Strength Of Lightweight Concrete Research Articles

Mechanical Behavior Analysis of Lightweight Concrete Reinforced by Metalized Plastic Waste Fibers

This study evaluates the impact of adding metalized plastic waste (MPW) fibers to lightweight concrete that is used as a filler material in building slopes and bridge ramps. The goal is to open up new opportunities for recycling plastic waste and promote a more sustainable and productive construction industry. This study examined the mechanical behavior of lightweight concrete (LC) at 3, 28, and 90 days, both with and without MPW fiber (1%, 2%, and 3%). Compression tests, 3-point bending tests, and pull-out tests were used to measure the fibers' compressive strength, flexural strength, and maximum load-bearing capacity, respectively. According to the results, the compressive strength (CS) and elasticity modulus (MOE) decreased with increasing fiber content when MPW fiber was added. In the long term, the CS and MOE decrease for the LC containing 3% MPW fiber was 8% and 7%, respectively, lower than for the control concrete. At 90 days, the flexural strength of the LC with 1% MPW fiber was marginally higher than that of the control concrete, rising by 2.40%. After this initial rise, however, the flexural strength declined as the fiber concentration increased, eventually reaching an 8% reduction for LC with 3% MPW fiber.The optimum method for determining maximal load-bearing and comprehending the deformation mechanism is hence the fiber pull-out test. The microstructure study of the LC examined how the pull-out test affected the quality of bonding at fiber-matrix interfaces. The tensile and flexural strength of lightweight concrete are enhanced by MPW fiber's ability to bear significant pulling stress.

Fractal model of the strength of lightweight concrete based on volcanic tuff taking into account the scale effect

The study proposes a fractal model based on B. Mandelbrot's geometry. Mandelbrot geometry to describe the scale effect in concrete. It has been experimentally established that under-loading concrete undergoes degradation of its structure, which is expressed in the sequential destruction of fractals at different scale levels. It was found that the scale reduction leads to an increase in concrete strength: 20x20x20 mm specimens showed the highest strength among all four compositions (23.3-25.3 MPa). The average density of tuff concrete was also investigated: the smallest specimens had a density of 1961.3 kg/m³, while the largest specimens had a density of 1974.2 kg/m³, which is explained by the heterogeneity of the structure and pore distribution. The water permeability of concrete, evaluated through air permeability, showed that specimens with higher air permeability (30.2-30.5 s/cm³) had better water resistance (W14). These data indicate a correlation between air permeability and water resistance, which may be due to the denser structure and improved pore distribution. The study of air permeability makes it possible to predict the durability of concrete structures when exposed to moisture, as well as to improve the quality of building materials and reduce the cost of their operation.

THE EFFECT OF POLYPROPYLENE FIBERS ON COMPRESSIVE AND SPLIT TENSILE STRENGTH OF LIGHTWEIGHT CONCRETE

This study was carried out to design lightweight concrete, which is enriched with polypropylene fibers using coarse pumice and sand fine aggregates. Lightweight concrete specimens were classified into distinct groups based on fibers content employed, namely a control group with 0 kg/m³ and the experimental incorporating 0.1 kg/m³, 0.3 kg/m³, 0.5 kg/m³, and 0.7 kg/m³ varying quantities of polypropylene fibers. Subsequently, after a curing period of 28 days, the hardened concrete test was conducted on cylinder specimens measuring 150 mm x 300 mm. The consistency of the fresh concrete mixture was tested using the Abrams cone test, which revealed a decrease in the workability of fibers-reinforced concrete with an increase in fibers volume in the mixture. The test aimed to determine the effect of polypropylene fibers on compressive and tensile strength of lightweight concrete. The optimal compressive and split tensile strength was observed at fibers volume fraction of 0.5, to obtain 7.84 MPa, or 56.68% increase in compressive strength, and 2.12 MPa or 42.86% rise in tensile strength. Based on compressive and split tensile strength obtained from this study, concrete was classified as highly lightweight structural concrete, which served as an insulator.

