*The Improvement of the Quality of Construction Foam and Non-Autoclave Foam Concrete… DOI: http://dx.doi.org/10.5772/intechopen.88234*

The stability of the foam was evaluated as the time of extraction (in minutes) of a half of the liquid phase from which the foam was prepared.

Foam stability in the cement paste was evaluated by the coefficient of the foam resistance. Determination of the resistance coefficient was made by mixing equal volumes of cement paste and foam for 1 min followed by measuring the volume of the porous paste. The resistance coefficient of foam in the cement paste is calculated as the ratio of the volume of the porous paste to the sum of the volumes of the cement paste and foam (with water/cement ratio = 0.4).

The results of the studies are shown in **Figures 1**–**4**. From the figures it can be seen that the stability of the foam stabilized with the SiO2 and Fe(OH)3 sols increases up to four times and the foam resistance coefficient in the cement

**Figure 1.** *Stability of the foam stabilized with SiO2 sol.*

**Figure 2.** *Stability of the foam stabilized with Fe(OH)3 sol.*

and other geometric defects. They reduce the quality category of foam concrete

*The expected influence of sols of different nature on the quality of foam, foam concrete, and its products.*

**Type of chemical bond**

Fe — O, Fe — N

**Expected effect**

• The increase of the foam stability rate in the cement paste and preservation of the concrete mix volume • The possibility of additives-electrolyte application • The increase of

compressive and tensile strength of foam concrete • The reduction of thermal conductivity coefficient and shrinkage of foam concrete in drying • The quality category increase of the foam concrete products

H—N • The foam stability increase

To obtain the first quality category is important because in carrying out a brickwork, it allows to place the foam concrete blocks on the construction glue (coefficient of thermal conductivity, λ ≈ 0.3 W/(m∙°C)), and not on the cement mortar λ ≈ 0.3 W/(m∙°C)). The use of construction glue is proved to increase the thermal insulating properties of masonry walls significantly. It is assumed that the stabilized foam and the use of the hardening accelerator will considerably increase

To confirm the stabilizing effect of SiO2 and Fe(OH)3 sols, the stability of the construction foam was investigated depending on the concentration of the dis-

In the study, a protein foaming agent "Foamcem" was used as a foaming agent, on the basis of which a 3% aqueous solution was prepared. In addition, SiO2 sol of the industrial production "SITEC" was used, its characteristics being shown in

Fe(OH)3 sol was obtained by the following method: 5 ml of a 10% solution of iron chloride FeCl3 was slowly poured into boiling water with a volume of 100 ml.

> **Concentration,** *ω*¼*SiO***<sup>2</sup> (%)**

1165 25.6 3.2 120–140

**pН Specific surface area, S (m2**

**/g)**

persed phase of the sols in the solution of the protein foaming agent.

**Table 2**. Also, Fe(OH)3 sol obtained in the laboratory was used.

products to category II (according to GOST 31360-2007).

**System "aqueous solution of protein foaming agent—sol of different nature"**

**complex**

SiO2 sol Silicon-protein complex Hydrogenous

Iron-protein complex Covalent

**Stabilizer Stabilizing**

*Foams - Emerging Technologies*

Fe(OH)3 sol

**Table 1.**

the number of products of the first quality category.

**3. Study of the stabilized foam properties**

**Title Density**

KZ-1 "SITEC"

**Table 2.**

**108**

**(kg/m<sup>3</sup> )**

*Main characteristics of the industrial SiO2 sol.*

Further, in order to determine the possible chemical bonds formed between the

molecules of the protein foaming agent and the injected sols, infrared Fourier spectroscopy of the following model systems was carried out: "aqueous solution of the protein foaming agent" and "aqueous solution of the protein foaming agent—

*The Improvement of the Quality of Construction Foam and Non-Autoclave Foam Concrete…*

From spectrum No. 2, **Figure 5**, the shift and broadening of the band in the region of 3311 cm<sup>1</sup> corresponding to the valence vibrations of the hydroxide (OH) groups in comparison with spectrum No. 1 are seen. This effect can characterize the occurring hydrogen bonds between the nitrogen atom in the protein and hydrogen of the OH group of SiO2 sol with the formation of a silicon-protein

In both spectra (**Figure 6**) the bands in the region of adsorption 1630–1510 cm<sup>1</sup> correspond to the deformation vibrations of the carbonyl group С=O of protein. The shift and broadening of this line can be observed on spectrum No. 1, which may correspond to the formation of a covalent bond of iron ion (III) with oxygen of the amide group in the composition of the iron-protein complex formed, as shown in **Figure 7b**. The region of 1150 cm<sup>1</sup> corresponds to the deformation vibrations of the NH▬C=O group, the shift and broadening of this band on spectrum No. 1 indicate a possible covalent bond of the iron ion (III) with nitrogen in the composi-

Thus, it can be concluded that the decoding of IR spectra of foaming agent solutions stabilized with various sols confirms the assumption expressed in **Table 1**

0 0.306 0.610 3013

52.9 0.8 52.9 0.8 53.2 1.2 52.1 1.1

*IR spectra: No. 1, the system "aqueous solution of the protein foaming agent." No. 2, the system "aqueous solution*

tion of the iron-protein complex formed, as shown in **Figure 7b**.

