MORPHOLOGICAL AND PROPERTIES OF PORTLAND-COMPOSITE CEMENTS WITH CLASS C FLY ASH

Portland-composite cements (PCC) were prepared with partial substitution of 5 to 25% of class C fly ash, obtained from East Java steam power plant. Properties of the composite cements was evaluated, through the setting time (initial and final) and compressive strength (3, 7, and 28 days) compared with control PCC. Setting time is retarded in Portland-composite cements with higher fly ash content. The retardation is highest in PCC with substitution of 25% fly ash. Lower compressive strength is obtained after 3 and 7 days of curing for PCC with 5-25% fly ash substitution in comparison with control cement, since pozzolanic reaction still did not show its effect. After 28 days, compressive strength was higher than that for control cement because pozzolanic reaction show its effect, highlighted by compressive strength increase of PCC substituted by 5% and 10% fly ash, 16.48 MPa and 16.52 MPa, respectively. This attributed to the differences in the pozzolanic activity of the applied fly ash. The compressive strength increase was explained by Scanning Electron Microscope (SEM), which shows that PCC with substitution of 10% fly ash had more Tobermorite presented compared to control cement

Mechanical And Microstructural Assessment Of Synthetic Aluminosilicate Based Geopolymer Dental Material

Orthodontic treatment with fixed brackets was performed to transmit the pressure from the wire to the periodontal tissues to produce tooth movement. Ceramic material can be used not only to improve the aestheticness but also maintains good mechanical properties. This study aims to determine the mechanical properties and morphological of synthetic aluminosilicate based geopolymer for aesthetic orthodontic brackets applications made by synthesizing alumina (Al2O3), silica (SiO2), and magnesia (MgO) from sol-gel method. Geopolymer nanocomposite was made by activating synthetic precursor with alkali solutions consists of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solution which has molarity variations of 8M (GP-8M) and 14M (GP-14M). The test results using an X-Ray Diffractometer (XRD) showed that the crystalline phase of (Mg,Si)Al2O4 spinel was successfully presented in the synthesized nanocomposite. The average hardness test results using the Vickers hardness tester for Geopolymer Nanocomposite with 8M and 14M alkali activator were 259.15 and 298.90 VHN, respectively. The results of the surface morphological characterization using Scanning Electron Microscope (SEM) of the samples showed the porosity of GP-14M was smaller than GP-8M, which explains the hardness test value difference. This shows Geopolymer is a potential material for orthodontic brackets manufacture

Effect of Quenching Medium and Tempering Temperature on Microstructure and Hardness of JIS SUP 9 Steel: Pengaruh Media Pendingin dan Temperatur Tempering pada Mikrostruktur dan Kekerasan Baja JIS SUP 9

JIS SUP 9 steel is one of the materials commonly used for suspension components in motorized vehicles with medium carbon steel base material. It must have good hardness and toughness so that failure does not occur during operational. This research was conducted to increase the hardness of JIS SUP 9 Steel through a heat treatment and various quenching media. The heat treatment was carried out with 830-880ºC temperature with a holding time of 7 minutes then cooled using water and oil. After treatment, tempering was carried out with a holding time of 7 minutes and then cooled in room temperature. Hardness testing was carried out using Microhardness Vickers and then the microstructure was observed using an Olympus Metallurgical Microscope. The results show that heat treatment followed by rapid cooling increases the initial hardness of JIS SUP 9 (229 VHN) steel. The decrease in hardness after the tempering process will be higher with increasing tempering temperature. The results of the microstructure of the sample without heat treatment showed pearlite and ferrite phases. After heat treatment, tempered martensite, residual austenite and carbide phases appear. It can be concluded that changes in the microstructure affect the hardness of JIS SUP 9 steel

Properties of nanocellulose and zirconia alumina on polymethylmethacrylate dental composite

Background: Polymethylmethacrylate (PMMA) is one of the synthetic polymers generally used for temporary jacket crown restorations because of its good translucency, making its aesthetic value higher, but its mechanical properties, such as hardness and flexural strength are lower than composite resins. Hence, adding zirconia and cellulose filler is necessary to enhance its mechanical properties. Purpose: This is an experimental laboratory study to make nanocomposites with PMMA as a matrix with crystalline nanocellulose, zirconia, and alumina added as fillers. Methods: The crystalline nanocellulose filler was synthesized by acid hydrolysis. Zirconia and alumina were synthesized using the sol-gel technique and then characterized by transmission electron microscope and X-ray diffraction. The Micro Vickers hardness test and three-point bending tested mechanical properties. The analysis was carried out with a one-way analysis of variance, followed by a post hoc Tuckey’s test with a P < 0.05 taken as statistically significant. Results: The Micro Vickers hardness test showed the highest hardness in the group with a ratio of PMMA and zirconia-alumina filler of 50%: 2%: 48% (12.73 VHN). The results of the three-point bending test showed that the highest flexural strength was found in the control group (19.4 MPa). Conclusion: The addition of crystalline nanocellulose, zirconia, and alumina increase the hardness of the nanocomposite, while the flexural strength was lower than PMMA without filler addition

Study of Reduced Graphene Oxide addition on the Electrical Conductivity and Flexural Strength of Metakaolin-based Geopolymer

Geopolymer with reduced Graphene Oxide (rGO) composite obtanined through Hummers method. This material is a substitute option for graphene because the nature of rGO is easier to produce in large quantities. In theory, it is expected that rGO can increase the flexural strength and electrical conductivity of geopolymer. The rGO composition used varies from 0-1 wt%. Geopolymer and their constituents were characterized by the Three Point Bending, EIS, SEM, FTIR, XRD, and XRF tests. Fly ash-based geopolymers have a flexural strength of 5.2 MPa at a composition of 0.5 wt% rGO, while metakaolin-based geopolymers with an addition of 0.25% rGO produce the highest flexural strength of 5.53 MPa. A frequency of 100,000 Hz tends to facilitate greater electrical conductivity, on fly ash-based geopolymers found electrical conductivity of 5.08 x 10-3 S / m, while for metakaolin-based geopolymers the electrical conductivity is higher ie 1.01 x 10-1 S / m.