Assessment of Lightweight Concrete Properties with Zinc Oxide Nanoparticles: Structural and Morphological Analyses

In recent decades, the use of nanotechnology has increased in many disciplines. Specifically, in the concrete industry, nanotechnology has been used to develop more eco-efficient solutions. There is a rapidly growing interest in using nanoparticles in concrete to tackle environmental impacts. Among the nanoparticles investigated, zinc oxide (ZnO) shows great potential because of its material properties, such as reactivity, non-toxicity, a hard and rigid structure, photocatalytic and photoluminescence properties, and chemical, electrical, and thermal stabilities. This paper focuses on the analysis of the effect of ZnO nanoparticles in lightweight concrete at different concentrations (0.5, 1, 1.5, and 2.0 wt%) using two different methods including (i) addition and (ii) partial substitution for cement. Mechanical properties are determined by compressive strength tests. Chemical and morphological characterization is performed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. This study reveals that an increase in the percentage of ZnO nanoparticles as a substitute for cement directly decreases the compressive strength of lightweight concrete. For ZnO nanoparticles in the addition method, compressive strength is 10% lower than in the control specimens. However, the conclusions indicate constant compressive strength for all ZnO nanoparticle concentrations in the addition method.

Impact of thermal loads on silica fume-modified lightweight concrete: Machine learning approach to assess compressive strength evolution

Fire resistance of concrete is complex to comprehend as it is a composite material with ingredients of varied thermal properties. As the behaviour of concrete subjected to thermal loads is complex and required exhaustive experimentation, the use of soft computing techniques can be beneficial for predicting the residual compressive strength of concrete. Leveraging the power of machine learning (ML), specifically Artificial Neural Network (ANN), Random Forest (RF), and AdaBoost (AdB) models, this study aims to overcome the limitations of conventional prediction methods. Models were developed for the prediction of residual compressive strength of light weight concrete with silica fume (SF) exposed to thermal loads. Cement, silica fume, lightweight pumice aggregate, water-to-cement ratio, superplasticizer, and temperature were taken as input attributes while residual compressive strength was taken as output. Firstly, the data were subjected to extensive statistical analysis before the models were created. Additionally, hyperparameter tuning using grid search was done to increase the models' efficiency. The coefficient of determination (R2), root mean squared error (RMSE), and mean absolute error (MAE) as model evaluation parameters were used to evaluate the performance of various developed ML models. When the performance of models was compared, it was found that the AdaBoost (AdB) model outperformed all other ML models. Hence, this study highlights the significance of ML techniques in addressing complex engineering challenges and underscore the practical implications for optimizing structural design and performance.

Experimental study on the effect of basalt fiber reinforced expanded polystyrene foams on the compressive strength of lightweight concrete

Reducing the structural load and operational energy consumption of buildings is a trend in the development of the construction industry, and lightweight concrete has become a research hotspot because of its dual characteristics of low density and high strength. In this paper, a three-step method is used to prepare lightweight concrete composites. In the first step, basalt fiber powder was adhered to polystyrene foam ball expanded polystyrene spheres (EPSs) by the “ball rolling method” to obtain basalt fiber reinforced epoxy composite balls. In the second step, the epoxy resin composite ball and the configured cement matrix are filled into a prefabricated mold. Finally, the lightweight concrete specimens were overlaid, pressed into shape, and cured for 28 days. By changing the volume ratio, size, and wall thickness of the epoxy composite balls, as well as the length and content of basalt fibers, the lightweight concrete was exhibited a reduction in density and increase in strength. The results showed that the smaller the epoxy composite spheres and the larger the wall thickness are, the higher the compressive strength of the material for a certain volume ratio of epoxy composite spheres will be. The addition of appropriate hollow glass beads can reduce the number of pores in the matrix, but excessive hollow glass beads will reduce the bonding force of the concrete matrix. Basalt fibers not only improve the strength of EPSs but also serve to connect matrix–matrix and matrix–epoxy composite spheres.

