2. Preparation of foaming agent pussy

To prepare the blowing agent used pussy casein glue, resin and water, and sometimes, in order to regulate the rigidity and stability of the foam, the foaming agent is introduced into the lime and the PRS.

Foam pussy prepared in a vertical blade mixer at 10-20 minutes. In a continuously operating mixer poured heated to a temperature of 30-35 ° C water and then pour casein powder glue and stirring was continued until complete dissolution of glue. Consumption of glue of 10 g per 1 liter of water. After complete dissolution of the adhesive is introduced into the mixer rosin milled, sieved with a sieve-up responses tures, 0.5 mm in an amount of 10 g per 1 liter of water and stirring was continued for 20-25 minutes. After the foaming agent is considered ready to perform these operations.

For foamer working solution is diluted with water in a ratio of 1: 9 (by volume). whipping the foam from the solution to produce a frequency penovzbivatele rotation shaft 250-300 min.

For a rigid foam of the foaming agent components when preparing hydrated lime is introduced at the rate of 1 liter of water of 18 g lime. The introduction of a small amount of foaming an aqueous solution of sulfite-alcohol stillage with a density of 1.04 Lena resistance increases.

3. Preparation of the aqueous suspension of aluminum

In order to activate the aluminum powder and better mixing with its processing solution produce surfactants. Uncalcined aluminum powder PAC-3 and PAC-4 is mixed with a solution of the PRS, rosin soaps, etc.

Mixing is carried out in the following order. The flask was 10.7 L (with laboratory studies 0.5-1 liters) cautiously pour the required amount of powder is then poured into a solution of surfactant in an amount of 5% (based on dry substance) on the amount of aluminum powder and 1.3 l (in laboratory studies 0.3-0.5 liters) of water. After thorough mixing for 2-4 minutes, when all the powder particles are wetted by the solution suspension is considered finished.

Selection of the composition of the heat-insulating cellular concrete products produced for a given average density and strength in the smallest possible consumption of binder and blowing agents.

Initial data for selection are given the average density of the samples in the dry state and their cube compressive strength, as well as the type of blowing agent and raw materials.

For aerated concrete with specified performance characteristics empirically establish vodotverdoe ratio (A / F), a blowing agent flow rate and the proportion between the component and the silica binder (Pk: Rvyazh = C).

To test mixtures cellular concrete relationship between the component and the silica binder taken from Table 2.

Table 2 - Correlation between the component and the silica binder to test batches of cellular concrete

Kind of cellular concrete	Meaning С
	1	2	3	4	5
Autoclave activity using 70% lime	2,4	2,7	3,0*	3,3	3,6
Same with PC or lime-slag cement	0,75	1,0+	1,25	1,5	1,75
Same as with the use of mixed cement binder or nepheline	1,0	1,25	1,5*	1,75	2,0
Neavtoklavnogo using PC or mixed binder	0,5	0,75*	1,0	1,25	1,5

Remarks:

1. The values ​​of C marked with * is taken as the baseline.

2. A lime with activity% With options are multiplying tabular data by an amount A / 70.

 3. The initial proportion of lime (n) in the mixed cement-lime binding material to make autoclaved concrete is equal to 50%, and for neavtoklavnyh - 25%.

The selection of the cellular concrete structure consists of the following steps:

1) determination of the source vodotverdogo ratio (A / F);

2) calculation of the flow of materials for one batch of parent stock;

3) Preparation of test mixtures and samples molding;

4) steam curing the samples for a given mode;

5) testing of samples and the calculation of the final composition of cellular concrete.

For initial A / F take such values ​​that correspond to yield a solution, given in Table 3.

The fluidity of the solution is determined by its face breaking (in cm) using a device Suttarda which consists of copper or brass of a hollow cylinder with an inside diameter of 5 cm and a height of 10 cm, the glass sheet square shape with a side of 45 cm and a sheet of paper with deposited thereon concentric circles every 0.5 or 1 cm, which during the experiment placed under glass.

