Portland cement is one of the main building materials. This available dry mix is a powdered binder produced by grinding Portland cement clinker and gypsum stone. When it comes into contact with water, the cement turns into an elastic cement dough, which subsequently hardens to form a strong artificial stone.
This type of cement is most widely used in all countries. In Russia, it annually produces more than 60 million tons of Portland cement of various brands.
What does the M500 marking mean?
Cement grade-a conditional value that is expressed in numbers and means the strength of the finished concrete after 28-day aging. M500 grade cement (compressive strength — 500 kg per square centimeter) is most widely used in construction.
In accordance with the current standards, Portland cement M500 is produced both in pure form-with the index “D0″, and with special additives-modifiers – D5-D20. The letter ” D ” indicates the presence of additives in the cement, and the next digit indicates their amount (D20-20% of additives).
The main purpose of modifying additives is to give the solution additional properties. This can be increased resistance to aggressive media (for example, sea water), increased frost resistance, rapid hardening, etc. The manufacturer can also introduce technological additives into the cement composition (which facilitate the grinding process, transportation of cement by pipelines, etc.).
According to the new standards, in addition to the number of modifier additives, the marking indicates the type of Portland cement, followed by the letter designation of mineral additives.:
- CEM I-pure cement, without additives;
- CEM II-portland cement with additives.
In the new standard, there is no concept of a brand as such, there is a concept of a strength class. If earlier the strength of cement was denoted in kilograms per square centimeter, now in megapascals (MPa). Mark M500 corresponds to the designation-42,5. further, the subclass is indicated: H-normal hardening, b-accelerated hardening.
Here is an example of decoding Portland cement according to the modern standard of designations:
CEM I 42,5 B-Portland cement without additives with a strength corresponding to the M500 grade, fast-hard.
Technical specifications
Unlike other mineral binders (gypsum, lime), all types of Portland cement harden and gain strength not only in air, but also in water. Excellent quality of cement of this brand is a slight deformation of concrete after solidification.
Cement M500 in accordance with the requirements of GOST 31108-2003 must have the following characteristics::
- Compressive strength (after 28 days) – not less than 40 MPa;
- Start (time) of setting – at least 50 minutes;
- Uniformity of volume change-no more than 10 mm;
- Frost resistance-70 cycles of complete freezing / thawing.
The mixture can be stored in an airtight container for up to one year.
Scope of application
Portland cement M500 is used for the preparation of heavy concrete, masonry mortar and plaster. Concrete and reinforced concrete products based on this cement are characterized by high strength, stability, resistance to aggressive media, and durability. Cement of the 500th grade is successfully used in the construction of critical civil and industrial structures:
- for laying the foundations of large-scale objects;
- in the manufacture of paving slabs, expanded clay blocks and other construction and finishing materials;
- for the construction of bridge crossings and other load-bearing structures;
- during the construction of hydraulic structures;
- For filling pile foundations on flooded soils;
- when building modern highways, etc.
Cement consumption rates M500
As practice shows, it is more profitable to buy Portland cement of the highest grade. For example, when choosing the M500 for the preparation of concrete and masonry mortar requires about 15% less than the lower grade of cement M400. It is also more convenient in terms of transportation.
For the production of one cubic meter of concrete of the common M200 brand, it is enough to buy 400 kg (8 standard bags) of M500 cement.
For a simpler and more understandable calculation of the amount of cement required, you can use the formula: for concrete structures that are not subjected to heavy loads, it will be enough to mix M500 cement with sand in a ratio of 1 to 5.
For laying foundations, filling floors and other critical elements, the proportion must be at least 1:3. For the preparation of masonry mortar builders are usually guided by the ratio of 1: 4.