Use  foam  in  the  construction  industry.  Part  3
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Protect the surface of the concrete floor
To protect the concrete floor, which is operated in the normal mode, or is subject to wear in areas with high traffic, there are several ways to protect the surface.
   Comparable ways: their cost, appearance and ability to perform the task to protect.
   In this article, we consider three ways to finish and protect the floor. Each of them has its advantages and disadvantages.
  
   Thin fil...

Finishing compositions based on water glass. Part 3
When used as part of exhaustion moderator comes coagulation and solidification of liquid glass. However, due to the presence in the composition of Portland cement with a finishing time is an increase strength of the coating due to hydration of cement minerals. Thus from colloids formed during the coagulation liquid glass are actively assigned to the water for hydration of cement, a porous media formed tumors filled Portland cement, which leads to...

Finishing compositions based on water glass. Part 2
Studies in Berlin Institute Federal institute for Materials Research and Testing, show that the average density of 1730 kg/m3 brick large proportion of pores having a size in excess of 1 micron is more than 90% [3] and they are responsible for the increased migration of fluids through brickwork.
   Most fully meet these requirements structure obtained by coagulation and water-soluble potassium silicate forming silica with a high sp...

Modernization and repair of self-propelled machines. (3)
Hardening electrolysis BORATING hinge pins and bushings mates working equipment hydraulic excavators EO-4121 (EA-4321) gives an increase in wear resistance 4-6 times compared to the bulk quenching details.
   Taking into account the high wear resistance of brazed blades, hardened sintered alloys (see Table 1), are recommended for carbide knives dumps graders DZ-122 and RS-98, combined machine E-405 based on KAMAZ, for front dumps a t...

Specialized exhibition Architecture. Construction (END)
Mari-lime brick and gas silicate blocks
   JSC "MZSK" produces silicate brick and a half, color (white, yellow, black, red, blue, green, brown).
   For the production of silica brick used quartz sand from quarries near the plant. Limestone enters the factory with Dobryatinskogo deposit Vladimir region. Silicate brick (Table 1) is used for masonry exterior and interior walls of buildings and structures, as well as ...

Geophysical processes primers and security. Part 5
In the center of Moscow can distinguish vertical structure comprising a crashing into the Earth`s crust magma elongated cylinder (Fig. 2) [5]. In the center section marked lack of extensive vertical zone converted waves ("blind spot"), going from the depths of 70-80 km to 7.5 km. Such "blind spots" are characteristic of the earth`s crust with the introduction of monolithic dense mantle rocks such as gabbro, diabase, etc. In such a zone Tashkent e...

Finishing compositions based on water glass. Part 1
The quality of the decoration of buildings for new construction and reconstruction depend not only on their aesthetic, but also the operational parameters, as good-quality finish - a guarantee of durable service basic designs, long maintenance-free operation, the costs for maintenance and care. Traditional binders used for the production of finishing compositions, liquid glass is widely used, but it has some drawback: coatings based on it gaining...

On possible amendments to the equation Griffiths
Griffith presented a picture of destruction allowed to formulate the problem of determining conditions of the beginning of crack propagation and find its general solution.
   As seen from the above schemes, in the process of crack propagation material directly adjacent to it "coasts" unloaded relaxes. This means that the stress and strain it decreases, and the elastic energy stored earlier in this area of ​​the body is re...

Construction skyscrapers - the requirements of modernity. Part 4
The program is a high-rise building in Moscow
   The project is now a high-rise building in Moscow is implemented in two main areas: the construction of business center "Moscow City" and implementation of the program of the Government of Moscow "New Ring of Russia."
   1. Moscow international business center "Moscow - City"
   The project includes the construction of buildings on the territory of abou...

Degree project - beginning of the road. (3)
Given the great diversity of subject matter and content of diplomas in various specialties, the jury is faced with great difficulties in determining the winners - "Who better violinist or a dancer?". Nevertheless, often based on emotional perception and can estimate the relevance and novelty, and the author`s contribution to the thesis project or job. Absolute winners in recent years have been graduates of Rostov CSO GASU St. Petersburg, Nizhny N...

 

 
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 Use  foam  in  the  construction  industry.  Part  3

As is the case with conventional concrete, substantial impact on air shrinkage foam has water-cement ratio. Nevertheless, a relatively high foam shrinkage deformation means that designers and manufacturers of aerated products should adjust process in order to avoid formation of shrinkage cracks.
   Long-term deformation (or creep) increases with a decrease in foam density [2]. At relatively high densities of specific creep (deformation / load, MPa) is comparable to conventional concrete creep, but at a density of less than 1000 kg/m3 creep significantly. Be influenced by the deformation of the low-density foam in the long run in the design and manufacture of aerated concrete products.
  
   Durability foam
   The process speed is usually controlled by the destruction of the degree of penetration into the concrete of moisture, air and other aggressive media. Porosity and permeability of concrete, are generally considered as an indicator of durability. Foamed concrete is made by introducing a large amount of air in the cement slurry, however, this material has a very high porosity. Reduced density foam causes an increase in porosity. The high porosity of the material is one of the reasons behind the durability of foam.
   High porosity, however, does not necessarily lead to high permeability. Using a foaming agent provides appearance quality long constitutes a closed non-interacting bubbles, which provides high porosity at a low permeability material.
   The ease with which the fluid can penetrate into the foam, is determined by measuring the water absorption of the dried samples to constant weight upon immersion in the water and reaching the maximum weight of [7]. Water absorption is usually expressed as a percentage of weight gain. These results appear to indicate that the reduction in the density of concrete leads to increased water absorption. This could mean that the reduction in the density of foam would reduce durability.
   However, the volume of absorbed water is not increased in a significant decrease in the density range. Hence, it is possible to obtain foam, which absorbs less moisture than conventional concrete. This, in turn, suggests the possibility of manufacturing durable structural elements with foam.
   Rapid methods for the determination of corrosion resistance indicates that the foam can have the same durability as the conventional concrete strength of 25 MPa. Steel reinforcing bars were omonolicheny foam concrete and subjected to the subsequent action of salt solutions and the electron current to accelerate the corrosion process. [8] The mass loss due to corrosion of rebars were lower for rods with a protective layer of foam than that of the rods to the protective layer of ordinary concrete. The cellular structure of foam and possible porosity interporous partitions does not necessarily make foam less resistant to moisture penetration, dense structure than concrete.
   Air pores in the foam structure, may act as a buffer, preventing the rapid penetration. When security measures construct containing foam, may be less permeable and more durable than conventional concrete low strength.
  
   To be continued.
  

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