RU2774975C1 - Method for preparation of dry raw mixture for foam gypsum - Google Patents

Abstract

FIELD: construction materials.

SUBSTANCE: invention relates to construction materials, namely to a method for preparing a dry raw material mixture for foam gypsum, widely used as sound-insulating and heat-insulating floors, for filling multilayer enclosing structures during thermal insulation work in the conditions of a construction site. The method for preparing a dry raw mixture for foam gypsum includes the preparation of a dry foaming agent by mixing in a mixer for 3-4 minutes of the liquid foaming agent PBNS with a sorbent: the waste of crushing expanded clay sand of grain composition 0.315-1.25 mm at a ratio, wt. %: 1:12, followed by mixing for 2-3 minutes of the resulting dry foaming agent with a binder: semi-aqueous construction gypsum, grade G5B-II, with the following ratio of components, wt. %: PBNS foaming agent : specified expanded clay sand crushing waste : specified gypsum - 1:12:93. The invention is developed in the dependent clause of the formula.

EFFECT: development of the composition of a dry mixture of long-term storage, obtaining a stable, homogeneous and durable foam gypsum.

1 cl, 1 dwg, 7 tbl

Description

One of the main tasks of the modern building materials industry is the production of effective modern materials made using simplified technology or those that save expensive raw materials. These mixtures could be widely used as soundproof and heat-insulating floors, in foam-gypsum manufacturing technology, as well as for filling multilayer enclosing structures during heat-insulating work at a construction site.

Known foaming agent for the manufacture of porous products (US Pat. RF No. 2203868, C04V38/10, published 10.05.2003), which is obtained by the following method. Prepare an aqueous solution of alkali of the required concentration. A 2% NaOH solution is introduced into the pre-dosed and heated pitch with constant stirring. The amount of pitch in the emulsion is 10%. The process proceeds at a temperature of 70-80 ^about C until a homogeneous emulsion is obtained. The resulting emulsion is mixed with liquid glass. The foam is prepared by direct bubbling of a foaming agent heated to a temperature ^of 35-40 ° C.

The disadvantage of analogue is that liquid foaming agents make it difficult to accurately dose the components, which causes great difficulties in production and instability of the properties of the foam-gypsum mixture.

A known method for the manufacture of gypsum foam products, a composition for the manufacture of gypsum foam products (US Pat. No. 2099305, C04V28/00, pub. 20.12.1997). The method consists in the fact that when preparing foam in a foam generator from a mixture of a surfactant with water and a thickener, the thickener is pre-mixed with a polymer binder, and a polymer binder hardener and a gypsum hardening accelerator are additionally added to the foam generator as additives. The foam is whipped up to a factor of 8-9, stabilized with a mixture of a polymeric binder with a thickener, mixed with gypsum. Products are subjected to two-stage drying. At the first stage, the temperature is raised ^to 60-80 ° C for at least 4 hours and the product is kept for 6-8 hours, and at the second stage, the coolant temperature is raised ^to 80-100 ° C for at least 3 hours and the product is kept in within 4-6 hours.

The disadvantage of this method is: a complex manufacturing process (several stages); the need for drying (there is an increase in the cost of the final product); lengthy acquisition process.

The closest to the proposed method for preparing a dry raw mix for foam gypsum is a method for preparing a dry raw mix for foam concrete, including dosing and mixing Portland cement and a blowing agent obtained by the method of preparing a dry fine foam concentrate (US Pat. RF No. 2342347, IPC S04V38 / 10, pub. 27.12. 2008), with the following ratio of components, wt.h: Portland cement 250-400, foam concentrate 1.1-5.0, water-absorbing additive 3.0-22.0. The method consists in mixing the foam concentrate with a water-absorbing additive, which is used as quicklime or its mixture with silica or semi-aqueous gypsum, or the Penetron Admix waterproofing additive at a ratio of the indicated concentrate and additive 1: 1-8, the resulting mixture is kept until complete hydration reactions.

The disadvantage of this method is the need for additional grinding of the foaming agent, which leads to an increase in the cost of the components, a complex process of mechanical activation (additional processing of the material, additional equipment is required).

The objective of the invention is to develop a dry raw mix with a long-term storage foaming agent for the preparation of foam gypsum, which would improve the manufacturability of its preparation, ensure accurate dosing of the initial components of foam gypsum.

The technical result of the invention is to obtain stable properties, homogeneous and durable gypsum foam.

The technical problem is solved in a method for preparing a dry raw mix for gypsum foam, including preliminary preparation of a dry foam concentrate, dosing and mixing of a dry foam concentrate with a binder, while a dry foam concentrate is obtained by mixing in a mixer for 3-4 minutes a liquid foam concentrate PBNS with a sorbent - waste from crushing expanded clay sand grain composition 0.315 - 1.25 mm at a ratio in wt.h: 1:12, followed by mixing for 2-3 minutes of the resulting dry foam concentrate with a binder - semi-aqueous building gypsum grade G5B-II, with the following ratio of components in wt.h : foaming agent PBNS: specified waste of expanded clay sand crushing : specified gypsum - 1:12:93.

