Consumption of materials per 1 m3 of concrete: optimal proportion, features of calculation and recommendations

At the construction site of any level, froma skyscraper up to a summer cottage, not to do without concrete. This material is used for pouring foundations, erecting walls in monolithic construction, installing ceilings and screeds, laying bricks and other artificial stone. The preparation of concrete in the correct proportion not only ensures the durability and strength of structures, but also avoids unnecessary costs for materials.

Composition of concrete

In the simplest case, concrete consists of three components:

• Binder.
• Aggregate.
• Water.

Consumption of materials per 1 m3 of concrete is determinedproperties of these materials. As a binder in the production of the mixture, the cement of the M100-M600 grades is used for strength. When mixed with water, a viscous mass forms, upon solidification of which an artificial stone is formed. In the role of filler use sand or various types of rubble. This increases the strength of the frozen solution, since the strength of the rubble is higher than the strength of the cement. In addition, the use of aggregate reduces the shrinkage of the cement mixture.

In addition to the main components, various additives are included in the concrete composition, which impart additional properties to the mortar: frost resistance, water resistance, color, etc.

The required consumption of materials per 1m3 of concrete - gravel, cement, sand - is determined based on the requirements for the characteristics of the mixture.

Basic characteristics of concrete

The most important characteristic of concrete is its strengthon compression. Depending on it, a strength class is established. Denoted by the English letter "B" and numbers corresponding to the strength of the sample in MPa. Concrete grades from В3,5 to В80 are produced, in civil construction the most widely used are solutions В15 - В30. In addition to classes, a stamp may be used to indicate strength. Denoted by the Latin letter "M" and the number corresponding to the strength in kg / cm square. Classes and brands are quite accurately correlated, for example, M200 solution corresponds to class B15, and M300 to class B22.5.

Consumption of materials per 1 m3 of concrete can vary significantly depending on the required grade or grade of solution.

It should be noted that the actual class of concreteis determined only in laboratory conditions on day 28. Therefore, if it is necessary to know exactly the brand of the mixture, several samples - cubes or cylinders 100 mm high - should be poured at the stage of its preparation. It is possible to determine the strength of concrete by the instrument method or the Kashkarov hammer, but these methods are less precise.

Select the required class of concrete

The required grade of concrete must be specified inproject documentation for the construction site. In case the construction is carried out independently, it is necessary to determine the brand of the mixture, since this will have a decisive effect on the strength and cost of the erected building or structure.

The purpose of concretes of the most common brands is given below.

• M100 - it is used for the device of the concrete, installation of parebrikov, small architectural forms;
• M150 - used for the installation of tracks, fencing of supports fences;
• M200 - for the erection of walls, fenders;
• M250 - production of monolithic foundations, grillage, foundation slabs, low-loaded slabs, ladders, retaining walls;
• M300 - for any loaded structures: walls, ceilings, foundations;
• M350 - bearing walls, columns, ceilings, beams, monolithic foundations.

Sand parameters

For the preparation of the solution sand is usedvarious origin: career or river. The second is more preferable, since it has a larger granule size and does not contain impurities. The quarry sand may differ in its granulometric composition. It is preferable to use sand with medium and coarse granule size. Since quarry sand can have clay or other impurities in its composition, it is recommended to sift it.

It is extremely important to pay attention to the humidity of the sand. Depending on this, the amount of water added to the mixture should be adjusted. Taking into account humidity and granulometric composition, the density of bulk sand can vary from 1.3 to 1.9 t / m3 cube, this should be taken into account when calculating the consumption of materials per 1 m3 of concrete.

Choice of rubble

Crushed stone in the concrete mix increases the strength of concrete and reduces its shrinkage when it solidifies. When choosing rubble, its fraction and origin are most important.

In construction, gravel fractions are used:

• from 5 to 20 mm;
• from 20 to 40 mm;
• from 40 to 70 mm.

Depending on the raw material, crushed stone is classified into:

• Limestone, based on sedimentary rocks.
• Gravel of rolled up debris of rocks.
• Granite, obtained by crushing granite and granite-gneiss rocks.

The best parameters for strength havegranite crushed stone, so if concrete is prepared for responsible structures - foundations, columns, floors, it is better to use it. We must not forget that the rubble used should not contain impurities, especially clays.

Water-cement ratio

In the production of concrete,ratio of cement to water. Water is necessary for the chemical reaction of cement hydration leading to the formation of cement stone. This ratio determines the class of the concrete mixture to a decisive degree. It is important to consider the cement brand. The lower the water-cement ratio, the stronger the concrete. The minimum ratio necessary for cementing cement is 0.2. In practice, concrete is used with a water-to-cement ratio of 0.3-0.5. Mixtures with a large water-cement ratio are practically not used.

Determination of the proportions of the concrete mixture

As a rule, Cement M400 and M500 are used for the preparation of concrete. In practice, in order to determine the cement consumption per 1m3 of concrete, the following table is used.

These data are given for conditions with normaltemperature and humidity, as well as for cement, the parameters of which correspond to those indicated on the package. In real life, a surplus of cement 10-15% should be envisaged.

Further, according to a known amount of cement, the consumption of materials per 1m3 of concrete is calculated, the optimum proportion of cement to sand and gravel is given in the table.

For example, the consumption of materials per 1 m3 of M200 concrete will be: cement of the brand M500 - 240 kg, sand - 576 kg, crushed stone - 984 kg, water - 120 liters.

Production of concrete

When large volumes of concrete work are advisableBuy ready-mix concrete at a nearby factory with a mixer delivery. In the conditions of industrial production, the norms of consumption of materials per 1 m3 of concrete are kept quite strictly. If this is not possible, you can prepare the necessary amount of the mixture and at home. It is important to properly assess their capabilities - concreting a separate structure must be done in one run.

Before mixing the mixture, determine the consumption of materials per 1m3 of concrete. Calculation of the consumption rate of components is not necessary, it is enough to use the table below.

The mixture is prepared in a concrete mixer of the appropriate volume, laying in it the measured portions of dry cement, sifted sand and gravel. Water is recommended to be added in batches in the last turn.

Additives

In addition to the main components, additives for various purposes are added to the concrete:

• Modifiers. Designed to increase the strength and increase the frost resistance of concrete.
• Plasticizers. Increase the mobility and water resistance of the mixture.
• Mobility regulators. Allow to extend the setting time, keep mobility during transportation.
• Antifreeze additives. Provide a normal setting of the solution at negative temperatures, down to minus 20 degrees.
• Accelerators of grasp. Increase the setting speed ensuring the fastest strength set in the first day.

When using additives, the consumption of materials per 1 m3 of concrete should be determined taking into account the manufacturer's recommendations. Violation of the instructions for use can have quite the opposite effect.