| you are: Structurally-mechanical properties of the cement test
The Structure of a cement stone is substantially defined by the mechanism of its hydration. As a result of interaction of cement with water are formed ' internal ' hydration products in the space originally occupied with cement grains, and ' external ' the products of hydration filling space, originally occupied with water. гидроизоляция пенетрон
The Quantity of internal hydrosilicate of calcium is much more, than external. Internal hydrosilicate turns out as a result topohimicheskoj hydrations alita and belita, i.e. By direct joining of water to a firm phase. Internal hydrosilicate has thin and dense structure; the relation can be from 0,5 to the big sizes on Taylor.
External products of hydration are formed through dissolution out of grains of cement and consist of a small amount of external hydrosilicate, large crystals and ettringita.
Particles of gel of hydrosilicate (kristallity) represent submicrocrystalline thin plates (' a foil ') from two-three structural layers; the thickness of each layer - nearby 6 And, and diameter of a particle - less than 100 A.Sledovatelno, a firm phase in gidratirovannom cement is in a condition of rather strong smashing. The specific surface portlandtsementa makes 0,3-0,45 Рј2Рі; in the course of hydration occurs dispergatsija cement and the specific surface of a firm phase increases in 100 200 times. for example, the specific surface of the cement stone made with the water cement relation 0,6, after 512 sut tverdenija at 100%-s' humidity was equal 782 Рј2Рі (at hydration of 91% of cement). Gluing ability of the cement test depends on dispersion of a firm phase: it raises in process of cement hydration, i.e. At transformation of the increasing quantity of cement into gel.
|
