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Pada daerah tarik, tulangan di dalam beton memiliki peranan yang sangat penting. Meskipun demikian, tegangan tarik yang terjadi ini bisa saja menyebabkan rentannya tulangan karena retak berpotensi menyebabkan korosi akibat terbukanya celah pada tulangan. Pada makalah ini, cairan mikroba yang terdiri dari bakteri dan jamur bersamaan digunakan untuk meningkatkan kemampuan tarik beton. Selain itu, diusulkan juga penggunaan pemanfaatan agregat kasar buatan (AB) yang mengandung mikroba untuk menggantikan agregat kasar natural (AN) dalam campuran beton pada daerah tarik beton. Cairan mikroba ditambahkan ke dalam campuran beton maupun AB sebanyak 400 hingga 6000 ml/m3. Pengujian kinerja AB dilakukan dengan menggunakan spesimen silinder untuk pengujian kuat tekan beton dan pengujian kuat tarik belah beton. Penambahan cairan mikroba terbukti dapat meningkatkan kuat tekan beton sebesar 12% dan kuat tarik belah beton sebesar 26% pada variasi AN 100%. Didapatkan hasil bahwa substitusi material AB dalam campuran beton dapat menurunkan kuat tekan beton, akan tetapi dapat meningkatkan kuat tarik belah sebesar 6,4% pada variasi 50% AB. Pengendapan mineral kalsium karbonat pada pori-pori di dalam beton serta adanya kapang akibat kerja jamur adalah penyebab meningkatnya lekatan pada matriks di dalam beton. Dibuktikan juga bahwa koloni bakteri bertambah di dalam beton terus bertambah yang berkontribusi pada peningkatan kepadatan beton.

This paper presents the results of an experimental study on Autoclaved Aerated Concrete (AAC) containing Sidoarjo Mud (Lusi) mud to utilize the mud. Autoclaved aerated concrete (AAC) made from fine Artificial Lightweight Aggregate from Lusi mud and Fly Ash as a filler, sintered Lusi mud as the binder, aluminium powder as the foaming agent. Autoclaving process was conducted at 14 bars for 6 hours. AAC prepared in 3 (three) compositions, based on the variation of filler. The filler used in the research were sands (M-sand), fine ALWA made from Lusi mud (M-0), and fine ALWA made from Lusi mud mixed by fly ash (M-50). The workability of AAC investigated in this research was compressive strength of the AAC after 14 days, density, and X-Ray Diffraction. Experimental data showing that the compressive strength of AAC depends on the filler that is used, AAC classified at AAC-3 and AAC-4. The density of all the AAC can’t be classified as lightweight concrete. Experiment data showed the density occurs at 1148,0 kg/m3 to 1206,4 kg/m3. Chemical compounds of AAC with fine ALWA filler consisted of quartz, hematite, tobermorite, calcite, anorthite, magnetite, lime, and forsterite.

This study presents the use of reclaimed asphalt pavement (RAP), and fly ash as artificial aggregate and filler in asphalt concrete. Because of the limited availability of natural materials, infrastructure development has become a concern. Therefore, it is necessary to reuse and recycle waste materials. One such innovation is artificial aggregates. The disadvantage of RAP is that its gradation exceeds the standard; its asphalt penetration and ductility exceed the requirements. The weaknesses of artificial aggregate are high water absorption, spherical shape, and low aggregate interlocking. In this study, the artificial aggregate was produced using the fly ash and alkali activator. Alkali activator consisted of Na2SiO3 and 8M NaOH at a ratio of 2.5. The mixtures containing different percentages of artificial aggregate (45, 55, 65, and 75%) were produced, and the fly ash filler content was 5%. Different tests including XRF, SEM, and Marshall tests were conducted. The artificial aggregate is hydrophilic owing to the high silica content; thus, it has high water absorption. This results in a low adhesion between the asphalt and aggregate. The best composition of asphalt concrete is 55% artificial aggregate, RAP, fly ash filler, and asphalt. The asphalt concrete containing artificial aggregate has high stability and is stiff and light. However, it requires a high asphalt content because of high water absorption. It is unsuitable for application in high traffic roads but suitable for medium traffic ones.

