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American Society for Testing and Materials

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2331&context=eispapers1

Effects of fly ash characteristics and alkaline activator components on compressive strength of fly ash-based geopolymer mortar

Fly ash is a waste from coal burning, that are generated with fluctuation both in its physical and chemical characteristics. This characteristics of fly ash when used in the making of geopolymer concrete will greatly affect the final products obtained. The pH value measured in fly ash, according previous research, can influence the setting time of geopolymer and fly ash with high pH values can cause flash-setting in the concrete. Understanding more clearly about the factors that affect the setting time of fly ash based geopolymer is important for further progress and development of the material. It was found that factors that influence the setting time of geopolymer was not only from the physical and chemical properties of the fly ash itself. Other factors such as composition and mix design, manufacturing process and environmental conditions can also affect its setting time. The experimental results showed that fly ash particle size, CaO and MgO content, in addition to ratio of sodium silicate and sodium hydroxide in the alkali solution, molarity of NaOH, initial temperature of the mixture, curing temperature, and mix volume could potentially influence the setting time of the geopolymer mixture.

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Factors Affecting the Setting Time of Fly Ash-Based Geopolymer

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.

Review on Alkali-Activated Fly Ash Based Geopolymer Concrete

Effect of Curing Temperature and Fiber on Metakaolin-based Geopolymer

The effect of loss of ignition, specific gravity, fineness, specific surface area and soluble fly ash to compressive strength of geopolymer paste were studied. Six fly ashes from two different sources and different time of collection were evaluated. Sodium hydroxide and sodium silicate were used as alkali activator. Concentration of sodium hydroxide and mass ratio of sodium hydroxide to sodium silicate were fixed 14M and one respectively. The result indicated that the improvement in compressive strength of geopolymer paste was more influenced by fineness, specific surface area and soluble content of fly ash. Soluble content of fly ash greatly affected the compressive strength of geopolymer paste compare to the compressive strength of cement paste with 20% fly ash replacement.

Characterization of Fly Ash on Geopolymer Paste

This paper presents an observation on fly ash quality in East Jawa, Indonesia. The ash samples were collected from 16 fly ashes produced by some Indonesian power plants. The samples are majority categorized as class F fly ashes with good pozzolanic characteristics according to the standard. The samples were examined for their physical, chemical and mechanical properties with compression test. The test was conducted by making some mortars and paste containing fly ash as cement replacement in accordance with three methods. The compressive strength results were compared with the control specimens made from ordinary Portland cement to obtain a strength activity index (SAI). The results showed that physical properties of fly ash influenced the mechanical properties of mortars more than those showed by chemical characterization.

A Comprehensive Characterization and Determination of Fly Ashes in Indonesia Using Different Methods

Sovereignty remains a crucial debate in international law. Simultaneously, regionalism offers a new pathway for which sovereignty is often contested whether it surrenders due to economic interests. This paper revisits the notion of state sovereignty in the light of economic globalization and enquires about legal personality in international relations. Overall, this paper emphasizes revisiting the concept of sovereignty and legal personality in this 21st century, which has evolved amidst the more globalized world due to international economic relations. The present study was based on historical and analytical methods as doctrinal research. The historical approach was adopted to study international treaties and agreements to know the historical background and evolution of international economic law institutions. Then, it exemplified the European Union's evolution that transcends the state boundaries, following the debate on the relevance of the state sovereignty after the Brexit case under the discussion of the waning of the state sovereignty. Finally, this discussion ended with the international legal personality owned by regional bodies, taking the EU and ASEAN as the comparison. At the outset, the EU was projected as the new governance structure that gradually disrupted the state concept under the Westphalian Peace 1648 due to its member states' desire to form the state-level structure. The European Union redefines the new model of sovereignty against the Westphalian model, which is incomparable to the ASEAN intergovernmental model and other regional bodies regarding sovereignty concerns and legal personality.

Sovereignty and legal personality: a lesson from european union's evolution to supranationalism

Teachers are one of the main components in the world of education where they have a role in improving the quality of education. Where the quality of this education can be seen from the quality of teachers, but the quality of teachers is not only determined by the way of teaching and learning in the classroom, therefore it is necessary to conduct an assessment of teacher performance to measure the duties and responsibilities and obligations of each teacher. So to make it easier to analyze data and see the quality of teachers, a dashboard is designed to monitor teacher performance assessments that have been set by Cinta Kasih Tzu Chi High School based on document studies and interviews with school principals. Dashboard is one solution to present data in the form of visualization which is considered to provide clarity of information to be conveyed. This dashboard design uses a user centric method to describe the end-user design process that influences how a design is formed by utilizing Google Data Studio which will present information based on key performance indicators in graphic form to make it more interactive and easy to understand.

https://aptikom-journal.id/index.php/itsdi/article/download/569/229

Muhammad Bahrul Ulum

Papers

Characterization of Fly Ash on Geopolymer Paste

A Comprehensive Characterization and Determination of Fly Ashes in Indonesia Using Different Methods

Sovereignty and legal personality: a lesson from european union's evolution to supranationalism

Design Dashboard Monitoring Teacher Performance Assessment at Cinta Kasih Tzu Chi High School