Experimental Investigation of Mechanical Properties of Concrete Mix with Lightweight Expanded Polystyrene and Steel Fibers

The demand for lightweight aggregates in concrete compositions for diverse structural and non-structural applications in contemporary building construction has increased. This is to achieve a controllable low-density lightweight concrete, which reduces the overall structural weight. However, the challenge lies in achieving an appropriate strength in lightweight concrete while maintaining a lower unit weight. This research aims to evaluate the performance of lightweight concrete by integrating expanded polystyrene (EPS) as a partial replacement for coarse aggregate. Test specimens were cast by blending EPS with coarse aggregate at varying proportions of 0%, 15%, 30%, and 45%, while maintaining a constant water-to-binder ratio of 0.60. To enhance the bonding and structural capabilities of the proposed lightweight concrete mixes, reinforcement with 2% and 4% steel fibers by volume of the total concrete mix was incorporated. Silica fume was introduced into the mix to counteract the water hydrophobicity of EPS material and enhance the durability of lightweight concrete, added at a rate of 10% by weight of cement in all specimens. A total of 60 samples, including cylinders and beams, were prepared and cured over 28 days. The physical and mechanical properties of the lightweight EPS-based concrete were systematically examined through experimental testing and compared against a standard concrete mix. The analysis of the results indicates that EPS-based concrete exhibits a controllable low density. It also reveals that incorporating reinforcement materials, such as steel fibers, enhances the overall strength of lightweight concrete.

The Effect of Kevlar Fibers on the Mechanical Properties of Lightweight Perlite Concrete

Fiber-reinforced concrete contains a fibrous material that increases its structural cohesion. The use of separate short fibers distributed in a random direction improves the strength of Lightweight Concrete (LWC) without exceeding its upper-density limit, improving its high fragility and mechanical properties compared to Natural-Weight Concrete (NWC). This study investigated the effect of adding Kevlar 49 fibers with three percentages of cement weight, 0.5, 1, and 1.5%, on the workability, dry density, and tensile and compressive strength of LWC. The use of Kevlar fibers in different proportions improves mechanical properties, significantly increases durability, and reduces the workability of LWC. The increase in compressive strength when adding 0.5% fibers was 19 and 15% and when adding 1% was 10 and 6%, after 7 and 28 days, respectively. At 1.5%, after 7 and 28 days, there was a decrease in compressive strength due to fiber agglomeration. Additionally, increasing the fiber dose from the optimal value caused a sharp decrease in workability by 37-40%.

Flexural Residual Strength of Lightweight Concrete Reinforced with Micro-Steel Fibers

Flexural Residual Strength of Lightweight Concrete Reinforced with Micro-Steel Fibers

Preparation and Compression Resistance of Lightweight Concrete Filled with Lightweight Calcium Carbonate Reinforced Expanded Polystyrene Foam.

Lightweight concrete is widely used in the construction industry due to its low density and high strength. In this paper, lightweight concrete was prepared by a simple two-step method. Firstly, the light calcium carbonate reinforced epoxy macrospheres (LCR-EMS) material was obtained by adhering calcium lighter carbonate powder to the expanded polystyrene foam spheres (EPS) material using the "balling method". In the second step, the LCR-EMS was mixed with water, cement, and the hollow glass microspheres (HGMS) material using the "molding method" to obtain lightweight concrete. The combination of macroscopic photographs and microscopic morphology shows that the LCR-EMS material itself is uniformly encapsulated and well bonded to the matrix. Test results show that the density of the lightweight concrete decreases with an increase in the volume fraction of stacked LCR-EMS, the diameter, and the proportion of HGMS in the matrix, but it decreases with a decrease in the number of layers of LCR-EMS. The compressive strength of lightweight concrete exhibits a completely opposite trend. When three layers of LCR-EMS were used as filler material, the density and compressive strength of the concrete were 1.246 g/cm3 and 8.19 MPa, respectively. The density and maximum compressive strength of lightweight concrete were 1.146 g/cm3 and 6.37 Mpa, respectively, when filled with 8-9 mm-2L-90 svol% of LCR-EMS and 40 wt% of HGMS in the matrix. Compared with lightweight concrete filled with 90% EPS, the density increased by 20% while the compressive strength increased by 300%.

