Concrete Placement: an overview
Concrete is an artificial stone material that is used in construction and is obtained by hardening a mixture, usually consisting of cement, sand and water. Sometimes special additives are placed in it, in accordance with the requirements and climatic conditions, and sometimes they are made without water, such as asphalt concrete. A variety of methods help to achieve high-quality concreting in a variety of areas: both very hot and cold.
The composition of the mixture is determined in accordance with the requirements for the final object. For example, you need to know what the compressive strength should be, what the bulk mass is supposed to be, and, of course, how it will be laid. The styling technology depends on many factors, but it is thanks to the various options and choice that you can always achieve the desired result.
Features of work
Concrete Placing consists of several actions:
- Submission to the place of work.
Concrete Placing and the work involved are very labor intensive and energy intensive. In large plants, all work is carried out using special machines, such as pavers or concrete distributors. But at the same time, of course, we also need workers who must follow the process. Moreover, it is very important that workers have experience and knowledge, professional skills. In this case, the control over the laying will be carried out efficiently, and, as a result, the laying of concrete will give the result expected by the client.
Concrete must be laid in forms so that there are absolutely no free places and internal voids. Particular attention should be paid to corners and bottlenecks, if any.
Before you start laying the mixture, you need to carefully check the readiness of the formwork and, in addition, decide on some points, without which you can not start laying.
What do you need to clarify?
Technical parameters that you need to find out before Concrete Placing starts:
- consistency and mobility of the mixture, its composition;
- by what method the mixture will be supplied to the place of work;
- how the solution will be distributed and compacted;
- what will be the thickness and sequence of the laid layers;
- feed rate of the mixture stream;
- the number of workers and the necessary mechanisms;
- whether the required amount of mixture is ready.
Surface cleaning and preparation
Before starting Concrete Placing, you must definitely clean the place where concrete will be poured. Debris, dirt, possibly snow or ice, and anything that could interfere with installation should be removed.
If there are oil residues on the surface, the surface must be washed with special cleaning agents.
Do not leave water on the surface.
When laying the mixture on its surface, it is also necessary to prepare and carefully clean it from the cement film.
For this, do not use jackhammers and other similar tools. Such cleaning can weaken the underlying concrete layers, which means that the contact between the layers, the overall strength and reliability of the structure will probably deteriorate. To avoid dehydration, the surface should be well moistened, but remove any remaining water before pouring.
In this case, the mixture or concrete laid on the contact surface cannot be of poor quality. The fittings must be prepared by cleaning it of dirt.
The following supply methods are convenient for concreting foundations:
- unloading directly from the mixer tray directly into the formwork, provided that there is a spatial possibility for the mixer to approach the place of work, at a distance of the length of the tray;
This will greatly facilitate and speed up the work process. Thinking about it, of course, is best at the construction planning stage. If access is not possible, then a different method should be used.
- if it is impossible to drive the mixer to the place of work, it is necessary to provide a feed through the gutter. The gutter is made from any material at hand, most often from ordinary boards.
In this case, additional working hands will be required. One meter tray requires one person with a shovel to push the mixture through the gutter.
It should also be taken into account that the lower the mobility of concrete or mixture, the harder the process will be, even if the gutter has an inclination towards the formwork.
What is needed for concreting walls, columns and monolithic slabs?
An automobile concrete pump is used when there is no other option for solving the task. When using an automobile concrete pump, it is necessary to pay attention to the fact that the prepared concrete must have increased fluidity, but, of course, with the preservation of its brand.
To use the bell, in other words, a bowl with a closing drain hole in the lower part, additional equipment is required, that is, a crane. It is with a crane that a bell filled with concrete rises up, and then through the drain hole the concrete is poured into the right place.
One of the common laying technologies is the arrangement of horizontal layers. Their thickness varies from 30 to 50 centimeters. Layers are laid in one direction. The thickness of one layer should not have differences.
Laying is recommended to be carried out non-stop. Each new layer needs to be laid and then densified before the previous layer sets.
But this is not the only way to fill. You can fill each block individually to the entire height. If you didn’t have enough mixture during layer-by-layer pouring, then to continue work you need to wait until the filled layer is completely dried.
Distribution is not necessary if possible supply to any site. If this is not possible, then the concrete moves horizontally with shovels or other tools, equipment.
Double transfer by technology is not allowed, as this threatens stratification. The thicker the layers are poured, the less work will be done on the distribution.
The speed of the distribution work is very high, since after it there are still other work that needs to be done before setting.
Concrete level control must be taken care of even at the stage of mounting the formwork or knitting the reinforcing cage.
Leveling technology depends on the type of concrete structure. If the structure has a relatively small area, it is easiest to mount the formwork, aligning its top to the desired level. If the formwork is placed without alignment, then a level mark can be drawn inside it, for example, by pulling the cord. To draw a line inside the formwork is a bad idea, during pouring it will be smeared with concrete and will cease to be visible.
