The proportions of the preparation of concrete mix at home

Stone material is obtained by mixing and hardening of a compacted mass containing a binder, filler and water. The proportions of the concrete play a role in creating durability and the likelihood of not collapsing under compression. Special additives are added to the mix to improve material properties when used in various designs.

Concrete composition and special additives

During production, sand, crushed stone, cement and water are mixed, the concentration of ingredients is determined by the brand of binder cement, aggregate size, and sand quality. The concrete mass includes a number of water repellents, plasticizers. During the concreting process, water and cement remain the main binding components of the mixture.

According to the purpose, there are ordinary mixtures for civilian and industrial construction, special solutions for laying roads, erecting hydraulic structures, and thermal insulation devices. There are compounds for special purposes that resist high temperatures, chemical aggression, and protect against radiation.

Concrete is subdivided in accordance with GOST 74.73 - 2010, GOST 25.192 - 2012, depending on various indicators:

• type of binder - slag, super-cement, alkaline, alabaster, silicate compositions;
• structure - porous, dense mixtures, aggregates of special consistency;
• curing conditions - hardening in the natural environment, with heat and moisture treatment, various pressures.

The proportion of cement and sand for concrete remains important. Additives impart specific characteristics and properties to mixtures.

Types of regulatory additives in accordance with GOST 24.211 - 2008:

• plasticizers to reduce the volume of water, stabilizers to prevent delamination;
• mobility adjusters for long distance transportation;
• additives to increase frost resistance, corrosion resistance, water resistance;
• retarders to delay the onset of setting;
• accelerators for fast hardening.

Components are introduced to increase the density, impact resistance, abrasion of the artificial stone. Photocatalytic components allow the solid material to self-clean from dirt and dust. The concrete formula involves the introduction of mineral ingredients to increase the viscosity and pozzolanic activity.

Requirements for the composition of concrete

The mixture is produced in factories or prepared at the construction site. In this case, the proportions of the concrete composition must be observed in order to produce a material with the required qualities. The main characteristics are the density of the concrete and the amount of the binder.

By density, artificial stones are divided into types:

• especially heavy with a density of more than 2500 kg / m³;
• heavy - 2200 - 2500 kg / m³;
• lightweight - 1800 - 2200 kg / m³;
• lungs - 500 - 1800 kg / m³;
• especially light - less than 500 kg / m³.

The brand is assigned according to each area of ​​application. The conditions of preparation and transportation over a distance, hardening circumstances are taken into account. The size of the coarse filler is selected, which is linked to the capacity of the concrete mixer, its type, dimensions of the product and the level of reinforcement.

The astringent ingredient influences the quality of the mixture:

• lean concrete is characterized by a low concentration of cement and an increased inclusion of crushed stone;
• fatty - high proportions of binder and a small amount of coarse filler;
• commercial - the proportionality of the components is taken according to standard recommendations.

The filler makes up to 85% of the volume in the mixture, it forms a solid core, reduces shrinkage and prevents cracking. It is necessary to have all the required parts for mixing concrete in a home concrete mixer and to observe the accuracy of the dosage.

The composition and proportions of concrete for a bucket and for a concrete mixer

The proportion of cement and water (W / C) is called the water-cement module, which is taken into account in the production of concrete mass. The smaller the W / C ratio, the stronger the mixture is. Theoretically, the ratio should be within 0.2, but such a dough has poor plasticity and is inconvenient to work with. In practice, a batch is made with an indicator of 0.3 - 0.5.

Adding a lot of water is a mistake in the proportion of concrete for a foundation or other construction. The mobility of the concrete mass increases, but the compressive strength and density decrease. The pores in the mixture appear as a result of the evaporation of excess moisture, which has not reacted with the cement during the hardening process. Water does not fully react if there is not enough binder cement.

Grades of concrete stone are determined taking into account the ultimate compressive strength, which is determined by testing standard cubes of solidified material with a size of 200 x 200 mm. The accepted brands are M600, M500, M400, M300, M150, M100 and less. Concrete shows different reliability depending on the stone filler (crushed stone, slag, gravel, expanded clay) and on the characteristics of the cement.

Cement М400

When using a binder of this brand for the manufacture of concrete M200, a proportion of 1: 3: 5: 0.5 is taken, where the portions of cement, sand, filler and liquid are indicated in order.

If you take a household concrete mixer with a mixture volume of 110 liters at the outlet, the preparation of concrete will require the number of components:

• cement - 18.5 kg;
• sand - 52 kg;
• crushed stone - 115.7 kg;
• water - 5.8 liters.

It is better to use medium to coarse natural sand. The use of clay sand is limited. A small amount of clay particles reduces the strength of the concrete. The sand is enriched in the process of washing, mixing with imported high quality material.

