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Quality and identification methods of main raw materials for wall putty production
Xinyang Shenghua Chemical Technology Co.,Ltd. specialize in producing all kinds of mixing equipment, including putty powder mixer, real stone lacquer mixer, thermal insulation mortar mixing equipment, dry powder mortar equipment and so on. Buy Shenghua putty mixer, we provide free technical guidance.
After customers buy putty powder mixer, it is sure to choose the raw material for putty powder. The putty has many kinds of raw materials. The main materials are heavy calcium carbonate, cement, calcium hydroxide, gypsum powder, bentonite, quartz powder. The auxiliary materials include glue powder, cellulose, PP fiber and so on. The quality control and inspection methods of these materials are as below:
1. Heavy calcium carbonate
Calcium carbonate, the chemical molecular formula is CaCO3, the settling volume 1.1-1.9ml/g, abbreviation calcium powder, belongs to the natural carbonate mineral, adopts the mechanical direct comminution grinding method. It has good thermal stability (below 4000C), strong inertia, good whiteness, low oil absorption rate, no crystalline water, innocuity, tasteless, flammability and dispersibility. After grinding into powder, under 100 mesh, commonly named as single fly powder, more than 200 mesh are commonly referred to as double fly powder, more than 1250 mesh called ultrafine powder.
At present, in the market heavy calcium powder, many kinds of mineral, mainly white dolomite, calcite, marble, white marble, limestone, and shell and so on. Calcite is best, such as large crystalline calcite
, like complex three sides and rhombic aragonite, and small crystal calcite.
If you want the wall putty to get light, shiny surface, should select the calcite with a good crystalline state, high crystal content and fine grinding powder. If no light surface needed, the dolomite, quartzite, and wollastonite, which have less crystalline content and less fine grinding powder, are enough.
Visual sense: the volume of the pile powder is large, the texture is slightly light, the feeling is smooth, and easy stick to finger. This putty is easy to scrape, smooth and easy to get light. Most of them are calcite. If the pile powder volume is small, the texture is slightly heavy, hand feeling is unsmooth, the scraper is more laborious, This putty is difficult to get ligh. These are non calcite.
Some internal wall or exterior wall putty products contain 65-75% heavy calcium powder, and the proportion is large. It is very important to choose suitable and stable quality calcium carbonate powder.
2. Calcium hydroxide
The appearance of calcium hydroxide is solid white powder. It is formed by the reaction of quicklime and water. The chemical formula Ca (OH) 2 is slightly soluble in water. Calcium hydroxide is a kind of strong alkali, has strong stimulation to the skin, and has corrosion to the wound. It is commonly used in building decoration material, and its application history is very long.
The addition of calcium hydroxide to the putty product will produce rigid gel, which will increase the bonding strength (dry strength and wet strength), water resistance and stability of putty.
There are many sources of calcium hydroxide, and the quality of producing areas in Zhejiang Jiande and Guangxi Guilin is better. With good whiteness, no black spot impurities, fine, light weight (large volume of pile), low moisture content.
As the main cementitious material for outer wall putty, the cement has the advantages of high strength, good stability and not afraid of water. The quality of the cement and the stability of the cement are very important. It is suitable to choose the high quality famous brand cement, the model is 42.5P.W ordinary white Portland cement, and it can also be used in 42.5P.O. Portland cement.
Gypsum is monoclinic mineral, and its main chemical component is calcium sulfate (CaSO4) hydrate. Gypsum is a widely used industrial material and building material. Gypsum generally refers to two kinds of minerals, gypsum and anhydrite. The raw gypsum is two water calcium sulfate (Ca [SO4].2H2O), also called two water gypsum, water gypsum or soft gypsum, monoclinic system, crystal is plate like, usually dense lump or fibrous; anhydrite is anhydrous calcium sulfate (Ca [SO4]), trapezoid system, crystal plate. The natural two water gypsum can be obtained by calcining and grinding. It can get beta hemihydrate gypsum (2CaSO). H2O), that is, building gypsum, also known as plaster and mortar. If the calcination temperature is 190 degrees C, the model gypsum can be obtained, and its fineness and whiteness are higher than those of plaster. If gypsum is calcined at 400-500 C or higher than 800 degree C, that is, floor plaster, and its setting and hardening are slow, but the strength, wear resistance and water resistance of the hardened gypsum are better than that of the ordinary building gypsum.
Gypsum used for gypsum putty powder is better choose beta type semi hydrated gypsum (2CaSO4. H2O).
5. Sodium bentonite
Bentonite is a montmorillonite mainly in water bearing clay. Because of its special properties, such as swelling, adhesion, adsorption, catalysis, thixotropy, suspension and cation exchange, 2-5% can be added to the putty of the inner wall, which can increase the viscosity, thixotropy, and ease construction of the putty.
The artificial sodium bentonite is different from the natural sodium bentonite because of different natriation conditions; natural sodium bentonite, has more expansion force and more dispersive than that of artificial sodium bentonite. Therefore, the bentonite used for interior wall putty is suitable for natural sodium bentonite with good whiteness, high gum price and large expansion ratio.
6. Glue powder
Glue powder is one of the essential raw materials for putty. At present, the cementitious materials used in the powder of the inner and outer wall putty (including diatom mud wall material) are used mainly for the redispersible latex powder, the polyvinyl alcohol powder, the compound resin powder, the plant type dispersible glue powder, the compound glue powder and so on, with many kinds and different properties, because of the raw material production plant. One sided publicity or even misleading has caused many manufacturers to have a vague understanding, lack of understanding and authenticity.
Putty with glue powder, should have good bonding strength, stability, environmental protection and pollution-free.
The commonly used cellulose varieties for putty are methyl cellulose ether (MC), hydroxypropyl methyl cellulose ether HPMC, Sodium carboxymethyl cellulose (CMC), sodium carboxymethyl starch (CMCS, also called starch cellulose). Select suitable cellulose varieties according to product needs. For the viscosity and stability of cellulose products, not the higher viscosity the better quality, but the more stable, the better quality.
8. PP fiber
Staple fiber (also known as PP fiber) is mainly divided into two types: O and Y.
Y type fiber is thicker and easier to disperse in mortar, but its distribution density in mortar is not as good as O type. Therefore, the tensile and cracking resistance of Y type wire is not as good as that of O type. The fracture strength, diameter and length of the polypropylene staple fiber determine its effect in the thermal insulation mortar. Therefore, it is suggested that the O type, high quality polypropylene staple fiber with a diameter of about 20μm and a fracture strength of more than 400MPa are used in the formula.
In the production processing, some bad manufacturers mix the oil or water material into the polypropylene fiber, in order to increase the weight of the product to achieve the purpose of low price sales. Adulteration will not only greatly reduce the performance and quality of PP staple fiber, but also significantly damage the bonding strength and stability of mortar, which should cause industry concern.
PP fiber is mainly putty for exterior wall and 2-3mm for fiber length.
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