Types of cement and their applications
Clinker: Portland cement clinker is a composite product that consists mainly of calcium silicates and aluminates and is obtained from the thermal-chemical reaction of lime and clay materials in a cement kiln to a certain temperature.
Portland Cement: Portland cement is a water-based adhesive obtained by combining clinker powder with a suitable amount of gypsum in the mill. Portland cement with the characteristics specified in this standard creates heat in the vicinity of water and as a result of hydration reactions, and the resulting dough is trapped and hardens over time and acquires a stable resistance in suitable environmental conditions. If this cement is mixed and mixed with suitable water and aggregates, the mortar or concrete will create the desired efficiency and psychology, which will gain certain resistance over time and will be sufficiently durable in the face of environmental conditions.
Additives: Materials that regulate the properties of cement and its adhesion. Raw crystallized calcium sulfate is a common and virtual additive that is added to the cement production process when grinding clinker.
B - types of cement
1 - Cement type 1
This type of cement, also called ordinary Portland cement, is used for general purposes where a special feature of concrete is not required. In general, it is better not to use this cement in cases where special properties of other cements are required, especially in corrosive environments containing invasive concrete ions.
Recently, this type of cement is produced and supplied in three classes: 325-1, 425-1 and 525-1. For high-strength classes (435-1 and 525-1) and in tropical areas where there is a risk of increasing the concrete temperature to 32 و C and in bulk concreting to more than 15 c C, the use of this class of cement should be used with caution. Will happen.
2 - Cement type 2
This type of cement is used in cases where the average hydration temperature and resistance to sulfate attack are moderate. Due to the limitation of the alumina phase and the lower C3S in this cement, which causes these special properties, its initial and final compressive strength is less than that of type 1 cement. Type 2 cement usually gets slower than Type 1 cement and produces less heat in the setting. This cement can be used in bulk concreting. This cement is used in water and soil environments where the concentration of sulfate is moderate and for concreting in relatively warm weather where there is a risk of increasing the temperature of ordinary concrete to more than 32 C C and bulk concrete to more than 15 C C. River. This type of cement is not recommended for use in environments containing chlorine and sulfate ions simultaneously and in environments containing high concentrations of sulfate, as well as for concreting in cold weather.
3 - Type 3 cement
This cement has almost the same basic components as Type 1, except that it is finely ground and therefore has a faster setting. Type 3 cement achieves high strength in a short period of time, usually within 1 week or less, and its 7-day strength is about 28 days of type 1 cement strength. This type of cement produces more heat than the type 1 cement when it is trapped, and when it is used, it wants to remove the mold earlier than usual and use and load the concrete. In cold environments, this cement can be used to shorten the time required to protect the poured concrete. Type 3 cement is also called precast cement.
4 - Cement type 4
Type 4 cement is slower to produce less heat when trapped. The amount of C3S and C3A in this type of cement is lower than other types of cement and has more than C2S. This type of cement is used where the intensity and amount of heat produced is important. Concrete made with this cement has a slower growth resistance; That is, it takes later. The main application of this type of cement is in large concrete buildings such as dams. Type 4 cement is also called late cement cement. This type of cement is used in hot weather and temperatures above 40 to 50 degrees Celsius to facilitate concrete care. Consumption of this type of cement in hot weather prevents cold connection. Of course, if there is a risk of lowering the concrete temperature to less than 5 degrees Celsius, it is better not to use type 4 cement for concreting.
5 - Cement type 5
This cement is suitable for consumption in concretes that are exposed to sulfate attack and is therefore known as anti-sulfate cement. According to the Iranian Concrete Regulations (ABA), for all concrete structures located in severe water and soil environments, type 5 cement should be used. Of course, if the chlorine ion environment is accompanied by sulfate ions, the application of this cement should be done with caution and with the necessary tests. Type 5 cement takes longer than ordinary cement and has a resistance limit of 3, 7 and 28 days for this cement less than other Portland cements, and therefore has limitations for structures that require more resistance.
6 - pozzolanic cement
The pozzolanic material is silicate and almost like cement, but does not cause a cement reaction. In pozzolanic cement, a maximum of 85% of it is cement (types 1, 2 and 5). This type of cement is used for general purposes in the manufacture of mortar or concrete and is supplied with the "PP" mark. In addition to having the practical characteristics of the clinker of the used cements, this cement has special properties according to the type and characteristics of the pozzolan used. Low initial and final hydration temperatures, reduced concrete permeability and significant durability in corrosive environments, adsorption of cement alkalis and the ability to retain the properties of fresh concrete for longer periods of time are among the properties that are widely used in tropical areas. And bulky concreting, the use of poorly reactive aggregates with alkalis, use in environments containing sulfate and chlorine ions, the ability to transport to greater distances and overall greater durability and stability.
In special pozzolanic cement, the volatile pozzolanic material makes up 15 to 40% by weight of the cement.
Due to having a smaller share of clinker than similar Portland cement, this cement has a longer hardening and initial setting, so it is better to remove the mold or load this type of concrete over time. Also, due to the absorption of water and the reduction of flow and loss of slump, it is appropriate to avoid using more water for the flow of concrete and to use lubricants.
7 - White cement
The dark color of cement is due to the presence of iron sulfate and magnesium sulfate in cement. Fuel soot and furnace recovery conditions may also cause dark cement paint. Therefore, in order to whiten the cement, iron and magnesium sulfate must be removed from the cement and also the appropriate combustion conditions must be used. Therefore, for the production of white cement, clay soil with a sulfate content of magnesium and magnesium less than 0.8% is used.
8 - colored cement
Cement in red, yellow, blue, etc. are the same as ordinary cements, which are made of 2 to 15% colored stone powder. Usually white cement is used in light colored cement and ordinary gray cement is used in dark colored cement. Usually in the preparation of green cement from cream stones, blue cement from cobalt stones, yellow cement from iron ore (in the form of iron hydroxide or hematite), red cement from iron oxide in the form of ferrite (Fe2O3). And black cement use dual-capacity iron oxide (FeO).
9 - building cement
This type of cement is used in the construction of brick mortar, block work, interior and exterior lining of buildings, flooring, tables, etc. The following benefits are mentioned for this type of cement:
- Creating the desired adhesion of building cement mortar with other materials
- Better performance of cement mortar compared to other cements
- Less shrinkage of building cement mortar compared to other cements
- Low water absorption, better resistance to chemical attack, staining and frost damage, mortar of this cement has a water absorption equivalent to half the water absorption of cement mortar without bubble material.
10 - Other types of cement
There are a wide range of types of cement, the names of which are not included in this brief. Here are some of the most important ones:
Slag cement: This cement is produced with the addition of slag to the smelting iron furnaces and is used when the average resistance to sulfates or the average heat of hydration is considered.
* Source: Cement Technology Monthly (Specialized Cement and Concrete Yearbook of 1397)