Analisa Sifat Mekanis Beton Geopolimer Berbahan Dasar Fly Ash Dan Trass Sebagai Pengisi Dengan Aktifator Larutan Sodium Hidroksida 8 Dan 10 Molar

Penelitian ini menggambarkan beberapa usaha dalam memanfaatkan material pozolan alami yaitu trass sebagai pengganti semen. Trass pasuruan mempunyai komposisi yang mirip dengan fly ash, tetapi senyawanya tidak bersifat amorf. Trass pasuruan hanya dapat dijadikan sebagai bahan pengisi atau filler dalam pembuatan beton geopolimer yang berbahan dasar fly ash dan diaktifkan oleh aktifator alkalin berupa larutan sodium hidroksida. Hasil pengujian menunjukkan bahwa kekuatan tekan binder dan beton geopolimer sangat dipengaruhi oleh molaritas larutan sodium hidroksida juga perbandingan aktifator yang digunakan. Pada binder yang memiliki molaritas larutan sodium hidroksida 8 molar, kuat tekan tertinggi dimiliki oleh binder yang memiliki perbandingan aktifator 2,5. akan tetapi pada beton terdapat sedikit perbedaan. Kuat tekan hidroksida 8 molar tertinggi dimiliki oleh beton yang memiliki perbandingan aktifator 2. Sedang pada beton dan binder yang bermolaritas larutan sodium hidroksida 10 molar kuat tekan tertinggi dimiliki oleh beton dan binder yang memiliki perbandingan aktifator 2,5. Pengikatan, porositas serta kuat tarik memiliki pola seperti beton bermolaritas sodium waktu halnya pola yang terjadi pada kuat tekan beton. Analisa perbandingan dengan beton konvensional menunjukkan bahwa trass memiliki sifat mekanis yang lebih baik pada beton semen ==================================================================================================================================== This research describes several efforts to utilize natural pozzolan material, namely trass, as a substitute for cement. Pasuruan trass has a composition similar to fly ash, but the compound is not amorphous. Pasuruan trass can only be used as a filler in making geopolymer concrete which is made from fly ash and is activated by an alkaline activator in the form of sodium hydroxide solution. The test results show that the compressive strength of the binder and geopolymer concrete is greatly influenced by the molarity of the sodium hydroxide solution as well as the ratio of the activator used. In a binder that has a sodium hydroxide solution molarity of 8 molar, the highest compressive strength is possessed by a binder that has an activator ratio of 2.5. However, in concrete there are slight differences. The highest compressive strength of 8 molar hydroxide is possessed by concrete which has an activator ratio of 2. Meanwhile, in concrete and binder which has a sodium hydroxide solution molarity of 10 molar, the highest compressive strength is possessed by concrete and binder which has an activator ratio of 2.5. Bonding, porosity and tensile strength have a pattern similar to that of sodium molarity concrete over time, as well as the pattern that occurs in compressive strength of concrete. Comparative analysis with conventional concrete shows that trass has better mechanical properties than cement concret

Pengembangan Desain Master Plan Taman Rekreasi Sebagai Upaya Peningkatan Potensi Wisata Berbasis Alam Di Desa Wonokerso

Desa Wonokerso yang terletak di Kecamatan Pakisaji, Kabupaten Malang merupakan sebuah desa dengan topografi yang relative datar. Wilayah desa yang relative datar membuat sebagian lahan desa digunakan sebagai lahan pertanian padi. Dengan letak yang strategis, yang dilalui jalan utama penghubung ke Kepanjen, Desa Wonokerso menjadi area yang cocok untuk pengembangan taman hiburan atau rest area. Peningkatan potensi wisata Desa Wonokerso dengan pembuatan master plan rest area ini telah dimulai oleh mahasiswa Kuliah Kerja Nyata (KKN). Akan tetapi pengembangan taman rekreasi masih diperlukan, terutama di penambahan kolam renang anak. Oleh karena itu dalam pengabdian wilayah mitra ini, solusi yang ditawarkan adalah pelaksanaan re-desain master plan rest area atau taman hiburan dengan penambahan kolam renang anak. Tujuan kegiatan pengabdian kepada masayarakat adalah membuat desain master plan rest area dan kolam renang. Metode yang digunakan adalah model pendampingan partisipatif akan dilakukan dalam proses desain master plan. Warga desa, Bumdes, dan perangkat desa secara aktif dilibatkan dalam proses desain, agar kebutuhan warga terwadahi dengan tepat di dalam desain. Hasil kegiatan pengabdian kepada masyarakat ini menghasilkan master plan yang menjadi pedoman oleh masyarakat desa. Selain itu warga, Bumdes maupun perangkat desa menyatakan puas dengan hasil desain master plan taman rekreasi di Desa Wonokerso.