This study was conducted as a part of a research to assess the influence of the volumetric properties of geopolymer artificial aggregates made of fly ash to the performance of asphalt mixture to be used in pavement layers. This paper presents the parameters adopted during the production of geopolymer artificial aggregates which may affect the volumetric properties and the structure of the aggregates. The investigated volumetric properties included specific gravity and water absorption. In the experiment laboratory, two variables were utilized for producing the artificial aggregates, which might affect the considered volumetric properties. Those variables are pan-granulator slopes and alkaline ratios (the ratios of Sodium Silicate to Sodium Hydroxide). The pan-granulator slopes were set at 3 different angles, i.e. 45o, 50o, and 55o. The selected alkaline ratios were 1.5, 2.0, 2.5, and 3.0. The test results indicated that the best volumetric properties were obtained at a slope of 50oand alkaline ratio of 2.5. The bulk specific gravity values at the best volumetric properties were found to be: 1) oven dry at 1.9 grams/cm3; 2) saturated surface dry (SSD) at 2.0 grams/cm3, and 3) apparent at 2.1 grams/cm3with 6% water absorption. In addition, the interfacial transition zone and microstructure aggregates were examined by using Scanning Electron Microscope (SEM). In this study, it was found that there were effects of Na2SiO3/ NaOH ratios and the granulation method on the volumetric properties.

This paper presents more convenient deflection function that properly substitutes slow converging series function by Naiver for simply supported quadrilateral thin plate. The formulation of the deflection function was conducted by using variational approach. During formulation, Rayleigh-Ritz procedures was used and coordinate function that satisfies kinematic boundary condition and the minimum potential energy principle was developed. In addition to coordinate function, modification factor was applied to the main function for curve fitting purpose. To validate the current study, comparisons were done with Navier’s solution and finite element analysis. The results shown that the deviation for mid-point deflection of current study was very small, i.e. around 0.03%, from Navier’s solution. Furthermore, it has been investigated that finite element analysis also resulted closer result with current study. This study will minimize the computation time by eliminating long and slowly converging series coordinate function in Navier’s solution.

We isolated a strain of Bacillus safensis, which we called IDN1, from natto sold in Indonesia. In order to gain insights into its genomic structure and understand its biology, we used the Oxford Nanopore MinION platform followed by PCR to verify the ends and determine its full circular genome sequence.

This paper presents the benefits of PVA fibers in improving the mechanical properties of class F fly-ash-based geopolymer concrete. The activator used in the geopolymer was 8M sodium hydroxide (NaOH) and sodium silicate (Na2SiO3), with a mass ratio of Na2SiO3 to NaOH varied from 1.5 to 2.5. Cylindrical specimens with a diameter of 100 mm and a height of 200 mm were prepared for mechanical strength tests. The PVA fibers in the geopolymers were fixed at 0.4%, 0.6%, and 0.8% by total volume. Some mechanical tests were carried out, including compression, splitting, direct tensile and elastic modulus tests. It was found that the mixture with a ratio of alkalis of 1.5 and the PVA fiber content of 0.4% had the best workability. The highest compressive strength was obtained in a mixture with alkali activator ratios of 1.5 and 2.0, and with 0.6% fiber addition. The ratio of the tensile (and splitting-tensile) strength to compressive strength was found to increase with the certain amount of PVA fibers and the ratio of the alkali activators. The workability issue and fiber direction in the concrete were the dominant factors influencing the properties of geopolymer concrete.

