Compressive Strength Of Foamed Concrete Research Articles

Development of an environmentally foamed concrete incorporating red mud.

In this work, an efficient utilization method for red mud (RM) is provided through recycling RM as a mineral admixture for the preparation of foamed concrete (FC). Specifically, FC with different RM contents was prepared and investigated in terms of workability, mechanical properties, and hydration products. Results show that adding RM can significantly shorten the setting time, while it inevitably weakens the mechanical properties and fluidity of FC. However, the compressive strength of FC can still meet the strength predicted by the specification requirements when the RM replaces cement with 60% content (3d > 1.6MPa). Most importantly, the heavy metals leaching from RM-based FC under the action of rain is still unclear, so a device for simulating stormwater runoff was designed to test the heavy metal leaching risk of RM-based FC. The findings indicate that the solidification of cement and the high basicity of the matrix can effectively reduce the leaching risk of heavy metals from RM in FC. Although the pore structure analysis demonstrates that the porosity and connected pores of FC will be deteriorated as RM concentration increases. The results are of great significance for the recycling of waste and the sustainable development of building materials.

Strength characteristics of foamed concrete under coupling effect of constant compressive loading and freeze-thaw cycles

In cold regions, foamed concrete used for the tunnel reserved deformation layer is usually subjected to environmental factors, such as the groundwater erosion, peristaltic pressure of surrounding rock, and freeze-thaw cycles. In this research, experiments considering single-factor (i.e., water immersion, constant compressive loading, and freeze-thaw cycles) and coupled multi-factor effects (the coupling of water saturated - constant loading and constant loading - freeze thaw cycles) were conducted on foamed concretes with different densities to examine the strength variation under different conditions. The results show that under the effect of single-factor environment, the average compressive strength of saturated foamed concrete is about 10% lower than the dry foamed concrete. The compressive strength of foamed concrete significantly decreases at the beginning of constant compressive loading but gradually increases with the loading time. Furthermore, the strength loss of foamed concrete after 30 freeze-thaw cycles can exceed 10%. Under the multi-factor coupled environment, the hydraulic effect accelerates the degradation of foamed concrete, particularly in terms of water saturation - constant loading coupling. Furthermore, for loading - freeze thaw cycles coupling, the compressive loading of 0.3 fc (fc is the unconfined compressive strength at 28 days) can improves the frost resistance of foamed concrete. In addition, the results of orthogonal analysis prove that the density has the most important influence, followed by the freeze-thaw cycle and the slightest effect of constant compressive loading. Additionally, a prediction equation of compressive strength as a function of density, freeze-thaw cycles, and the constant pressure value was established to describe the strength variation of foamed concretes under coupled-loading effects.

Machine learning approach for predicting compressive strength in foam concrete under varying mix designs and curing periods

Efforts to reduce the weight of buildings and structures, counteract the seismic threat to human life, and cut down on construction expenses are widespread. A strategy employed to address these challenges involves the adoption of foam concrete. Unlike traditional concrete, foam concrete maintains the standard concrete composition but excludes coarse aggregates, substituting them with a foam agent. This alteration serves a dual purpose: diminishing the concrete’s overall weight, thereby achieving a lower density than regular concrete, and creating voids within the material due to the foam agent, resulting in excellent thermal conductivity. This article delves into the presentation of statistical models utilizing three different methods—linear (LR), non-linear (NLR), and artificial neural network (ANN)—to predict the compressive strength of foam concrete. These models are formulated based on a dataset of 97 sets of experimental data sourced from prior research endeavors. A comparative evaluation of the outcomes is subsequently conducted, leveraging statistical benchmarks like the coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE), with the aim of identifying the most proficient model. The results underscore the remarkable effectiveness of the ANN model. This is evident in the ANN model’s R2 value, which surpasses that of the LR model by 36% and the non-linear model by 22%. Furthermore, the ANN model demonstrates significantly lower MAE and RMSE values compared to both the LR and NLR models.

