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Performance of Workability and Compressive Strength on Self-Compacting Geopolymer Concrete Based On High-Calcium Fly Ash With Addictive Admixture Yuyun Tajunnisa; Nur Achmad Husin; Sigit Darmawan; Ridho Bayuaji; Raden Buyung Anugraha; Arwinda Aribah Cahyani
IPTEK The Journal of Engineering Vol. 9 No. 1 (2023)
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23378557.v9i1.a16237

Abstract

Geopolymer concrete has been developed as a replacement for conventional concrete with other pozzolan materials, which have a high silicate alumina content. Fly ash is a material that contains a high silicate alumina of 22%. The high content of Al and Si increases the compressive strength of concrete. High-calcium fly ash is abundantly found in Indonesia. However, it has not been widely used for industry or research, and this is due to the fast hardening time of concrete. Therefore, it has the potential to be developed. High-quality concrete has a low cement water factor that causes low workability in concrete. Self-compacting geopolymer concrete (SCGC) has been developed as a high-quality concrete innovation with high workability. Concrete is produced by using gravel, sand, fly ash, alkaline activator, and water materials. This study used 14 Molar levels of NaOH. The variations used were 0%, 3%, 5%, and 7% superplasticizers (SP) made from polycarboxylate. This study used a dry mixing method to overcome the setting time on concrete. The results show that the workability that can be achieved is 645mm, and the compressive strength achieved is 41.7 Mpa
Sulphate Resistance of Geopolymer Concrete Based on High Calcium Fly Ash Yuyun Tajunnisa; Nur Achmad Husin; Indra Komara; Moch.Ahdian Wildan Nafi; Mitsuhiro Shigeishi
IPTEK The Journal of Engineering Vol. 9 No. 1 (2023)
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23378557.v9i1.a16235

Abstract

The inclusion of fly ash class C, which is widely available locally, can influence the progress of strength and durability qualities of geopolymer concrete when exposed to significant environmental conditions. Alternative geopolymer combinations appropriate for curing at ambient temperatures were employed to investigate the impacts of fly ash class C based geopolymer concrete. To react with fly ash class C, a combination of sodium hydroxide and sodium silicate alkaline activator was used. Fly ash class C was added as 20% of the total binder without using ordinary Portland cement. The durability of fly ash class C based geopolymer concrete in sulphate environments was tested. The changes in weight, length and compressive strength due to exposure in magnesium sulphate solution for different periods of time were determined. The test results demonstrate that fly ash class C based geopolymer concrete cured at normal temperatures has good resistance to sulphate attack. In general, inclusion of fly ash class C in geopolymer concrete improved strength and performed satisfactorily in sulphate environments when cured in ambient temperature.
Performance Changes in Mass and Compressive Strength of High-Calcium Fly Ash Based Geopolymer Concrete Due to Sodium Sulphate Exposure Yuyun Tajunnisa; Nur Achmad Husin; Andri Kusbiantoro; Ahmad Daffa Azmi; Khansa Fadilah Ashara; Mitsuhiro Shigeishi
IPTEK The Journal of Engineering Vol. 10 No. 1 (2024)
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23378557.v10i1.a16232

Abstract

The sulfate environment is one of the conditions that significantly affect the durability of concrete. Sulfate attack causes cracks and affects the quality of the concrete. Therefore, it is necessary to innovate concrete that can withstand the aggression of this sulfate attack. Geopolymer concrete is a breakthrough that can be developed as an alternative material without using Portland cement as the ingredients, yet by using class F fly ash as the primary source material. On the other hand, the availability of class C fly ash with high CaO content is highly abundant in Indonesia. The high calcium content in this fly ash will cause the fresh geopolymer concrete to harden rapidly. Previous studies used sucrose as an additive to overcome this rapid hardening problem. However, its effect on the geopolymer concrete exposed to sulfate ingression requires further investigation. In this study, the geopolymer concrete was produced by using class C fly ash and sucrose. The sulfate ingression was simulated by immersing the concrete specimen in the sodium sulfate solution while the mass changes and compressive strength were examined. pH measurement of the sodium sulfate solution was also carried out to provide a different perspective on the data analysis. Cylindrical specimens, measuring 10 cm x 20 cm, were produced using the dry-mixing method and the characteristic strength of 28 MPa according to SNI 2847–2019. From the results, geopolymer concrete with sucrose showed a high workability performance through the high slump value obtained. Nevertheless, the experimental results also indicated the declining strength of geopolymer concrete after the sulfate exposure. However, only a slight reduction was observed. The strength residue still satisfies the minimum requirement of SNI 2847-2019. It shows the potential of geopolymer concrete to be used as a construction material in a harsh environment with high sulfate content.