Properties Of Foamed Concrete Research Articles

Investigation of Effect of Proposed Two-Stage Foam Injection Method and Modified Additive on Workability of Foam Concrete.

This article presents the results of an investigation of the proposed method and the influence of a modified additive on foam concrete properties. X-ray diffraction analysis showed that the modified additive has a variable mineralogical composition, and the joint use of the components contributes to the synergistic effect, improving the processes of cement hydration. Microscopy of the foam concrete samples showed the presence of microcracks and micropores in samples both with and without the additive. However, the use of the additive significantly reduced their number and size, which indicates an improvement in the structure of the material. The strength values showed that the samples with the additive have high strength. In particular, the strength values of samples of type 3 at different stages of curing exceed those of samples of type 1 by 1.32-1.51 times and samples of type 2 by 1.07-1.10 times. The obtained strength values are 2.82-3.21 MPa for type 1, 3.64-4.04 MPa for type 2, and 4.39-4.84 MPa for type 3, which corresponds to grade D600. The evaluation of water absorption also confirmed the advantages of the proposed method and the additive, significantly reducing the water absorption of the samples and increasing their hydrophobicity. The obtained values of water absorption are 13.8-16.6% for type 1, 13.7-16.1% for type 2, and 9.5-11.2% for type 3.

The surface treatment of PVA fibres to enhance fibre distribution and mechanical properties of foam concrete

Fibres are often used to improve the mechanical properties of foam concrete. However, the poor dispersion of PVA fibres in foam concrete significantly restricts their reinforcement efficiency. Limited studies have been conducted on improving the distribution of PVA fibres in a cementitious matrix, particularly in relation to foam concrete. This is noteworthy because pore structure, which can be significantly influenced by the fibres and fibre treatment agents, is a critical parameter that affects the mechanical properties of foam concrete. Therefore, this study employed polar agents (non-ionic surfactants) to treat the fibre surface, aiming to enhance the distribution and reinforcement efficiency of PVA fibres in foam concrete. In view of safety and feasibility, two non-hazardous polar agents, namely PEG-PPG-PEG (designated as PA A) and Polyoxyethylene (20) cetyl ether (designated as PA B), were used to treat the PVA fibres. The impact of fibre treatments on fibre dispersion and pore structure was investigated, and the compressive strength and flexural behaviour of foam concrete were measured before and after the treatments. PA A was found to be unsuitable for fibre treatment due to its poor bonding with the fibre surface. On the other hand, PA B exhibited good bonding with PVA fibres, resulting in enhanced fibre dispersion and pore structure in the foam concrete. Compared to plain foam concrete, the fibres treated with PA B increased the compressive and flexural strength by 47.4 % and 190.3 %, respectively. Moreover, the treated fibres (by PA B) were observed to improve the 0.8 mm toughness of foam concrete by 27.2 %.

Optimization of waste tyre steel fiber and rubber added foam concretes using Taguchi method and artificial neural networks

This research presents a study on the waste tyre steel (WTS) and rubber particles (RP) added foam concrete using Taguchi method and Artificial neural networks (ANN) by revealing its potential utilization in construction industry. The fresh and hardened characteristics of foam concretes were experimentally tested. Twenty-five different samples were first prepared according to the Taguchi design and compressive and flexural strengths, dry density and thermal conductivity of the samples were optimized. A Quasi-Newton based ANN algorithm was proposed to obtain prediction equations for the flexural and compressive strength of foam concretes. ANOVA analysis was also conducted to determine the most important factors. The results showed that the combined utilization of WTS and RP decreases the harmful effect of RP on the strength properties of foam concretes. Taguchi optimization results were confirmed through validation tests. With the proposed ANN method, R2 values were obtained as 0.9775 for compressive strength, 0.9723 for flexural strength, 0.9654 for dry density and 0.9527 for the thermal conductivity measurements. Both Taguchi and ANN system were found to be suitable for the design and estimation of the responses.

