What is heavy concrete used for in individual residential

Liquid concrete mixes are currently an indispensable building material, without which virtually no construction site can do, ranging from the construction of farm buildings in private households and ending with the construction of large industrial facilities. Concrete mortar, depending on its technical parameters and performance, can be of various types and brands.

Moreover, if you look at GOST for heavy concrete, it becomes clear that this type of mortar is used in monolithic-frame construction for pouring walls, foundations and floors of buildings.

Use of heavy duty concrete

In order to understand in more detail what the concrete of heavy grades is, this article will discuss the main properties and main technical characteristics of this material, as well as the possibility of its use at various stages of housing construction.

In addition, the reader will be presented with detailed instructions, which describes the technology of self-preparation of heavy concrete mortar directly on the construction site.

Classification of various types of concrete

Concrete mortar is a thick mixture of a binder (various brands of cement), ballast aggregate (sand, screenings, crushed stone, gravel) and water, which are thoroughly mixed together in a certain proportion.

The specific gravity of a concrete solution is characterized by its average density, therefore, depending on this indicator, all construction solutions can be divided into several types.

1. Particularly light, or else they are called ultralight concretes, as a rule, have a cellular structure with closed pores and are made of lightweight aggregates with the addition of volcanic pumice or limestone. The specific gravity of this material ranges from 100 to 500 kg / m 2, which is achieved by saturating the liquid mortar with a large number of air or gas bubbles, which form the porous structure of the material. Due to its low weight and low thermal conductivity, this material is widely used as heat insulation of buildings, as well as for the construction of light interior partitions.

1. Light grades of concrete mortar have a density of from 500 to 2000 kg / m ?, and for their manufacture light porous coarse aggregate with the addition of carbonate sediment is used. Finished structural parts made of this material are widely used for the construction of internal and external walls in monolithic-frame construction, as well as for the installation of supporting elements of building structures of low-rise buildings.
2. Heavy grades of building concrete are made of high-quality cement with the addition of ballast aggregate in the form of river or quarry sand, gravel, granite rubble or other dense rocks.. For example, structural concrete is heavy according to GOST 26633 91 and has an average density of from 2,000 to 2,500 kg / m 2, which allows it to withstand high compression loads. In civil engineering, this material is widely used for the manufacture of strip, grillage and monolithic concrete foundations, for erecting walls and pouring ceilings for monolithically frame construction, as well as for the manufacture of finished reinforced concrete structures of high strength in concrete goods plants.

1. Particularly heavy or superheavy concretes, which have an average density of from 2500 to 7000 kg / m ?, are used only on the construction of special facilities, such as nuclear reactors. For their manufacture, expensive or rare, but very dense materials with high specific gravity, for example, magnetite, barite, cast-iron or steel shot, are used as aggregate. The very high price, high proportion and excessively high density make it inappropriate to use such materials in civil engineering.

Specifications

In addition to the average density, the classification of concrete solutions is carried out according to several important features: medium compressive strength, purpose, internal structure, nature of the binder and type of ballast aggregates.

As an example, consider the technical characteristics of heavy concrete class B15 M200, which is the most popular material in individual and commercial housing construction.

1. The average density of structural heavy concrete grade M200 grade B15 is 2385 kg / m ?.
2. Average strength at compression load is 196 kg / cm ?.
3. Portland cement M400 or M500 is used as a binder.
4. As a fine ballast aggregate, quarry or river sand with a particle size of 0.15 to 5 mm is used, and granite gravel or crushed stone with a particle fraction of 6 to 70 mm is used as coarse aggregate.
5. After solidification, the monolithic concrete massif has a dense stone structure with small closed pores.
6. The setting time of the finished solution, depending on the temperature and humidity of the surrounding air, can be from 4 to 12 hours. The time of full maturation of cement stone under normal conditions is 28 days.

Tip! To change the setting time of the solution, regardless of the impact of external factors, and improve its consumer qualities, there are special modifying additives that are introduced into its composition during the preparation process.

Basic properties

The quality of the final product made of monolithic concrete depends largely on the consistency and physical properties of the liquid mortar.

In order to get a little understanding of this issue you need to know the basic criteria for the correct choice of concrete mix.

