What is a concrete grade?
Concrete is a compound with multiple applications. It is typically used for laying foundations, constructing floors and stairs, or hardening subgrades. Architectural concrete is used to fix interiors and facades, for example. When choosing a mix for a particular project, we must pay attention to the grade of concrete. What should we know about it? Let's check! Published: 03-14-2023 The quality of concrete: definition In construction material wholesale stores or in the product catalogs of online stores, we can find various names of concrete . Symbols include capital letters followed by two digits. How to read symbols like: C25 concrete or B100 concrete ? A builder or architect can easily decode them. However, non-professionals often don't know how to interpret an acronym included in a product description. These letters and digits represent the grade of the concrete. It is a parameter that defines the compressive strength of the material, expressed in megapascals (MPa). Strength tests are carried out on concrete blocks in the shape of a cylinder or cube. The first number (for example, C20) defines the specific compressive strength of the concrete, determined in cylindrical samples after 28 days of curing. The value following the / sign, known as the modulus or slash, represents the specific resistance when compressing a 15 cm × 15 cm × 15 cm cubic sample, determined after 28 days. The higher the grade of concrete, the higher its compressive strength.
Concrete grades: table If we type the term 'concrete grades' into a search tool, we will easily find an updated list and new concrete designations, which are often presented in table form. According to the PN-EN 206 standard, titled 'Concrete – Specification, performance, production and conformity' (the latest version is PN-EN 206+A2:2021-08), concrete grades are: Grades C: normal and heavy concretes (C8/10 to C100/115), LC grades: lightweight concretes (LC8/9 to LC80/88). The letter C means concrete. C and LC are new grades of concrete, established as a result of the implementation of European standards in local construction materials markets. (Some manufacturers continue to add the old designations, such as B, to make product identification easier for CZ Leadscustomers.) Old and New Concrete Designations: B Concrete How to interpret the new concrete names? Builders who have used B designations for concretes for many years often still use the old nomenclature. However, it is worth looking at the table of new and old concrete grades and then comparing the designations. In the current classification, grade C concrete replaced the old class B, for example: B15 concrete is now C12/15 concrete, B20 concrete is now C16/20 concrete, B25 concrete is now C20/25 concrete, B30 concrete is now C25/30 concrete, B45 concrete is now C35/45 concrete, B55 concrete is now C45/55 concrete, and B60 concrete is now C50/60 concrete. The old name concrete B35 refers to the group of concretes C30/37.
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Lean concrete (B10 grade) is now designated as C8/10 concrete. C20 concrete: compressive strength C20/25 (B25) concrete is widely applied, for example, in single-family homes. This is because it is easy to process, relatively cheap and very durable. That commonly available compound shows good strength parameters: the strength of a cubic sample is 20 MPa. For cylindrical samples, the specific strength index is 16 MPa. If we want to obtain better resistance parameters, we must use C25/30 (B30) concrete, whose resistance is 9 MPa higher for cylindrical samples and 10 MPa higher for cubic samples. Concrete C: division and applications What should we know about grade C concrete and its applications? Here is a brief summary: C10 (C8/10) concrete , also known as lean concrete , is used to stabilize subgrades; It is a substrate and leveling material, C25/30 concrete : the resistance parameters of this compound are very good, which is why it is used for foundations, floors and stairs (let us note that it was previously B30 concrete; the new designation can be found in the updated standard PN-EN 206) , C16/20 concrete : its properties are similar to those of C20/25 and C25/30 concrete; It is used for the construction of columns, foundations or walls, C45/55 concrete : it is also structural concrete, which is used to build prefabricated elements, wells or industrial pavements, concrete 55 , C50 : a concrete with improved compressive strength, which proves good in structures such as industrial tanks, bridges or supporting columns. The new concrete grade designations apply throughout the European Union. Standardization made it much easier for builders to choose suitable materials that correspond to design assumptions. In addition, laboratories around the world are working to improve the resistant behavior of concrete. The construction materials market continues to offer new and improved products, which requires modifying and updating the corresponding standards. The PCC Group offers a wide range of concrete admixtures and admixtures , including, for example, plasticizers and microsilica .
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