Table 3 - The values ​​of fluidity solution

The average density of aerated concrete in the dry state, kg / m3	Foam on the cement, lime, mixed binder	Aerated on
		HRC and mixed binder	exhaust	nepheline cement	Lime-slag cement
400	34	34	25	42	26
500	30	30	23	38	24
600	26	26	21	32	22
700	24	22	19	26	20
900	20	15	15	18	14

Note. The temperature of the aerated solution should be in the range from 37 to 43 ° C for gaseous silicate - from 30 to 45 ° C for foam - from 20 to 40 ° C.

Before the test, the cylinder and the glass with a soft cloth dampened with clean water. Glass is placed in a strictly horizontal position and give it the cylinder so that the outer contour of the cylinder coincides with a circle with a diameter of 6 cm. The test solution is poured into a cylinder the brim and leveled surface with a knife or trowel mortar. Then the rapid and precise movement upward lift cylinder; solution thus spread on a glass pellet having a diameter determined by the consistency of the mixture.

To prepare the solution requires 0.4 kg of dry mix (original composition) and 0,16-0,28 l of water.

Mixing water for aerated preheated to a temperature of 70-80 ° C. The dry mixture is placed into a cup and the water is poured thereto in portions to obtain a creamy mass of well mixed.

B / T as a mixing weight ratio of water to dry mass of the mixture taken as the original, if the fluidity of the resulting solution deviates from the data in Table 1 is not more than ± 1 cm.

Calculation of material consumption per 1 batch of the original composition. Consumption of mineral components of cellular water mixture (in kg) for one batch is determined by the following formulas:

Binder: vyazh P = (ρ dry / Kc (1 + C)) * V

Lime: Ri = n Rvyazh

Cement: DC = Rvyazh - Rea

Silica component: Pk = Rvyazh C

Ground gypsum dihydrate: Pr = Ri * 0.03

Water: The = (Fk Rvyazh +) V / T

Where:

р_suh - given the average density of aerated concrete in the dry state, kg / l;

K_с - magnification weight of the dry mixture by curing the binder;

V - volume of the batch, L, equal to the volume of forms to be filled from the same batch, multiplied by a factor of excess mixture, taken equal to 1.05 for the foam and 1.1-1.15 for aerated concrete (the manufacture laborator¬nyh samples in excess of the mixture ratio both cases, take not less than 1.5);

C - the number of parts of the silica component per 1 part of binder;

n - the proportion of lime in the binder;

W / S – W/S attitude.

When calculating the flow blowing agent (foaming agent or a blowing agent) are pre-porosity value, which must be created blowing agent to obtain the desired average density of aerated concrete

where: W - the specific volume of the dry mixture, l/kg.

Number of blowing or foam theory should be such that the selected volume of gas or foam injected volume corresponded to the porosity found by the formula.

In fact, the blowing agent is not fully utilized pas creating porosity in the solution, so the flow rate (Pn) take more than theoretically necessary:

where: K - yield pores (amount of gas or foam volume produced from 1 kg of a blowing agent), l / kg;

and - the utilization rate blowing agent.

The initial value of K_c, W, K and α are taking the following: K_c = 1.1; α = 0,85; K = 18-20 l / kg using a foaming agent, and K = 1390 l / kg using aluminum powder; W - in the table 4 depending on the type of silica component, binder type and ratio.

Table 4 - Type of silica component, binder type and ratio

Type silica component	Type of binder
	PC		mixed binder (C: D = 1: 1), nepheline cement		lime		lime-slag cement
	C	W	C	W	C	W	C	W
Sand (ρ = 2,65)	1	0,34	1,5	0,36	3	0,38	1	0,32
Ash (ρ = 2,36)	1	0,38	1,5	0,40	3	0,40	1	0,36
Light ash (ρ = 2,0)	1	0,44	1,5	0,48	3	0,48	1	0,42

Aluminum powder introduced into the solution as vodnoalyuminievoy suspension. For behold preparation to 1 wt. h. The aluminum powder is consumed 0.05 wt. h. The dry surfactant (rosin soap, CC, or PRS al.) and 10-15 wt. h. Water. This water is taken into account in the total amount of mixing water.

