Tackifier Addition on Cushion Compound Formulation for Tire Retreading Application

Tire retreading is a prospective industry. Old tires are repaired and retreaded with suitable tread compounds to fulfill the requirement as the new ones. One of the important components in tire retreading process is cushion compound. Cushion compound consists of unsaturated rubber, in this case natural rubber Hevea brasiliensis was used, less phr of filler compared to the retread compound, and additives such as peptizer, tackifier, processing oil, antioxidant, activator, accelerator and curatives. Tackifier is an important component in cushion compound since its role to make a bonding between different layer, the initial tire after buffing and new retread layer. Tackifier should has good resistance, good compatibility and does not affect the rheological and dynamical properties of bonded rubber. The general tackifier that used in industries are hexamethyl tetramine as methylene donor and resorcinol as methylene acceptor. There is certain reaction between those two additives that determine how good the performance of cushion compound and its effect to retreading process. To obtain optimum reaction, comparison between resorcinol and hexamethyl tetramine were varied as 1:1 (FRR1), 1:2 (FRR2) and 1:3 (FRR3). Hardness test, compression test, rebound resilience, tensile and tear strength, and FTIR were done to observe the optimum variation for retread application. Compared to the control with no tackifier at all, FRR2 showed the optimum result with 21.75 MPa (min. 19 Mpa) and 454,54% elongation at break (min. 450%). The most interesting result was observation by using FTIR, it was detected that the crosslink density was significantly higher than other formulation. It is a new breakthrough which is minimum tackifier with certain treatment could give better performance.

Variasi Kadar Filler Pada Campuran Beton Aspal Menggunakan Bahan Tambah Anti Stripping

Filler function to fill cavities between aggregate granules which can affect the characteristics of asphalt concrete mixture. The purpose of this study is to obtain the characteristics of AC-WC asphalt concrete mixtures and determine the optimum variation of filler content on AC-WC asphalt concrete mixtures using cement fillers and anti-stripping additives that meet the specifications of Bina Marga 2010. ; 5.5%; 6%; 6.5%; 7%; 7.5%; and 8% each made with a variation of cement filler of 1%; 3%; 5%; 7%; and 9%; the addition of Wetfix Be 0.3% to the asphalt. The method of implementation is by mixing the wetfix Be first with asphalt, then aggregating according to the ideal mix gradation proportions. Dependent variables (research parameters) include density, percent cavity in aggregate (VMA), percent cavity filled with asphalt (VFB), percent cavity against mixture (VIM), stability, melt, and results for Marshall (MQ). Marshall testing method based on SNI 06-2489-1991. The results of the study obtained KAO in 1% cement filler variation; 3%; 5%; 7%; and 9%, each at 6.75%; 6.5%; 6.35%; 6.5% and 7.125%. KAO average of 6.65%. The range of cement filler levels which still meet the Marshall parameters at 2% cement filler up to 9%. The optimum cement filler content for asphalt concrete mixture is 5.5%, with a VMA value of 19.19%; VFB 77.12%; VIM 4.39%; Stability of 1670.48kg; melting 4.80mm, and MQ 349.78 kg / mm, meeting the specifications of Bina Marga 2010.

The Effect of Compost Raw Materials (Market Waste, Yard Waste, and Cow Rumen) to Quality and Quantity of Compost

This study combines market waste (MW), yard waste (YW) and cow rumen (CR) as raw materials to obtain the optimum C/N ratio of compost raw materials. Composter consists of 6 variations, namely variation 1 (70% MW: 30% YW), variation 2 (60% MW: 20% YW: 20% CR), variation 3 (50% MW: 30% YW: 20% CR), variation 4 (40% MW: 40% YW: 20% CR), variation 5 (30% MW: 50% YW: 20% CR) and variation 6 (20% MW: 60% YW: 20% CR). This study aims to analyze the effect of variations in compost raw material composition so that the most optimum variation is obtained for the composting process. The method used was semi-aerobic composting. The results of observations on compost maturity for temperature, pH, texture, color and odor parameters have met SNI 19-7030-2004 standards with composting time of 12-21 days. The results of compost quality analysis including water content, organic C, nitrogen, C/N ratio, phosphorus, and potassium have not all variations fulfilled the SNI 19-7030-2004 standard, namely the value of the C/N ratio in variation 6 which exceeds the standard. Of the total compost as much as 3 liters, the solid compost yields of 0.5-1.25 liters and liquid compost from 0.05 to 1.5 liters were obtained. Based on the results of scoring on maturity, quality, and compost quantity, the best variation was found in variation 2

