Strength is one of the most important characteristics of concrete. It is the reason why concrete works so well in various situations and is likely the most popular building material in the world.
Concrete is made from a combination of cement, aggregate and water. By changing the proportion of water in favor of cement (the so-called water-cement ratio), we obtain a stronger, more durable product. This is due to the fact that a large amount of water increases the porosity of concrete, as a result of which it becomes more susceptible to external forces and weather conditions.
Unfortunately, there is a cost. An excessive amount of cement also negatively affects the strength of the concrete – cracks can then occur in its structure.
The water-cement ratio is not the only parameter that determines the strength of concrete. Other important factors include the quality of the aggregate used (mainly its type and particle size), the cement class as well as chemical additives, which can significantly improve the properties of the concrete if selected appropriately.
The concrete strength is indicated by classes, defined on the basis of the PN-EN 206-1 standard introduced in 2004. There are as many as sixteen classes for ordinary concrete. They are designated with numbers (e.g. C8/10), where the first number indicates the compressive strength of cylindrical objects, and the second of cube objects (the values are given in Megapascals).