Properties of alkali activated lightweight aggregate generated from Sidoarjo Volcanic Mud (Lusi), fly ash, and municipal solid waste incineration bottom ash

Production of artificial lightweight aggregate (LWA) from industrial by-products or abundant volcanic mud is a promising solution to prevent damaging the environment due to the mining of natural aggregate. However, improvements are still needed in order to control the high water absorption of LWA and strength reduction in resulting concrete or mortar. Hence in this research, fly ash, municipal solid waste incineration bottom ash (MSWI BA), and Sidoarjo volcanic mud (Lusi) were employed as a precursor and activated using NaOH 6 M and Na2SiO3 in producing LWA. The influence of the type of the precursors on the physical properties of resulting LWA was investigated. The effect of replacing natural fine aggregate with the resulting LWA on the compressive strength and volume density of mortar was also determined. Finer particles, a high amount of amorphous phase, and low loss on ignition (LOI) of the raw material improved the properties of resulting LWA. Mortar compressive strength was decreased by 6% when replacing 16% by volume of natural fine aggregate with fly ash based LWA. Compared to the expanded clay LWA, the properties of alternative LWAs in this study were slightly, but not significantly, inferior. Alternative LWA becomes attractive when considering that expanded clay LWA requires more energy during the sintering process.Fil: Risdanareni, Puput. Universitas Negeri Malang; Indonesia. University of Ghent; BélgicaFil: Villagrán Zaccardi, Yury Andrés. University of Ghent; Bélgica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Schollbach, Katrin. Eindhoven University of Technology; Países BajosFil: Wang, Jianyun. Xi'an Jiaotong University; ChinaFil: de Belie, Nele. University of Ghent; Bélgic

Hardness improvement on low carbon steel using pack carbonitriding method with holding time variation

Carbonitriding is a surface hardening process of steel by heating on critical temperature, quench and followed by tempering process. In this research, pack media in carbonitriding was used as a new method. Usually, this process has been obtained using gas and liquid carbonitriding methods. The specimen used in this research is low carbon steel (St. 41) consist of 0.1517% carbon, 0.1994% of silicon, 0.5631% of manganese, 0.0224% of phosphorus, and 0.047% of sulfur. Temperature for pack carbonitriding was at 700 °C, 750 °C and 800 °C and holding time variation 60 minutes and 120 minutes respectively. The result showed that carbonitriding temperature difference affect the mechanical properties of steel St. 41. Steel hardness was increased at lower holding time (60 minutes) compared to 120 minutes. The result showed that at 700 °C and 750 °C with 60 minutes variation, the steel hardness increase from 85.7 HRB to 95.7 HRB and at 800 °C the hardness decrease to 93.1 HRB. Meanwhile, at holding time of 120 minutes, steel hardness decrease from 94.1 HRB to 92.7 HRB. This result caused by austenite phase produced at longer period of holding time

Alkali activated lightweight aggregate as bacterial protector in manufacturing self-healing concrete