When concreting a floor slab or foundation, beacons are used to control the level. More often these are pieces of reinforcement exposed in one plane. When concreting floors where high accuracy is required, the surface is leveled with beacons from guide profiles laid in the floor plane.
The seal is carried out using a vibrator. Without it, it will not be possible to perform compaction work. A vibrator is a special equipment that is used to compact concrete mixtures. The use of a vibrator allows to reduce the level of porosity of concrete, to improve the penetration of cement mortar into the cracks, which will ensure reliable adhesion of the mortar to the poured surface.
The frequency of the step of using a vibrator depends on the density of the solution and the characteristics of the tool. With a correctly calculated step, keeping the vibrator in one place is enough from 5 to 15 seconds.
For laying with open surfaces and large areas, not deep, but surface vibrators are used. During operation, they transmit vibrations through a metal pad attached to them.
The quality of the floor directly depends on the preparation process. Floor laying can be carried out both on the bearing plate, and on gravel and sand cover.
In the second embodiment, the surface must be flattened and compacted. Carrying out laying work on a bearing plate having cracks, it is necessary to do preliminary repair work.
Fill cracks can be the same solution that will cover the floor. Concrete floor is popular for a long time, as it has the perfect combination: reasonable price and excellent quality.
Floor laying begins after the waterproofing layer. Strength can also be improved by using reinforcement, which can be carried out with reinforcement, mesh or fiber.
In order to arrange a floor with a hardened surface, the concrete grade must be correctly selected, it must in no case contain additives.
Self-leveling floors, both with a hardened surface and without it, can be done in warehouses, living rooms, shops and on the street, for example, in a parking lot. The concrete floor can be both the final coating and the basis for the next layer.
The process of filling the floor has many difficulties. It is necessary to ensure that the floor is as even as possible. In this case, it is necessary to take into account the design features of the base, as well as its slope and other points.
After pouring concrete
As soon as concrete is poured, compacted and leveled in accordance with the project, it is time to take care of the conditions for its maturation. To do this, you need to perform only a few measures: to prevent drying out and (in the winter you can not allow freezing) of concrete, especially in the early days, and also to protect it from atmospheric precipitation during the setting period. To protect against drying out and precipitation, the freshly laid concrete is covered with plastic wrap. At temperatures above +5 ° C, this is enough.
Concreting technology in the winter implies that the concrete is heated – electrode or using a heat gun under some kind of awning. In the first three days, concrete matures with the release of heat. If it is possible to arrange a thermally insulated shelter of the structure, in which the concrete temperature does not fall below +5 ° C until a set of 50% of the calculated strength (and this is about 3 days), additional heating can not be arranged. If heating was set, then it is also stopped by a set of 50% strength (as a rule, the same 3 days).
After removing the heating, the concrete can freeze – there is nothing wrong with this, the process of curing will resume with increasing temperature above zero.
In hot weather, concrete needs to be moistened daily, even when it is covered with a film: the film is removed, the surface is spilled with water and covered again. And so 5-7 days. After a week, the shelter can be removed and the formwork removed if the concrete structure is not a ceiling. Actually, shelters and formwork are removed from the foundations even for 3-4 days from pouring (and it happens, even earlier), although this is not entirely correct. The formwork of the suspended ceiling is made after a set of 80% strength. After dismantling, the structure can be loaded – to build walls, etc., but without fanaticism, not forgetting about 28 days for a full set of strength.
Benefits of Professional Concrete Placing
If the concrete laying works were carried out by professional craftsmen, then the laid concrete will:
- Durable – it can be guaranteed that for a long time the concrete will not collapse, no cracks will appear in it. Accordingly, the service life will be as long as possible;
- Fills with an even layer and will be qualitatively aligned. This is especially important when installing concrete floors;
- Ready for use at the agreed time. After a certain time, it will already be possible to carry out further work on finishing the concrete surface or directly use it for its intended purpose.
Concrete Placing: price and what it depends on
The cost of laying concrete is from $ 3.75 to $ 5.75 per square foot. The final price of the work is influenced by several factors:
- Laying area — how many square feet need to be treated;
- Installation conditions – depending on where the installation will be performed;
- The need to use overall equipment;
It should be noted that our craftsmen are able to work quickly, always fulfill their work responsibilities on time. Laying time does not affect the quality of the result. Our masters professionally perform work on laying concrete. We can work in different conditions, even in very difficult conditions, when it is not easy to lay concrete using conventional equipment. We work with orders of various volumes, we know how to fill large and small areas.
Concrete is one of the most durable materials, it is a fact. However, it becomes such not only because high-quality materials are used for its installation. It is necessary that the work is carried out by professional craftsmen who know what actions need to be taken to lay the concrete as high quality as possible. The quality of concrete laying affects its operating time. Laying defects are expressed in the fact that in the near future it is necessary to carry out repair work or even completely remove concrete that has cracked and has become unusable. To prevent this from happening, we recommend contacting professionals with experience in concrete laying.