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You will need

• - Architectural design with calculations of the strength class.

Instructions

1

Strength concrete Is a volatile parameter, it canCalculate finally only after the completion of the hardening process, and this process lasts exactly 28 days. Only through this interval can determine the design or design strength.

2

The main range used in construction is calculated from grades 100, 200, 300, 400, 500. Class strength directly depends on the proportion of cement in the mixture. The main range varies from B 7.5 to B 40; full - from B 3.5 to B 80.

3

In your project documentation, drawn up by a professional architect for obtaining a building permit, a class concrete, necessary for the construction of the foundation and masonry works. Based on these parameters, order the concrete mixture.

4

To check whether concrete is reallycorresponds to the declared class, make small boxes in the size 15х15х15. Moisten the molds, pour the concrete mixture, thread it with a piece of reinforcement. Forms put in a room with a temperature of 20 degrees and humidity of 90%. After 28 days, contact an independent construction laboratory. Trial concrete cubes will be checked with a sclerometer by a shock pulse, ultrasonic and destructive method.

5

If you buy concrete without checking, then remember,that a self-respecting company will always produce a mixture according to the declared characteristics. The strongest brand will be made from portland cement 800, which corresponds to class B 60, the average strength of such concrete is equal to 786 kgf / cm2. This species concrete used for high-rise buildings. The lowest strength in concrete brand Portland cement m50 with a class B 3.5 and strength of 46 kgf / cm2.

6

For the construction of a single-storey house it is sufficient to use the brand of Portland cement M400, class B30 with a strength of 393 kgf / cm2.

In the construction market, cement is proposedconsumers in a variety of categories. This applies to the prices of certain mixtures, but when choosing cement, more attention should be paid to its performance characteristics. Cheap cement is unlikely to help you achieve good results. Alternative materials are also offered, but no construction without cement is not complete.

On a category this material is divided intodepending on what its composition is and in which area it can be applied. Choosing cement for work is not difficult - you just need to get acquainted with the information on the labeling of mixtures.

Thanks to the marking, the buyer can receiveinformation about the main characteristics of cement. For example, a certain cement mortar is marked with the letter "M" and a certain numerical value. This marking shows the greatest load that this type of cement can withstand.

Also in the labeling of the material may be presentthe letter "D", equipped with a numerical value. This characteristic indicates the ratio of additives that are present in a concrete package of cement, in percentage terms. Considering this characteristic, it should be understood that the amount of additives contained in the mixture will directly affect both the strength and plasticity of the material.

Instructions

1

Cement - the most popular binding, without whichthere is not a single construction. There are several brands that designate a complex of its properties and in accordance with them determine the scope of its application. The cement grade indicates its compressive strength. The actual strength is called active. For example, with compressive strengths of 44 MPa, the activity will be 440 kgf / cm2, hence the cement grade is M400.

2

Binding with these characteristics everywhereUsed in the process of manufacturing concrete for pouring foundations, building blocks, paving slabs. Grades M500 and higher are used in the production of high-strength concrete for the casting of reinforced concrete structures.

3

One of the most important properties of cement isthe rate of its solidification. It is expressed in the buildup of strength for a certain period of time and depends on the mineralogical composition of the binder, its microstructure and grinding fraction. Of Portland cement, the fastest-hardening is sulfate-resistant. It has a higher resistance to the effects of liquids containing sulfates. Concretes made on the basis of fast-hardening cement have a low heat transfer coefficient.

4

When buying cement, you need to pay attention toits ability to retain moisture. This property is called "water retention". It determines the uniformity of the concrete mix and the strength of the bonding of the binder to the aggregate and reinforcing material. If the ability to retain water is insufficient, a stratification of a concrete structure or article may occur. In due measure, Portland cement M400, M500, M600 have this property.

5

Another important property of cement - uniformitychanges in volume. The standard indicator adopted as a building standard in many countries is the expansion of portland cement from 0.5% to 1.3%. For example, in the US, the permissible expansion is 0.8%, in China 1.3%. During the hydration of cement, heat is released. This is another property of this binder, which attracted attention for the reason that the temperature of concrete during its laying often increases markedly. This causes an increase in stresses associated with uneven cooling of the upper and lower layers of the composition, which can lead to the cracking of the finished product.

6

The normal density of cement is the indicatorthe amount of water needed to produce a solution of a certain consistency. The average density of the binder is 22-27%. It is increased by introducing fine-grained additives in the cement that have the property of water absorption (treble, opoka, etc.). The lower the normal density, the less water you need to get quality concrete. A reduction in its quantity leads to a reduction in the consumption of cement. Therefore, in the production of reinforced concrete products, cements with reduced normal density are used.

You will need

• - calculator;
• - ruler or tape measure.

Instructions

1

Select the brand of solution that is suitable forthe kind of work that you are going to perform. Depending on the nature of the work performed, a solution (sand-cement, concrete, slag cement, etc.) of different strength (brand) may be required. In particular: - mortars of the grade M200 - M300 are used for floor screeds, - for masonry of brick or block walls - M50 - M100, - for manufacturing slag blocks - M35 - M50; - for the manufacture of clay blocks - M50 - M100, - for plastering the walls of the house - M50 - M100, - for the foundations - a concrete mortar M 200 - M 300.

2

Determine the brand of cement that will be required forproviding the required grade of solution. For sand-cement mortars, the cement brand should be approximately two to three times higher than the design grade of the solution. If you need a solution of the brand M200, you must purchase cement grade M400 or M500. For the casting of blocks of cellular concrete (slag concrete, expanded clay, etc.), the cement brand should exceed the grade of the solution by 6-8 times. So for the production of cellular concrete grade M50 you will need cement M300 or M400.

3

Calculate the required volume of the solution. For floor screed, wall plaster, foundation and other such monolithic structures from concrete, the required volume is calculated by multiplying the corresponding parameters (thickness, length, width) with each other. The required quantity of mortar for masonry is assumed to be 0.2 - 0.25 m³ per 1 m³ of masonry, for the construction of walls from blocks of standard size - 0.05 m³ of solution per 1 m³ of masonry.

4

Find on the Internet a recipe for cookingsolution of the brand you need using a certain grade of cement (step 2). The most widely used is M400 cement. With its use it is possible to prepare solutions of the widest purpose. In particular, for the preparation of 1 m³: - claydite M75 will require 250 kg of cement M400, - cinder block M50 - 200 kg; - concrete M300 for foundation - 380 kg - sand-cement plaster or mortar M100 - 340 kg.

5

Based on the required volume of the solution (step 3) andthe amount of cement needed to prepare 1 m³ of solution (step 4), calculate the amount of cement that you need. For example, if you need to lay down a garage of brick with a wall volume of 10 m³, the required amount of cement is calculated as follows: 10 * 0.25 * 340 = 850 kg, where: - 10 - the volume of masonry in m³ - 0.25 - solution consumption per 1 m³ of masonry in m³ - 340 - quantity of cement required to prepare 1 m3 of solution in kg.

Formulation for the preparation of cement mortar

Preparation of M75 solution

Naturally, the cement must be absolutely dry andwithout lumps. It is best if the cement, compressed in the fist, flows through the fingers, if it is pressed into a lump, then it is better not to use such cement at all.

Preparation of M50 solution

Preparation of M25 solution

Mortar for brick masonry

To prepare a mortar solution, hydrate lime is not used, only cement, sand and water. If necessary, plasticizers for concrete are added.