PENGARUH WAKTU CURING TERHADAP KUAT TEKAN GEOPOLIMER BERBASIS FLY ASH

Abstract:. Suralaya power plant produces fly ash about 219.000 ton per year. Fly ash contents of silica and alumina as major components that can be used as precursors for geopolymer, a three dimensional networks aluminosilicate polymers. This research aim is to utilize fly ash for geopolymer made by mixing fly ash, fine aggregate, and alkali activator in a cubic mould and curing was carried out at room temperature for 7 and 28 days. After 28 days of curing the compressive strength of geopolymer reached 41.70 MPa. XRD characterization shows Albite (NaAlSi3O8) formation which has similarity to geopolymer compound. Fourier Transform Infra Red spectra show siloxo and sialate bond. These are typical functional groups that are found in geopolymer materials.Keyword: geopolymer, fly ash, aluminosilicate, alkali activator, albite, siloxo, sialateAbstrak: Pembangkit Listrik Tenaga Uap (PLTU) Suralaya menghasilkan fly ash (abu terbang) sekitar 219.000 ton per tahun. Fly ash memiliki silika dan alumina sebagai komponen utama yang dapat digunakan sebagai prekursor untuk geopolimer, suatu material polimer aluminosilikat tiga dimensi. Penelitian ini bertujuan untuk memanfaatkan fly ash untuk geopolimer yang dibuat dengan mencampur fly ash, agregat halus, dan aktivator alkali dalam cetakan kubik dan pengawetan dilakukan pada suhu kamar selama 7 dan 28 hari. Setelah 28 hari curing kekuatan tekan geopolimer mencapai 41,70 MPa. Karakterisasi XRD menunjukkan pembentukan Albite (NaAlSi3O8) yang memiliki kemiripan dengan senyawa geopolimer. Hasil spektroskopi Fourier Transform Infra Red (FTIR) menunjukkan ikatan siloxo dan sialate yang merupakan gugus fungsional khas yang ditemukan dalam geopolimer.Kata Kunci: geopolimer, abu terbang, aluminosilikat, alkali aktivator, albite, siloxo, sialat

Comparative Study on Mechanical Properties of Waste Composite Materials for Bricks Application

This study discusses mechanical properties and analysis of composite materials to develop building bricks for structural lightweight concrete replacement applications made from three different waste materials, i.e. sawdust, polyethylene terephthalate (PET) plastic bottle, and used diaper. All waste materials are used to mixture composite, as cement replacement, with a mixture of 0, 5, 10, 15, and 20 percent of the total weight. This study uses a quantitative method with the sample used as cylindrical tube with 20 mm of diameter and 40 mm of height. Tests were carried out in the form of compressive and specific gravity tests to determine the mechanical and physical properties of the composite material. The use of waste materials as mixtures for composite manufacture with a water per cement ratio of 0.4 at the age of 28 days results in the best compressive strength of 20.70 MPa (5 percent of sawdust), 33.04 MPa (5 percent of PET), and 18.05 MPa (5 percent of used diaper). The density value shows that the addition of waste materials tends to decrease the weight of the composite result. Based on these results, it can be concluded that the use of waste composite materials is a potential replacement for lightweight structural concrete as an effort to reduce the cement requirement for building material applications.DOI: 10.17977/um024v7i22022p09

PROPERTIES AND MORPHOLOGICAL OF MORTAR CONTAINING USED ENGINE OIL

Engine oil has an important role in the design and operation of all automotive engines. Used engine oil is a waste product produced in high quantity in the workshop garage which commonly found in most cities in Indonesia. The utilization of used engine oil has shown potential as retarder by reduce the setting time of mortar. In this study mortar was made by mixing cement,light aggregate, water, and engine oil both new and used as admixture ranged 0-1%. Mortar sample treatment is carried out at room temperature. The samples were tested for setting time and compressive strength after 3, 7 and 28 days curing. Scanning Electron Microscope characterization was carried out to to find out the morphological structure of resulting mortar. Results shown that the mortar with the addition of 0.75% used engine oil has the highest compressive test result of 9.31 MPa when the mortar reached 28 days compared to mortar without engine oil addition has a compressive test result of 7.546 MPa. SEM Images shown there are more ettringite presents in mortar with used engine oil addition

The Effect of Pulp Industrial Waste as Chemical Admixture to Compressive Strength of Fly Ash Based Alkali Activated Materials

Black liquor is a toxic by-product from industrial pulp manufacture. It contains sodium hydroxide that can be used as precursor activator for alkali activated material, which is an aluminosilicate material that can be prepared from thermal activation of solid material containing alumina and silica as precursor and alkali activator solution. In this work, alkali activated mortar was prepared by mixing fly ash as main precursors, aggregate, followed by addition of activator solution containing sodium hydroxide solution and waterglass, and chemical admixture which is lignin or black liquor. The best compressive strength was 34.40 MPa achieved in addition of 10 wt% of black liquor to alkali activated mortar. X-ray diffraction demonstrated the formation of albite in mortars, indicating that geopolymerization have been successfully formed. FTIR spectra showed the presence of siloxo and sialate peaks which commonly found in geopolymerization