PENGARUH PENAMBAHAN LARUTAN ASAM TERHADAP SETTING TIME DAN KUAT TEKAN GEOPOLIMER BERBAHAN DASAR FLY ASH TIPE C

Jason Ghorman Herianto, Evelin Anastasia, Antoni Antoni, Djwantoro Hardjito

Abstract


Perkembangan fly ash sebagai bahan pengganti semen saat ini sudah banyak digunakan khususnya pada beton geopolimer. Fly ash tipe C dengan kandungan CaO yang tinggi bila digunakan sebagai material dasar geopolimer dapat menyebabkan terjadinya flash setting atau pengerasan beton yang sangat cepat namun juga dapat meningkatkan kekuatan tekan pada beton geopolimer. Hal ini dapat menimbulkan masalah apabila digunakan sebagai bahan dasar beton geopolimer dalam skala yang besar yang memerlukan setting time yang cukup lama. Kandungan CaO dapat diindikasikan dengan nilai pH fly ash sehingga penelitian ini menggunakan larutan asam untuk menurunkan nilai pH awal dari fly ash. Berdasarkan hasil penelitian, didapatkan bahwa penambahan larutan asam pada fly ash dapat menyebabkan pH awal fly ash berkurang namun initial setting time yang didapatkan justru bertambah cepat ± 40-60%. Initial setting time yang paling cepat dialami fly ash yang ditambahkan dengan larutan asam klorida (HCl). Selain itu, penggunaan larutan asam pada fly ash dapat menyebabkan kekuatan mortar geopolimer menurun. Dengan demikian, penggunaan larutan asam dapat menurunkan pH fly ash tetapi tidak dapat membuat setting time geopolimer berbahan dasar fly ash tipe C menjadi lebih lama.

Keywords


fly ash, flash setting, setting time, kuat tekan, larutan asam, nilai pH, penurunan pH awal.

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References


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