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Abstract

Fly ash is a silica or alumino silica material that can be used as a constituent of cement in the concrete manufacturing process. Utilization of fly ash aims to improve durability and minimize the reduction of concrete’s compressive strength exposed to an acidic environment, which can be achieved through the pozzolanic reaction of fly ash with Ca(OH)2 within concrete. The reduced content of Ca(OH)2 through pozzolanic reaction will minimize the tendency of ettringite formation (compounds that cause deterioration and decrease the compressive strength of concrete). In order to determine the relation between fly ash replenishment into concrete with concrete’s characteristics (compressive strength and durability) under acidic environment, the research is conducted by varying the fly ash composition ranging from 0%, 5%, 25%, 50%, up to 75%, and the concentration of H2SO4 solution as an immersion medium ranging from 0%, 5%, 10%, up to 15% (v/v). The research is carried out by immersing the concrete samples for 4 days in H2SO4 solution with various concentrations. Characterization of concrete’s durability and compressive strength is reviewed from the concrete’s weight loss percentage and reduction of concrete’s compressive strength percentage after immersion. Based on the research results, for each variation of H2SO4 concentration used, the minimum concrete’s weight loss percentage (maximum durability) and the minimum reduction of concrete’s compressive strength percentage is found in the use of fly ash by 75%. For each concentration variations of H2SO4 solution as an immersion medium ranging from 5%, 10%, up to 15% (v/v), the minimum concrete’s weight loss percentage was 0.47%, 0.87%, 1.28% (respectively), whilst the minimum reduction of concrete’s compressive strength percentage was 5.71%, 14.29%, 17.14% (respectively). It was concluded that the use of fly ash can improve the durability and minimize the reduction of compressive strength of concrete exposed to an acidic environment.

Bahasa Abstract

Pengaruh Penambahan Fly Ash pada Proses Pembuatan Beton terhadap Karakteristik Beton di dalam Larutan Asam Sulfat. Flyash merupakan material aluminosilica yang dapat dimanfaatkan sebagai konstituen semen pada proses pembuatan beton. Pemanfaatan flyash bertujuan untuk meningkatkan daya tahan serta meminimalkan penurunan kekuatan tekan beton yang terpapar pada lingkungan asam. Hal ini dapat dicapai melalui reaksi pozzolanic antara flyash dengan Ca(OH)2 yang ada di dalam beton. Menurunnya kandungan Ca(OH)2 melalui reaksi pozzolanic akan meminimalkan terbentuknya senyawa ettringite (senyawa penyebab deteriorasi dan penurunan kuat tekan beton). Untuk mengetahui hubungan antara penambahan flyash terhadap karakteristik beton (kuat tekan dan daya tahan) pada lingkungan asam, maka penelitian dilakukan dengan memvariasikan komposisi flyash pada beton mulai dari 0%, 5%, 25%, 50%, hingga 75%, serta konsentrasi larutan H2SO4 sebagai media perendaman mulai dari 0%, 5%, 10%, hingga 15% (v/v). Penelitian dilakukan dengan merendam sampel beton selama 4 hari padal arutan H2SO4 dengan berbagai variasi konsentrasi. Karakterisasi daya tahan dan kuat tekan beton ditinjau melalui persentase kehilangan berat dan persentase penurunan kuat tekan beton setelah proses perendaman. Berdasarkan hasil penelitian, untuk setiap variasi konsentrasi larutan H2SO4 yang digunakan, diketahui bahwa persentase penurunan berat beton minimum (daya tahan maksimum) serta penurunan kuat tekan beton minimum ditemukan pada penggunaan flyash sebesar 75%. Untuk setiap variasi konsentrasi media perendaman larutan H2SO4 mulai dari 5%, 10%, hingga 15% (v/v), penurunan berat beton minimum secara berturut–turut adalah 0.47%, 0.87%, 1.28%, sedangkan penurunan kuat tekan beton minimum secara berturut–turut adalah 5.71%, 14.29%, 17.14%. Disimpulkan bahwa penggunaan flyash dapat meningkatkan daya tahan serta meminimalkan penurunan kuat tekan beton yang terpapar pada lingkungan asam.

References

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N. Gamage, K. Liyanage, S. Fragonemi, S. Setunge, Overview of Different Types of Fly Ash and Their Use as A building and Construction Material, http://www.civil.mt.ac.lk/conference/ICECM_2011/SEC-11-35.pdf, 2011.

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