Prediction of the compressive strength of lightweight concrete containing industrial and waste steel fibers using a multilayer synthetic neural network

The use of waste and industrial steel fibers as part of the materials used in concrete can increase resistance and reduce cost and air pollution. It also saves energy. One of the important measures for technical inspections and assessment of the existing condition of structures, especially bridges, which is the most important communication factor, is to check the compressive strength. Considering that the calculation of compressive strength in the laboratory is done with the intervention of human power and is undoubtedly affected by human error, we decided to use it through.Predicting the mechanical properties of concrete reinforced with steel fibers based on artificial neural network models without the need to conduct any laboratory studies will save money in construction projects. Unlike classical methods in statistical theories, neural networks do not require any specific model or function along with limiting assumptions to linearize problems.For this purpose, this research was done with the aim of compensating this problem and with the aim of building a neural network with high accuracy that can make the desired predictions with the least error. In this research, this modeling was done using artificial neural networks (ANN) and Levenberg algorithm. The data used to train the neural network was collected from 45 different mixing schemes. Then the compressive strength of the sample is determined experimentally. The parameters considered for the ANN inputs are the values of steel fiber, water, water-cement ratio, cement and superlubricant. The objective data of this study included the compressive strength of each of these mixing designs at the ages of 7, 28 and 60 days. Then, to design the neural network, 75% of the data were considered as training data, 15% as target data and 15% as validation data. The compressive strength of concrete samples made from waste steel fibers increases. One of the reasons for this result is the placement and uniform distribution of fibers in the cement matrix, or in other words, the optimal amount of desired fibers in concrete. For experimental information and data, results can be seen with the help of neural network in data analysis. It was observed that the validation is correlated with a correlation coefficient above 99% and the constructed neural network has sufficient accuracy and validity.

Strength of light weight concrete containing fly ash cenosphere

The study's main focus is on finding a modern substitute for grit in light-weight concrete (LWC). The researcher is concentrating on partly replacing sand with readily available solid wastes like cenospheres, which are likely to support waste management and also provide a potential replacement for the most exploited. Three different series of mortar cubes with three identical specimens each were used in the experimental research. The observed outcomes have demonstrated the better compatibility of using fly ash up to 25% and cenospheres at 30% as a sand replacement in LWC with improved strength characteristics. In the construction of concrete structures, Light Weight Concrete (LWC) is quickly gaining acceptance for a variety of uses. When building concrete structures, Light Weight Concrete (LWC) is quickly becoming satisfactory for a variety of uses. Fly ash and cenospheres are added to concrete to improve its workability, strength, and longevity. They serve as pozzolanic components. In order to determine the best replacement for mineral admixtures like fly ash and bagasse ash in concrete, various ages of the materials were used to examine the strength characteristics such as cube compressive strength, cylinder compressive strength, and split tensile strength. The ideal replacement amount of fly ash and cenosphere was determined after comparing the strengths. According to the effects of the various fly ash and cenosphere fractions used to substitute the sand, the mechanical properties change to utilise cenosphere and fly ash.

Effects of Kortta fibres and microsilica on the mechanical properties of lightweight concrete in oil product environments

Crude oil and its products are strategic and vital goods for most countries in the world. It is necessary to store these products in the production and transfer chain and send them to refineries, ports, and airports for military and national purposes. Lightweight concrete is propounded as a useful replacement for normal concrete due to its low specific weight and acceptable resistance property; however, compared to normal concrete, it is considered to be more permeable, less durable, and less resistant. Therefore, in this study, the reliability of this synthetic material in oil conditions has been investigated. In this regard, two groups of samples were investigated under normal and oil environmental conditions, polymer Kortta fibres with percentages of 0; 0,5; 1,0; 1,5; and 2,0 % and microsilica with percentages of 0 and 15 % by cement weight were incorporated alone and combined. Subsequently, tests were performed on the specimens after 90 days. The results showed that the combination of microsilica and Kortta fibres causes a significant increase in lightweight concrete strength and impermeability.

The Effect of Nanosilica and Steel Fibers on The Mechanical Behavior of Structural Lightweight Concrete

The low strength of lightweight aggregates diminishes the strength of lightweight concrete, and the concrete's fragility impedes the ductile behavior of structures subjected to seismic stresses. The use of reinforcing materials and fibers may increase the strength of lightweight concrete by compensating for the impact of reduced strength caused by the use of lightweight particles and preventing the rapid breakdown of concrete. The performance of the materials used is an effective determinant of structural member behavior. Therefore, for computational analysis of finite elements to accurately anticipate the behavior of structural parts, precise behavioral models of materials are required. This study studied the tensile behavior of lightweight structural concrete containing steel fibers (at a volume percentage of 1%) and nanosilica reinforcing pozzolan (at a weight percentage of between 1 and 3%), using tensile strength as one of the influencing factors. together with the strain corresponding to the maximal stress. The inclusion of steel fibers and nanosilica had the largest influence on enhancing the tensile behavior of lightweight concrete, according to the data. By adding 3% nanosilica and 1% steel fibers to light concrete, the direct tensile strength has risen by 74%. In addition, the indirect tensile strength is somewhat greater in all samples than the direct tensile strength.