Effect of Mineral Powders on the Properties of Foam Concrete Prepared by Cationic and Anionic Surfactants as Foaming Agents.

Foam concrete is a type of cement mortar in which air bubbles are introduced using an appropriate foaming agent. The complex conditions for the preparation of solid particle stabilized foams limit their wide application in construction. In this study, a method of adding small amounts of calcite (Cal) and muscovite (Mus) to the cement paste matrix is proposed to improve the properties of foam concrete prepared with cationic and anionic surfactants as foaming agents. The effects of mineral powders on the flowability, compressive strength, water absorption, pore characteristics, thermal conductivity and frost resistance of foam concrete were investigated and the enhancement mechanism was revealed by the results of XRD, low-field nuclear magnetic resonance (LF-NMR), Fourier transform infrared spectroscopy (FTIR) and SEM. The results showed that the mineral powders interacted with anionic and cationic surfactants through physical adsorption. Whether anionic or cationic surfactants were used as foaming agents, the addition of mineral powders promoted the formation of shell-like structures around the foam, thus enhancing the performance of foam concrete. As a result, the fluidity, compressive strength and frost resistance of the foam concrete increased, the water absorption and thermal conductivity decreased, and the average size of the pores decreased.

Investigations on the performance of xanthan gum as a foam stabilizer and assessment of economic and environmental impacts of foam concrete production

The properties of foam concrete are greatly influenced by the quality of the foam used. The stability of the foam is a vital property that needs dire attention when selecting surfactant. This paper evaluates the role of Xanthan gum (XG) as an additive in the performance improvement of foam produced with two different surfactants, viz., Hingot (Natural surfactant) and Nonylphenol ethoxylate (NPE) (Synthetic surfactant). Different characteristics of foam and surfactant, such as initial foam density, foam drainage, foam bubble microstructure, surface tension, and viscosity of surfactants, are experimentally evaluated. Addition of XG results in a 10-fold increment in viscosity for both Hingot and NPE surfactant solutions. The above enhancement in viscosity results in a substantial reduction in bubble size and an increment in lamella thickness. Further, the reduced surface tension of Hingot surfactant also contributes to a significant reduction in the rate of bubble coalescence. Having studied the surfactant and foam behaviour, the next phase comprises studies on the influence of XG on consistency, setting behaviour, compressive strength, and thermal conductivity of foam concrete with two different densities, viz., 1000 kg/m3 and 1500 kg/m3. Results show that the addition of XG results in a reduction in consistency and an increase in demoulding time of foam concrete. Besides improvement in foam performance, a substantial increase in compressive strength and reduction in thermal conductivity of FC is also observed due to XG addition, indicating that foam bubble microstructure has a significant impact. The last phase involves the life cycle assessment (LCA) of the FC produced with the aforementioned surfactants, which is the first of its kind study that considers the impact of surfactants across various environmental categories. Results of the LCA analysis show that the total cumulative energy demand of preparation of 1 kg of Hingot solution is less than that of 1 kg of NPE surfactant solution. The environmental impact analysis also favours Hingot as a sustainable and economical alternative to NPE surfactant. Results of LCA analysis of FC indicate that foam concrete with 1000 kg/m3 performs better than AAC block and conventional clay brick. Furthermore, the studies highlighted that there is more scope for improving the performance of LCA of FC through using various mineral admixtures as replacement for cement.

