Strength development of gypsum-based self-leveling mortar

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The shrinkage rate of cement-based self-leveling mortar is much higher than that of gypsum-based self-leveling mortar. By 28 days, the shrinkage rate of cement-based self-leveling mortar is about 1.17 mm/m. With the continuation of time, the shrinkage rate of cement-based self-leveling mortar reaches about 1.31 mm/m in 3 months, but the gypsum-based self-leveling mortar remains at about -0.19 mm/m, that is to say, the high shrinkage rate in cement-based self-leveling mortar is likely to lead to cracks in self-leveling mortar, so in the actual construction process, necessary maintenance measures should be taken to ensure the quality of the project.

strength development
The strength development of gypsum-based self-leveling mortar has a great relationship with the drying degree of mortar itself. In addition to the crystal water required for the formation of gypsum dihydrate, the remaining excess water in the mortar gap will evaporate into the air by means of capillary holes in the mortar, thus forming strength, that is to say, the development of its strength is proportional to the drying rate of gypsum-based self-leveling mortar.
Gypsum-based self-leveling mortar not only has high early strength (6h>6N/mm2), but also develops rapidly in the later period, reaching more than 30 N/mm2 in 28 days.
The bonding strength of gypsum-based self-leveling mortar in different drying cycles (1d.2d and 7d) increases rapidly with the extension of the drying cycle of gypsum-based self-leveling mortar. For example, the bonding strength of 28 days 0.8 N/mm2 (bonding after 1d) and increases to 1.4 N/mm2 (bonding after 7d), with an increase of about 35%.
That is to say, for the gypsum-based self-leveling mortar, the extension of the drying time will contribute to the strength development of the gypsum-based self-leveling mortar itself, and under the same conditions, the development of the early bond strength of the cement-based self-leveling mortar is obviously better than that of the gypsum-based self-leveling mortar.

thermodynamic performance
Gypsum-based self-leveling mortar at 50 ℃ conditions, basically stable, that is no longer too much change, such as 28 days and 194 days of shrinkage and compressive strength almost consistent, which also proves that gypsum-based self-leveling mortar is particularly suitable for floor heating system.

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