Additive of light burned magnesia

After pure water solution reacts with magnesium oxide, Mg(OH)2 is loose and has no strength. In 1867, Swedish scholar Sorrell invented magnesia cement. The strength of magnesium chloride aqueous solution as curing agent in dry environment is almost the same as the compressive strength and flexural strength of ordinary silicon cement. Compressive strength is 110Mpa/28d, and flexural strength is 20Mpa/28d. (1) magnesium chloride hexahydrate (MgCl2·6H2O) curing agent makes magnesia cement have the same compressive and flexural strength as ordinary silicon cement, but it can only be used in dry environment. Magnesium chloride hexahydrate, also known as bischofite, is soluble in cold water at 0℃, and has a relative density of 1.56 and a melting point of 712℃ when the water solubility ratio is 281 g/100 g. Heating to 118℃ to start hydrolysis, and decomposing into MgO and HCl at high temperature. MgCl2·6H2O→Mg(OH)Cl+HCl+5H2O Mg(OH)Cl→MgO+HCl To tetrahydrate, dihydrate, monohydrate and anhydrous magnesium chloride. Its content accounts for 15 ~ 20% of MgO (2) Magnesium sulfate heptahydrate (MgSO4·7H2O) is both a curing agent and a waterproof agent, with a molecular weight of 246.48 as colorless crystal or powder. No bromine, bitter taste. Dissolved in water, it becomes anhydrous magnesium sulfate (MgSO4) at 250℃, and it is reduced to MgO above 400℃. It is the reaction product of MgO and H2SO4. The content of MgO is 15 ~ 20%. The manufacturing cost is higher than MgCl2·6H2O. (3) Ferrous sulfate heptahydrate (FeSO4·7H2O) is a waterproof agent, with light blue single crystal italic, also known as copperas. Its relative density is 1.898 (at 18℃), and it is easily soluble in water, and there is naturally produced copperas. The mixing amount accounts for 3% of the total amount. (4) Styrene-butadiene latex (SBR solid content ≥45%) is waterproof latex, and its content accounts for 6 ~ 12% of the total content. (5) chloroprene latex, also known as chloroprene latex, accounts for 6 ~ 12% of the most stable waterproof latex in magnesium oxide materials, and 1% (OHCH2CH2) 3N is added at the same time. (6) Silica sol, styrene-acrylic latex, Ding Qing latex, etc. can be used as waterproof latex, accounting for 6 ~ 12% of the total amount. (7) SiO 2 additive accounts for 10 ~ 15% of the total amount. (8) Uraldehyde resin and melamine are also waterproof agents, accounting for 2 ~ 3% of the total amount. (9) Phosphoric acid (H3PO4), also known as orthophosphoric acid, is a better curing waterproof agent, and its content accounts for 4% of the total amount. (10). Modified sodium silicate is a good curing waterproof agent, accounting for 1 ~ 3% of the total amount