Concrete is the most used construction material worldwide as it is strong, durable, and affordable. However, the long lifespan of concrete could decrease drastically due to the occurrence of unavoidable cracks. The presence of cracks larger than 0.3 mm in concrete structures could shorten their service life span as cracks will allow water and CO2 to penetrate concrete and induce corrosion of the embedded steel reinforcing bars. Thus, concrete repair becomes a necessary action to prevent further damage in concrete structures when cracks occur. Unfortunately, the concrete repairing cost has been reported to be quite expensive. In Europe, the estimated repair costs could reach half of the construction budget. To mitigate these forthcoming high maintenance costs, which are expected to increase even further with increasing concrete consumption, a new material that could solve this durability issue is self-healing concrete Among developed self-healing techniques, bacteria-based self-healing concrete using microbially-induced calcium carbonate precipitation (MICP), was reported to provide excellent performance for healing cracks in concrete. The basic principle of this technique is that microorganisms will provide a local micro-environment with conditions that allow the precipitation of calcium carbonates that could heal the crack. The hydration process in concrete that leads to decreasing pore sizes of the hardened material could crush the bacteria, and the high shear forces during concrete mixing could harm the bacteria inside concrete. Thus, a carrier to protect the bacteria before crack occurrence is needed. Porous aggregates appear to be attractive carriers as they are compatible with the concrete matrix and affordable. Previous research has shown that by encapsulating spores or cells of B. sphaericus, B. cohnii, B, alkalinitrilicus, S. Pasteurii, B. pseudofirmus, Diaphorobacter nitroreducens and Pseudomonas aeruginosa into various porous aggregates, by using urea hydrolysis, denitrification or conversion of organic compound metabolic pathways, after immersion in water up to 100 days, crack widths in the range of 0.20-0.79 mm could be entirely healed. However, from an environmental point of view, common porous aggregate carriers available on the market, such as expanded clay aggregates, are not so environmentally friendly because they require a high temperature for production. Two important properties should be met for the LWA to be suitable as a bacteria carrier. First, the LWA should enough pores with sizes 2 to 5 times the bacteria size. It also needs to have a high porosity to allow more bacterial cells to penetrate into the pores. The second requirement is that it needs to iv be strong enough to survive concrete mixing. Revisiting all the basic requirements of a porous carrier, alkali activated LWA could be a suitable bacteria protector candidate. It was reported to have high water absorption and adequate crushing resistance (Illikainen, 2017). From an environmental point of view, utilising alkali activated LWA can avoid the use of a high sintering temperature needed to produce commercial porous LWA such as expanded clay. The first aspect to investigate in the production of alkali activated LWA is the concentration of NaOH as the primary alkali activator besides sodium silicate. Three NaOH concentrations of 4, 6, and 8 molars were tested to activate fly ash in alkali activated LWA production in the first stage. A relatively low NaOH concentration was chosen to manufacture LWA, as high NaOH concentration would speed up the chemical reaction too much, which could disturb the agglomeration process in LWA production. Based on the results when investigating the properties of fly ash-based alkali activated LWA and its resulting mortar, a NaOH concentration of 6 molars is sufficient for the LWA production. A significant decrease in amount of macropores was obtained with a NaOH concentration of 6 molars. Moreover, the major amount of pores in this LWA was in the size range that allows bacteria to penetrate (6-15 µm). In mortar application, replacing 16% volume of fine aggregates with fly ash-based LWA activated with NaOH concentration of 6 molars (FA 6M LWA) delivered a similar strength to a mortar containing expanded clay LWA (EC LWA). In order to screen suitable alkali activated LWAs as a bacteria protector, waste products besides fly ash such as municipal solid waste incinerator bottom ash (MSWI BA) and Sidoarjo volcanic mud (Lusi) were also employed as an alternative binder in the production of alkali activated LWA. Sodium silicate was mixed with sodium hydroxide with the concentration of 6 molars at a weight ratio of 1.5 and was used as alkali activator in the LWA production. The results show that Lusi and fly ash-based LWA meet the requirements to be employed as a bacteria carrier. Those two LWA had a water absorption of more than 20% over 24 hours with its major pores size between 6 to 10 µm. When those two novel aggregates were incorporated into the mortar, a comparable compressive strength to mortar containing EC LWA was achieved. Moreover, increasing the aggregate replacement rate up to 30% did not drastically decrease the properties of the resulting mortar. In contrast, with the same aggregate replacing rate, mortar containing MSWI BA suffered from expansion. A preceding treatment to remove metallic aluminium would be needed here, before using the MSWI BA for making LWA. The metallic aluminium in MSWI BA LWA seems to be toxic v to the B. sphaericus cells. Only limited amount of urea could be decomposed by bacteria after encapsulation into MSWI BA LWA. On the other hand, no issues occurred when bacteria were encapsulated into EC, FA 6M and Lusi 6M LWA. By replacing 16 % of fine aggregate with FA 6M LWA in mortar production, a comparable chloride migration coefficient and capillary water uptake in the mortar were observed as for mortar containing EC LWA and for a reference mortar without LWA. Furthermore, the carbonation resistance of mortar containing FA 6M LWA was comparable to mortar containing EC LWA. A denser interfacial zone between EC LWA and FA 6M LWA with the cement paste contributed to