The effect of fly ash as coating powder on compressive strength of lightweight concrete

Expanded polystyrene (EPS) has been used and studied for decades in lightweight concrete. Because EPS beads are incredibly light, using these beads in concrete will cause the particles to segregate. Furthermore, the hydrophobic nature of EPS materials weakens the bond between them and cement paste. This research will investigate the compressive strength of lightweight concrete using EPS beads as a coarse aggregate replacement, focusing on the effect of fly ash coating with a binder made from a mixture of Polyvinyl Acetate (PVA) and water. A comparison of density and compressive strength between normal concrete and concrete made from EPS beads was conducted in this study. EPS beads will replace 100% of coarse aggregate. Coated EPS beads that were being produced in this research have an average weight per volume of 246–251 kg/m3. The concrete that uses EPS beads coated with fly ash showed positive results for an increase in compressive strength of 8%, 20%, 38%, and 27% at the age of 7, 14, 28 and 56 days of concrete with EPS beads without modification.

Machine Learning-Based Predictive Modeling of Sustainable Lightweight Aggregate Concrete

Nowadays, lightweight aggregate concrete is becoming more popular due to its versatile properties. It mainly helps to reduce the dead loads of the structure, which ultimately reduces design load requirements. The main challenge associated with lightweight aggregate concrete is finding an optimized mix per requirements. However, the conventional material design of this composite is quite costly, time-consuming, and iterative. This research proposes a simplified methodology for the mix designing of structural and non-structural lightweight aggregate concrete by incorporating machine learning. For this purpose, five distinct machine learning algorithms, support vector machine (SVM), artificial neural network (ANN), decision tree (DT), Gaussian process of regression (GPR), and extreme gradient boosting tree (XGBoost) algorithms, were investigated. For the training, testing, and validation process, a total of 420 data points were collected from 43 published journal articles. The performance of models was evaluated based on statistical performance indicators. Overall, 11 input parameters, including ingredients of the concrete mix and aggregate properties were entertained; the only output parameter was the compressive strength of lightweight concrete. The results revealed that the GPR model outperformed the remaining four machine learning models by attaining an R2 value of 0.99, RMSE of 1.34, MSE of 1.79, and MAE of 0.69. In a nutshell, these simplified modern techniques can be employed to make the design of lightweight aggregate concrete easy without extensive experimentation.

Compressive behavior of lightweight concrete using aerogel-reinforced expanded polystyrene foams

The continuous development of the construction industry is also pushing concrete to change. Lightweight and high-strength concrete is becoming more and more important. Aerogel reinforced Epoxy Macrospheres (AR-EMS) were obtained by the ball rolling method. The lightweight concrete was prepared by mixing AR-EMS, cement, and hollow glass beads into the mold by the molding method. In this experiment, the influencing factors such as stacking volume fraction, inner diameter, wall thickness of AR-EMS and different types of hollow glass microspheres (HGMS), different content and length of glass fibers (GF) in matrix were studied. The comprehensive microstructure and performance characterization results show that AR-EMS binds well to the concrete matrix, and the addition of long fibers effectively improves the compressive strength of lightweight concrete. The lightweight concrete can meet the requirements of both high strength (11.46 MPa) and low density (0.897 g/cm³) when the matrix is filled with 2 wt% of 12 mm GF and AR-EMS with 9–10 mm-2layers-90%. Compared to the concrete without GF and the EPS-filled concrete, the maximum compressive strength was increased by 69% and 398%, respectively.

