In variants D0 and D20 are mainly made of cement grades M500 and M400, also known as “five-hundred” and “four-hundred,” respectively. It is designed for masonry and plastering works, and is used in pouring foundations, production of structures, beams and floor slabs made of concrete, in residential and industrial construction.
M500″ designation means that this cement can withstand a load of 500 kg per cm
In the cement mixture of D0 grade, no additives. This is pure clinker. A D20 is characterized by 20% of modifying additives in the composition.
What is clinker and what does cement consist of?
The lion’s share of the composition of the cement mixture is clinker, a special mass that is made from high quality limestone and clay. After firing at 1450 degrees, this raw material turns into a powder-like mass. It, in turn, is the cement – or forms the bonds in the concrete after mixing and hardening. Also gypsum is sometimes added, but not more than 1% of the volume, so as not to change the performance of the material.
In the production of some brands special modifying additives are introduced into the mixture. They change the properties and performance of the material. Nevertheless, in some cases during construction these “additives” are undesirable, and the cement composition with them is used primarily for finishing and construction work, in which high strength is not needed.
D0 cement does not contain any modifying additives, it consists only of clinker and, in some cases, gypsum. This material is characterized by the highest strength, excellent frost and moisture resistance, and maximum durability. “Five-hundredths” D0 clinker not only withstands the nominal loads of 500 kg per m
D20 contains 20% of modifying “additives”. As a consequence, it has a lower strength, lower curing rate and other performance characteristics.
Main difference of cement D0 to D20
The main difference between these grades lies in the scope of use. So, regarding the “five hundredths”:
M500 D0 is used in the construction of large industrial buildings, bridges, airfield pavements and similar heavy-duty facilities, which critically require high strength;
M500 D20 is used in the construction of private houses, in finishing work and casting monolithic products.
Regarding the “four-hundredths”:
M400 D0 is used in private construction, the construction of industrial facilities, for the manufacture of monolithic and precast structures;
M400 D20 is used in the manufacture of concrete structures.
So, When selecting cement, it is worth evaluating the planned use – and already be guided by it in selecting the brand.
Why additives are needed
It would seem that if all these “additives” so impair the performance of finished concrete structures, why introduce them at all? Nevertheless, they are not included in the mix to make it cheaper.
“Pure” cement mixtures are characterized by a fairly average resistance to aggressive factors from the external environment. They do not tolerate sharp changes in temperature, especially in conditions with cold winters or even permafrost. They do not cope well with repeated exposure to moisture. And additives in the mixture help the material become more practical.
The positive effects of “additives” are as follows:
Increased resistance to permanent or short-term exposure to moisture, including soil or naturally formed in basements and similar depressions;
The ability to resist the appearance and action of corrosion, which is especially important for reinforced concrete structures and laid through the floor slabs of various utilities;
Internal strength, which manifests itself in the prolonged action of low temperatures and sudden changes in climatic conditions.
Of course, the hardening speed and mechanical strength of such materials will be lower than that of pure clinker, but in some operating conditions they will show themselves more reliable and durable.