Improving the properties of cement
The cement started to produce in the 19th century. Then it was processed at high temperature a mixture of limestone and clay.
Today, the cement composition can be varied depending on various additives.
There are several types of cement:
- Silicate (Portland cement): mixture of gray-green powder and water well solidified in air and in water. Is the basis for many types.
- Plasticized: not destroyed at low temperatures, in water, in the sun. Freezes well in any conditions.
- Slag: a mixture of clinker, slag and gypsum (or lime). Applied for construction of warehouses.
- Aluminous cement quickly sets and hardens independently from weather conditions. Not affected by moisture, frost, and corrosion.
- Kislotoupornyj: not soluble in water, stable under the action of acids. Consists of quartz sand and kremneftoristyj sodium.
- Color: silicate cement with dyes. Used in decoration of buildings.
A closer look at the most popular form of cement – lime (or Portland cement). It has high environmental performance, a minimal amount of harmful chemicals, dries fast and inexpensive. The versatility of this type due to the fact that when you add additives, it acquires new properties.
In accordance with GOST 24211-2008 «Additives for concrete and mortar», there are different types of additives (or supplements). Basic properties of additives:
- the material components;
- facilitate the treatment process.
The material components are:
- mineral (hydraulic and pozzolanic);
Regulatory components perform several functions:
- reducing the time of setting of the solution;
- increase strength;
- the reduction in cure time.
The addition of certain substances in the composition of traditional concrete allows you to:
- increase resistance to water, low and high temperatures, corrosion;
- to increase or decrease ductility or density of the mixture;
- the use of cement when decorating.
Additives for stability when temperature difference
Today the weather in Central Russia has climatic records: frosts are replaced by abrupt warming, and the day can fall monthly rainfall. Temperature changes negatively affect durability of concrete. When cooling is a part of the water freezes and melts due to global warming and increases in volume. How effectively resists concrete this increase is called the frost resistance of concrete.
To increase this ratio, the most commonly used plasticizers. They allow you to create the required density of the mixture. As additives usually used toxins or other substances of sedimentary origin.
Additives to improve the structure of cement
Additives can improve the elasticity of the concrete, resistance to deformation, adhesion to the materials. So, adding gypsum reduces the period of hardening.
Additives against corrosion
The addition of a mixture of substances with anti-corrosion action not only helps to avoid corrosion, but also to protect from moisture.
The use of additives
The use of plasticizers to the dry mix helps to reduce the consumption of water and product. As a result, the solution becomes more plastic, are able to close all openings.
For uniformity consistency are used starch or cellulose. They help to prevent delamination of the concrete.
The use of fibers prevents cracks, increases the strength of the mixture. In addition, the mixture may self-align.
Gidrolizatami help to improve the water resistance of the mix to control the curing process of the composition.