Mix proportion optimization and early strength development in modified foam concrete: an experimental study

The influence of the single polycarboxylate superplasticizer (PCE) and blending it mixed hydroxypropyl methylcellulose (HPMC) on hardening moulding quality and surface pulverisation of foam concrete was investigated. An orthogonal experimental design was employed to determine the optimum combination of parameters for four property indexes (PIs) in this paper. A multi-index matrix analysis method was used to evaluate the parameter combinations and obtain the overall optimal performance for the PIs. The effect of calcium formate (CaF) on the early compressive strength of modified foam concrete with the most optimal combination in different density grades was also studied. The results indicate that the incomplete cement hydration reaction is the essential cause of pulverisation, which can be alleviated by adding a suitable PCE. Defoaming and precipitation occur when the PCE incorporated exceeds 0.1%, which can be mitigated by the addition of 0.02 to 0.06% HPMC. The orthogonal analysis indicates that the anti-cracking agent has a more substantial effect on the strength of the foam concrete than the thickening agent. The most significant factor of mechanical properties is PP fiber followed by dispersible latex powder (DLP). The optimal combination of foam concrete is 0.06% HPMC, 0.3% DLP, and 0.5% PP fiber. The early compressive strength of foam concrete can be significantly enhanced by increasing the CaF content. However, increasing the density level results in a decrease in the 28-day compressive strength of the foam concrete.

Effect of formic acid as an accelerator on foam-stability, compressive strength, and pore size distribution of foam concrete

In this study, the formic acid as an accelerator was used to increase the properties of the foamed concrete. The impact of formic acid on the performance of foam concrete was investigated experimentally. The experimental results reveal that using formic acid as an accelerator can significantly increase the rate of yield stress evolution in the matrix. The matrix with the higher yield stress evolution rate tends to increase the stability of the fresh foam concrete. In addition, the –COOH in formic acid can absorb the moisture in the foam, thus increasing foam drainage. The excess formic acid in the base mix can reduce the stability of the fresh foam concrete. The compressive strength of foam concrete can be significantly increased with the addition of 1.0% formic acid. A more homogeneous and finer pore structure of foam concrete can be obtained with the incorporation of 1.0% formic acid, which may result in lower water absorption and higher compressive strength.

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.

Static Compressive Properties of Polypropylene Fiber Foam Concrete with Concave Hexagonal Unit Cell

For the purpose of studying the influence of fiber on the negative Poisson’s ratio effect of foam concrete, a concave hexagonal unit cell structure of polypropylene fiber foam concrete was proposed. The effects of different fiber volume contents on the structural mechanical parameters, Poisson’s ratio, and energy absorption capacity of the unit cells were studied by static compression of concave hexagonal unit cells and cube specimens. The results show that the compressive strength of foam concrete is reduced by adding polypropylene fiber, and the peak stress of concave hexagonal unit cells decreases less rapidly than that of cube specimens. The proper amount of polypropylene fiber can enhance the deformation ability of the unit cells in foam concrete, and the Poisson’s ratio of the unit cells in foam concrete with 1.5% fiber content is the lowest. In the process of failure of concave hexagonal unit cells, the failure phenomenon is mainly concentrated on the concave surfaces on both sides, and the cracks are distributed in the form of “upper left and lower right” or “lower left and upper right”. When the content of polypropylene fiber is 0.5%, the total energy absorbed by the concave hexagonal cells in the compression deformation process increases by 12.98%.

The Effect of The Use Of Foam Agent and Clam Shell Powder on The Compressive Strength and Absorbency of Concrete

