Geopolymer is a renewable construction material that reduces dependence on ordinary portland cement (OPC), where OPC manufacturing impacts carbon dioxide (CO 2 ) emissions. The main aspect of geopolymers being studied is the precursor of pozzolanic material, used as a cement substitute because it contains aluminosilicate (Si-Al). Polymerization occurs between the precursors, reacted by alkaline activator solution (AAS). Sodium hydroxide (NaOH) and sodium silicate (Na 2 SiO 3 ) were used as AAS. In this study, local precursors from industrial waste and biomass were utilized. Fly ash was employed as a reference in the precursor by 5% -10% substitution of glass powder, rice husk ash, bagasse ash, and palm shell ash. Moreover, 2% superplasticizer and 5% extra water were used to increase the flowability of fresh geopolymer. Tests were carried out on the setting time of paste, flow table, and compressive strength of geopolymer mortar. The tests were on the initial setting time of 25-75 minutes and the final setting time of 40-115 minutes. The setting time results revealed that the time of each substitution accelerated geopolymerization due to the substitution of precursors containing higher CaO and SiO2. Setting time and flowability/workability had a linear regression correlation (R 2 ) of 0.95, with the flow table ranging from 180-250 mm. The compressive strength ranged from 25.88 -36.36 MPa through a curing temperature of 70 o C for 24 hours, followed by curing at ambient temperature for up to 28 days.
Beton merupakan suatu material yang banyak digunakan dalam dunia konstruksi. Namun, setiap produksi beton menimbulkan dampak buruk pada pemanasan global. Semen sebagai bahan pengikat beton dapat menyumbang emisi CO2 sebanyak 8% dalam setiap produksinya. Proses pengecoran pada beton juga dapat menghasilkan polusi suara akibat penggunaan alat vibrator. Para peneliti terus berupaya menghasilkan beton yang lebih ramah lingkungan. Self Compacting Geopolymer Concrete (SCGC) merupakan kombinasi baru antara beton geopolimer dan Self Compacting Concrete (SCC) yang masih terus diteliti dan dikembangkan hingga saat ini. SCGC merupakan beton ramah lingkungan karena tidak menggunakan semen portland sebagai bahan pengikatnya. Penggunaan beton SCGC tidak memerlukan vibrator karena memiliki sifat flowability yang baik. Penelitian ini menggunakan bahan pengikat berupa material pozzolan yang mengandung senyawa kimia berupa SiO2 dan Al2O3. Tahapan penelitian ini dilakukan dengan mencari metode curing dan mix design optimal dalam penyusunan SCGC. Pengujian XRF perlu dilakukan dalam penelitian ini untuk mengetahui kandungan senyawa kimia pada fly ash Tjiwi Kimia. Beberapa pengujian beton segar SCGC diperoleh hasil berupa slump flow 690 mm, T50 2,4 detik, v-funnel 8,35 mm, dan rasio l-box 0,84. Sifat mekanik beton diuji berdasarkan kuat tekan, kuat tarik belah, dan kuat lentur dengan hasil rata-rata sebesar 27,05 MPa, 6,32 MPa, 1,91 MPa.
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