In addition, additionally, basalt fiber 6 mm long is introduced into the resulting dry raw mix in an amount of 1.5 - 2.0%.

The method of preparing a dry foaming agent is solved by physical and chemical (sorption) - by mixing with a powdered or granular porous sorbent. The first step is to obtain a "dry" foam concentrate. To do this, we dose the waste of crushing expanded clay sand into the mixer and proportionally feed the liquid foaming agent, while mixing. Stirring for 3-4 minutes is sufficient for adsorption and uniform distribution. Further, gypsum binder is dosed onto the obtained composition of the “dry” foaming agent. The mixture is stirred for 2-3 minutes.

The whole cycle takes approximately 12-15 minutes, depending on the volume of the mixer.

After mixing and obtaining a homogeneous structure, the dry gypsum mixture is packed into valve bags of 20-35 kg, depending on the type of bags chosen.

For a functional additive, sorbents (light aggregates) for gypsum materials were used, common heat-insulating fillers - perlite, vermiculite and expanded clay sand:

1. Expanded vermiculite produced by Alternativa LLC. Bulk bulk weight 150 kg/m ³ and fraction 2.0 mm. Physical and mechanical parameters are shown in table 1.

2. Expanded perlite sand grade VPM M75 GOST 10832-2009 produced by Alternativa LLC. The main physical and mechanical indicators are presented in table 1, and the chemical composition is presented in table 3.

3. Waste from crushing expanded clay sand (KP) produced by Ufa Gypsum Company LLC, grade M350, M400 in terms of bulk density, corresponding to GOST 32496-2013.

Table 1

Item No. Indicators Characteristics of various types of sorbents Vermiculite Perlite Crushing waste KP one Volumetric bulk weight in kg / m ³ 150 75 350-400 2 Thermal conductivity coefficient, W/(m °С) 0.055 0.043 0.14 3 Humidity, % 3 2 0.5 four Grain composition, mm 0.71-4 0.1-1.25 0.315-1.25

The chemical composition of the sorbents is shown in Table 2.

table 2

No. p / p Material The content of oxides, wt.%: _{SiO2 Al2O3 _ Fe2O3 _} CaO MgO SO _{3 K2O N2O} FeO _TiO2 p.p.p. one Expanded clay
sand 64.08 14.36 6.42 1.87 1.84 0.57 1.92 1.04 0.19 0.89 5.89 2 Perlite 73.2 13.1 1.0 0.7 0.3 - 4.1 3.8 - - 3.5 3 Vermiculite 38.0 15.1 5.6 1.2 22.1 - 5.6 0.3 1.1 1.5 6.2

As a synthetic foaming agent used: foaming agent PBNS - an aqueous solution of anionic surfactants with stabilizing additives TU 2481-002-31232365-2006. Foaming agent synthetic, hydrocarbon, biodegradable, designed to obtain stable low expansion foam. Manufactured by OOO Zavod TechnoKhimSintez. The physical and mechanical properties of the foaming agent PBNS are presented in Table 3.

Table 3

Name of indicator Characteristics Appearance 20-25°C Clear liquid without sediment Density at 20°С, kg/m ³ 1000-1200 Hydrogen index (pH), within 6.5-8.5 Pour point, °С -3 The ratio of the foam of the working solution with a volume fraction of 4%, not less than 5 (lab method) Foam stability, s, not less 300

Semi-aqueous building gypsum grade G5B-II produced by Ufa Gypsum Company LLC, produced in accordance with GOST 125-79, was used for the study. Physical and mechanical properties of the gypsum binder are shown in Table 4.

Table 4

No. Index unit of measurement Meaning one Grinding fineness, sieve residue % 5-6 2 Normal Density % 61 Setting time
-Start
-the end min 6
ten four Bending strength:
-In 2 hours
- dried to constant weight MPa 2.5
5.2 5 Compressive strength:
- In 2 hours
- dried to constant weight MPa 5.3
13.5

For mixing, a laboratory stirrer was used at high speeds of 1200-1300 rpm. The water-gypsum ratio in all formulations was 1.0. The properties of gypsum foam obtained from “dry” PO with different ratios of “liquid” PO and sorbent are presented in Table 5. For example, if the ratio of PO : Sorbent is 1:6, then with gypsum it will be PO : Sorbent : Gypsum 1:6:93.

Table 5

composition number Name of the sorbent Ratio PO:Sorbent The resulting volume of gypsum foam from 1 kg of dry mix Density, kg/m³ Strength, MPa one Perlite 1:6 2.7 390-410 0.31-0.39 2 Perlite 1:12 3.1 340-365 0.24-0.34 3 Perlite 2:3 3.4 301-335 0.11-0.12 four Vermiculite 1:6 2.8 380-410 0.34-0.43 5 Vermiculite 1:12 2.5 435-451 0.45-0.51 6 Vermiculite 2:6 3.2 330-350 0.21-0.26 7 Crushing waste KP 1:6 3.15 350 0.25 eight Crushing waste KP 1:12 3.6 250 0.09 9 Crushing waste KP 2:6 3.6 285-320 0.09-0.13

Based on the data obtained in Table 5, depending on the types of sorbent and foaming agent, the optimal ratio of components was revealed - composition No. 8 1:12 using waste from crushing expanded clay sand.