Concentration of the dispersed phase of the sol in the

The surface tension coefficient of the foaming agent

*\*The value of the surface tension coefficient at the ambient temperature of 21°C.*

*Values of the surface tension coefficient of foaming agent solution stabilized with SiO2 sol.*

)

foaming agent solution (%)

, 10<sup>3</sup> (J/m<sup>2</sup>

solution, σ\*

**Table 3.**

the injected sol" (**Figures 5** and **6**).

*DOI: http://dx.doi.org/10.5772/intechopen.88234*

complex, as shown in **Figure 7a**.

**Figure 5.**

**111**

*of the protein foaming agent—SiO2 sol."*

**Figure 3.** *The coefficient of resistance of the foam stabilized with SiO2 sol in the cement paste.*

**Figure 4.** *The coefficient of resistance of the foam stabilized with Fe(OH)3 sol in the cement paste.*

paste increases from 0.9 up to 0.98. These results agree with the forecast as shown in **Table 1**.

Further, in order to clarify the stabilizing mechanism, the surface tension of the foaming agent solution was measured at different concentrations of the dispersed phase of SiO2 sol, as shown in **Table 3** [10]. The table shows that with increasing the sol concentration, the surface tension practically does not change.

Further, the foam multiplicity (frequency rate) when introducing of SiO2 and Fe (OH)3 sols into the solution of the foaming agent was investigated. The foam multiplicity was determined by the ratio of the foam volume (l) to the foam solution volume (l). It was found that the multiplicity of the foam on the sol basis does not change, which correlates with the results of measuring the surface tension of the modified foam solutions. The value of the foam multiplicity was 13.

*The Improvement of the Quality of Construction Foam and Non-Autoclave Foam Concrete… DOI: http://dx.doi.org/10.5772/intechopen.88234*

Further, in order to determine the possible chemical bonds formed between the molecules of the protein foaming agent and the injected sols, infrared Fourier spectroscopy of the following model systems was carried out: "aqueous solution of the protein foaming agent" and "aqueous solution of the protein foaming agent the injected sol" (**Figures 5** and **6**).

From spectrum No. 2, **Figure 5**, the shift and broadening of the band in the region of 3311 cm<sup>1</sup> corresponding to the valence vibrations of the hydroxide (OH) groups in comparison with spectrum No. 1 are seen. This effect can characterize the occurring hydrogen bonds between the nitrogen atom in the protein and hydrogen of the OH group of SiO2 sol with the formation of a silicon-protein complex, as shown in **Figure 7a**.

In both spectra (**Figure 6**) the bands in the region of adsorption 1630–1510 cm<sup>1</sup> correspond to the deformation vibrations of the carbonyl group С=O of protein. The shift and broadening of this line can be observed on spectrum No. 1, which may correspond to the formation of a covalent bond of iron ion (III) with oxygen of the amide group in the composition of the iron-protein complex formed, as shown in **Figure 7b**. The region of 1150 cm<sup>1</sup> corresponds to the deformation vibrations of the NH▬C=O group, the shift and broadening of this band on spectrum No. 1 indicate a possible covalent bond of the iron ion (III) with nitrogen in the composition of the iron-protein complex formed, as shown in **Figure 7b**.

Thus, it can be concluded that the decoding of IR spectra of foaming agent solutions stabilized with various sols confirms the assumption expressed in **Table 1**


### **Table 3.**

*Values of the surface tension coefficient of foaming agent solution stabilized with SiO2 sol.*

### **Figure 5.**

*IR spectra: No. 1, the system "aqueous solution of the protein foaming agent." No. 2, the system "aqueous solution of the protein foaming agent—SiO2 sol."*

paste increases from 0.9 up to 0.98. These results agree with the forecast as

(OH)3 sols into the solution of the foaming agent was investigated. The foam multiplicity was determined by the ratio of the foam volume (l) to the foam solution volume (l). It was found that the multiplicity of the foam on the sol basis does not change, which correlates with the results of measuring the surface tension

of the modified foam solutions. The value of the foam multiplicity was 13.

sol concentration, the surface tension practically does not change.

*The coefficient of resistance of the foam stabilized with Fe(OH)3 sol in the cement paste.*

*The coefficient of resistance of the foam stabilized with SiO2 sol in the cement paste.*

Further, in order to clarify the stabilizing mechanism, the surface tension of the foaming agent solution was measured at different concentrations of the dispersed phase of SiO2 sol, as shown in **Table 3** [10]. The table shows that with increasing the

Further, the foam multiplicity (frequency rate) when introducing of SiO2 and Fe

shown in **Table 1**.

