Elemental chemical composition showed an increased mass content of calcium (Ca = 5.9 & # 37;) in the samples, which contributes to the formation of anorthite, which increases the strength of products, and an increased mass content of carbon (C = 14.79 & # 37;) indicates the introduction of fuel into the raw. The increased mass content of fuel in the raw material promotes uniform sintering inside the ceramic sample. Increased mass content in the sample of iron (Fe = 2.98 & # 37;) and alkali (R 2 O = Na 2 O + K 2 O = 2.57 & # 37;) will promote the formation of a liquid phase at 950 & # 176; C. X-ray phase analysis is confirmed by element-by-element analysis that increased calcium content contributes to the formation of anorthite