1. The plasticity of the solution, which is commonly understood as the ability of the liquid mixture to completely fill the form of installed formwork, not splitting into separate components and not leaving empty voids and cavities.
2. Mobility is characterized by the height of the precipitation of a truncated cone molded from this mixture under its own weight. According to this indicator, all solutions are divided into hard, which do not give precipitation at all, slow-moving, with a draft of 10–30 mm, mobile with a draft of 40–150 mm and cast, which precipitate more than 150 mm. The mobility of the mixture depends on many factors, such as the quantity and quality of cement, the particle size of the ballast aggregate, the proportion of water and cement in the solution.

1. Watertightness is characterized by the density of concrete and is directly dependent on the size and number of pores in the structure of the material, which remain from the evaporated excess water that has not entered into the hydration reaction with cement. Also, this parameter depends on the number and volume of air bubbles that were not removed during the process of pouring and compacting the liquid mixture. To improve water resistance, it is necessary to use a low water / cement ratio, as well as to use special plasticizing agents.
2. Frost resistance is commonly understood as the ability of a hardened and matured monolith to withstand multiple cycles of alternate freezing and thawing without damage and destruction. All concretes of heavy grades are divided into several classes according to their frost resistance: Мрз 50, 100, 150, 200, 300, 400, 500. The number after the designation indicates the number of cycles of safe freezing / thawing.
3. At first glance, monolithic concrete seems to be an absolutely fire-resistant material, but in fact, with prolonged heating to a temperature above +200 ° C, its strength decreases by 25-30%, and with prolonged exposure to temperatures above +500 ° C, its destruction occurs. To increase the fire resistance of the solution, special heat-resistant aggregates and additives are added to the composition of heavy concrete, for example blast furnace slag or liquid glass.

Tip! To improve the water resistance of monolithic concrete, you can use special impregnations based on polyurethane or epoxy resins. Protecting the surface from water ingress into the monolith, this treatment significantly increases its frost resistance.

Scope of application

According to GOST 10268 80 for concretes of heavy grades, this material, by its physical and technical characteristics, fully complies with the general construction requirements for building materials for the construction of residential, commercial, as well as industrial buildings and structures.

For this reason, the most common brands of heavy concrete are widely used both in the field of individual housing construction and in the sector of construction of municipal and commercial real estate.

Due to good workability, wide availability, relatively low cost and high performance, heavy concrete grades are most often used to perform the following types of work:

1. Production of strip, monolithic, pile-borne and grillage foundations of residential and commercial buildings on all types of soil.
2. Construction of monolithic walls, as well as the casting of monolithic floors and interfloor ceilings in monolithic-frame construction of individual and multi-storey buildings.
3. Manufacturing of individual structural elements of buildings and structures capable of bearing significant static and dynamic loads (plates, trusses, lintels, crossbars, flight of stairs, etc.).
4. Filling of the bearing basis and reinforced concrete coupler of floors, blind areas of the base, garden and sidewalk paths and so forth.
5. Arrangement of artificial ponds, pools, fountains, monolithic septic tanks, construction of buried cellars and caissons of water wells.
6. Making a garden fence, fences, curbs, support pillars or decorative small architectural forms using metal reinforcing wire or mesh.

Cooking technology

During the manufacture of liquid concrete mix with your own hands, it is very important to choose the right proportions, observe the recipe and preparation technology, as well as perform thorough mixing of all the components of the solution, because this will mainly determine the final result of the concrete work.

A small amount of mortar can be prepared by hand, however, in the case of construction of a house or an outbuilding on the site, it is better to use an electric concrete mixer or, in other words, a mixer.

1. The mixer should be installed on a horizontal flat platform near the place of work, ensuring it is in a stable position.
2. Connect the power supply, start the engine and pour the right amount of water into the bucket. If necessary, add a plasticizer or other modifying additives and wait until they are completely dissolved.
3. Pour in half of the required volume of sand, then add the required amount of cement, and then all the remaining amount of sand.
4. After one minute, load the necessary amount of gravel or crushed stone into the bucket and leave to work for another two minutes.

Without stopping the mixer, making sure of the high-quality mixing, the required consistency and homogeneity of the mortar, unload the concrete mix into the prepared container, garden cart, or immediately inside the installed formwork.

Table 1 shows the volume ratio of building materials for the preparation of heavy concrete of various grades.

Tip! In order to avoid sticking of the solution to the walls of the bucket and the blades of the mixer, before starting work it is recommended to lubricate them with thick used oil or grease.

Conclusion

After reading this article, it becomes clear how wide the scope of application of monolithic concrete of heavy grades is, and how many important parameters must be taken into account when purchasing or making a mortar independently.

For more information, you can watch the video in this article or read similar materials on this subject on our website.