Studi Karakteristik Agregat Pasir Pantai Mangoli, Sosowomo dan Loto dalam Komposisi Beton

AbstrakPasir sebagai agregat halus memegang peranan penting dalam menentukan karakteristik struktur beton yang dihasikan, sebab agregat halus mengisi sebagian besar volume beton. Pasir pantai sebagai salah satu jenis material agregat halus memiiki ketersediaan dalam kuantitas yang besar namun sifat fisik yang dimiliki perlu diteliti lebih lanjut. Penelitian ini bertujuan untuk mempelajari komposisi material pasir semen dari tiga quary pasir pantai yang berbeda dibandingkan dengan pasir gunung. Didapatkan kekuatan optimum serta pengaruh variasi faktor air semen (FAS) terhadap kuat tekan dan modulus elastisitas beton pasir pantai. Benda uji yang dibuat adalah selinder dengan ukuran 150 x 300 mm dengan variasi faktor air semen (FAS) 0,4; 0,5; 0,6 dan 0,7. Benda uji selinder diuji pada saat umur 28 hari. Hasil penelitian menunjukan bahwa pengujian kuat tekan dari tiga quarry yang berbeda dihasilkan kuat tekan paling tinggi dari pantai Loto. Dari material pasir pantai Loto dilaksanakan pengujian modulus elastisitas dengan nilai FAS divariasikan. Hasil menunjukan terjadi kenaikan nilai kuat tekan dari FAS 0,48 dan 0,4 dari 22,84 MPa menjadi 26,64 MPa, selanjutnya kuat tekan dari FAS 0.5, 0,6 dan 0,7 mengalami penurunan dari 20,32 MPa menjadi 13 FAS 80 MPa dan 11 FAS 73 MPa. Maka variasi optimum yang dapat digunakan adalah variasi FAS 0.4. Begitu pula dengan modulus elastisitas juga mengalami kenaikan dari FAS 0,48 dan 0,4 dari 25063,5 MPa menjadi 26292 MPa, selanjutnya variasi FAS dari 0,5; 0,6 dan 0,7 mengalami penurunan dari 23465 MPa menjadi 18906 MPa dan 15133,5 MPa. Maka variasi optimum yang didapat adalah variasi FAS 0,4.Kata kunci: pasir pantai, kuat tekan beton, modulus elastisitas. AbstractSand as fine aggregate plays important role in determining the characteristics of resulted concrete structure since fine aggregate fills the most part of concrete volume. Beach sand as one of types of fine aggregate material is available in large quantity; however, its physical characteristics need further examination. The research aimed to study the composition of cement sand material and three different beach sand quarries. The optimal strength and the influence of water cement factor (FAS) variation on the pressure strength and modulus elasticity of beach sand concrete were obtained. The test object made was a 150x200 mm cylinder with variation of water cement factor (FAS) of 0.4; 0.5; 0.6 and 0.7. The cylinder was tested on the 28th days. The research result indicates that the test of pressure strength of the three quarries was different. The highest pressure strength was obtained from Loto Beach. Modulus of elasticity testing was conducted on sand material from Loto Beach with varied FAS values. The result indicates that there was an increase in the value of pressure strength of FAS 0.48 and 0.4 from 22.84 MPa to 26.64 MPa. The pressure strength of FAS 0.5, 0.6 and 0.7 experienced a decrease from 20.32 MPa to 13 FAS 80 MPa and 11 FAS 73 MPa. Thus, optimum variation that can be used was FAS 0.4. The modulus of elasticity was also experienced an increase from FAS 0.48 and 0.4, which was from 25063.5 MPa to 26292 MPa. Further, variation of FAS from 0.5; 0.6 and 0.7 experienced a decrease from 23465 MPa to 18906 MPa and 15133.5 MPa. Therefore, the optimum variation obtained was variation of FAS 0.4.Keywords: beach sand, pressure strength of concrete, modulus of elasticity.