Infrastruktur dan fasilitas transportasi merupakan hal-hal yang sangat diperlukan untuk menunjang aktivitas masyarakat, pembangunan dan pengembangan wilayah. Manajemen aset infrastruktur dan fasilitas transportasi perlu dikelola dengan baik. Dalam rangka penghematan sumberdaya alam, maka pemanfaatan RAP sebagai hasil pengerukan sebagian perkerasan jalan sangat diperlukan. RAP merupakan material sisa, sehingga terdapat kelemahan yang dapat mempengaruhi kinerja teknisnya. Oleh karena itu memerlukan penambahan material lain untuk dapat memperbaiki sifat material RAP. Penambahan zat aditif mampu memperbaiki sifat RAP terutama dari sisi kelemahan aspal RAP pada lapisan aspal beton. Tujuan studi ini adalah memperoleh hasil analisis terhadap sifat fisik dan kimia zat aditif untuk memperbaharui sifat aspal RAP pada lapisan aspal beton . Metode yang digunakan adalah studi literatur dari peneliti terdahulu dan analisis zat aditif terhadap parameter pengujian aspal. Hasil yang diperoleh adalah pemanfaatan zat aditif berpengaruh terhadap nilai penetrasi, daktilitas, viskositas aspal. Penambahan zat aditif pada RAP dapat meningkatkan nilai penetrasi aspal RAP dan mengurangi viskositas, sehingga mengurangi getas pada aspal RAP dan meningkatkan kinerja campuran aspal beton. Zat aditif NR aman dan layak digunakan untuk aditif pada perkerasan jalan dengan RAP.

The evaluation of the pull-out experimental result of the steel reinforcing bar on fly ash-based geopolymer concrete prism is presented in this study. A single reinforcing bar with the nominal diameter (db) of 13mm was pulled out from the geopolymer concrete prism. Three sizes of geopolymer concrete prism were presented, 100×100×200, 150×150×200, and 180×180×200 m3. Hence the ratio of cover thickness to diameter of the bar (c/db) were 3.4, 5.4, and 6.6. The effects of embedment length (Ld) that were 3db, 5db, and 7db were investigated. The results showed that the embedment length changed the mode of failure. The pull-out failure occurred on the specimens with the short embedment length (3db), splitting failure occurred on the long embedment length, and the bar ruptured on the large specimens with longer embedment length (7db). The highest of maximum pull-out load and the bond strength obtained were 77.58 kN and 42.13 MPa, respectively. The maximum pull-out load increased with increasing the embedment length. The bond strength decreased as the embedment length increased.

Cracks are caused by many factors. Shrinkage and external loading are the most common reason. It becomes a problem when the ingression of aggressive and harmful substance penetrates to the concrete gap. This problem reduces the durability of the structures. It is well known that self – healing of cracks significantly improves the durability of the concrete structure. This paper presents self-healing cracks of cement paste containing bentonite associated with ground granulated blast furnace slag. The self-healing properties were evaluated with four parameters: crack width on the surface, crack depth, tensile strength recovery, and flexural recovery. In combination with microscopic observation, a healing process over time is also performed. The results show that bentonite improves the healing properties, in terms of surface crack width and crack depth. On the other hand, GGBFS could also improve the healing process, in terms of crack depth, direst tensile recovery, and flexural stiffness recovery. Carbonation reaction is believed as the main mechanism, which contributes the self-healing process as well as the continuous hydration progress.

This paper presents the application of�fly ash�combining with microbes in concrete to reduce cement content.�A class F fly ash as cement replacementwas applied with ratios of 20%, 30%, 40%, and 50% to reduce hydration heat. Microbes from bacterial consortium were applied to as the filler to increase concrete compressive strength. The concrete mix design from SNI 03�2834�2000 was applied for a compressive strength target of 30 MPa. The mechanical test was carried out consisting compressive and tensile test.�Concrete�workability�and the heat hydration measurement were performed for fresh concrete.�The results showed that the maximum strength of 45.10 MPa was obtained from specimens with 30% fly ash content.�Application of microbes associated with�fly ash content of 40% showed the maximum strength of 48.47 MPa.�It was found that the tensile strength also increased with the application of�fly ash�and microbes.�Hydration temperature of concrete decreased with the increase of�the ash�content.�This proves that the application of�fly ash�and microbes in concrete can reduce the cement as well as increasing the concrete performance.