In terms of quality foam must satisfy the following requirements: Exit long (K) is not less than 15; resistance, characterized by the use factor of the foam is not lower than 0.8.

To obtain the required quality foam empirically determine the ratio of "Water: a foaming agent" (by volume). The initial value of this ratio for different blowing agents are: SS ​​- 8 KK - 5, the foaming agent pussy - 9. Limits of changing the ratio of "Water: a foaming agent" are: for KK ± 1, ± 2 for others.

Exit then is determined from the foaming agent to foam volume ratio to its weight. The foam volume is measured in the hollow cylinder of diameter 7.5 cm and a height of 10-15 cm.

The output then using aluminum powder set by calculation:

2А1 + 3Са(ОН)₂ + 6Н₂О → 3СаО • А1₂О₃ • 6Н₂О + 3Н₂↑

From this it follows that the reaction of aluminum with 54 g lime 6 g of hydrogen released. One mole of gas occupies the volume under normal conditions of 22.4 liters therefore 1 g of aluminum highlights, under normal conditions:

3*22,4 / 54 = 1,244 l hydrogen

When the mixture temperature t, ° C, the amount of hydrogen released by 1 g of aluminum is calculated on Gay-Lussac's Law:

К = 1,244 (1 + t / 273) L / g

Preparation of mixtures and molding samples

After calculating the initial composition proceed to the preparation of batches in order to identify the optimum B / T. For this purpose, five batches prepared from the starting composition, differing from each other A / F and at ± 0,02 ± 0,04. From each batch formed three samples.

In these and subsequent solution team fights determined density (pp kg / l) controlling the temperature thereof (in the manufacture of aerated concrete), and determine the average density of the honeycomb mixture (convent, kg / l). According to the obtained values ​​pp and convent in each kneading calculate the actual value of the porosity created by the blowing agent:

П_г = (Р_р - Р_п) / Р_ц

where: RP - consumption of blowing agent to 1 liter of cellular concrete (aerated concrete for this value can be neglected), kg.

Water solid composition ratio having no rainfall after porization and showed the highest value Pg is taken as optimal.

To identify the optimal temperature of the solution (aerated concrete composition in the selection) prepared five mixtures with optimum A / F, changing the temperature of the solution within ± 3 and ± 7 ° C of the initial (40 ° C).

The optimum ratio between the silica component and the binder are changes in the number C, preparing five batches with optimal values ​​of A / F and the temperature of the solution.

Consumption blowing agent for these mixtures specify by multiplying the calculated rate it (initial value α and K), the correction factor K, calculated from the ratio of the desired porosity (GHG) emissions to the porosity, actually resulting in mixing, at which made optimum V / T and the optimal temperature .

From each batch of samples 3-6 is formed or the size 7h7h7 10h10h10sm. Before spinning the samples must be well cleaned and greased mold, and the molding of gas-concrete samples also heat up to a temperature of 40-45 ° C..

The degree of filling of gas concrete mixture forms set calculation by weight or by volume. In the first case, determine the mass of gas concrete mixture (MCM), put in the form:

m_cм = 1,1(1-П_г) р_р V_ф

where: V_ф — mold volume, liters.

In the second case the fill height is determined (h) as a fraction or percentage adjustment form h= 1,1(1—Пг).

Foam concrete mixture is prepared in the following manner. In foam mixed laboratory foam concrete mixer poured prepared beforehand aqueous foaming agent solution in an amount of 5-6% of the drum volume foam mixer and include the motor. Foam whipping time is typically less than 5-6 minutes. Then a certain calculation weighed amount of foam and inject it into the solution with continuous stirring, after which finish smooth.

