In the process of many construction works, it is necessary to prepare concrete or cement mortar.
The scheme of preparation of concrete in the concrete mixer.
If you need an amount of concrete that exceeds the capabilities of the manual kneading, it is best to carry out the preparation of concrete in the concrete mixer.
A small amount of concrete can be made by hand. At the same time any suitable capacity is used: basin, bucket. Sometimes the mortar is kneaded directly on the surface of the construction site. This is done using conventional shovels or any other mixer.
Types and types of concrete mixers
A concrete mixer, or mixer, is a construction unit intended for the preparation of concrete and mortars in proportion on the basis of cement.
There are several types of these mechanisms. Two of the most widely used are: forced action mixer and gravitational action mixer.
"Gravitational" concrete mixer is a mixer, the body of which rotates around its axis. It can be in the form of a barrel, drum, or other open container installed at an angle on the carrier frame. Inside, special blades are rigidly attached to the body. They are responsible for uniform mixing of the mixture.
The scheme of gravitational concrete mixers.
The angle of inclination of the concrete mixer may vary. This is necessary to control the intensity of mixing, as well as the discharge of an already prepared solution.
The rotation of the body can be carried out both manually and with the help of engines. Most often used electric drive, but there are other options.
For example, a mobile mixer mounted on a car platform is driven by a motor vehicle drive. Such a concrete mixer allows you to both prepare concrete in large quantities, and quickly deliver it to the right place.
Devices of the gravitational type, provided proper operation, allow to obtain a quality final product. These concrete mixers are compact, do not consume much electricity. On average, the power of electric motors of gravity mixers does not exceed 700 watts.
Gravity type concrete mixers are easily disassembled, conveniently transported. They are produced in a large assortment. Differences can be in the methods of attachment to the frame and the volume of the mixing tank, from 40 to 600 liters. This allows you to choose the best option for concrete mixers in relation to construction conditions.
Another significant plus is the price.
If it is necessary to obtain highly homogeneous in proportions of high-density formulations in which the proportion of liquid is small, compulsory-type mixers are used.
These are capacities in which the body is stationary and the internal blades rotate.
This design allows for more thorough mixing of the components.
Scheme of forced type concrete mixer.
The result is a mixture used for the manufacture of various kinds of concrete structures: paving slabs, wall and ceiling blocks.
Basically, such mixers are used in the industrial production of reinforced concrete structures.
The price of a forced-type concrete mixer is quite high. Therefore, the use of such a device in private construction is unprofitable.Back to table of contents
The main types of cement mixtures
There are many options for cement-based mortars. They differ in the purpose, the composition of the source components. Of great importance are the proportions of the constituent parts of the mixture.
There are four main, “basic” types of cement mixtures:
- Cement mass - "dough". Ingredients: cement, water.
- Simple solution. Composition: cement, water, aggregate (sand).
- A solution with lime. Ingredients: cement, water, aggregate (sand), lime.
- Concrete. Composition: cement, water, fine aggregate (sand), coarse aggregate (gravel).
In addition to the main components for the preparation of concrete and other mixtures, various plasticizers are used to increase the strength and plasticity of the original product.
There are no universal recipes for making concrete in a concrete mixer. The proportions of the main and additional components will be different, depending on the quality of the cement and the desired grade of concrete.
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The main stages of concrete preparation
The scheme of preparation of concrete mix.
The technology of concrete preparation in a concrete mixer is quite simple and can be divided into several main stages.
Stage one - the preparation of components.
It is necessary to prepare in advance the estimated number of all components. Sand, if necessary, sift. Rubble or gravel must be cleaned from dust, clay and earth. Water must also be purified. The presence of additives is undesirable in it: salts, minerals. Compliance with all these conditions will allow both to prepare high-quality concrete and make other mixtures.
Stage two - installation of a concrete mixer.
The concrete mixer is installed on a flat solid surface. Construction skews are undesirable, as they will adversely affect the quality of the original product and lead to premature failure of the mixer. Do not “hang out" the device during operation. It is desirable to fix the frame. Under the risers of the unit, if necessary, enclosed wooden or other supports.
The third stage is the preparation of the mixer.
The blades and the inner surface of the case of the concrete mixer must be lubricated with a substance that does not allow the prepared mixture to adhere: used engine oil, technical fat composition. You can use a cement mortar combined with a fine filler.
Stage four - loading the unit.
Scheme for determining the plasticity of a concrete solution.
One of the main rules is to avoid overloading. Overloading is fraught with a decrease in the quality of concrete and can lead to the disabling of the mixer itself. To obtain the best results, it is very important to follow the sequence of loading components On this account there are many mutually exclusive options.
The order of loading obtained in practice by the method of numerous samples is given:
- Most of the water is poured.
- A part of the rubble is filled up, which will perfectly clean the inner surface of the concrete mixer from previous batches.
- All the cement is added, which is perfectly stirred using the rubble.
- All the sand and the rest of the rubble is added.
- In the resulting mixture is carefully added water, the amount of which is regulated by the real density of the solution.
The next, fifth stage is the mixing process.
The whole procedure of concrete preparation in the concrete mixer should not last more than 2 minutes. Otherwise, evaporation of water may begin. And this will lead to a deterioration of the plastic properties of the mixture.
The sixth stage - check the finished mixture.
From the mixer pour a small amount of the resulting solution. The finished solution should have a smooth surface. Using a shovel, several “ribs” are applied to the surface of the mixture. The shape of the ribs must be maintained. This indicates that the concrete is ready in the concrete mixer. Otherwise, the mixture must be run in the "revision".
Stage seven - unloading the finished mixture.
Stage eight, final. After preparing the concrete, clean the mixer.
Cleaning must be done after the end of work with the mixer. Otherwise, the remains of concrete inside the tank will harden, and the process of their removal may lead to loss of the unit.
The tank is cleaned with water pressure or by repeated pouring and scrolling. You can add gravel to the water, which, as an abrasive, will remove the remnants of the adhered mixture.Back to table of contents
- The yield of the finished product is 2/3 of the volume of the capacity of the mixer.
- To liquefy too thick mixture it is better to use not water, but cement paste.
- The amount of water in the solution should not be more than half the amount of cement.
- Cooking time 1 m3 concrete in a 200 l concrete mixer - 1 hour.
With proper use of a concrete mixer, the question - how to make concrete - is not a question.