An orthogonal experimental study on the influence of steam-curing on mechanical properties of foam concrete with fly ash

Foam concrete can be widely utilized as precast walls for its low density, excellent heat resistance and sound insulation. The challenge of its application is its low strength due to the porous matrix, which prolongs the demolding time. Steam curing at an early time is a common strategy to improve its early-age strength. Here, an orthogonal experiment (OA16) was adopted to investigate the influence of curing parameters on the properties of foam concrete. Specific compressive strengths (SCS) given as the ratio of the strength and the density at 12 h (12 h) and 28 days (28d) were calculated to evaluate the early-age and long-age strength. The range analysis and the analysis of variance (ANOVA) showed that the optimum steam-curing system that can yield the highest 12 h SCS (1.9 MPa, which meets the demand for demolding) is that preheating temperature of 25 ℃, preheating duration of 4 h, curing temperature of 50 ℃, together with 1.5% early-strength agent Na2SO4. Compared to the normal cured concrete, the addition of mineral power (fly ash by 20%) will successfully increase the early-age strength under steam curing, while XRD, SEM and FTIR analysis all show there are more hydrated products formed after steam curing and the activity of fly ash is activated to form C-S-H gels. However, improving early-age strength too much will lead to a deficiency of later-age strength growth. MIP analysis also exhibited high pore probability in the sample cured under higher steam-curing temperatures. These results can provide experiences for the wide application of foam concrete in precast walls and help improve the efficiency of their template turnover.

About Dynamics of Improving the Foam Concrete Technological and Operational Properties upon Disperse Reinforcement with Polypropylene Fibers

Introduction. The efficiency of the foam concrete products manufacture and application in construction is briefly overviewed. The reasons constraining the nomenclature of the manufactured products are listed. The information about evolvement of the foam concrete disperse fiber-reinforcement technology is provided. The need for scientific research aimed at studying the dynamics of the foam concrete technological and operational properties upon disperse reinforcement with polypropylene fibers is formulated.Materials and Methods. The composition and properties of the materials used for manufacturing the foam concrete mixtures are listed. The methods used for assessing the technological and mechanical properties of the materials under study are indicated.Results. The results of the experimental assessment of the polypropylene fiber length and amount influence on the dynamics of the plastic strengthening growth of the equally dense foam and fiber-reinforced concrete mixtures are presented. The scope of the polypropylene fiber influence on the dynamics of the studied mixtures plastic strengthening is analysed. The scientific substantiation of the reasons accelerating the mass transfer processes during the disperse reinforcement of mixtures with fibers is given. The results of the bending tensile strength tests of the large-size D600 concrete specimens are presented.Discussion and Conclusion. The efficient positive influence of the polypropylene fiber, in correlation with its length, on the following foam concrete properties has been distinguished:speed of phase transfer;ultimate extensibility;elasticity and strength modulus of D600 concrete.

Revealing the impact of isolated pores on the properties of foam cement using hollow microspheres

Since foam concrete inevitably leads to foam bursting and merging during the molding process, the relationship between specific pore connectivity and pore diameter distribution on foam concrete properties is still difficult to characterize exactly. This study intentionally introduced hollow microspheres of three sizes (40 µm, 60 µm, and 80 µm) into foam concrete to control the number and diameter of isolated pores. The influence of isolated porosity and pore diameter distribution on the properties of foam concrete were evaluated by dry density, mechanical property and thermal conductivity. Meanwhile, the SEM and X-CT technologies were employed to assess the pore structure of the sample, and the measured thermal conductivity was compared with the theoretical thermal conductivity calculated by the formula based on the isolated porosity. Finally, the correlation between isolated pores and heat transfer paths were analyzed by the calculated tortuosity. The results of the dry density and mechanical tests indicated that the dry density tended to be lower with the increase of isolated pores’ diameter, which 80 µm hollow microspheres resulted in a notable reduction in the dry density within the three size groups, whereas 28 days compressive strength trended oppositely. The 40 µm hollow microsphere specimen with a dry density of 400 kg/m3 exhibited the better mechanical property among three groups, which was 1.82 MPa, due to the uniform distribution within the matrix, preventing fusion between foams. Specifically, the trend of the theoretical value calculated by the formula was consistent with that of the measured value, proving that the decrease in thermal conductivity of sample can be attributed to the increase of isolated porosity. The lowest thermal conductivity and highest tortuosity were achieved by specimens mixed with 80 µm hollow microspheres at the dry density of 300 kg/m3, which were 0.07045 W/(m·K) and 2.015, respectively, demonstrating that specimens mixed with 80 µm hollow microspheres exhibited a more complex heat transfer path than the other two groups.