Retrofitting methods are widely used to reinforce existing concrete structures and frames. Strengthening becomes necessary when building codes mandate a higher load carrying capacity originated from, for example, changes in earthquake zone mapping. A haunch conclusively relocates the formation of plastic hinges away from the beam-column-joint. Geopolymer concrete is an environmentally friendly material, based on fly ash. Utilizing a haunch with this material is effectual and sustainable. The low workability of geopolymer concrete was in this study improved by adding a superplasticizer, which effectiveness was trigger by the presence of low volume Portland cement and water creating a Self-Compacting-Geopolymer-Concrete (SCGC). This SCGC ensured easy fabrication in the field, and improved the compaction and homogeneousness of the haunch. A full-scale experiment based on water-loading was conducted on an existing building to analyze the behavior of a SCGC haunch. The research concluded that the SCGC resulted in a high-performance haunch with good compatibility to the structure, the integrity of the haunch and the structure was maintained up to working-loading conditions. The load carrying capacity and the serviceability greatly improved. Analytical comparison to the prismatic section showed that the SCGC haunch reduced the deflection at mid-span to 77%.

This paper presents mechanical properties of geopolymer mortar with metakaolin as a base material. Cylindrical specimens were prepared with a diameter of 5 cm and 10 cm height. Four compositions of geopolymer paste varied with adding polyvinyl alcohol fiber (PVA) from 0% to 1% by volume of paste. After casting, steam curing method was conducted at 40 o C, 60 o C and 80 o C for 24 hours. A control specimen was cured at room temperature. Some tests were performed for setting time, compressive strength, split-tensile, direct-tensile and porosity. It showed that the strength of fibrous specimens was 67.29 MPa at of 56 days without steam curing. When curing temperature was risen from room temperature 80 o C, the strength increased up to 14% at 28 days. Ratio of split to compressive strength was about 10% when 1% fiber was applied. However, an optimum result was shown by specimens containing 0.6% fibers according to direct-tensile test. It is recommended to apply steam curing at 60 o C-80 o C to increase the tensile strength.

The drying cycle can affect embankments based ontheir physical properties and induce soil cracks. This paper investigates the unsaturated physical behavior of material from flood embankments located at the Bengawan Solo River, Pelangwot village, Bojonegoro, East Java, Indonesia. The volumetric shrinkage and degree of compactedness of the soil are important factors that control the soil behavior due to dry conditions. Some tests were conducted to study the desiccation process, in which soil samples were placed in a circular desiccation plate with soil thickness of 10 mm and a 100 mm plate diameter. A water retention curve was obtained to analyze the material properties during shrinkage. Next, the effect of the drying process on geometric characteristics of crack patterns was analyzed by image processing. Then, photo records of cracked soil from laboratory tests were assessed to determine the soil crack intensity via a Fuzzy C-Means (FCM) method using MATLAB software. The image analysis results show that the geometric characteristics of crack patterns were influenced by the drying process with a decrease in water content at 10% intervals until the air-dried condition was achieved. This is consistent with field observations; this indicates that image processing can be used quantitatively to analyze the drying process dependency of soil cracking behavior.

Special structure prone to explosion requires special material. Identification of special material is required to find the right concrete properties. Researching material behavior using explosion test is costly. Therefore, prediction using simulation is needed. In this study, we use ANSYS Workbench as a simulation program. The explosion test model comprised a non-reinforced slab 500×500×50 mm and TNT cube. It was found that the compressive strength minimum of the concrete slab that withstand the explosion of 30 grams TNT was 20 MPa. The Young modulus affects to the concrete behavior using default RHT Concrete properties. It had instability against modified concrete properties when performing numerical analysis.

