Answers to FAQ's

Is if the actual strength of a cement is 61 MPa after 28 days and 68 MPa cement B, is the amount of cement can be reduced by over 10 percent at all times maintaining the same strength of actual blend?

Yes and no. The value describes the capabilities of this change, the better the actual size (or insignificance) particles of cement grain is the fineness or specific surface area according to Blaine, that is the area per unit mass of cement (usually grams or kilogram). The larger the surface area, the finer granules, which means that the less may bind more material. The units are cm²/g or m²/kg. The standard for the size of the Portland cement is from 3700 to 4100 cm²/g (i.e. from 370 to 410 m²/kg). In our example, the theory amount of cement can be reduced by more than 10%, but actually, if you can reduce the dose of cement depends on the composition of the mixture. The finer the grain contains - the more the need for cement.

It is regardless of the amount of cement mixture composition is the same?

No. The general assumption is one thing - the thicker the grain in the mix, the less the need for the cement to achieve the desired strength. Just less space that the cement must be "glued" together. For example - terrazzo is an artificial stone, which is a mix - hard rock grit and cement. 5-8 mm for grain are typically a mixture of 2: 1, that is, two stone parts, one part cement. For sand - depending on its thickness, this ratio can be as high as 1: 1.

All cements white brand IR 42.5, or 52.5 IR within their classes are the same?

No - each manufacturer is required to publish full details of the produced cement and share them interested. For some time, the results are simply available on the Internet on the appropriate tabs on the sides of the manufacturers. Cement, 52.5 IR assay could have actual strength after 28 days as measured in MPa, both 61 and 63, and even 75 ... This means that actually the final cement is generally a special cement, which allows to achieve a really high strength , especially after the addition of the corresponding "chemistry".

Does anyone cement of the same class and of the same type (eg. 52.5 IR) just reacts to supplements?

In theory yes, because each of them must meet certain specified standards, but even a slightly different composition (eg. The amount of alkaline compounds) can cause a different time, different pace, a different susceptibility reaction to this or any other supplement with the task of changing its physical properties.

Yes - that the role of gravel and sand can have in principle, be any hard rock granulation corresponding to 2 to 8 mm, or 16 mm, or more (eg. basalt,granite, river gravel etc.).