PENGARUH KOMPOSISI BAHAN BAKU KOMPOS (SAMPAH PASAR, ARANG AMPAS TEBU DAN RUMEN SAPI) TERHADAP KUALITAS KOMPOS

These research combines market waste (MW), charcoal sugar waste (CSW), cow rumen (CR) and compos (C) as raw materials of compost. The composter consists of 5 variations; variation 1 (80% MW: 20% GW), variation 2 (80% MW: 10% CSW: 10% C), variation 3 (80% MW: 10% CSW: 10% RS), Variation 4 (70% MW: 10% CSW: 10% CR: 10% C) and variation 5 (60% MW: 20% CSW: 10% CR: 10% C). This research aims to analyze the effect of composition of compost raw material variation to obtain the most optimum variation for the composting process. The method was takakura semi aerob composting. The result of observation were on compost maturity and quality that have fulfilled SNI 19-7030-2004 standart in micro element. The quantity of compost solids 0.8-1.1 liter. Based on the results of scoring on the maturity, quality, and quantity of compost, obtained the best variation was variation 2 which has time to compost for 8 day.Keywords: charcoal sugar waste, cow rumen, market waste, quality, quantityABSTRAKPenelitian ini mengkombinasikan bahan baku sampah pasar (SP), arang ampas tebu (AAT), rumen sapi (RS), dan Kompos Jadi (KJ). Komposter terdiri dari 5 variasi yaitu variasi 1 (80% SP:20% AAT), variasi 2 (80% SP:10% AAT:10% KJ), variasi 3 (80% SP:10% AAT:10% RS), variasi 4 (70% SP:10% AAT:10% RS:10% KJ), variasi 5 (60% SP:20% AAT:10% RS:10% KJ). Tujuan penelitian ini yaitu untuk menentukan komposisi bahan baku yang optimum dengan metode yang digunakan yaitu pengomposan semi aerob dan menggunakan teknik pengomposan komposter takakura. Setiap variasi diuji kematangan dan kualitas kompos lalu dibandingkan dengan SNI 19-7030-2004 pada parameter unsur makro. Kuantitas hasil kompos yang dihasilkan pada penelitian ini sebanyak 0,8-1,1 liter. Dosis optimum yang baik untuk dijadikan kompos yang dinilai dari sistem skoring yaitu campuran pada variasi 2 dengan waktu lamanya pengomposan yaitu selama 8 hari.Kata Kunci: Arang ampas tebu, kuantias, kualitas, rumen sapi, sampah pasar.

