The formula and process of the new gypsum mortgage

The formula and process of the new gypsum mortgage

Excellent lightweight plastering gypsum formula should do the following (I worked as a product craftsman in Saint-Gobain and other companies successively)

1: The construction property is better, as the workers’ right to speak increases, the construction property is the first;

2: Reduce cracking, which is a quality requirement

3: Whether it can be sprayed by machine

4: The initial and final setting time is stable


Based on the above requirements, the formula design is as follows


• Gypsum powder: 730 kg

• Calcium Hydroxide/Slaked Lime: 10-20kg

• Stone powder/heavy calcium powder: 200 (to be graded with gypsum powder)

• Vitrified beads: 50-70 kg (depending on the coating rate)

HPMC cellulose: 1.8-2.5 kg (viscosity 20,000-40,000)

• Air-entraining agent: 80-150g

• Thixotropic agent: 0-1 kg

• Auxiliary to change water demand: 0-0.5 kg

• Retarder system: superfine tartaric acid + protein; or pure tartaric acid system


The formulation technique breaks down as follows

Main ingredients:

The necessity of stone powder/calcium carbonate: the need for grading, the basic and general requirements for making dry powder mortar is to do a good job of grading, grading can have an impact on various indicators of the product, such as constructability, strength, etc.;

It is said on the market that Saint-Gobain’s material is easy to use, one of the main reasons is that their perlite is imported from Turkey, and the perlite (we call it glass beads) is self-graded, (of course, the strength is also high, If the specific gravity is light, it will not be unfolded),

The choice of stone powder should be determined according to the construction gypsum powder. If the gypsum powder is fine, it is recommended to use coarse stone powder for better grading effect; if the local quartz powder (above 120 mesh) is rich in resources, quartz powder can also be used


Why Add Calcium Hydroxide/Slaked Lime: 3 Reasons

1: Good workability, non-stick sharpening, good machine spray pumpability

2: Reduce early cracking, especially reduce cracking caused by overburning gypsum

3: Machine spraying construction must be added; most of the small material additives such as cellulose ether and starch ether dissolve faster in an alkaline environment, and machine spray products should release the additives better. Calcium ash should be added; especially the domestic cellulose ether mesh is relatively thick, while foreign products are relatively fine (domestic is 80 mesh, foreign is 180 mesh), Saint-Gobain imported HPMC from abroad in the early days, and later because of cost control Domestic and foreign HPMC, used in 1:1 ratio

*Calcium hydroxide should be paid attention to, because calcium hydroxide is also a three-phase product, and attention should be paid to controlling the content of raw powder (calcium oxide) not to be high, otherwise it will cause disadvantages; if the ratio of raw powder is too high, it will continue to eat water, resulting in later stages Phenomenon of poor workability or post-thickening

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