acceptable durability performance in their resulting mortar. In the production of bacteria-based self-healing concrete, bio-agents such as nutrients, urea, and calcium sources are needed to support the MICP process, which uses the urea hydrolysis pathway. The problem is that the yeast extract needed for bacteria spores to germinate into vegetative cells was reported to have a negative effect on the mechanical properties of the resulting mortar. This research introduced three yeast extract concentrations of 0, 2, and 5 g/l in mortar production. The results allow to recommend a yeast extract concentration of 2 g/l in mortar when the presence of yeast extract is mandatory. The compressive strength of the resulting mortar was decreased by about 16% compared to that of the reference sample. While in the sample with 5 g/l yeast extract, the compressive strength could decrease up to 50% compared to the reference sample. When vegetative cells were used as a healing agent, omitting yeast from the mortar mix is possible. The absence of yeast only decreased the workability of fresh mortar but did not disturb the casting process. Thus, no decrease in bulk density and compressive strength compared to reference mortar was observed when yeast extract was omitted from the mortar mix. The following research phase applied FA 6M LWA and Lusi 6M LWA as vegetative cells carriers. The result shows that cells inside the FA 6M LWA still survived even when cracks were fabricated at the age of 90 days. In the crack width range of 0.3-0.4 mm, the healing ratio of mortar which used FA 6M LWA as bacteria carrier, was slightly better than that when EC LWA was used. The average healing ratio in a crack width range of 0.3-0.4 mm for the FA 6M LWA sample after being subjected to wet-dry cycle curing for 30 days was 54%, while it was 47 % in the EC LWA sample. Even though the crack healing ratio at the crack mouth observed in all LWA carriers was relatively low, the sealing efficiency of the mortar containing immobilized cells in EC and FA 6M LWA could reach up to 100%. Through the crack observation on vi the sides of the sample, some precipitation was observed in the bacteria samples. However, this precipitation was not sufficient to reach the top surface where the crack closure monitoring was performed. Nevertheless, it was sufficient to prevent water from penetrating through the crack. At the same time, bacteria encapsulated in Lusi 6M LWA did not provide good healing performance. The high pH of Lusi 6M LWA may have damaged the bacteria cells inside the LWA's pores. This resulted in either a limited amount of healing product or no healing at all in the Lusi 6M LWA samples. When cracks were fabricated at the age of 28 days, the role of LWA as internal curing agent makes the reference sample deliver the same healing performance or, in some cases, even better than for the bacteria-based samples. This condition makes it difficult to see the effect of adding immobilized bacteria into LWA. The sealing efficiency results of samples cracked at the age of 28 days is also not convincing. The high leakage that occurred after bacteria were encapsulated into the LWA was one of the major issues to be overcome to improve the healing performance of mortar, when using LWA as a bacteria carrier. Thus, suitable coatings that could prevent bacteria leakage were screened. Among three coating agents applied on the EC and FA 6M LWA, bacteria inside LWA's pores only survived when sodium alginate coating was applied. The urease activity of bacteria inside LWA's pores after being coated with sodium alginate was lower compared to that in the uncoated samples. However, the cells inside LWA's pores survived and were able to actively decompose the urea. In contrast, no urea could be decomposed by the bacteria impregnated LWA coated with sodium silicate or polyvinyl alcohol (PVA). The leakage of bacteria also decreased after a sodium alginate coating was applied. Without the coating application, the bacteria leakage could reach 31%, while the bacteria leakage was not more than 7% after the coating application. The last stage in this research investigated the performance of the mortar after applying sodium alginate coating on EC and FA 6M LWA. In this part, spores and cells from B. sphaericus were used as healing agents. In the samples containing vegetative cells, yeast extract was omitted from the mixture, while in the spore containing samples, yeast extract with a concentration of 2 g/l was added to support the germination process of spores. The results show that sodium alginate coating has a negative effect on the compressive strength. The compressive strength of the resulting mortar decreased up to 33% relative to the reference sample. Regarding healing performance, in the FA 6M LWA sample group, the sodium alginate coating only slightly improved the healing capability when spores were employed as a healing agent, while there was no significant improvement vii due to the sodium alginate application in the vegetative cells group. In contrast, for EC LWA carriers, sodium alginate coating tends to slightly decrease the healing capability of the resulting mortar both when using cells or spores. In conclusion, this thesis successfully investigated the feasibility of using waste materials such as fly ash, Lusi and MSWI BA as artificial lightweight aggregate. Among others, fly ash-based alkali activated lightweight aggregate proved to deliver comparable properties with commercial expanded clay LWA when employed as fine aggregate replacement in mortar production. The durability performance delivered by mortar containing fly-ash based LWA was also comparable to mortar containing EC LWA. This novel LWA was providing excellent autogenous crack healing. Fly ash-based LWA provided sufficient protection for the vegetative cells of B. sphaericus to heal the cracks at later age (90d). Even though the healing performance provided by this fly ash-based LWA is not as excellent as for EC LWA, this finding could pave the way for further improvements to move towards the use of artificial aggregate from waste material as bacterial carrier in the production of self-healing concrete

