Mobility of concrete: dilution with water. determination of

Concrete - just an indispensable material for construction, which is used everywhere. But in order to choose the right type of solution, it is necessary to take into account the main characteristics of the mass, such as workability, sediment cone and mobility of the mass. And just about the fact that the mobility of concrete and will be discussed in this article.

Basic terms and definitions

Before determining the main characteristics of the solution, it is necessary to clearly understand what this building material is.

Concrete is a compound consisting of four main components:

1. Cement;
2. Sand;
3. Water;
4. Crushed stone

Note! If rubble is not present in concrete, then it is just cement.

The main task of concrete is to combine all components into a monolithic structure. Achieving this goal is only possible if the correct proportions of the two main components, such as water and cement, are observed.

Sand and crushed stone are referred to as fillers of the composition, and are used to impart strength to the mass and reduce possible deformations of the solid product after solidification. It is these fillers that make up the structural framework of a monolithic product, which allows you to increase the elasticity of the structure and reduce deformation under severe loads.

Mobility

Mobility или эластичность раствора – важное свойство, способное повлиять на выбор материала для строительства зданий и сооружений различного назначения. Mobilityю называют способность массы заполнять форму, в которую она помещена.

Note! The ability of the mass to fill the form can manifest itself both under the influence of external forces, and under the influence of its own mass.

Mobility бетонной смеси по госту подразделяется на 4 категории от п2 до п5 в зависимости от количества добавленной жидкости. Чем меньше жидкости, тем гуще раствор, самый густой обладает показателем п2 самый жидкий соответственно п5.

In terms of plasticity, building material is divided into 2 groups:

1. Sedentary mix or hard. They contain a small amount of water and are unable to, under the weight of their own weight, without the influence of external forces, fill in the form in which they are placed. Such compositions have indicators n2 or n3. Laying sedentary mass is carried out using vibrating and sealing equipment, which allows you to remove voids from the monolith;

Council If construction work with the use of hard concrete is carried out in winter, the solution must first be heated.

1. High mobility mixtures, liquid or cast. Solutions of this type have indicators equal to p4 or p5. These masses are used in the process of pouring formwork, densely reinforced products and columns with their own hands.

Water dilution

Low elasticity of the material can significantly increase the time for construction work, provided that there is no necessary equipment on the construction site. And in order to solve this problem, many resort to the dilution method, making mixtures n2-n3 mixtures n4-p5.

Note! Experts do not recommend to resort to the dilution method, because the ratio of fluid and cement in the raster is fundamental, the violation of which will lead to loss of strength and quality of the design.

If the compaction is done correctly and the dilution method is excluded, you will get a solid, robust construction, which can be machined using methods such as cutting reinforced concrete with diamond circles and diamond drilling holes in the concrete.

Mobility indicators

In the case when the brand of concrete on mobility was chosen correctly, but it is ordered from the supplier and you have doubts about the compliance of the delivered product with the stated characteristics, and the price of the mixture is not so small, then you can check on the construction site.

Determination of the mobility of the concrete mix can be made directly during unloading in 2 ways:

• Determining the method of analysis of the monolith;
• Cone for determining the mobility of the concrete mix.

Determination of elasticity by analyzing monolith

Instructions for such verification stipulate the possibility of determining any indicator of the plasticity of the mixture:

1. Before starting the inspection, several cube-shaped boxes with a side size of 10-15 cm should be constructed from wooden boards;
2. Before pouring concrete into the prepared forms, the wood should be slightly moistened to prevent moisture from being taken from the solution;
3. The solution is poured into the boxes, after which the mass must be pierced with a sharp rod of reinforcement, thus sealing the monolith and releasing the air;

Council Additional compaction can be achieved by tapping with a hammer on the walls of the drawers.

1. Cubes should dry for 28-30 days at a temperature of at least 20⁰C and humidity not less than 90%;
2. After the created samples dry out, they should be sent to the laboratory, where the mixture will be checked for compliance with the stated indicators.

The apparent disadvantage of this method is its duration, because they often use the method of determining plasticity using a cone.

Determination of cone elasticity

To use this method, you will need a cone to check the mobility of the concrete, which is approximately 30 cm.

This check is performed as follows:

1. The cone is filled with mortar;
2. Concrete pierced to seal and remove voids;
3. The cone is removed and placed next to the solution;
4. We make a check for elasticity:
5. If the concrete sediment is 5 cm, then you have a hard concrete;
6. If the draft is more than 5 cm, then this is mobile concrete.

Finally

Working with concrete, it is necessary to choose the right grade of material in accordance with the elasticity of the mass and the purpose for which it will be used. Well, if you doubt that, for example, the mobility of P3 concrete is easy to verify using the methods described.

The video in this article will tell you even more about how important it is to correctly select concrete in accordance with the parameters of elasticity of mass.