Investigation of the effect of autoclaving on foam concrete properties

The physical, mechanical and thermal properties of foam concrete, one of the lightweight concrete types, are closely related to its density. A decrease in density leads to a decrease in volumetric stability in the fresh state on the one hand and an increase in drying shrinkage and weakening of mechanical properties on the other. In this study, it was aimed to determine the appropriate density for autoclaved foam concrete as a wall filling and thermal insulation material at the required standards. Water/binder (0.60), lime/cement (0.25) and binder/aggregate (0.62) ratios were kept constant in foam concretes produced at dry densities of 300, 400 and 500 kg/m3 using Portland cement, powdered quartz, hydrated lime and synthetic foaming agent. Half of the prism specimens (40 mm × 40 mm x160 mm) in each density class were cured in a climate chamber at 20 ± 5 °C and 95% relative humidity for 28 days, and the other half were autoclaved at 170 °C and 14 bar pressure for 12 h. In autoclaved foam concrete specimens, compressive strengths increased by 237, 323, 443%, flexural strengths increased by 116, 308 and 342%, while thermal conductivity coefficients decreased by 14, 15 and 17% due to increasing density. It was found that autoclaving significantly improved the mechanical and thermal properties of foam concrete and the standard requirements were met at a density of 300 kg/m3.

Experimental and Theoretical Justification of the Foam Fiber-Reinforced Concrete Application Expediency in Earthquake-Resistant Construction

Introduction. Based on the evolutionary approach to the analysis of the lightweight concrete application expediency in earthquake-resistant construction it has been revealed that development of the above mentioned technologies fosters the reduced material consumption in construction and the increased durability of buildings under the seismic loads. The efficient solutions for constructing the earthquake-resistant buildings are constantly searched for, and the reasons for reducing the range of energy-efficient products made of the autoclaved aerated concrete are noticed. The research is aimed at compiling an inventory of modern technological methods of increasing the buildings seismic resistance.Materials and Methods. The list and properties of raw materials used for single-stage technology manufacture of the foam concrete mixtures have been provided. The list of equipment used for assessing the studied materials’ mechanical properties has been defined.Results. The new experimental data confirming the significant influence of the individual properties of fiber on the value of the dispersedly reinforced foam concrete ultimate deformability and bending tensile strength has been obtained. The positive effect of the length of fiber on the foam concrete mechanical properties has been confirmed. The considerably positive effect of the dispersed reinforcement on the homogeneity of mechanical properties observed in the foam concrete mass has been distinguished.Discussion and Conclusions. The work performed has elucidated the importance of the individual properties of fiber as a tool for managing the operational properties of foam concrete. The ultimate properties of the aerated rock material are influenced by the length of fibers and their ultimate deformability. The length of fiber is important for the bending tensile strength, whereas the values of this parameter in the composite material are regulated by the ultimate extensibility.

Approximative approach to optimize concrete foaming concentration in two stage foaming

The article presents the results of a study on foam concentration for the production of foam concrete using a two-stage foam introduction method. The research was conducted by evaluating the strength and density of foam concrete samples manufactured using both the proposed and conventional methods. The optimal composition was determined through several iterations, considering adjustments to the overall quantity of foaming agent and the water-cement ratio. The study revealed that the two-stage foam introduction method enhances the strength properties of foam concrete by promoting the formation of a more uniform porous structure within the material. The initial introduction of a low-concentration foam solution in water creates favorable conditions for the subsequent introduction of a high-concentration foam solution, serving as a structural-forming component. The optimal approach for achieving a stable porous structure involves an initial foam introduction of 15% and a subsequent introduction of 85%. Furthermore, the research highlights the nuances of the relationship between foam concentration, strength, and density of foam concrete, offering deeper insights into the structural properties of the material. The effectiveness of the proposed methodology is substantiated by the achieved technological solution, which provides a pragmatic approach to enhancing the efficiency of foam concrete production through precise foam concentration at both the initial and subsequent stages of the manufacturing process.

