Januarti Jaya Ekaputri

Bio: Januarti Jaya Ekaputri is an academic researcher from Sepuluh Nopember Institute of Technology. The author has contributed to research in topics: Fly ash & Compressive strength. The author has an hindex of 13, co-authored 91 publications receiving 478 citations. Previous affiliations of Januarti Jaya Ekaputri include Universiti Malaysia Perlis.

Review on Alkali-Activated Fly Ash Based Geopolymer Concrete

Abstract: 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.

The Influence of Alkali Activator Concentration to Mechanical Properties of Geopolymer Concrete with Trass as a Filler

Abstract: This paper describes one of the varying factors influencing the mechanical properties of geopolymer concrete. Fly ash and volcanic material called trass was used as raw materials, while sodium Hydroxide (NaOH) and Sodium silicate (Na2SiO3) was applied as an alkali activator. Mechanical properties were assessed by compressive test, the concentration of NaOH used in this study was eight and ten Molars, and ratio of Na2SiO3 to NaOH by mass was 0.5, 1, 1.5, 2, and 2.5. Test results indicated that the strength of geopolymer concrete and binder were hardly influenced by concentration of NaOH in solution and the activator ratio. Binder with activator ratio of 2.5 has the highest compressive strength both in 8M and 10M NaOH system. However, in concrete, there are a few difference, concretes made with 8M NaOH and activators ratio of 2 have the highest compressive strength. This result might due to the low workability of fresh geopolymer concrete. On the other hand, binder and concrete made with 10M NaOH, showed the highest compressive strength when they were made with the activator ratio of 2,5.

The Influence of Si:Al and Na:Al on the Physical and Microstructure Characters of Geopolymers Based on Metakaolin

Abstract: A research has been conducted to investigate the physico-mechanical and microstructure properties of geopolymers synthesised from metakaolin activated with sodium silicate solution. A wide range of physical and mechanical properties of geopolymers were studied such as bulk density, porosity, Vickers hardness, compressive strength, thermal expansion and thermal conductivity. It was found that these properties were directly related to geopolymers process variables such as Si:Al, Na:Al, Na2O:H2O, time and curing temperature. The structure of the resulting geopolymers was studied by using X-Ray diffraction (XRD) and the microstructure of geopolymers paste and the interfacial transition zone (ITZ) between the aggregate and the matrix of geopolymer were studied by using Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM). The results gave a new insight into the composition-microstructure-property relationship of geopolymers and paving the way to the production of geopolymers with improved performance in a variety of applications.

Factors influencing strength and setting time of fly ash based-geopolymer paste

Abstract: In general, fly ash is often used as a binder in geopolymer mixture. In this paper, seven samples of fly ash were collected from five Indonesian power plants. The variation of fly ash may depend upon many factors. However, there is no standardization of fly ash used for geopolymer binder. This experiment was conducted to study and categorize fly ashes both by assessing their physical and chemical characters. All fly ashes were activated with alkali activator to prepare geopolymer paste. Ratio of fly ash to the alkali activator was kept constant at 65 : 35. Compression test was conducted at three, seven, 14, 21, 28, and 56 days to identify the strength development of each sample. The result revealed that the content of CaO in fly ash affected the setting time and early strength development. In three days paste with CaO content more than 20% gain 54% of its 28-day strength. It is caused by both hydration and polymerization reactions. A range of Si to Al ratio contributed to the strength.

American Society for Testing and Materials

Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

Properties Of Concrete

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Design And Control Of Concrete Mixtures

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