At all times, man for his needs was engaged in construction, starting with ancient buildings and ending with modern technical masterpieces. In order for buildings and other constructions to remain reliable, a substance is needed that will not allow the separate parts to disintegrate.
Cement is a material that serves to bond building elements. Its application is great in the modern world. It is used in various fields of human activity, and the fate of all structures depends on it.
History of occurrence
Cementing materials began to be used in ancient times. At first it was unburnt clay. Due to its ease of preparation and prevalence, it has been used everywhere. But due to its low viscosity and stability, clay has given way to heat-treated materials.
In Egypt, the first high-quality building materials were obtained. This is lime and gypsum. They had the ability to harden in the air, which is why they were widely used. These building materials met the requirements until shipping began to develop. It became necessary a new substance that would resist the action of water.
In the XVIII century, material was invented - romance. This is a product that could harden both in water and in air. But the intensified development of industry required better materials and binders. In the 19th century, a new substance for binding was invented. It is called Portland cement. This material is used to this day. With the development of mankind, new requirements are presented to binders. Each industry uses its own brand with the necessary properties.
Composition
Cement is the main component of the construction industry. The main components in it are clay and limestone. They are mixed with each other and subjected to heat treatment. Then the resulting mass is ground to a powder state. Gray fine mixture - this is cement. If mixed with water, then the mass will eventually become like a stone. The main feature is the ability to harden in air and resist moisture.
Cement Mortar
In order for the building mass to be of the required quality, the composition should include at least 25% of the liquid. Changing the ratio in any direction leads to a decrease in the operational properties of the solution, as well as its quality. Curing occurs 60 minutes after adding water, and after 12 hours the mixture loses its elasticity. It all depends on the air temperature. The higher it is, the faster the mass hardens.
To obtain a solution, sand is needed, in which cement is added. The resulting mixture is thoroughly mixed and filled with water. Depending on the work performed, the solution may be ordinary or enriched. The first consists of the proportions 1: 5, and the second - 1: 2.
Types and production of cement
At the moment, many varieties of cementitious material are being produced. Each has its own degree of hardness, which is indicated in the brand.
The main types include:
- Portland cement (silicate). It is the founder of all kinds. Any brand uses it as a foundation. The difference is the number and composition of additives that give the cement the necessary properties. The powder itself has a gray-green color. When liquid is added, it hardens and hardens. It is not used separately in construction, but is used as the basis for the creation of composite materials.
- The plasticized composition reduces costs, has the ability to remove the mobility of the solution and perfectly resists the effects of cold.
- Slag cement. This is the result of crushing clinker, blast furnace slag and adding active additives. It is used in construction for the preparation of mortars and concrete.
- Aluminous. It has high activity, setting speed (45 minutes) and hardening (complete occurs after 10 hours). Also a distinctive property is increased resistance to moisture.
- Acid resistant. It is formed as a result of mixing quartz sand and sodium silicofluoride. Sodium water glass is added to prepare the solution . The advantage of this cement is its resistance to acids. The disadvantage is a short service life.
- Color. It is formed by mixing Portland cement and pigment substances. Unusual color is used for decorative work.
Cement production consists of 4 stages:
- Extraction of raw materials and its preparation.
- Firing and getting clinker.
- Grinding to a powder state.
- The addition of necessary impurities.
Cement Production Methods
There are 3 methods that depend on the preparation of raw materials for heat treatment:
- Wet. With this method, the required amount of fluid is present at all stages of cement production. It is used in situations where the main components cannot participate in the process without the use of water. This is a chalk with a high moisture content, plastic clay or limestone.
- Dry. All stages of cement production are carried out with materials containing a minimum amount of water.
- Combined. Cement production includes both wet and dry methods. The initial cement mixture is made with water, and then it is filtered as much as possible on special equipment.
Concrete
This is a building material that is formed by mixing cement, filler, liquid and necessary additives. In other words, it is a hardened mixture, which includes crushed stone, sand, water and cement. Concrete differs from mortar in its composition and dimensions of the filler.
Classification
Depending on what bonding material is used, concrete can be:
- Cement. The most common type in construction. It is based on Portland cement, as well as its varieties.
- Gypsum. It has high strength. As a binding material, gypsum stone is taken .
- Polymeric. Based on polyester resins. Suitable for work on horizontal and vertical surfaces. It is an excellent material for decorating and landscaping.
- Silicate. The binders are lime and siliceous substances. Its properties are very similar to cement and is used in the production of reinforced concrete structures.
Depending on the purpose, concrete can be:
- Normal. Used in industrial and civil engineering.
- Special. Found its application in hydraulic structures, as well as in road, insulation and decorative works.
- Special purpose. It is concrete resistant to chemical, thermal and other specific influences.
Cement cost
Manufacturers produce products packaged by weight. The weight of cement bags is 35, 42, 26, as well as 50 kg. It’s best to buy the last option. It is most suitable for loading and saves on packaging. Depending on the object where the repair work will be carried out, cement of various grades is used, which has its own cost. When paying, each bag of cement is taken into account. Its price is fixed and may fluctuate depending on the requirements of the seller.
Before you begin to calculate cash costs, you need to decide on one more nuance. Sometimes you can see an ad that shows the cost below the standard. Do not fall into such a trap. In such cases, expensive cement is diluted with cheaper. By winning a few rubles, you will lose the quality of the building material.
Take one 50 kg bag of cement. The price of the M400D0 brand will be 220 rubles. The cost of others may vary, but on average it:
- M400D20 - 240 rubles.
- M500D0 - 280 rubles.
- M500D20 - 240 rubles.
If you need to use only a couple of bags of cement, then it is most profitable to buy them at the nearest store selling building materials. And if you need a large quantity, then you should contact the manufacturer.
Cement consumption
Before performing any construction work, the question arises of how much cement is needed and what kind of consistency the mortar should be. In the ideal case, strength should be maintained and the proportionality of the components should not be exceeded.
When a responsible and serious work is ahead, mixing cement and sand “by eye” is unacceptable. If you do not spare the binder, then with large volumes it will cost a huge amount of money.
So how much cement is needed for the work done? Building standards (SNiP) will help answer. It takes into account all the reasons that affect the manufacture of the mixture. Focusing on the brand of composition and taking into account all factors, you can clearly find out the rate of cement consumption per 1 cubic meter of solution.
The main feature that many developers do not take into account is that cement is distributed in voids between sand particles. Remember that the composition is active. With long-term storage in the room, the 500 brand will become 400 in a few months. Therefore, when buying, you should always ask for a certificate with the date of issue.