Special property of aerated concrete - the set of closed pores filled with water only under specific conditions. Consequently, even after prolonged soaking in aerated water, the central part of the test samples remained relatively dry. The system does not disclose, the cells filled with water, forms a buffer cavity, which moves over being frozen water. Thus, the aerated concrete due to its structure creates conditions for high frost resistance.
On top of that moisture aerated immediately after fabrication equals 0,3-0,6 humidity standard tests. In standard operating conditions nazyschennost moisture products of aerated concrete is always lower its moisture content immediately after autoclaving. On this basis, samples of aerated concrete in laboratory testing at the alternate freezing and thawing have a moisture content which should not have a building structure of aerated concrete in real terms.
Analysis of frost resistance of samples of aerated revealed important data on the dependence of the rate of technological parameters of manufacturing. So examining individual hydrosilicates calcium autoclaved, it was concluded that, despite the low strength, hydrosilicates (highly basic) have a higher resistance to frost than hydrosilicates nizkoosnovnye.
This is because hydrosilicates (highly basic) have a complex crystal structure with a varying number of molecules of H2O, located between the levels of the crystal lattice. Crystal splice these hydro has high density, open porosity 20-30% higher than that of the splice hydrosilicates nizkoosnovnyh. Just this property determines the free migration of moisture when it is freezing and increase the volume without causing deformation and, consequently, high frost resistance of highly basic hydro.
Many scholars have attempted to establish the relationship between technological parameters determining the phase composition of the aerated tumors, and its frost resistance. These data are relevant regime autoclaving, type of binder, the composition of the mixture. In all studies, at the same phase composition of the tumors in aerated concrete, fixed effect on the frost-aerated form of binder. Show the least frost [url = http://www.aerobel.ru/product.html] building blocks [/ url] on the basis of lime, the increase in cement content increases the frost resistance.
An important factor that contributes to the stability of aerated with alternate freezing and thawing, according to characteristics of the structure of porosity. The pores on the effect on the frost can be divided into 3 types: backup (200 m); hazardous (200 to 0, 1 micron) safe (less than 0, 1 micron). Experimentally established that if the ratio of pores with a diameter greater than 200 microns in pore volume with diameters ranging from 200 to 0.1 microns is greater than 0.09, then the silicate unit will have a high frost resistance. In reality, this ratio for the building blocks are much higher. Although this is not a prerequisite for the withdrawal of the high value of gas silicate frost, but it certainly shows their superiority in resistance to freezing compared to brick.
Decrease in the proportion of hazardous since the introduction of silicate mixture of portland cement additives is a major cause of a positive influence on the frost-silicate products. For example, the addition of a wall blocks a density of 500-600 kg/m3 of portland cement in an amount of 20-25% by weight of dry matter decreases by 2 times the amount of dangerous long diameter of 0,1-0,2 mm. And as a consequence of frost aerated sharply rises to 25 cycles of thawing and freezing.
Analyzing the above, we conclude that in comparison with traditional materials aerated concrete has a high frost resistance, and high levels of frost resistance of cellular concrete is provided with an adverse in terms of frost phase state neoplasms wall blocks. While reducing the humidity of gas silicate blocks frost resistance increases significantly.
For example, when humidity 8% by weight of only 20 percent of samples noticed signs of defects to the 1200-th cycle of freezing and thawing. When full-scale surveys of buildings with normal operating conditions, even using them for a period of 35-40 years, Walling in the construction of which used gas silicate blocks, not found any defect that would have been the cause of the influence of alternate thawing and freezing.
No comments:
Post a Comment