A foaming agent is a concentrated solution of surfactant material that must be dissolved in water before mixing with other concrete material. The foaming agent is used to produce lightweight concrete with a density is £ 1.900 kg/m³. Using foam agents may affect the compressive strength and absorbency of the concrete. Hence, adding clam shells is expected to improve the compressive strength of the foam concrete. In addition, it is also essential to investigate the effects of utilizing foam agents and clam shells on the density of the foam concrete. Nine concrete mixes namely 1 variation of standard concrete, four variations of concrete mixes with foam agent, and four variations of concrete with foam agent and calm shell have been studied to investigate the parameters.The variation of foam agents in the eight concrete mixes were 5%, 10%, 15%, and 20% by water weight. The last four variations contained clamshell of 5% by weight of fine aggregate. The foam agent wasfoamingduced by mixing with a ratio of water and foam agent of 40:1. The experimental results show that at the variation of 20% foam agent, the density reduced by 34.55% and 26.89% for foam concrete with and without clam shell compared to normal concrete. I contrast, adding clamshell also lowered down the compressive strength of foam concrete by 79.86% and 74.96% for the variations. Meanwhile, the highest absorption rate of 1.65% or increased about 6.45% from normal concrete occurred at a variation foam agent of 15% mixed with clamshell. It was concluded that the use of clam shell in the foam concrete seems to decrease the strength of the foam concrete. However, in terms of density, the use of clam shells benefits foam concrete by lowering the self-weight of concrete.

Influence of self-ignition coal gangue on properties of foam concrete with steam curing

This paper aims to study the influence of coal gangue (CG) on compressive strength, drying shrinkage, air void structure, and microstructure of foam concrete with steam curing. Coal gangue foam concrete (CGFC) mixtures were prepared by introducing CG at levels of 10−50 % to replace ordinary Portland cement. Steam curing was applied to increase the early-age strength of CGFC. Experimental results showed that with the increase of CG dosage from 10 % to 50 %, the 1 d compressive strength of foam concrete was increased firstly and then decreased. With the same level of bulk density, the incorporation of 30 % CG reached the highest 1 d strength. The addition of 50 % CG decreased the drying shrinkage by 18.8 % for steam-cured samples. Air bubbles and porosity of foam concrete were coarsened by the steam curing but refined by the incorporation of CG. The mineral compositions results indicated that the steam-curing could accelerate the hydration of cement and the pozzolanic reaction of CG, being contribute to the improvement of early-age compressive strength. The scanning electron microscope images exhibited the formation of micro-cracks in steam-cured foam concrete samples which was alleviated by adding CG. Therefore, the utilization of coal gangue in foam concretes benefits both the environmental pollution control and the factory manufacture of lightweight wall panels for building structures.

Preparation and performance analysis of recycled PET fiber reinforced recycled foamed concrete

Construction waste and waste fabric are two major types of solid waste that lead to landfill issue and environmental pollution. Considering the need for more efficient handling method by simultaneously handling both solid waste materials, this study reports an innovative solution to transform waste concrete and waste polyester fabric into environmentally friendly product, recycled foamed concrete (RFC). The dry density, compressive strength, water absorption, frost resistance and chemical erosion resistance of plain RFC (PRFC), PET fiber reinforced RFC (PETRFC) and recycled PET fiber reinforced RFC (RPETRFC) were evaluated. The results indicated that the added recycled powder (RP) can improve the compressive strength of foam concrete. Moreover, the addition of PET fiber (0.1 wt.% content and 6 mm length - optimum) improved the compressive strength (especially the early strength) and durability but had no significant effect on dry density and water absorption. Recycled PET fiber presented a better enhancement effect than PET fiber. The dry density and 28-day compressive strength of RPETRFC were 5.2% and 5.1% higher than those of PETRFC, respectively, and water absorption was 10.7% lower than that of PETRFC. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis indicated that recycled PET fiber had a multifilament structure, which can effectively improve the pore structure of RFC without changing the hydration mechanism. This study demonstrates a new direction for recycling waste concrete and polyester fabric with excellent economic and environmental benefits, and the findings provide reference for the development of lightweight RFC with improved physical properties and durability.

Study on Influence Factors of Compressive Strength of Low Density Backfill Foamed Concrete Used in Natural Gas Pipeline Tunnel

Foamed concrete is mostly used for backfilling of long-distance tunnels and compressive strength is an important technical index to control the quality of foamed concrete. The influence factors on compressive strength of low-density foamed concrete were obtained by the single factor test method based on the targeted dry density and compressive strength. The results show that the HT composed of pollution-free animal protein oil and vegetable oil is an efficient foaming agent and can produce stable foams. The cementation ability of cement can be fully expressed when a water to cement ratio of 0.45~0.5 is employed, making foamed concrete have a compressive strength higher than 2 MPa. The foam content is inversely proportional to the compressive strength and dry density of foamed concrete, and the volume ratio of slurry to foam should be 2:1~3:1. The content of fly ash is also inversely proportional to the compressive strength but positively proportional to the dry density. When the content of admixture is 40~55%, the compressive strength of foamed concrete with low density is not less than 2 MPa. The mixing proportion can be changed in the reasonable range to meet the requirements of different projects.