Promulgation of sustainable palm oil clinker sand in the development of structural and non‐structural lightweight foamed concrete

AbstractThe excessive exploitation of natural resources, such as mining or river sand in concrete, has resulted in several catastrophic disasters worldwide. Furthermore, the low compressive strength of lightweight concrete (LFC) has limited its use as structural concrete. In this research, the feasibility of replacing natural mining sand (MS) as fine aggregates in the development of LFC with local agro‐industrial waste material, namely palm oil clinker (POC), which can be considered a sustainable material, at different replacement ratios of 0%, 25%, 50%, 75%, and 100% was investigated. Because of the porous structure of POC, a volume‐based method was employed in the mix design of using the specific gravities to produce LFC with three different target densities of 1100, 1300, and 1500 kg/m3. The investigated parameters include workability, compressive strength, splitting tensile strength, flexural strength, ultrasonic pulse velocity (UPV), and scanning electron microscope (SEM) images. Overall, 100% replacement of MS volume with POC with the sieve size below 0.6 mm resulted in a 90‐day compressive strength of 26.7 MPa in the LFC with a density of 1500 kg/m3. Similar to the compressive strength, the utilization of the sustainable POC as fine aggregates slightly improved the tensile and flexural strengths of LFC. On the other hand, replacing 100% of MS with POC with the sieve size below 0.6 mm reduced the flow test results of LFC from 405 to 350 mm. The use of POC in LFC improved the bonding between cementitious material and fine aggregate, according to the UPV results.

The Effect of Plastiment-VZ on the Compressive Strength and Flexural Strength of Lightwieght Concrete Using Aluminium Powder

One of the approaches to producing lightweight concrete is by adding the aluminum powder to the cement mixture to create air bubbles in the concrete as such enabling pores to appear in the concrete. Aluminum powder can reduce the weight of lightweight concrete despite its tendency to reduce compressive strength. The compressive strength of concrete can be increased by certain methods, one of which is by the addition of Plastiment-VZ admixture. This study aims to investigate the effect of the use of Plastiment-VZ admixture on the compressive strength and flexural strength of lightweight concrete. The normal concrete compressive strength is designed to the range of 0.7 MPa – 5.0 MPa. The concrete testing specimens were in the form of a cube of 15 cm x 15 cm x 15 cm for the compressive test and beams with dimensions of 15 cm x 15 cm x 60 cm for the flexural test. The test results of the compressive strength obtained for normally aerated concrete (0% of Plastiment-VZ) is 6.31 MPa; and for the variation of 0.2% is 6.52 MPa, for 0.4% is 6.8 MPa, and for 0.6% is 8.04 MPa. The highest increase in strength occurred at 0.6% variation, which is 27.46% above normally aerated concrete. The degrees of flexural strength of the concrete produced from each variation of 0%; Based on the findings, it can be concluded that Plastiment-VZ has a significant effect on increasing the compressive strength and flexural strength of lightweight concrete. The more quantity of Plastiment-VZ is used, the higher the compressive strength and flexural strength are produced; even though, the optimum level for the use of Plastiment-VZ for aerated concrete has not been found.

Effect of waste glass powder, microsilica and polypropylene fibers on ductility, flexural and impact strengths of lightweight concrete

PurposeToday, using lightweight structural concrete plays a major role in reducing the damage to concrete structures. On the other hand, lightweight concretes have lower compressive and flexural strengths with lower impact resistance compared to ordinary concretes. The aim of this study is to investigate the effect of simultaneous use of waste glass powder, microsilica and polypropylene fibers to make sustainable lightweight concrete that has high compressive and flexural strengths, ductility and impact resistance.Design/methodology/approachIn this article, the lightweight structural concrete is studied to compensate for the lower strength of lightweight concrete. Also, considering the environmental aspects, microsilica as a partial replacement for cement, waste glass powder instead of some aggregates and polypropylene fibers are used. Microsilica was used at 8, 10 and 12 wt% of cement. Waste glass powder was added to 20, 25 and 30 wt% of aggregates, while fibers were used at 0.5, 1 and 1.5 wt% of cement.FindingsAfter making the experimental specimens, compressive strength, flexural strength and impact resistance tests were performed. Ultimately, it was concluded that the best percentage of used microsilica and glass powder was equal to 10 and 25%, respectively. Furthermore, using 1.5 wt% of fibers could significantly improve the compressive and flexural strengths of lightweight concrete and increase its impact resistance at the same time. For constructing a five-story building, by replacing cement with microsilica by 10 wt%, the amount of used cement is reduced by 5 tons, consequently producing 4,752 kg less CO2 that is a significant value for the environment.Originality/valueThe study provides a basis for making sustainable lightweight concrete with high strength against compressive, flexural and impact loads.