▎ 摘　　要

NOVELTY - The method for preparing sandless gypsum-based self-leveling slurry, involves (1) mixing hydroxyapatite and aminopropyl trimethoxysilane, and grinding to obtain modified hydroxyapatite, (2) soaking graphene in strong acid solution, soaking, and drying under reduced pressure to obtain insoluble matter, preparing ammonia lignosulfonate and water into solution, adding insoluble matter, stirring, leaving still, reducing pressure and concentrating to obtain grafted graphene, (3) taking gypsum, sodium silicate, cement, modified hydroxyapatite, grafted graphene, water-soluble resin, water reducing agent, stabilizer and inorganic fiber, and mixing gypsum with sulfur gypsum and modified gypsum. The preparation method of modified gypsum, involves mixing phosphogypsum and alkaline water, soaking for 3-5 hours, draining water, and heating phosphogypsum at 200-300degrees Celsius for 30-50 minutes. USE - Preparation of sandless gypsum-based self-leveling slurry used for self-leveling of building floors. ADVANTAGE - The water-soluble resin group has several carboxyl groups, thereby ensuring enhanced hydrophilic effect. Since amino groups are combined on the surface of modified hydroxyapatite, enhanced coating effect on calcium sulfate whiskers or carbon fibers is achieved. The whisker or carbon fiber filling combined with the groups of modified hydroxyapatite strengthens the grafted graphene, so that the strength of slurry is increased. DETAILED DESCRIPTION - The method for preparing sandless gypsum-based self-leveling slurry, involves (1) mixing hydroxyapatite and aminopropyl trimethoxysilane at mass ratio 10:1-1.5, and grinding for 20-30 minutes at 30-35degrees Celsius to obtain modified hydroxyapatite, (2) soaking graphene in strong acid solution at 20-25degreesC for 20-30 minutes, and drying under reduced pressure to obtain insoluble matter, preparing ammonia lignosulfonate and water into solution with mass fraction of 0.8-1 %mass, adding 10-12 %mass insoluble matter, stirring at 50-55degreesC for 30-40 minutes, leaving still for 3-5 hours, reducing pressure and concentrating to obtain grafted graphene, (3) taking 150-180 parts mass gypsum, 20-30 parts mass sodium silicate, 50-80 parts mass cement, 1-5 parts mass modified hydroxyapatite, 7-13 parts mass grafted graphene, 10-19 parts mass water-soluble resin, 0.5-0.8 part mass water reducing agent, 1-2 parts mass stabilizer and 1-1.5 parts mass inorganic fiber, and mixing gypsum with sulfur gypsum and modified gypsum at mass ratio of 1:(3-4). The preparation method of modified gypsum, involves mixing phosphogypsum and alkaline water at mass ratio of 1:20, soaking for 3-5 hours, draining water, and heating phosphogypsum at 200-300degrees Celsius for 30-50 minutes.