Random Foam Meso-Model and Mechanical Properties of Foam Concrete

Random Foam Meso-Model and Mechanical Properties of Foam Concrete

A Review on Durability of Foam Concrete

Foam concrete is a promising material in building and construction applications, providing such outstanding properties as high specific strength, excellent thermal insulation, and effective acoustic absorption in human-inhabited buildings. However, because the porosity and permeable water absorption properties of foam concrete are significantly higher, its durability is often not comparable to that of ordinary concrete, and so the durability of foam concrete requires significant attention during the life cycle of building applications. Durable materials can greatly reduce the environmental impact of waste from maintenance and replacement and the consumption of natural resources resulting from the production of repair and replacement materials. After hardening, the durability of foam concrete includes freeze-thaw cycle resistance, elevated temperature resistance, carbonation resistance, efflorescence resistance, sulfate resistance, chloride resistance, alkali-silica reaction, and so on. This paper reviews articles on the durability of ordinary Portland cement (OPC) foam concrete, geopolymer foam concrete (GFC), magnesium phosphate cement (MPC) foam concrete, sulphoaluminate cement (SAC) foam concrete, and limestone calcined clay cement (LC3) foam concrete and compares their durability to provide a reference for the life cycle design and service life estimation of foam concrete members.

Experimental Investigation on Strength Properties of Foam Concrete

Today, energy is at the forefront of issues that are critical to all governments. The ever increasing global population, along with expanding industry, has resulted in an inevitable increase in energy demand. Nowadays, in order to get desired benefits while using less energy, the issue of insulation has arisen, and thus the necessity of insulation has increased. Foamed concrete has properties such as a high strength-to-weight ratio and a low density. The use of foamed concrete minimizes dead loads on the structure and foundation, aids to energy saving, and saves construction labour costs. In this study the mechanical properties of foamed concrete was analyzed and the strength prediction of compressive was determined with the help of MATLAB. Interaction terms such as cement, flyash, marble sludge powder, water and foaming agent within a volume were inferred as a input and compressive strength is the output with training of 3 hidden layers were used to improve the efficacy of the predictive modeling of the foam concrete.

Fabrication of foam concrete by use of novel foam generator — vortex jet apparatus: study of foam concrete properties

A new method of foam concrete production by use of vortex jet apparatus (VJA) is studied. The foam produced by VJA exhibits high stability and narrow size distribution of the bubbles’ diameter and the latter correlates well with diameters of foam concrete pores. VJA is a compact device allowing to generate foam without compressor, inhausting the air from the ambience resulting from vacuum in the center of vortex flow. Owing to additional opportunities (compared e.g. with usual axial ejector) like ability to suck the air, longer residence time and higher kinetic energy transformed further into dispersion of the bubbles new device lets to control the parameters of the foam and the density of the foam concrete, thus allowing to create foam with smaller diameter of the bubbles and higher stability. A mechanism of large pores isolation during water absorption tests was proposed. Main properties of foam concrete produced in this study: real and apparent densities, open and total porosities, thermal conductivity and thermal capacity, water absorption, compressive and flexural strengths have been measured; their values fully meet the requirements of Russian and French standards. The main part of pores was attributed to the open porosity because of very close values of total and open porosities. Equations characterizing relative mass of water absorbed by the foam concrete and the fraction of open porosity filled with the water were found as functions of apparent density. It was found that foam concrete production with wide range of densities (from approx. 480 till 1640 kg/m3) is easily attainable by means of VJA. Hence, the VJA could be used as an effective tool for foam generation and foam concrete production.

