2. magnesium oxide contains three substances, over-burning product, under-firing products, active magnesium oxide, magnesium oxide activity and now we'll talk about the main components important to generate MOC building materials industry is magnesium oxide and magnesium chloride, more precise point that should be generated to produce a chemical reaction with magnesium oxychloride cement inside the active magnesium oxide and magnesium chloride binding inside. Why the low activity of the product not? Below a simple explanation: activity, over-burning, less burned magnesium oxide is a component in inverse proportion, and since the resulting magnesium oxychloride cement part by activity in the building materials industry so burnt goods and products are under-firing excess impurities.