Collaborative disposal of multisource solid waste: Influence of an admixture on the properties, pore structure and durability of foam concrete

Solid waste building material treatment is an essential means of disposal and an active research area. Despite this, the multisource characteristics, large volumes and complex compositions of solid waste necessitate new requirements for its treatment. In this paper, a typical resource-based coastal city is considered the research object. Fly ash (FA), furnace slag (FS) and mineral powder (MP) are taken as samples to investigate the influence of admixtures on the properties, pore structure and durability of foam concrete by three-factor and three-level orthogonal tests. Results indicate that foam concrete with different admixtures can have various mechanical and thermal insulation properties. The compressive strength of foam concrete can increase to 3.90 MPa, and its thermal conductivity can reach 0.1347 W/M·k. MP has the largest apparent effect on the compressive strength, while FS has the most obvious impact on the thermal conductivity. The durability analysis shows that the number of freeze-thaw cycles foam concrete can withstand is 25–100 cycles. The collaborative disposal of multisource inorganic solid waste has high potential for being applied as inner partition walls and thermal insulating components in buildings. This paper provides valuable guidance for the sustainable and clean utilization of multisource inorganic solid waste.

Resource Utilization of Waste Mud -- Preparation and Properties of Foamed Concrete

The compressed and dehydrated mud was made into filter cake, and then fly ash, silica fume and cement were added to it to prepare foamed concrete with sodium α-olefin sulfonate as foaming agent. By analysing the changing characteristics of the compressive strength, apparent density, water absorption and microstructure of the foam concrete, the key mechanism of making the foam concrete was analysed in depth. The results show that mud filter cake can improve the comprehensive performance of foamed concrete. The best mix ratio is 20% of mud filter cake, 50% of cement addition, 20% of fly ash, 10% of silica fume, 0.55 of water cement ratio and 55% of foam volume. The compressive strength of foam concrete is 1.6MPa and the apparent density is 660.26kg/m3. The water absorption rate is 23.73%, which accords with China Construction Industry Standard JG / T266-2011. Proper addition of mud filter cake can improve the pore structure and cementing material matrix of foamed concrete, and enhance the strength of foamed concrete. However, too much addition will produce connected pores and cracks, and reduce compressive strength. The results can provide theoretical basis and technical reference for mud resource utilization.

Optimization of Cuttlefish Bone Towards Compressive Strength of Foam Concrete

Development and testing of other foam concrete materials, as well as the inclusion of a marine-based filler, cuttlefish bone powder, may be one of the most advanced products suitable for cementitious materials to be added in concrete to provide a sustainable environmentally friendly alternative solution on construction industry in Malaysia. Cuttlefish bone will have some advantages and benefits in foam concrete since it contains high amounts of calcium carbonate, which is believed can improve the concrete’s strength and encourage foam concrete to achieve an early strength. The objectives of this research is to determine the optimum percentage of cuttlefish bone additive towards increasing the strength properties of foam concrete. In this research, there were 42 foam concrete cube samples prepared, each group of samples containing different amounts of cuttlefish bone additive (1%, 2%, 3%, and 4%). All the samples were tested for compressive strength at 1, 3, and 7 days of age. According to the findings, an improvement in the foam concrete when the cuttlefish bone additive content from 1% to 4% added which result in the enhancement of the behavior of foam concrete. In addition, this research reveals that cuttlefish bone additive has better characteristics to normal OPC, making it an effective addition to concrete.