One of the assets of land transportation infrastructure that obtained attention now is the road. Road construction can support the developing economy, industry, trade, people and good mobility, regional development. Management of road infrastructure assets require to prioritize natural resources managements efficiently as possible. Reclaimed Asphalt Pavement (RAP) is the result of dredging material with aggregate gradation condition that are not in accordance with the needs of the gradation envelope. Utilization of RAP as a pavement layer is an effort to converse the use of natural materials. The efficiency aspect of RAP aggregate use needs to be done by determining the road pavement layer that is most appropriate to the condition of the RAP aggregate so that the addition of new aggregates is kept to a minimum. The aim of this study was to obtain a suitable pavement layer determination based on the aggregate gradation of RAP and standard specifications. The method used literature study from previous research and RAP aggregate sieve analysis from national roads in East Java Province. The results showed that the utilization of RAP from national roads based on the RAP aggregate conformance value were AC-WC layer of 82.292%, AC-BC layer of 68.75% and AC-Base layer of 41.667%. Based on the gradation analysis, it is found that the RAP aggregate is best suited for the AC-WC layer, because it requires optimal RAP aggregate and the most efficient of additional aggregate.

This paper presents the effect of the reinforcing bar diameter (db) and concrete cover thickness to reinforcing bar diameter ratio (c/db) to the bond strength between reinforcing bar and geopolymer concrete by using the experimental pull-out test. The mass ratio of sodium hydroxide (NaOH) to sodium silicate (Na2SiO3) was 2.5 with an 8 M concentration of sodium hydroxide were used in this research. Class F fly ash from Suralaya Power Station, Banten, Indonesia was used as raw material to produce geopolymer concrete. The maximum diameter of coarse aggregate was 10 mm. The result indicated that the maximum pull-out load on reinforcing bar diameter of 16 mm was higher than the diameter of 13 mm. The pull-out failure occurred on the ratio of c/db more than equal of 4.3. The bond strength increased as the ratio of c/db increased, up to 4.3. However, more than 4.3 was the insignificant effect.

Geopolymers have currently drawn great attention of scientists and engineers, mostly in the construction sector. The superior properties of geopolymer and waste valorization are the main factors of the application. To improve the workability and easiness application, a dry activator was implemented to produce a green and sustainable geopolymer. Dry activator was produced by calcining the mix of sodium hydroxide and either unwashed or washed geothermal sludge at a specified temperature. The dry activator was mixed with fly ash to produce the green geopolymer mortar. The compressive strength of the mortar was analyzed accordingly. Thus, the compressive strength as the response variable was processed with Research Surface Methodology (RSM) using minitab® 19. Meanwhile, the independent variables were the activator ratio (Na2O/SiO2) and the calcination temperature 400, 500, and 650 °C. The optimum condition has been reached by using washed geothermal sludge calcined at 400 °C with a Na2O/SiO2 ratio of 0.692 with 27.5 MPa of compressive strength. A more economical and sustainable green geopolymer is the concern of geopolymer applications nowadays. The green geopolymer produces less Carbon Dioxide compared to ordinary portland cement and geopolymer (concrete and mortar) as much as 31% and 23%.

Semburan Lumpur Sidoarjo (Lusi) masih berlangsung sampai sekarang. Inovasi pemanfaatan Lusi menjadi pilihan alternatife karena belum ada cara untuk menghentikan semburan. Fly ash limbah dari PLTU juga dimanfaatkan untuk dijadikan pasta dengan Lusi sebagai material bauatan berbasis pasta berdasarkan nilai kuat tekan dan keausan. Pembuatan pasta silinder 5 cm x 10 cm untuk diuji kuat tekan pada umur 7, 21, 28 hari, dimana pasta terdiri dari pasta geopolimer dan pasta semen. Lusi terkalsinasi 800 ° C dengan ukuran lolos ayakan 200. Metode moist curing digunakan untuk mejaga benda uji selama masa perawatan sebelum pengujian tekan. Dari hasil pengujian kuat tekan pasta geopolimer Lusi 20% : fly ash 80% dengan molaritas 12 M mempunyai kuat tekan pada umur 28 hari sebesar 33.00 MPa dengan keausan 25.08%. Kuat tekan lebih tinggi pada umur 28 hari didapatkan pada pasta semen, dengan perbandingan Lusi 10% : fly ash 30% : semen 60% dengan water to binder 0.27 sebesar 39.83 MPa dengan keausan 30.60%. Sehingga material Lusi dan fly ash bisa dijadikan material buatan berbasis pasta berdasarkan ASTM C 131-03.