The influence of expanded polystyrene granules on the properties of foam concrete

The influence of expanded polystyrene granules on the properties of foam concrete

A Validation Study on Mechanical Properties of Foam Concrete with Coarse Aggregate Using ANN Model

The usage of foam concrete (FC) was extended from being used as a filler material to an alternative concrete due to the effect of conventional concrete on global warming. The diversified perspective on FC as an alternative to conventional concrete is due to its low density (400–1800 kg/m3) and good thermal conductivity, which also results in the reduction of costs in production, labor, and transportation. Generally, FC is produced by adding a pre-made foam to the cement slurry consisting of cement and aggregates. Here, the study was carried out by the addition of a coarse aggregate and foaming agent (i.e., 12%, 6%, 3%, 2%, 1%) at varying percentages in FC to improve the strength characteristics. FC was tested for its physical and mechanical properties. From the experimental results, an Artificial Neural Network (ANN) was developed to predict the strength of FC. The results from training and testing of the Polynomial Regression Analysis model (PRA) through ANN have shown great potential in predicting compression, split tensile, and flexural strength of FC. It was found that the strength of FC is increased with the reduction of foam volume and increase in coarse aggregate volume. However, a strength of 25.6 N/mm2 is achieved when 1% foam and 50% coarse aggregate is used.

Influence of blast-furnace slag on some properties of foam concrete

Foam concrete is lightweight concrete. It has been proven to be more environmentally beneficial than conventional concrete because it uses less natural resources. Besides, saving natural resources and making effective use of industrial waste as aggregate in concrete is a pressing issue. Currently, the effective use of industrial waste is of interest to many researchers. As a result, the current study seeks to investigate alternative fines sources by examining the impact of granular blast furnace slag as a substitute for sand aggregate on the properties of foam concrete. This paper builds on the author’s earlier research into the impact of blast furnace slag on the properties of foam concrete. In total, four foam concrete mixtures with densities of 1700 kg/m3 and 900 kg/m3 and sand replacement amounts of 100% blast furnace slag were created. GOST has been used to measure the compressive strength, elastic modulus, and porosity of foam concrete. According to the findings, using blast furnace slag instead of sand makes foam concrete thicker and less porous. These findings result in higher foam concrete compressive strength and elastic modulus. Furthermore, the author used Hoff’s equation and Zheng’s equation to calculate theoretical porosity and compare it to observed porosity. The measured results indicate that the theoretical and measured porosity have a reasonably close relationship.

Effect of sugarcane bagasse ash on compressive strength and water absorption of foam concrete using sea sand and seawater

The rapid development of infrastructure has led to a shortage of construction materials. Therefore, the utilization of waste or potential materials is gaining attention. This study aims to investigate the effect of partially replacing Portland cement with sugarcane bagasse ash (SCBA) in Phu Yen province and sea sand-seawater (SSSW) on the properties of foam concrete. Portland cement was replaced with SCBA at 0, 5, 10, and 15% by mass of the binder. The results showed that the compressive strength of foam concrete was reduced at 7 days due to the SCBA replacement. However, the inclusion of 5% and 10% SCBA increased the compressive strength and reduced the water absorption of foam concrete compared to the reference concrete at 91 days. Moreover, the combination of SCBA and SSSW significantly contributed to the enhancement of compressive strength and reduction of water absorption of foam concrete at 91 days, especially when SCBA replacement was less than 10%. In general, the use of SCBA and SSSW is feasible in the production of foam concrete, considering the increasing scarcity of construction materials and the goal of reducing CO2 emissions.

Influence of Pulverized Cow Bone as Partial Replacement of Cement and Demolished Concrete as Full Fine Aggregates on Properties of Foam Concrete

Influence of Pulverized Cow Bone as Partial Replacement of Cement and Demolished Concrete as Full Fine Aggregates on Properties of Foam Concrete