Studies on influence of characteristics of surfactant and foam on foam concrete behaviour

This paper describes an extensive laboratory-based investigation conducted to evaluate the relative performance of foam produced with two different synthetic surfactants namely Sodium lauryl sulphate (SLS) and Nonylphenol ethoxylate (NPE) along with an additive Carboxymethyl cellulose sodium salt (CMC) for use in foam concrete. The different essential characteristics of foam and surfactants such as initial foam density, foam stability, average bubble size and viscosity of surfactant solution are investigated in the present study through systematic experimental design based on response surface methodology. Further, based on studies on microstructure of foam concrete, it is found that selection of surfactant and CMC concentration have significant influence on foam characteristics and hence on the air void size distribution of foam concrete. In addition, the dependence of the compressive strength and water permeation characteristics of foam concrete on the air void size parameters of concrete is also investigated. Experimental outcomes indicate that increase in surfactant concentration from 3% to 6% results in 24%–44% reduction in median air void diameter in concrete which eventually led to 29%–37% enhancement in compressive strength of foam concrete mixes. In the same line, addition of CMC to surfactant solution enhances viscosity of surfactant solution significantly and thereby results in improvement of foam microstructure, concrete air void microstructure and eventually improves compressive strength of foam concrete. Further, improved microstructure with smaller air voids in foam concrete with NPE + CMC results in 10%–25% relatively higher compressive strength than SLS + CMC foam concrete mixes.

Evaluation of Suitability of Carboxymethyl Cellulose in Performance Improvement of Sodium Lauryl Sulfate Foam and Compressive Strength of Foam Concrete

Abstract Currently, foam concrete is commonly used for various construction applications such as partitions, filling grades, road embankment infills, and sound and heat insulation. It is to be noted that the foam production parameters have significant influence on the cellular structure of foam concrete, which governs the material properties of concrete. Hence, in an attempt to improve the foam quality, the present work focuses on evaluation of the suitability of viscosity enhancing agent carboxymethyl cellulose (CMC) in performance improvement of foam produced with surfactant sodium lauryl sulfate (SLS) for use in foam concrete production. Firstly, the influence of the addition of CMC on behavior of foam produced with surfactant SLS was studied by evaluating essential characteristics such as foam density, foam stability, and viscosity of surfactant solution. As a next step, the microstructure of foam and its behavior in cement slurry and mortar at the optimized concentrations of SLS and CMC were studied. Experimental studies revealed that the addition of 0.2 % CMC to 2.5 % SLS surfactant solution resulted in a 134 % increase in viscosity of surfactant solution, which eventually resulted in tremendous improvement in foam quality in terms of 34 % reduction in foam drainage (at the 5th minute after foam generation) and 22 % reduction in larger size foam bubbles (D90). Furthermore, as the air void microstructure of foam concrete is dependent on the foam bubble sizes, the reduction in foam bubble sizes resulted in 20 % enhancement in compressive strength of foam concrete. The addition of CMC is also found to affect the workability of foam concrete mixes, which is evident from the reduction in flow spread and the increase in flow time. Also, as the foam has retarding properties, the increase in foam content is found to increase the demolding time requirement of foam concrete specimens.

Karakteristik Beton Busa Akibat Variasi Foamed dan Subsitusi Fly Ash Terhadap Semen

Foam concrete is a concrete technology that is applied to buildings. The advantage of foam concrete is that it is lightweight and fast in building work. The use of foamed in foam concrete reduces the density of foam concrete. Substitution of fly ash for cement can increase the compressive strength of foam concrete. The variations of foamed used in this study were 30%, 40%, and 50%. The substitution of fly ash for cement in this study was 0%, 5%, and 10%. In the specific gravity test, the smallest value was 1,156 kg / m3 resulting from a variation of 50% foamed and 0% substitution of fly ash for cement, while the largest weight was 1,670 kg / m3 resulting from 30% foamed variation and 10 fly ash substitution. % against cement. In the compressive strength test at 28 days of concrete, the highest value was obtained with a value of 2.573 N / mm2 resulting from 30% variation of foamed and 5% substitution of fly ash for cement, while the lowest compressive strength was 1.986 N / mm2 resulting from variations of foamed 30 % and 10% substitution of fly ash for cement. The optimum composition of foam concrete in this study was found in a mixture with 40% foamed variation and 5% fly ash substitution for cement with a value of 2,312 N / mm2 and a specific gravity of 1438 kg / m3. The optimum use of fly ash is obtained at a substitution percentage of 5% for cement. Foam concrete using styrofoam and polypropylene fibers is good for non-structural elements in buildings such as wall panels. Keywords: Light weight concrete, foamed concrete, fly ash

