<![CDATA[Pendahuluan: Limbah gipsum tipe III (dental stone) dapat menimbulkan masalah pencemaran lingkungan karena sulit diuraikan serta dapat bercampur dengan limbah makanan. Permasalahan tersebut diatasi dengan mendaur ulang gipsum dengan cara menambahkan kombinasi zat aditif untuk mempercepat waktu pengerasan dan menambah kekuatan tekan gipsum. Tujuan penelitian adalah menganalisis pengaruh penambahan kombinasi larutan seng sulfat dan kalium sulfat terhadap kekuatan tekan dan waktu pengerasan pada gipsum tipe III daur ulang. Metode: Desain penelitian adalah eksperimental laboratorium. Penelitian ini dilakukan pengambilan masing-masing 4 sampel pada 3 kelompok perlakuan penambahan kombinasi zat aditif. Penelitian dilakukan di Laboratorium Universitas Baiturrahmah dan Laboratorium Teknik Metalurgi Universitas Andalas. Hasil: Kelompok 1 penambahan K2SO4 1,5% + ZnSO4 4,5% hasil kekuatan tekan 4,68 MPa dan waktu pengerasan 96 jam. Kelompok 2 penambahan K2SO4 2% + ZnSO4 5% hasil kekuatan tekan 3,12 MPa dan waktu pengerasan 91 jam. Kelompok 3 penambahan K2SO4 2,5% + ZnSO4 5,5% hasil kekuatan tekan 1,56 MPa dan waktu pengerasan 88 jam. Simpulan: Terdapat pengaruh penambahan larutan kalium sulfat dan seng sulfat terhadap kekuatan tekan dan waktu pengerasan pada gipsum tipe III daur ulang. Semakin tinggi jumlah penambahan zat aditif K2SO4 dan ZnSO4 pada gipsum daur ulang didapatkan nilai kekuatan tekan semakin rendah dan waktu pengerasan semakin singkat.Kata kunci: Gipsum daur ulang, kombinasi zat aditif, kekuatan tekan, waktu pengerasan. ABSTRACT Introduction: Gypsum waste type III (dental stone) can cause environmental pollution problems due to its difficulty in decomposing and potential mixed with food waste. This problem is overcome by recycling the gypsum by adding additives to speed up the hardening time and increase the compressive strength of the gypsum. The research objective was to analyse the effect of adding a combination of zinc sulfate and potassium sulfate solutions on the compressive strength and hardening time of recycled type III gypsum. Methods: The research design was laboratory experimental. This research was carried out by taking four samples each in 3 treatment groups with a combination of additives. The research was conducted at the Baiturrahmah University Laboratory and the Andalas University Metallurgical Engineering Laboratory. Results: Group 1: the addition of K2SO4 1.5% + ZnSO4 4.5% results in compressive strength of 4.68 MPa and a hardening time of 96 hours. Group 2: the addition of 2% K2SO4 + 5% ZnSO4 resulted in compressive strength of 3.12 MPa and a hardening time of 91 hours. Group 3: the addition of 2.5% K2SO4 + 5.5% ZnSO4 resulted in compressive strength of 1.56 MPa and a hardening time of 88 hours. Conclusion: There is an effect of adding potassium sulfate and zinc sulfate solutions on the compressive strength and hardening time of recycled type III gypsum. The higher the amount of K2SO4 and ZnSO4 additives added to recycled gypsum, the lower the compressive strength value and the shorter the hardening time.Keywords: Recycled gypsum, combination of additives, compressive strength, hardening time.]]>
