Abstract: Physical modification methods were used by processes, such as breaking, drying, milling, calcining and ageing. The effect of calcining heat on mechanical properties of titanium gypsum was studied. Sodium sulfate, calces and Portland cement were added to titanium gypsum for the chemical modification. The optimum mix of dosage of additives was obtained. The mechanism of the physical modification and chemical modification was discussed. The experiment showed that the mechanical properties of titanium gypsum samples were improved with 0.5% sodium sulfate, 3% calces and 5% Portland cement added after being calcined at 180 ℃ for 3 h. The mechanical properties of titanium gypsum samples: 2 h flexural strength was 2.6 MPa, 2 h compressive strength was 3.2 MPa, absolutely dry flexural strength was 4.58 MPa and absolutely dry compressive strength was 5.2 MPa. After modification, the strength indices of titanium gypsum samples were better than those of 1.6 Level in the national standard calcined gypsum.

Key words: titanium gypsum;physical modification;chemical modification;mechanical property