Loose and binding materials and mixtures / | Cementing materials: clay, lime, cement, plaster |
Destination cementitious materalov - tie into monolithic whole all the components of the future product or design. There are two types of binders - hardening only air - air and material properties on which the initial setting after the water can not be adversely affected. To air is clay, gypsum, lime and air. For hydraulic - hydraulic lime and cement.
Clay
The clay - is a soft, fine variety of rocks. Dilution with water forms a plastic mass, is easily exposed to any shaping. During firing, sintered clay, it hardens and becomes, and at higher firing temperatures and can achieve molten vitreous state.
Depending on the impurities clay takes a different color painting. The most valuable kind of clay raw material - white clay - kaolin.
The clay has the ability to absorb water up to a certain limit, after which she was not in a position to absorb or pass through. This property is used to create clay bulked waterproofing layers.
Depending on the temperature resistance of clay isolated lekgoplavkie clay, refractory and refractory. Their melting point, respectively: 1380 to 1550 and above 1550 degrees. Pure kaolin melts at a temperature above 1750 degrees.
refractory clays used as raw materials for the manufacture of refractory materials.
Lime
Lime obtained by firing limestone at high temperatures. Thus obtained is called lime-lime quicklime for being in contact with water is an active release of carbon dioxide. This process is called " quenching ". For most applications of lime it should be " quenched ".
repaid lime turns into a dough, which can be stored for many years. From the long-term storage properties of lime may even improve.
For the binder solution of lime putty mixed with sand. This solution is used when laying the foundations of a furnace, chimneys to 4-5 meters in height and is used for plastering the walls of houses and stoves.
Cement
The cement - the most common binder, allowing to obtain products and designs of the highest strength. Cement - the result of fine grinding of sintered products of one of the types of clay - marl or a mixture of limestone and clay. The sintering process is carried out in special furnaces.
When grinding the products made by sintering additive dosage gypsum, slag, sand and other components to obtain cement with a variety of properties.
Depending on the feedstock and additives introduced cements are divided into Portland cement and slag. Among potrlandtsementov quick-release and Portland cement with mineral additives.
Concrete structures that use one or another brand of cement can acquire unique properties. First of all, it is a particularly strong concrete, such as runways and airfields, missile launching sites, frost, fire and salt tolerant brand.
To indicate the maximum strength properties of cement used the concept of the brand. Brand 400 indicates that the plant laboratory at trial test of hardened cement cube with edge 100 mm crush on the press he sustained load of not less than 400 kg/cm2. The most common brands are from 350 to 500 are made the same brand of cement to 600 minutes, and even 700-mark.
All cements are fast enough hardening time. Start curing - setting - lies in the range of 40-50 minutes, and the end of curing is about 10-12 hours.
Gypsum
The gypsum is produced by burning rock - gypsum grinding and subsequent firing of the product. Gypsum is significantly inferior in strength cement products obtained by its use as a binder, as well as inferior to him in hygroscopic - the ability to resist the penetration of moisture into the body structure. Therefore, gypsum is used in the construction of solutions and working indoors. Gypsum is grade A -bystrotverdeyuschy (end setting for at least 15 minutes) and B grade - normally-(end setting - 30 minutes).
gypsum serves as the foundation of solutions to seal small cracks and uneven concrete surfaces of walls and ceilings, and plastering furnaces.