Construction materials production. Application of the AVS-100 unit

Expanded clay industry

 In the process of expanded clay production the argillous raw material homogenizes and mills in the drilling mud mixers and rollers. But these equipments not ensure qualitative desintegration. As result we obtain the expanded clay of low quality.

 Insufficiently desintegration and homogenizing of raw materials lead to the result when even 3% of carbonate inclusion in the low-melt expanded clay can make it unusable. Obtained in such way expanded clay lose its durability or destroyed upon storage by the reason of CaO hydration.

 The oversanded glay with free SiO₂ content to 10-30% is also not suitable for expanded clay production. All those problems can be successfully resolved by using Vortex Layer Machine – AVS-100 PC GlobeCore production. When we are using the unit AVS-100 for desintegration and homogenizing of the burden material we obtain the expanded clay of general engineering and special designations. In this case we also reduce the volume weight and increase the durability.

 Table 1

Results of desintegration and homogenizing of the burden material for expanded glay production by using AVS-100

Slip treatment of CaS0₄ with content of free SiO₂  up to 40% leads to reducing of volume weight of the expanded glay in 2 times and increasing of its durability. The expanded glay strength-density ratio is almost in two times higher in the expanded clay, which is made from the burden material the unit AVS-100. The reason of sharp properties increase of the expanded clay is obviously activation of the high-silica sand caused by creation of active center or other words free radicals creation which are produced by the reason of the bond rupture of Si—O.

Intensifier of Technological Process AVS-100. General view

 Activation of SiO₂ leads to active participation of the expanded glay in the silication and glass formation. After the expanded glay baking in its granules are absent coarse particles of SiO₂, which are the concentrator of tension. Presence of SiO₂ in the glass content increases its durability and thermostability.

 Good results are obtained by dry treatment of the raw material by the vortex layer. For example, from the monothermite (hydromicaceous clay) we obtained the light-weight fireproof aggregate which has the volume weight in 2 times lower but the durability in 2 times higher than which we have for the control sample (experiment 3, table 1). The positive result was obtained by dry treatment of the multicomponent burden material (with 50% ashes content) by vortex layer.

 The given examples shows you that the application of AVS-100 (Intensifier of Technological Process) is very perspective for obtaining of the expanded glay of high durability and thermostability from oversanded and over-carbonized materials, burden materials which contain up to 50% of  waste product, for example, the coal ash.

 Cellular concrete production

 Cellular concrete is made in result of solidification preliminarily blown-out mixture of the cementing medium, water, silicious component using gasifier of components. Most frequently as foaming agent used aluminum powder. The aluminum powder reacts with water solution of calcium hydroxide and disengages hydrogen.

 In fact, the quality of cellular concrete is high when the size of pores decreasing and homogeneity of porosity is rising.

 In order to ensure best quality of cellular concrete is necessary to distribute aluminum powder in its weight and increase the degree of dispersion. Besides, the one of technological factors which determines the cellular concrete structure is content of active CaO in mixture.

 As usual the preparation of gasifier reduces to partial paraffin film stripping from aluminum particle surface by mixing of this film with water and surfactant species, after these action need to introduce suspension into solution.

 Because of low efficiency of mixing devices, paraffin film practically not removed.

 In addition, there is a coagulation of aluminum particles, which leads to the local concentration of gas in the products, the appearance of voids and cracks. Because of shortage of gas emission in the case of gas silicate production is necessary to introduce up to 25% of lime into the mixture.

 The necessity of additional introduction of a lime into the mixture is specified by requirement to obtain the durability of concrete which allows to keeps it in vesicular condition by the end of gas emission using the hydration cementation.

 Application of AVS-100 unit for preparation of aluminum powder suspension in production of the gas silicate allows avoiding the coagulation of aluminum particles, raises their activity, gas yield and homogeneity of the mixture. At the table 2 you can see some of the comparative data of physicochemical properties of the gas silicate which was made by using the aluminum suspension fabricated by different methods.

 Table 2

Comparative data of physicochemical properties of the gas silicate which was made by using the aluminum suspension fabricated by different methods

 The table shows that usage of treated aluminum suspension by AVS-100 allows to obtaining the gas silicate which has the durability up to 10-30% and quality index up to 20-60% higher in comparison with the control sample (table 2, experiment 1).

 Application of Intensifier of Technological Process gives a possibility to decrease by 10 % gasifier consumption and by 2% lime consumption. At the same time there is no weighting of gasifier. On the contrary, the volume weight of the gas silicate is reduced but its durability is increased. Obviously, the quality of the blown-out concrete can be increased by the treating process by AVS-100 unit in the vortex field of sand-lime mixture or in the sand-cement mixture on purpose of activation of SiO₂ like we do the same in expanded-clay aggregate production.

The silica brick production

 The raw material for the silica brick production is the high-silica sand (92-95% of dry mixture) and the lime (5-8%). Structural capabilities of the brick directly depend from the degree of activation of SiO₂ andmixing uniformity of components.

 According to this fact, application of AVS for the treatment of dry mixture by the reason of mixing and activation of components is of the utmost interest. We have investigated the ways of sand-lime mixture activation by spillage of material through the vortex layer of the unit AVS-100.

 It is interesting to note that, in this short-duration treatment of the mixture (mixture particles locate into the vortex field for a fraction of a second) the grinding of the sand and the lime is not observed. The degree of activation can be determined by the changing of mechanical properties of obtained silica brick.

 Table 3

 As you can see from the table by the short-duration treatment of the mixture you can increase the durability of the silica brick in 3,5 times.

Obviously, similar processing sand-lime, lime-ash and lime-silica mixtures leads to an marked increase of the mechanical properties of silicate concrete, which are widely used in prefabrication.