**Figure 4.**

**110**

**Figure 3.**

*Foams - Emerging Technologies*

which results in the increase of the foam stability. For this purpose, electron microscopy of samples of the foam concrete with medium density D600 was carried out: a control sample and a sample prepared on the basis of the foam stabilized

*The Improvement of the Quality of Construction Foam and Non-Autoclave Foam Concrete…*

**4. Research of the foam concrete properties of various average**

Further the possibility of receiving heat-insulating non-autoclaved foam concrete of average density D200 on the basis of the foam stabilized with SiO2 sol

For light thermal insulating non-autoclaved foam concrete, one of the significant problems is the reduction of the volume of the foam concrete mixture because of the mixture destruction, which results in the deviation from the projected average density and uneven structure of the material and exerts a negative influence on the

It was assumed that a more stable foam will allow to avoid the destruction of the

The composition of the foam concrete with medium density D200 is shown in **Table 4**. Portland cement CEM 42.5 was used as a binder, dolomitized limestone was used as a filler, protein foaming agent "Foamcem" was used as a foaming agent, and SiO2 sol of industrial production was used as a stabilizer (SITEC company). To assess the stability of the foam concrete mixture, the volume instability of the foam concrete (mm) was measured at different contents of the dispersed phase of the sol in the foam. Volume instability was measured after 24 hours of the foam concrete hardening (**Figure 9**). From the figure it is seen that the use of the stabilized foam reduces the volume instability up to 0 when the concentration of the dispersed phase of sol in the foam is at least 0.2%. The coefficient of thermal conductivity of foam concrete of average density D200 at the design age was

mixture, to provide the necessary density of the foam concrete, and to obtain a

Further the physical-technical and thermal insulating properties of foam concrete and its products after the introduction of the stabilized foam into its

are shown in **Table 5**. During the preparation of foam concrete mixtures, 3% aqueous solution of foam on a protein basis stabilized with different sols was used.

the electrolyte additives to activate the hardening of cement and to obtain the improved physical and mechanical characteristics of foam concrete and its products. In the case of using a conventional foam solution, such additives destroy the

125 45 102 2.52 0.3

*Consumption of the materials for 1 m<sup>3</sup> of foam concrete of average density D200.*

The samples were being solidified under normal conditions for 28 days.

The compositions of the foam concrete mixtures of different average densities

During the experiment it was expected that a more stable foam will allow to use

**Cement (kg) Filler (kg) Water (l) Foaming agent (l) Stabilizer (SiO2 sol) (kg)**

in foam stability as well as confirm the assumptions made.

**densities on the basis of the stabilized foam**

properties of thermal insulating foam concrete.

λ = 0.04 W/(m∙°C); for comparison, λair = 0.029 W/(m∙°C).

reduced thermal conductivity coefficient.

composition were evaluated.

**Table 4.**

**113**

From the pictures it can be seen that the thickness of the foam film in the control sample is 450 nm and in the sample based on the stabilized foam is 3.5 μm, i.e., increase by one order. This result can explain the stabilizing effect and the increase

with the SiO2 sol (**Figure 8**).

*DOI: http://dx.doi.org/10.5772/intechopen.88234*

was investigated.

### **Figure 6.**

*IR spectra: No. 1, the system "aqueous solution of the protein foaming agent—Fe(OH)3 sol." No. 2, the system "aqueous solution of the protein foaming agent."*

**Figure 7.**

*Spatial stabilizing complexes formed by the introduction of various sols into the solution of protein foaming agent: (a) silicon-protein complex and (b) iron-protein complex.*

### **Figure 8.**

*Electron microscopy of the foam concrete samples of the medium density D600: (a) control sample and (b) sample based on foam stabilized with SiO2 sol.*

concerning the formation of hydrogenous and covalent chemical bonds in the composition of the stabilizing silicon- and iron-protein complexes.

Further, it was assumed that the appearance of chemical bonds and spatial stabilizing complexes should increase the thickness and strength of the foam film, *The Improvement of the Quality of Construction Foam and Non-Autoclave Foam Concrete… DOI: http://dx.doi.org/10.5772/intechopen.88234*

which results in the increase of the foam stability. For this purpose, electron microscopy of samples of the foam concrete with medium density D600 was carried out: a control sample and a sample prepared on the basis of the foam stabilized with the SiO2 sol (**Figure 8**).

From the pictures it can be seen that the thickness of the foam film in the control sample is 450 nm and in the sample based on the stabilized foam is 3.5 μm, i.e., increase by one order. This result can explain the stabilizing effect and the increase in foam stability as well as confirm the assumptions made.