High density penomassy (pn) is determined by weighing it in a container with a capacity of 0.5-1 liters.

Aerated concrete mixture was prepared as follows. First, a slurry of water and aluminum according to the procedure described above. Then, the resulting aqueous suspension is introduced into the aluminum already prepared solution under continuous stirring at that mass-chenie 2-2.5 min.

To determine the average density of gas concrete mixture produced her laying in the pre-prepared vessels cubic shape and capacity of 0.5-1 liters per height, some preliminary calculations.

After closure of blistering after about 1 hour, remove the excess metal ruler the expanded mass (crust), weighed containers with the remaining mass and its average density is calculated.

Steam curing samples of cellular concrete

After molding, the samples aged at 20-25 ° C for 6-8 hours for foam and aerated for 4-6 hours, after which they produce steam curing in a laboratory autoclave or steaming chamber.

Total autoclaving cycle consists of three periods:

I - rise in temperature and pressure;

II - isothermal holding at the maximum temperature and pressure;

III - reduction of pressure to atmospheric pressure.

Recommended modes of autoclave processing of samples:

1) for thermal insulation of cellular concrete density of 500 kg / m³ - 3 + 3 + 8 hours at the maximum vapor pressure of 0.9 MPa and 3 + 6 + 3 h at 1.3 MPa;

2) for thermal-structural concrete with average density 500 kg / cm³ - 6 + 8 + 6 hours at a pressure of 9 MPa and 6 + 6 + 6 at a pressure of 13 MPa.

Steaming mode at atmospheric pressure usually take the following:

- Raising the temperature from 30 to 90 ° C - 3 hours;

- Isothermal hold at 90 ° C - 14 hours and reducing the temperature to 50 ° C - 2 hours.

Test samples and the calculation of the final composition of cellular concrete

After the autoclaving the samples are removed from the forms, dried at a temperature of 105-110 ° C to constant weight and test (determined average density and tensile strength under compression). When tested for strength test pieces measuring 7h7h7 must see the results lead to sample size indicators ribs 10 cm by multiplying the numerical value with the edge strength limit of 7 cm sample by a correction factor, which in this case is equal to 0.9.

The results of the selection of cellular concrete composition is recommended to record the following form:

The desired average density of aerated concrete,кг/м3	The ratio between the silica and binder component	The proportion of lime in the binder	W / S	The solution temperature, 0С	Ρr, Density, kg / m3	Ρy, Density, kg / m3	The actual average density of the cellular concrete, kg / m3	Strength, MPa

The composition of the batch in which the samples showed the greatest strength, but not less than a given, is taken as optimum.

For the calculation of the final consumption of materials per 1 m3 or one batch to obtain the desired average density of aerated concrete must be taken to clarify the calculation of the initial value of K, W, Kc: and α.

Exit holes (K) for the foaming agent found from the ratio of the volume of foam to behold weight, and the yield then blowing did not specify.

Specific volume of dry mixture (W) are at an average density of the solution and vodotverdomu relation:

W = ((1 + W/S) / ρ_p) - W/S

The magnification factor is the dry weight of the mixture due to bound water (Kc) specify the actual values for р_сух и р_ц

Kc = (ρ_суп / ρ_я – m_п) · (1 + W/S)

where: mp - blowing agent consumption in kg per 1 liter of cellular concrete (aerated concrete for this value are neglected).

The utilization of blowing agent (α) are based on actual values Pg, R and V by calculating:

α = (Pg / KPp) · V

Example of calculation of cellular concrete composition

It wanted to get cellular concrete with mixed (cement-lime) binder with an average density of 500 kg / m³ with the greatest possible strength. 1 batch volume - 10 liters.

Raw materials; 500 Portland cement, ground limestone, quicklime activity of 70% fly ash (ore = 2,06g / cm3), a blowing agent - aluminum powder or pussy, surfactant - oil soap, retarding the rate of hydration, quicklime lime - gypsum dihydrate powder.

