What are the performance requirements of desulfurized gypsum in the construction field

In China, both natural gypsum and industrial by-product gypsum are rich in nutrient resources. At present, the research and utilization of gypsum products have entered a stage of rapid development, which is also the focus of national solid waste utilization and environmental protection projects. Gypsum sand is a new type of wall plastering material, which is made of hemihydrate gypsum as the base material, polymer as the cementitious material and inorganic filler by dry mixing. It is a new and improved interior wall plastering material, which changes the traditional habit of taking cement as the cementitious material and has excellent compatibility and adhesion with various bottom walls. At present, desulfurization gypsum and phosphogypsum are mainly used in the market, which can be used as the following mortar:

Light plastering gypsum mortar

Light machine sprayed gypsum mortar

Heavy gypsum mortar

Caulking gypsum

Gypsum white leveling mortar

Gypsum binder

Reinforced gypsum

Gypsum putty

Nowadays, the application of plastering gypsum has entered a rapid development stage, especially mechanical plastering construction, which has been widely used and recognized in the field of building plastering. The key to how to make plastering gypsum develop better and steadily lies in the quality of plastering gypsum.

The plastering gypsum widely used in the market is a single-phase plastering gypsum product mainly composed of building gypsum and a certain amount of aggregate, admixture and admixture. The promotion and application of gypsum based mortar has a good development momentum, but the quality of some products is not satisfactory, especially the products of small enterprises. Some people do not understand and understand the basic characteristics of gypsum. There is no technical support for the production and allocation of plastering gypsum. They only rely on a formula provided by additives or material distributors, and do not have the necessary quality inspection means, There is no guarantee condition for the ex factory quality and stability of products, resulting in frequent quality problems of one kind or another, which has a great impact on the application effect of building plastering engineering. Poor plastering gypsum will hinder the market promotion and have the potential risk of destroying the development prospect of plastering gypsum. Therefore, we must pay more attention to the quality of plastering gypsum.

For the healthy development of gypsum building materials and the survival of gypsum based mortar manufacturers, we must pay attention to the quality of gypsum based products. The preparation of high-quality gypsum based products should consider their good performance, and first meet the quality requirements in fineness, setting time, strength, water retention, bulk density and thermal conductivity in GB / t2627-2012 national standard, Attention must also be paid to the crack resistance, sagging, construction operability, workability, adhesion, viscosity and other related properties of materials. In order to produce ideal, stable and reliable plastering gypsum products, optimization and selection must be carried out in every small link, such as the selection of production equipment, the selection of reasonable process, the reliability of product quality, the accuracy of material measurement Selection of packaging and storage conditions; For preparing plastering gypsum, attention shall be paid to the selection of raw materials, such as fineness, gradation, mud content or powder content, moisture content and impurity content of hydrated gypsum, admixtures (fly ash, slag, heavy calcium, light calcium, quicklime, kaolin, lithium slag, silica fume, zeolite, etc.) and aggregates (river sand, artificial sand, tailings sand, air gathering sand, slag, slag, smelting slag, etc.) The temperature during preparation and various lightweight aggregates (perlite, vitrified beads, zeolite, sepiolite, polystyrene particles), etc. shall be repeatedly adjusted to determine the compatibility and dosage requirements for determining the setting time, operable time, strength, operability, crack resistance, sagging performance and other effects of suitable plastering gypsum products, and the addition of additives, especially retarders, on time, strength The influence of anti cracking and dusting, the influence of the viscosity of water retaining agent on the operability, water retention, slurry thickening, strength and bonding performance, and the compatibility of auxiliary admixtures on time, strength, crack resistance, sagging, adhesion and workability should be selected one by one. The preparation of plastering gypsum should also pay attention to the humidity of the market environment, The variability of temperature and the different performance of local wall materials can be adjusted to meet the quality requirements of plastering gypsum. Firstly, we talk about the quality performance of the basic raw material of gypsum based products. Because there is no suitable and reliable gypsum, high-quality gypsum based products will not be produced.

Under normal circumstances, desulfurization building gypsum has higher strength than natural building gypsum, smaller particle size, less water consumption for standard consistency and large loose capacity. When used to produce gypsum based products, it has poor workability and high viscosity than natural building gypsum, but it has poor bonding effect with the base, easy cracking and poor construction feel.

The performance of desulfurized gypsum in the construction field needs to be paid attention to. Firstly, the self performance of desulfurized gypsum powder should meet the GB / t9776-2008 standard, in which the flexural strength should reach grade 3.0, the content of calcium sulfate dihydrate is greater than 90%, and the content of calcium sulfite is less than 5%; Secondly, desulfurization building gypsum with stable setting time performance should be selected. Products with unstable setting time must significantly affect the construction and quality of gypsum based products; In addition, we should select desulfurization building gypsum for continuous and stable production. For enterprises that cannot continuously produce, the unstable factors of production products that open for three days and stop for five days or open during the day and stop at night increase; Fourth, in order to ensure the stability of desulfurized building gypsum, attention should be paid to the uniformity of quality and moisture content of dihydrate desulfurized gypsum; Fifth, to produce stable desulfurized building gypsum, we must first choose a stable heating temperature. Without normal and reliable heating conditions, there is no stable basis for calcination and dehydration; Finally, whether producing desulfurization building gypsum or plastering gypsum, in terms of the rationality and integrity of the production process, the selection of equipment, the layout of the process and the impact on the environment should be comprehensively and carefully analyzed and studied, so as to finally obtain that the gypsum based products have good stability.

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