preparation of concrete, cleaning of hardened cement, do-it-yourself repairs

A concrete mixer is equipment designed for preparing various mortars and mixing dry mixes. Its use ensures high productivity of work. At the same time, in comparison with the manual method, a higher quality finished material is obtained at the output. But in order to achieve this, it is necessary to mix concrete or another composition correctly, observing the proportional ratios between its components and the order in which they are added. There are different types of concrete mixers on the market. This affects the maximum size of the filler fractions that can be mixed during the preparation of the solution.

The device and principle of operation of the concrete mixer

Effective work with a concrete mixer requires knowledge of its design. This is necessary in order, if necessary, to be able to repair the independently used model of equipment and properly maintain it.

The device of any concrete mixer provides for the presence of the following common structural parts:

• containers (drum) for mixing the solution;
• frameswhich is a steel support structure on which all other elements of the concrete mixer are fixed;
• bladesdesigned to mix concrete or other mixtures and prevent them from sticking to the walls of the container;
• drive with a transmission mechanism and a control system for it.

These structural elements are shown in the photograph below.

The metal drum can be of various shapes, for example, cylindrical, pear-shaped, barrel-shaped.

The concrete mixer can work due to muscular strength or due to the presence of an electric motor or an internal combustion engine. In the first case, the drum is set in motion by the worker by rotating a special handle. But mechanical versions of the equipment are quite rare. The most widespread units with electric motors. They are equipped with a push-button post, with the help of which the operation of the mechanisms is controlled. The power of the installed drive determines the purpose of the equipment for domestic or professional use.

According to the installation method, concrete mixers are divided into stationary and mobile models. The latter are equipped with wheels for ease of transportation.

According to the method of mixing the solution, there are two types of concrete mixers:

• gravity;

• forced.

The principle of operation of a gravity-type concrete mixer is based on raising the mixed mixture by a rotating drum and its subsequent fall under the influence of gravity.. At the same time, the fixed blades placed inside the container additionally separate the composition, contributing to the faster formation of a homogeneous mass. The material is unloaded through the loading opening by means of a drum overturning mechanism driven by a wheel or a lever.

The rotation from the motor to the container in gravity models is transmitted through a gearbox or crown.

Forced Concrete Mixer works like a mixer: inside a fixed drum, a shaft with blades mixes the solution. The unloading of the finished composition occurs through a slide gate, which is located on the bottom of the tank. The shaft can be positioned horizontally or vertically (shown in the photo above). Forced-action models are equipped with more powerful electric motors than gravity ones, and are also more expensive.

Concrete mixer performance

The performance of a concrete mixer of both gravity and forced operation is determined by the following factors:

• the time of mixing the solution until ready;
• drum volume;
• electric motor power;
• material unloading time;
• the number of batches that can be cooked within an hour.

The mixing time is specified by the equipment manufacturer in the operating instructions for it. Fast kneading is considered to take place in about 2-3 minutes.

Power value determines the number of hours during which the concrete mixer can be operated without overloading the electric motor. To calculate how much concrete can be mixed with a concrete mixer per day, you need to perform the following simple mathematical operations:

• add the duration of loading, mixing and unloading;
• determine the number of batches per hour by dividing 60 minutes by the figure obtained in the paragraph above;
• find the volume of finished material in 1 hour by multiplying the capacity of the drum by the calculated number of batches;
• multiply the hourly productivity by the allowable number of working hours per day.

The productivity of gravitational action units is comparable to forced analogs with similar technical characteristics, in which the shaft is located vertically. Models with a horizontal shaft have lower performance. This is due to the fact that their shipping process takes longer.

Proper preparation of concrete mix

Foundation pouring, floor screed, laying of floor slabs, bricks, cinder blocks and many other construction and repair works are associated with the need to prepare concrete mortar in large quantities. At the same time, it is necessary to properly mix the concrete in a concrete mixer so that it turns out to be of good quality. In this case, after pouring and tamping, a solid monolith will be obtained.

Proper preparation of concrete is as follows:

• in the use of high-quality components (for example, not hardened cement of the required grade, clean sand with crushed stone);
• in good mixing of the final mixture;
• in keeping the proportions between the components.

Before you prepare the solution, you need to purchase all the necessary materials, having previously calculated their required amount. You will also need water.

The proportions of concrete for the foundation and other monolithic structures are determined by the brand of cement used: the higher it is, the less of this component is added to the mixed mixture. If the correct ratios are observed, the strength of the monolith remains at the proper level. When we prepare concrete, the moisture content of sand with crushed stone should also be taken into account: if they are wet, then less water needs to be added.

Before mixing the mortar, the concrete mixer should be placed in a stable position on a leveled hard surface. You need to place the equipment closer to the place of its use, so that later you do not have to carry it far in buckets. The wheels of the machine must be fixed in a stationary position with the help of brakes. To unload finished material an old bathtub or a large trough is well suited — it is convenient to draw a solution from them. Putting the bucket up and tipping over the agitator every time is a lot of work.

concrete mixing it is recommended to perform in the following order:

• pour water;
• pour cement;
• add the required fillers (sand with crushed stone);
• add the necessary additives if necessary (for example, a plasticizer);
• start the concrete mixer for the time indicated in the operating instructions for the model used.