MODERATOR TO FUEL RATIO AND URANIUM FRACTION ANALYSIS OF SQUARE LATTICE MOLTEN SALT TRANSATOMIC POWER

Molten Salt Reactor Transatomic Power (MSR TAP) is a further development of the nuclear reactor Generation IV Reactor Molten Salt Reactor (MSR). MSR TAP generates clean electric power. It has a passive safety, resistance to proliferation, and low cost. MSR TAP can consume the rest of the nuclear fuel/spent nuclear fuel (SNF) of a commercial Light Water Reactor (LWR) fuel or use the main fuel, a salt solution UF4 - LiF - BeF2. MSR TAP uses Zirconium Hydride material for the moderator. This research has a purpose to determine the optimal size of uranium mole fraction on fuel and moderator radius from core design in order to produce optimum enrichment with the value 1 < keff <1.0065 using MCNP5 program. On the other hand, this research also aims to look for the optimum enrichment, which have inherent safety characteristics with αVoid < 0. Variations were made including the changes in the geometry of the moderator radius with a variation of 0.5 cm, 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, and 4.5 cm; and the changes in the fuel uranium molar UF4 - LiF - BeF2 with molar variation of 15%, 20%, 25% and 30%. The geometry of Transatomic Power (MSR TAP) of companies Transatomic Power Corporation was used. The results show that the optimum variation is the salt solution UF4 - LiF - BeF2 with 25 % uranium mole fraction, 2.6 % enrichment and moderator radius of 1.5 cm. The optimum variation gives the keff value of 1.00124 ± 0.00078. The optimum value of reactivity void coefficient is -0.0684. It indicates an inherently safe design.Keywords : Molten Salt Reactor Transatomic Power, MCNP5, Uranium Fuel Mole Fraction, Optimum Variation, Moderator, Inherent Safety. ANALISIS FRAKSI URANIUM DAN RASIO MODERATOR – BAHAN BAKAR PADA SQUARE LATTICED MOLTEN SALT TRANSATOMIC POWER. Molten Salt Reactor Transatomic Power (MSR TAP) merupakan reaktor nuklir pengembangan lebih lanjut dari Reaktor Generasi IV Molten Salt Reactor (MSR). Reaktor MSR TAP ini menghasilkan daya listrik yang bersih, memiliki keselamatan pasif, mempunyai resistensi terhadap proliferasi, dan memiliki biaya yang rendah. Reaktor ini dapat mengkonsumsi bahan bakar nuklir sisa/spent nuclear fuel (SNF) dari penggunaan bahan bakar Light Water Reactor (LWR) yang komersial atau menggunakan bahan bakar utama yaitu larutan garam UF4 – LiF – BeF2. Moderator yang digunakan pada MSR TAP ini adalah moderator berbahan Zirconium Hydride. Penelitian ini bertujuan untuk menentukan ukuran perbandingan nilai fraski mol uranium dan jari-jari moderator yang optimal dari dari desain teras Reaktor MSR TAP agar dihasilkan pengayaan yang optimum dengan nilai 1 < keff < 1,0065 menggunakan program MCNP5. Selain itu penelitian ini juga bertujuan mecari pengayaan optimum yang mempunyai sifat keselamatan melekat dengan . Variasi yang dilakukan meliputi perubahan geometri jari-jari moderator dengan variasi 0,5 cm, 1 cm, 1,5 cm, 2 cm, 2,5 cm, 3 cm, 3,5 cm, 4 cm, dan 4,5 cm; dan perubahan molar uranium pada bahan bakar UF4 – LiF – BeF2 dengan variasi persen molar 15%, 20%, 25%, dan 30%. Geometri reaktor yang digunakan dalam silmulasi adalah MSR TAP dari perusahaan Transatomic Power Corporation. Hasil penelitian menunjukkan variasi optimum perbandingan moderator bahan dan fraksi mol bahan bakar larutan garam UF4 – LiF – BeF2 pada fraksi mol uranium bahan bakar pada variasi molar uranium 25% dengan pengayaan 2,6% dan jari-jari moderator 1,5 cm, dengan nilai keff 1,00124±0,00078. Koefisien reaktivitas void yang didapatkan dari variasi optimum tersebut adalah -0,0684 yang menandakan bahwa desain ini telah memenuhi syarat keselamatan melekat.Kata kunci: Molten Salt Reactor Transatomic Power, MCNP5, Fraksi mol uranium, Variasi optimum, Moderator, Keselamatan melekat.

Numerical Absorbing Boundary Conditions Based on a Damped Wave Equation for Pseudospectral Time-Domain Acoustic Simulations

In the context of wave-like phenomena, Fourier pseudospectral time-domain (PSTD) algorithms are some of the most efficient time-domain numerical methods for engineering applications. One important drawback of these methods is the so-called Gibbs phenomenon. This error can be avoided by using absorbing boundary conditions (ABC) at the end of the simulations. However, there is an important lack of ABC using a PSTD methods on a wave equation. In this paper, we present an ABC model based on a PSTD damped wave equation with an absorption parameter that depends on the position. Some examples of optimum variation profiles are studied analytically and numerically. Finally, the results of this model are also compared to another ABC model based on an hybrid formulation of the scalar perfectly matched layer.