Proportions of M400 cement, sand and crushed stone for obtaining different grades of concrete in a bucket (in kilograms):

• M100 - 1.0: 4.6: 7.0;
• M150 - 1.0: 3.6: 5.6;
• M200 - 1.0: 2.7: 4.9;
• M250 - 1.0: 2.3: 3.8;
• M300 - 1.0: 2.0: 3.5;
• M400 - 1.0: 1.3: 2.5.

Water is usually taken in half the amount of cement. The grade of concrete depends on what will be built, for example, a foundation for a fence, blind area, screed or pillar.

You need to mix the solution before use, in a volume that can be used in 2 hours.

Cement М500

The use of a binder of this brand with a similar proportion of 1: 3: 5: 0.5, where the portions of cement, sand, filler and water are indicated in order, gives the concrete grade M350.

To prepare the mixture in a concrete mixer with a finished mass output of 240 liters, the following components are taken:

• cement - 40.5 kg;
• sand - 113.8 kg;
• crushed stone - 235 kg;
• water - 12.65 liters.

Instead of sand, you can use the remains of metallurgy, mining, chemical industry. It is difficult to make even M400 concrete at home, and it is better to order the M500 brand at the factory. Manufacturers sell dry water mixing kits on site, but such kits must be obtained from a reputable supplier.

The proportions of the composition of concrete for the foundation of M500 cement, sand and filler for the preparation of various grades of concrete in a bucket (in kilograms):

• M100 - 1.0: 5.8: 8.1;
• M150 - 1.0: 4.5: 6.7;
• M200 - 1.0: 3.5: 5.5;
• M250 - 1.0: 2.6: 4.4;
• M300 - 1.0: 2.4: 4.4;
• M400 - 1.0: 1.7: 3.3.

The ratio is correct for concretes that are laid on a dense surface. The porous base sucks moisture from the mixture, so the solidified mass is 1.5 times stronger.

Basic rules and recommendations for mixing concrete

The mixture is carefully compacted during the manufacturing and laying process, and the proportions are observed.Air is expelled from the gaps, and the laitance is redistributed for tight adhesion to the solid aggregate. Manual electric vibrators are used when pouring monolithic areas, and vibrating tables are used in the manufacture of reinforced concrete and concrete blocks (slabs, girders, beams).

Waterproofing is carried out in 2 stages:

• strengthening additives are added to the composition;
• finished structures are covered with a waterproof layer of penetrating action.

Components are introduced into the mass that resist corrosion. The shape of the structure and location is chosen so that the finished product is less exposed to shear forces, bends and other types of destruction, and only takes the compressive load.

In winter, the concrete heats up at the construction site after being laid in the formwork. In frost, the interaction of water and cement is weakened, the mass does not gain strength. After defrosting, such items may fall apart into their individual components. For warming up, electrodes are inserted into the mass through which an electric current flows.

Features of concrete mixes

The concrete class is determined by the compressive strength. The cube is tested by compression and in 95 cases collapses from a single load, which is taken as the limit. The class is indicated by the letter B and numbers that indicate the value of the boundary pressure in MPA (megapascals), for example, B25.

When designing, the age of the mixture is assigned, which corresponds to its tensile and compressive strength along the central axis at a certain solidification time. Concrete grade with letter M and numbers from 50 to 1000 means ultimate strength in kgf / m³.

The workability of the mixture means the settling time of the cone of the selected concrete sample and is an important indicator when concreting with a concrete pump:

• super-hard - more than 50 seconds;
• hard - 5 - 50 sec .;
• movable - less than 4 sec.

Other indicators are bending strength, frost resistance, water resistance. Frost resistance is shown by the letter F and numbers 50 - 1000, which indicate the number of series of freezing and thawing until destruction. Water resistance is shown by the letter W and numbers 2 - 20, which indicate the amount of pressure that a cylindrical sample can withstand.

Scope of concrete

Artificial stone is used in different directions of construction, depending on what proportions of components, cement and additives were laid down in the production of the product.

Scopes of grades by strength:

• manufacturing of supporting foundation cushions - M100, M150;
• pouring monolithic screeds, bases, paths, retaining walls, blind area - M200;
• installation of monolithic strip foundations, slab foundations, load-bearing elements, road surfaces - M350;
• construction of structures for hydraulic structures, mines - М400 and М450;
• construction of structures with special quality requirements, for example, dams, dams, metro stations - M500, M550.

In private construction, different types of concrete are used. For laying the floors, warm species are taken with the use of slag, expanded clay instead of crushed stone. Woodworking waste is used as a filler, shavings, sawdust are used. Such mixtures are lighter and prevent hypothermia of the room. Compositions are reinforced with a mesh when constructing entrances to the house, descents to the garage, in order to reduce the effect of shear.

In capital construction, concrete is used for the construction of high-rise and low-rise buildings, arches, bridges, domes, beams and pipes. The metal frame in piece slabs, beams, girders expands the possibilities of using reinforced concrete products.