Density of cement
The density of cement is the ratio of its mass to volume. This characteristic allows you to correctly draw up the proportions of the concrete solution. Specific gravity in the everyday sense is identical to density and directly depends on the state of the material.
See online calculator - Density Calculator.
Freshly ground cement has a minimum specific gravity. The same can be said for Portland cement, which has just been unloaded from the tanker by pneumatic blowing. This property is manifested due to electrostatics as a result of the magnetization of individual particles of the material during their mutual friction. Cement grains move away from each other, which leads to a decrease in density.
During the delivery of cement, its pouring and long-term storage, there is a gradual decrease in electrostatics and shrinkage of the air jacket of the particles. This leads to compaction of the powder structure of the material. As a result, the specific gravity begins to grow. The density of fresh cement is from 1100 to 1200 kg per cubic meter, and of caked material - from 1500 to 1600 kg per cubic meter.
As for the bulk density of cement, in accordance with regulatory documents for enterprises manufacturing reinforced concrete products, it reaches 1300 kg per cubic meter. The density of the material is approximately 3200 kg per cubic meter. Such a paradox can be explained by air voids between material particles.
Voidness is characteristic of all types of materials with a powdery, granular or lumpy structure. Calculations that make it possible to determine the volume of voids in the material are carried out when choosing the composition of building mixtures and when making concrete mixtures in dry form. There is a selection of a certain composition of the filler (sand) with a different size of the fraction. Large grains should fill the maximum volume, after which medium-sized sand is placed between them, then the same is done with a fine aggregate. As a result, it is possible to obtain a structure having the maximum density.
Knowing the approximate values of the bulk density of cement allows you to batch the concrete yourself. It also helps determine how many bags of cement will be needed to prepare the concrete mix.