Gypsum based self-leveling mortar composition materials:

Active admixtures: self-leveling materials can use fly ash, slag powder, etc., as active admixtures, the purpose is to improve the particle composition of the material and improve the performance of the material hardening body。The hydration reaction of slag powder in alkaline environment can improve the compactness and late strength of the material structure。

Early-strength cementing materials: In order to ensure the construction time, self-leveling materials have certain requirements for early strength (mainly 24h bending and compressive strength)。Using sulphoaluminate cement as early strength cementing material, sulphoaluminate cement has fast hydration speed and high early strength, which can meet the requirements of early strength of materials。

Alkaline activator: Gypsum composite cementing material in the medium alkaline conditions under the absolute dry strength z high, available quicklime and 32.5 The cement regulates the pH value and provides an alkaline environment for the hydration of the gelled material。

Coagulant: Setting time is an important performance index of self-leveling material, and too short or too long time is not conducive to construction。The coagulant can stimulate the activity of gypsum, speed up the susaturated crystallization rate of gypsum dihydrate, shorten the setting time, and keep the setting and hardening time of self-leveling material in a reasonable range。

Superplasticizer: In order to improve the compactness and strength of the self-leveling material, it is necessary to reduce the water-binder ratio, and it is necessary to add superplasticizer under the condition of maintaining the good fluidity of the self-leveling material。

The mechanism of water reduction is that sulfonic acid and water molecules in the naphthalene series water reducer molecules are associated with hydrogen bonds to form a stable water film on the surface of the cementing material, which makes it easy to slide between the material particles, thus reducing the amount of mixed water required and improving the structure of the hardening body of the material。

Water retaining agent: The self-leveling material is constructed on the ground base, and the construction thickness is relatively thin, and the water is easily absorbed by the ground base, resulting in insufficient hydration of the material, cracks on the surface, and reduced strength。In this experiment, methyl cellulose (MC) was selected as the water retaining agent, MC has good wettability, water retention and film forming properties, so that the self-leveling material does not bleed and fully hydrated。

Redispersible latex powder (hereinafter referred to as latex powder) : latex powder can improve the elastic modulus of self-leveling materials, improve crack resistance, bond strength and water resistance。

Defoamer: Defoamer can improve the apparent properties of self-leveling materials, reduce bubbles during material molding, and play a certain role in improving the strength of materials。