Artificial stone, which is created by mixing water, a binder and aggregates (crushed stone, sand or gravel), and their further hardening, is called concrete.
As a building material, concrete began to be used in ancient times, the composition of which then markedly differed from the current one. There was a period when it was temporarily discontinued, but in the 19th century new hydraulic binders were invented, such as, for example, Portland cement, and concrete again gained popularity in construction. In the 60s of the XIX century. cement manufacturing technology was improved, brand strength increased and it began to be used as the main binder for concrete. At the moment, this product is one of the most important building materials, which is used in almost all areas of modern construction.
He received such recognition due to the following characteristics:
- the variety of properties acquired due to the variability in the use of the quality of stone and cement materials and the variety of methods of physico-chemical and mechanical processing;
- ease of work with concrete mix, which has high ductility and allows you to produce a wide variety of shapes and sizes of durable, high-strength building structures;
- the ability to fully mechanize the process of working with concrete;
- profitability, since its volume is 80-90% composed of stone aggregates of local production.
Production of a concrete mixture of high quality is possible only with the knowledge of technology, the skills to choose materials of a certain quality and the ability to calculate their ratio, find laying methods, compaction and preparation modes of the mixture.
For the construction of various engineering structures, different types of concrete are used ( depending on the area of application). There are several main signs by which the material is classified: specific gravity of concrete, its strength, type of binder, purpose and frost resistance. The main classification is by volumetric weight. Accordingly, concretes are especially light, light, heavy and especially heavy.
1. In the first - a significant number of medium and small cells of about 1-1.5 mm in size, so they are also called cellular. The specific gravity of concrete with a volume of 1 cubic meter is about 500 kg. As a rule, this type is used as a heat-insulating layer.
2. The lungs. This type includes those for which simple lightweight materials are used as aggregate - expanded clay, tuff, shell rock, or no aggregates are used at all, and foaming agents are added - aerated concrete, foam concrete, etc. The specific gravity of concrete with a volume per cubic meter is 500-1800 kg The bulk of its composition is sand - up to 600 kg. Such material is often used to make building blocks.
3. Heavy concrete contains coarse-grained heavy aggregates - gravel and crushed stone. One cubic meter weighs approximately 1800-2500 kg. This volume contains 1150-1300 kg of gravel or crushed stone, 600-750 kg of sand, 250-450 kg of cement, 150-200 l of water. Heavy concrete is classic and is used in many areas of construction.
4. Particularly heavy concrete contains barite, magnetite and some types of metal scrap. The specific gravity of concrete with a volume of 1 cubic meter can range from 2500 to 3000 kg. The main component of most of its mass is coarse aggregate. This type of concrete is mainly used for the manufacture of protective structures on AEC.
When calculating a cube of concrete, one should not forget that its components can have different specific gravities. For example, fine-grained aggregate is heavier than coarse-grained, and quarry sand is lighter than river sand.