The invention discloses a preparation method of
phosphogypsum-based anti-
cracking mortar applied to interior insulation of an external wall. The preparation method is characterized in that the anti-
cracking mortar comprises the following components in percentage by
mass: 40-80% of building
phosphogypsum, 20-50% of dried sand, 0-20% of
cement, 0-5% of
fly ash, 0-0.2% of a high-performance
plasticizer, 0-0.2% of a thixotropic agent, 0.1-0.3% of a water-retaining agent, 0.01-0.4% of a
gypsum retarder, 0-3% of a micromolecular
polymer and 0-0.25% of anti-
cracking fiber. According to the preparation method, the building
phosphogypsum prepared by washing and calcining industrial byproduct phosphogypsum is used as a cementing material, so that the problems that a
cement-based material is easy to shrink, hollow and crack are solved; through full use of the characteristics of fast setting and hardening, good volume stability and low own ratio of
compressive strength to
flexural strength of a
gypsum material, the anti-cracking
mortar, of which the ratio of the
compressive strength to the
flexural strength is lower than 2.5, the operable time is 1-2h, the final
setting time is shorter than 3h, the insulation board
bonding strength is higher than 0.10MPa and breakage occurs inside an insulation board, is prepared. The anti-cracking mortar is applied to the interior insulation of the external wall and low in cost, reduces the environment
pollution, and is simple in production process, low in
energy consumption and good in product performance; compared with other insulation board crack resisting products, the anti-cracking mortar has higher market competitiveness and is strong in practicality.