The temperature of the concrete mixture at the outlet of the concrete mixer should be approximately +5 to +30 degrees (for different brands of cement there may be slight deviations). In this case, the finished material will comply with technological standards.

Making a solution takes some time. The exact mixing time depends on the additives used and the consistency of the mixture. Therefore, it is recommended to visually monitor the quality of the material at the exit, in the presence of lumps, increasing its mixing time.

Cleaning the concrete mixer after work

After operation, the adhering solution remains on the walls of the drum, both outside and inside, from which they must be cleaned. The working material also accumulates between the blades, contaminating the frame. If the solution is allowed to solidify, then it will need to be beaten with a hammer or other suitable tools. This deletion method results in the following negative consequences:

• the appearance of dents;
• knocking down paint, after which the metal begins to rust and corrode at a faster rate;
• the impossibility of complete cleaning (the dried solution remains in hard-to-reach places, for example, at the junction of the blades with the body).

Also, shock removal has a bad effect on the support bearing, accelerating its failure.

To prevent such consequences, it is necessary to wash the concrete mixer from hardened cement immediately after completion of work. Timely washing is especially important when the mixed composition contains plasticizing additives with increased sticking properties: after hardening, it is very problematic to remove them.

Washing is recommended not only at the end of the work shift, but also during its process after a maximum of 2 batches. The cleaning process is best done by pouring water under pressure on a running concrete mixer. If this is not possible, then you need to pour water into the drum in the required amount and twist it. You can also wipe the walls outside and inside with a rag or brush.

The dirty water left after washing inside the container can be used for the next batch. It is impossible to leave it inside, because the plasticizer and cement that have settled in the liquid will seize. After cleaning, turn the container over so that the water is glass.

It is possible to reduce the destructive effect of the cement slurry and impair its ability to adhere to the walls of the concrete mixer drum. For these purposes, before starting work, the inner and outer surfaces of the container should be treated water-repellent and anti-corrosion compounds. Silicone or an automotive anti-corrosion agent is suitable as such materials. One-time processing is enough for about 3 months of regular operation of the equipment. After this period has elapsed, the drum can be recoated with a suitable compound.

The main malfunctions of the concrete mixer and their elimination

During operation, various breakdowns occur. In some cases, it is easy to repair a concrete mixer with your own hands, without contacting a service center specialist. Most often, malfunctions of concrete mixers are associated with the following components and parts.

Reducer

Gearbox failure is classified as complex and quite expensive. Often, replacing one gear is not enough. You have to install a new node.

Thrust bearings

To install a new bearing, you first need to remove the drum and gear. After that, you need to knock out the shaft. Then you need to pull the bearing off with a puller. Instead of a worn or broken one, you should put a whole unit and assemble the unit in the reverse order.

Ring gear or gear engaged with it

The crown may be sector or solid view. To replace without dismantling the concrete mixer, only the first type part will turn out. To remove the worn drive gear, unscrew the bolted connection fixing it. Then this part is dismantled, replacing it with a new one.

electric drive

If the electric motor is heated from a manual concrete mixer, then this may be caused by its overload or burning of the windings or wedging of the rotor. A multimeter will help determine the health of the electrical part of the engine. With its help, the integrity of the windings of the disconnected motor is determined. If a break is detected, you will need to purchase a new motor. In general, the list of problems associated with the electric motor is quite wide. Often their elimination requires special knowledge.

Belt drive (with pulley or belt)

It is convenient to carry out a belt tension or its change by two people. The features of the process are determined by the design of the operated concrete mixer. To change the worn plastic pulley, you will need to unwind its fasteners, after removing the container.

Button for turning on the electric motor of the concrete mixer

Set the start button to work as well helps multimeter. To do this, you must first remove the button and disconnect the appropriate wiring. After you need to disassemble the button. If the starter coil is intact, then the problem is that the contacts are dirty. It is enough to clean them with fine sandpaper to restore the functionality of the button. The burnt coil will need to be replaced with a new one.

Over time due to wear and tear holes in the drum. They are closed with pieces of sheet metal of a suitable size by welding or bolting. Infrequently, but it happens that the frame (bed) bursts. Eliminate the breakdown using a welding machine. Also rarely have to change the wheels.

To repair the equipment with your own hands, you will need to use various tools, devices and fixtures. An example list includes:

• multimeter;
• Bulgarian;
• electric drill;
• welding machine;
• a hammer;
• pliers and round nose pliers;
• spanners;
• screwdrivers;
• caliper, ruler or tape measure.

Replacing a worn bearing requires the use of a special puller.

Constant loads, improper maintenance and care, wear of parts over time lead to various kinds of problems with the concrete mixer. At the same time, you can entrust the repair of a concrete mixer to specialists or do it yourself. In the latter case, if the unit is not under warranty, then it will be possible to save a significant amount. In order for the operated equipment to serve for a long time without breakdowns, it must not be overloaded. It is also necessary to pay attention to the first signs of problems and eliminate them in time. The equipment should always be well cleaned of residues of adhering solution.