Flexural Test of Fly Ash based Geopolimer Concrete Beams

Fly ash is a by-product from the coal industry, which is widely available in Indonesia. Fly ash contains quite high silicate and alumina. Silica and alumina reacts with alkaline solution to produce alumina silicate gel which binds the aggregate to produce geopolymer concrete. Geopolymer concrete is introduced as an environmental concrete with high compressive strength. The use of geopolymer concrete beams is a solution to reduce the effects of greenhouse gases. This research uses experimental designs. The data are obtained from the testing of 4 pieces of reinforced geopolymer concrete beams and reinforced ordinary concrete beams with a / d of 1.11 and 2.24. The results are obtained from the maximum load that can be accepted by the beam. The results of this study are: (1) Geopolymer concrete cylinder has 26.78% higher compressive strength than ordinary concrete cylinders (2) Ordinary concrete beams can withstand 34.8% load higher compared to the geopolymer concrete beam (3) Reinforced ordinary concrete beams experience bending shear collapse while reinforced geopolymer concrete beam experience pure bending collapse

The Effect on Using Cells versus Spores of

Bacteria-based self-healing concrete has become an effective approach to mitigate microcracks in the concrete structure. However, there are still doubts about when to use vegetative cells or spores of Bacillus sphaericus as a healing agent. Thus, this research aims to give recommendations regarding this choice. Spores and cells were encapsulated into expanded clay aggregate to protect them from the harsh environment of fresh mortar. The viability of cells and spores after encapsulation was investigated. The 28- and 90-day mortar compressive strength was analysed. The healing performance of the resulting mortar samples that were cracked at the age of 28 and 90 days has also been observed. The results show that both cells and spores were still active after encapsulation. The yeast extract added to mortar containing spores decreased the compressive strength of the mortar compared to the reference sample. From the healing performance result, it seems that the spores are more suitable for mitigating microcracks in aged mortar, while cells are more suitable for mitigating early-age cracks in the mortar

Flexural Test of Fly Ash based Geopolimer Concrete Beams

Fly ash is a by-product from the coal industry, which is widely available in Indonesia. Fly ash contains quite high silicate and alumina. Silica and alumina reacts with alkaline solution to produce alumina silicate gel which binds the aggregate to produce geopolymer concrete. Geopolymer concrete is introduced as an environmental concrete with high compressive strength. The use of geopolymer concrete beams is a solution to reduce the effects of greenhouse gases. This research uses experimental designs. The data are obtained from the testing of 4 pieces of reinforced geopolymer concrete beams and reinforced ordinary concrete beams with a / d of 1.11 and 2.24. The results are obtained from the maximum load that can be accepted by the beam. The results of this study are: (1) Geopolymer concrete cylinder has 26.78% higher compressive strength than ordinary concrete cylinders (2) Ordinary concrete beams can withstand 34.8% load higher compared to the geopolymer concrete beam (3) Reinforced ordinary concrete beams experience bending shear collapse while reinforced geopolymer concrete beam experience pure bending collapse

Chemical and Physical Characterization of Fly Ash as Geopolymer Material

Research on finding suitable cement substitute material becomes massive due to environmental effect. Geopolymer as inorganic material is potential to be the smart solution to overcome global warming issue. Fly ash is a waste material rich in silica and alumina becomes popular raw material to produce geopolymer. The best properties ofgeopolymer paste come from the high quality of fly ash. Therefore, it is important to investigate various types of fly ash and geopolymer properties. Their chemical and physical properties characterized by XRF, pH value, XRD and SEM. The results showed that type of fly ash depended on amount of Si-based of Ca-based compound which consisted of spherical morphology. Geopolymer paste produced from the ash with different compound has bulky and irregular shape morphology. The pH value of each ash has also a correlation with the setting time of fresh paste