This present study analyzed the effect of Rhizopus oligosporus and Sporosarcina pasteurii addition on the properties and surface morphology of fly ash-based geopolymer paste mixtures as a green sustainable material. The addition of bottom ash and a foaming agent were also conducted to improve the paste quality. Compressive strength, porosity, X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM) tests were performed sequentially. The addition of microbes can improve the compressive strength of specimens by up to 43.75%. All microbe-added specimens exhibited a higher amount of closed porosity compared to the non-microbe-added specimens which also responsible to the higher compressive strength. The addition of foaming agent and bottom ash to the mixtures showed a negative effect to the inoculated microbes. SEM analysis showed the initial result of the potential of R. oligosporus and S. pasteurii as a self-healing agent for fly ash-based geopolymer pastes.

Production of ammonia required high capital energy intensive such as high temperatures (400 to 500 °C) and high pressure (15 to 30 MPa). We investigated a new way to produce green ammonia synthesis using new nanocatalyst and operate in room temperature and ambient pressure. The idea is to synthesize ammonia using Magnetic Induction Method (MIM) and Y3Fe5O12 (YIG) as magnetic nanocatalyst. YIG was prepared by sol gel method and sintered at various temperatures 950 °C, 1050 °C, and 1150 °C. X-Ray Diffraction (XRD) result shows that the major peak at [420] plane. The balance composition of YIG resulted by Energy Dispersive X-Ray (EDX) is in the form of Y3Fe5O12. Initial permeability results show, the highest value maximum permeability at 140 with the range of frequency 1Hz to100MHz obtained by 950 °C sample. The lowest value of relative loss factor obtained by 950 °C sample. YIG nanocatalyst and MIM method were successfully produce ammonia yield at 197 μmol, without MIM the yield was decreased by 14.28%.

A caution procedure to use embedded sensor to measure internal RH of low W/C ratio mortars is proposed in this paper. Specimens made from OPC mortar and the one made with 40% BFS replacement cured under a sealed condition at 20°C. The results showed higher internal RH decrement when BFS was applied. The slag content, the creation of the early hydrated products, pore structures of OPC mortars introduced with BFS are considered as the main factors.

Due to environmental pollution form cement industries, some efforts for alternative construction material are increasing. Recently, geopolymer concrete has drawn attention of researchers and engineers because of its lower carbon print and better mechanical property over Portland cement concrete. According to previous studies, geopolymer concrete results almost up to 90% reduction in carbon dioxide (CO2) emission to atmosphere. Mechanical properties of geopolymer concrete such as compressive strength, durability, sulfate resistance, early strength and low shrinkage are better than Portland cement concrete. In addition, the appropriate usage of one ton of fly ash earns one carbon-credit redemption value of about 20 Euros, and hence earned monetary benefits through carbon-credit trade.Therefore, this paper presents a review on the fly ash-based geopolymer concrete. The paper mainly covers composition, mixing and curing process, benefits, limitations and applications of alkali activated fly ash based geopolymer concrete.

This research use metakaolin and clay containing amorphous silica and alumina after calcination at 700°C. Mechanical properties and fire resistance of geopolymer paste increase as the ratio of silica to alumina. Mix design composition on this research based on the ratio of silica to alumina. The ratio of silica to alumina for metakaolin paste are 1.4 and 1.8. While for clay paste the ratio that used are 2.8 and 3.2. Na2SiO3 and NaOH with 10 M and 8 M were used as alkali activator at this research. Based on analysis the effect of increasing the ratio of silica to alumina increase fire resistance ability for both metakaolin and clay. However initial compressive strength is effected not only by ratio of silica to alumina but also the ratio of water to solid and SiO2/Na2O. The compressive strength decrease as the ratio of water to solid increases. Meanwhile compressive strength increase as the ratio of SiO2/Na2O increase.