Self-leveling gypsum

                                                                        Self-leveling gypsum

Self leveling gypsum is the abbreviation of self leveling floor leveling gypsum, also known as gypsum based self leveling mortar. It is a kind of dry powder material specially used for indoor floor leveling, which is made of high-strength gypsum, aggregate and various building chemical additives carefully configured and evenly mixed in the factory. The corresponding product standard formulated in China is jc/t 1023-2021 gypsum based self leveling mortar.
Production technology
Self leveling gypsum is divided into α- Hemihydrate gypsum type and type II anhydrite type (obtained by calcining dihydrate gypsum at 650 ℃ ~750 ℃) both add a certain proportion of retarder to the corresponding raw materials（ α- Hemihydrate gypsum type) or activator (type II anhydrite type), mixed with cement, water reducing agent, water retaining agent, fine aggregate (quartz sand), defoamer, etc., and mixed evenly. As the addition ratio of the above additives is very small, below 1%, and they are common chemical products, the essence of the self leveling gypsum production technology is α- Production technology of hemihydrate gypsum or type II anhydrite.
Chinese α- Hemihydrate gypsum is basically used in ceramic molds due to its low output and high production cost of high-quality natural gypsum. The production and sales of self leveling gypsum are extremely small, and the quality supervision is still blank. Since the physical and mechanical indexes formulated in jc/t 1023-2007 adopt the lowest value of the corresponding foreign standards, some manufacturers use building gypsum to produce self leveling gypsum. By increasing the proportion of chemical additives, the quality of self leveling gypsum is close to the physical and mechanical properties of jc/t 1023-2007. As a result, the price of self leveling gypsum sold in China is high and difficult to be popularized and applied.
Gypsum advantages
(1) The floor constructed with self leveling gypsum has accurate size, extremely high levelness, no hollowing and cracking; Easy and convenient operation with high efficiency; In addition, pumping construction can be adopted, and the daily paving surface can reach 800~1000m ²。
(2) It is used as the "floor heating" leveling covering layer (compared with other heating methods, the energy saving range of floor heating is about 20%. If the zoning temperature control device is used, the energy saving range can be as high as 40%), which will not cause cracking and bulging due to thermal expansion and cold contraction like the cement mortar layer.
(3) When self leveling gypsum and cement mortar are used in the leveling course of building ground, the final cost of the two materials is similar. If self leveling gypsum is used to replace cement mortar, the proportion of reduced cement consumption in the whole cement output is very small, less than 1%; Basically, it will not affect the interests of cement production enterprises. Therefore, the application of self leveling gypsum in China's building materials market has small resistance and great prospects.
(4) It has been widely used abroad for decades, with mature construction technology and supporting construction equipment.
(5) Workable thickness 3mm-10cm

Market Overview
In the construction of buildings in China, cement mortar and traditional manual methods are still used to make the leveling layer, and then the ground is decorated. As a result, the development of self leveling gypsum in China has the following characteristics:
(1) Only a few big cities have sales. There are less than 10 manufacturers, and the annual sales volume is only about 10000 tons. There is no large-scale production. In addition, most manufacturers use building gypsum to prepare, and increase the amount of chemical additives (the cost of additives accounts for about two-thirds of the production cost of self leveling gypsum) to ensure that the corresponding performance requirements are met. As a result, the application cost of self leveling gypsum is higher than that of cement mortar, which hinders the promotion and application and slows the development.
(2) As a ground leveling layer, self leveling gypsum has incomparable advantages over other materials, so its market prospect is broad. China's newly increased building area is nearly 2billion square meters every year. If 60% of the ground uses self leveling gypsum (about 20 kilograms per square meter), there will be a market demand of more than 20 million tons every year.
(3) High added value. For example, the price in Beijing is 1700 yuan / ton. If the high-strength gypsum produced by desulfurized gypsum is used to prepare self leveling gypsum, 40% sand can be added to reduce the cost to less than 700 yuan / ton.
(4) With the operability of national support policies, it can obtain the administrative support and promotion of the government like "gypsum dry powder mortar". For example, it is suggested that the national development and Reform Commission and the Ministry of construction stipulate that "if a new civil building does not use self leveling gypsum as the ground leveling layer, it will not be rated as an excellent project"; "Self leveling gypsum must be used for the ground leveling layer of 'floor heating' of civil buildings"; There are few units to examine and approve these policies, the decision-making is relatively simple, and the policies are issued quickly.

Development prospect forecast
China's new building area is nearly 2billion square meters every year, of which the North heating area has basically adopted floor heating, which is more conducive to the promotion and application of self leveling gypsum. If 60% of the ground uses self leveling gypsum as leveling layer, the annual demand for self leveling gypsum is 27million tons (22.5 kg per square meter), and the demand for its base material - high-strength gypsum is 14.58 million tons, that is, 17.5 million tons of desulfurization gypsum are required. However, there are less than ten manufacturers of self leveling gypsum in China, with an annual output of only about 10000 tons and no special construction machinery. Therefore, self leveling gypsum is the only gypsum product without large-scale industrialized production in China's building materials market. As an important product to replace cement and reduce carbon emissions in China, self leveling gypsum has the same social and economic benefits of energy conservation and emission reduction compared with the "gypsum dry powder mortar" promoted by the government. It can be seen that it is not far for the Chinese government to issue the promotion policy for self leveling gypsum (Shanghai has made the plan to develop self leveling gypsum in 2011 in 2009). The next decade will be a period of rapid development of self leveling gypsum in China's building materials market.