Investigation and Optimization of the C-ANN Structure in Predicting the Compressive Strength of Foamed Concrete.

Development of Foamed Concrete (FC) and incessant increases in fabrication technology have paved the way for many promising civil engineering applications. Nevertheless, the design of FC requires a large number of experiments to determine the appropriate Compressive Strength (CS). Employment of machine learning algorithms to take advantage of the existing experiments database has been attempted, but model performance can still be improved. In this study, the performance of an Artificial Neural Network (ANN) was fully analyzed to predict the 28 days CS of FC. Monte Carlo simulations (MCS) were used to statistically analyze the convergence of the modeled results under the effect of random sampling strategies and the network structures selected. Various statistical measures such as Coefficient of Determination (R2), Mean Absolute Error (MAE), and Root Mean Squared Error (RMSE) were used for validation of model performance. The results show that ANN is a highly efficient predictor of the CS of FC, achieving a maximum R2 value of 0.976 on the training part and an R2 of 0.972 on the testing part, using the optimized C-ANN-[3–4–5–1] structure, which compares with previous published studies. In addition, a sensitivity analysis using Partial Dependence Plots (PDP) over 1000 MCS was also performed to interpret the relationship between the input parameters and 28 days CS of FC. Dry density was found as the variable with the highest impact to predict the CS of FC. The results presented could facilitate and enhance the use of C-ANN in other civil engineering-related problems.

ВЛИЯНИЕ МИНЕРАЛЬНЫХ ДОБАВОК, ЛЕТУЧЕЙ ЗОЛЫ, ДОМЕННОГО ШЛАКА НА МЕХАНИЧЕСКИЕ СВОЙСТВА ПЕНОБЕТОНА

The present study evaluated the combined effects of organic-mineral additive based on a superplasticizer SR 5000F and the active mineral additive fly ash, blast furnace slag and silica fume SF-90 on properties of foam concrete. The calculation of mixture proportions of foam concrete is applied by the absolute volume method. Besides, the compressive strength and flexural strength of foam concrete are determined by Russian standard GOST 10180-2012. The porosity of the foamed concrete is determined by American standards ASTM C457-1998. The results from experiments show that flexural and compressive strength of the foam concrete obtained respectively, from 0.526 to 1.061 MPa and from 1.69 to 8.22 MPa. The relationship between compressive strength and curing age, compressive and flexural strengths of the FC were also determined in this investigation. The results of this study demonstrated that the use of fly ash and blast furnace slag to replace natural sand could produce foam concrete and environmental protection.

Development of a strength model for foam concrete based on water – cement ratio

Foam concrete is a lightweight concrete having many versatile features such as flowability, low density, self-compacting, thermal insulation properties, and adequate strength. However, the prediction of the compressive strength of foam concrete is always a challenge. There are various strength prediction models and relationships reported in the literature that are generally based on porosity, density, the volume of voids and space gel ratio, etc. In this paper, a new strength prediction model for the compressive strength of foam concrete is presented based on an effective water-cement ratio. Generally, the compressive strength of concrete is presented as a function of the water-cement (or binder) ratio. This model was developed by the inclusion of foam volume with water in w/c ratio which follows Abram’s strength-w/c law. This is a step ahead of the proposal of the equivalent water-cement ratio using the efficiency factor to include fly ash. The effectiveness of foam was considered as an important parameter for the precision of the model. In this paper, the proposed model was employed to predict the strength of foam concrete mixes reported in past studies. It was seen that this model is highly efficient compared to other models and easiness in predicting the strength since only water, foam, binder are involved.