To determine the effectiveness of the obtained "dry" PO, the effect of liquid and dry PO on the foam-gypsum mixture was studied. In composition No. 8, a foaming agent was introduced in two ways. First, PO was added to water in a liquid way and then mixed. And the second way, into a dry mix with a certain sequence. Figure 1 shows the results of the dependence of density on the amount of injected foaming agent, where position 1 is with a liquid foaming agent, and position 2 is with a dry foaming agent. Water-gypsum ratio was taken for all compositions of 1.0.

Based on the data obtained, it can be seen that the increase in the amount of foaming agent is more than 1 wt.h. not advisable, since already 1.5 wt.h. there is an increase in the density of the resulting gypsum foam.

To increase the strength, glass and basalt fiber produced by TPK Composite Materials LLC, 6 and 12 mm long, was added to the dry mix for gypsum foam. Physical and mechanical characteristics of glass and basalt fiber are presented in table 6.

Table 6

Characteristics Fiber name Fiberglass Basalt Fiber diameter, µm 2-20 7-23 Breaking load, MPa 1400-3450 2900-4150 Elongation at break, % 4.8 3.3 Operating temperature range, ^o C -60 to +460 -260 to +600 Resistance in acid/alkaline environments degrades sustainable Corrosion resistance Persistent Persistent Electrical conductivity Dielectric Dielectric Open flame resistance Combustion fire resistance

Table 7

No. Name of fiber type Amount of fiber, % Physical and mechanical indicators Density, kg / m ³ Strength, MPa The amount of foam gypsum obtained After pouring dry one Glass fiber, 6mm 0.1 650; 575; 678 380; 340; 405 0.18; 0.11; 0.17 2.8 2 0.3 3 0.5 508; 502; 478 325; 325; 310 0.17; 0.13; 0.17 3.5 four Glass fiber, 12 mm 0.1 2.8 5 0.3 569; 527; 552 355; 315; 325 0.16; 0.16; 0.16 3.3 6 0.5 499; 535; 473 315; 345; 300 0.18; 0.19; 0.13 3.5 7 Basalt fiber, 6 0.1 610; 668; 631 360; 400; 380 0.14; 0.19; 0.15 3.1 eight 0.3 9 0.5 683; 529 335; 340 0.1; 0.11 3.6 ten 1.5 369 230-245 0.05 3.375 eleven 2.0 390-410 220-230 0.1 4.3 12 3.0 Does not mix 13 Basalt fiber, 12 mm 0.1 507; 548; 565 310; 325, 350 0.09; 0.1; 0.12 3.3 fourteen 0.3 548; 616; 528 325; 370; 320 0.11; 0.16; 0.11 3.3 fifteen 0.5 539; 541; 505 325; 330; 305 0.11; 0.13; 0.09 3.5

Based on the results of table No. 7, we can conclude that the most optimal option is No. 10 and No. 11 with basalt fiber, in an amount of 1.5-2.0%. And if we compare the strength, density and volume of the resulting foam gypsum, then lineup #11 is the best lineup.

On the basis of the obtained dry mix (SSPG) gypsum foam has the following characteristics: density 220 - 350 kg/m ³ , strength 0.01 - 0.3 MPa and thermal conductivity 0.075 - 0.11 W/(mK).

Based on the data obtained, it can be concluded that the use of a dry foaming agent shows very good foaming results. The dry foam concentrate mixes better in the dry mix and spreads evenly. With the same amounts, the foaming agent in the "dry" form showed the best result. It can be argued that the use of expanded clay sand crushing waste for foaming agent absorption is the best option.

Claims (2)

1. A method for preparing a dry raw mix for foam gypsum, including preliminary preparation of a dry foam concentrate, dosing and mixing of a dry foam concentrate with a binder, characterized in that a dry foam concentrate is obtained by mixing in a mixer for 3-4 minutes a liquid foam concentrate PBNS with a sorbent - waste from crushing expanded clay sand grain composition 0.315-1.25 mm at a ratio, wt.h: 1:12, followed by mixing for 2-3 minutes of the obtained dry foam concentrate with a binder - semi-aqueous building gypsum grade G5B-II, with the following ratio of components, wt.h : foaming agent PBNS : specified waste of expanded clay sand crushing : specified gypsum - 1:12:93. 2. A method for preparing a dry raw mix for foam gypsum according to claim 1, characterized in that basalt fiber 6 mm long is additionally introduced into the resulting dry raw mix in an amount of 1.5-2.0%.

Images