1. Using the appropriate formula, calculate material consumption for 1 batch with the following initial values: Kc = 1.1; C = 1.5 and n = 0.5.

In Table 3, we find that rasplyv mass (solution flow) must be equal to 30 cm. Empirically establish that such a solution flow takes place at B / T = 0.64.

According to Table 4, we find that when using these materials W = 0,48 l / kg; Aerated for K = 1.39 l / g, and foam for K = 18 l / kg, or 0.018 L / g; α = 0,85.

By setting these values ​​to make calculations of materials consumption:

Binder

Lime Pl = 1,8 • 0,5 = 0,9 kg

Cement Pc = 1.8 - 0.9 = 0.9 kg

Silica component Psk = 1,8 • 1,5 = 2,7 kg

Ground gypsum dihydrate Pg = 0,9 • 0,03 = 0,027 kg

Water W = (1.8 4 - 2.7) ∙0.64= 2.88

Porosity, which must be created with a blowing agent to produce cellular concrete given average density:

Knowing the porosity define steamer consumption: aluminum powder:

oil soap for the preparation of water-aluminum suspension:

Р_м = 4,32*0,05 = 0,22 г;

aqueous solution of foaming (foam) for foam:

2. Prepare five batches with A / F equal to 0.60; 0.62; 0.64; 0.66 and 0.68. Assume that A / F = 0.64 proved to be optimal.

Having prepared five batches with different temperatures, we determine that at 40 ° C was observed maximal swelling mass.

3. In order to establish the optimum relationship between the component and the silica binder prepare five mixtures at W / S = 0.64 and at a solution temperature of 40 ° C, while taking the value of C in the following ranges: 1.0, 1.25; 1.5; 1.75; 2.0.

Assume that the strength after the test samples with composition C = 1.5 showed the greatest strength.

4. When the actual values ​​after appropriate measurements refine magnitude W, Kc and α.

Assume that actual measurements showed kg / l:

The density of the solution р_р = 1 ,45

The average density of gas concrete mixture р_я = 0,775

The average density of foam concrete mix р_и = 0,808

The average density of the concrete in the dry state р_сух = 0,544

Since the aerated concrete has turned harder given, then its members need to make adjustments.

The value of the share (absolute) amount of dry mixture (W) are specified on the actual density of the solution:

In fact, the resulting porosity (GHG) are counting on the actual density of the solution and the average density of the resulting mixture mesh net weight of foaming agent, ie, If the average density of foam concrete mix is equal to 0.808, the weight excluding the adjustable foam-it will equal 0,808-0,333 = 0,775.

- for foam concrete (aerated concrete).

Then refine the utilization rate of blowing agent. Determine α for aerated concrete, for which pre-calculate the actual volume of gas concrete mixture on its mass and average density:

Then use factor of a blowing agent (PAC-3)

Determine α in aerated concrete, pre-calculating the amount of foam concrete mix without taking into account the volume of foam:

We specify the value of the coefficient of bound water

5. According to some Ks values, W, PG and a final settlement of blowing agents consumption.

The required value of the amount of porosity

Consumption of PAC-3 in 1 batch on the specified data

Consumption of the working solution pussy on the specified data

Final data on the composition of cellular concrete is recommended to record the following form:

Name of materials	Material consumption, kg
	1 batch	on 1 м3
Astringent	1,8	180
Lime	0,9	90
HRC	0,9	90
silica component	2,7	270
Ground gypsum dihydrate	0,027	2,7
Water (total)	2,88	288
Gasifier (PAC-3), g	4,75	475
Foam (working solution), kg	0,367	36,7
The surfactant for the preparation of aqueous suspensions of aluminum (P 0.05), g	0,24	24

Control questions

1. How to determine the composition of cellular concrete, depending on the desired properties?

2. How to determine the composition of cellular concrete, depending on the raw materials used?

3. How to determine the composition of cellular concrete, depending on the blowing agents?