Percentage Of Metakaolin Research Articles

Influence of Steam Curing on the Performance of High-strength Concrete Incorporating Metakaolin

This study aims to investigate the influence of steam curing on the performance of high-strength concrete incorporating metakaolin. An experimental study was conducted to investigate the compressive strength, chloride permeability, initial surface absorption, and water absorption, as well as thermal degradation under various steam curing scenarios. Four concrete mixtures were prepared in this study, each with different percentages of metakaolin, as partial substitution of cement weight of 0%, 5%, 10%, and 15%. The water–binder ratio was set to 0.32 in all mixtures. The specimens underwent steam curing for 0, 4, 8, and 16 hours at a temperature of 55 °C. Results indicate that the specimens that have been steam cured and contained metakaolin exhibit improved compressive strength during the initial stages of their strength development. Steam curing has been demonstrated to enhance the concrete’s resistance to chloride penetration and reduce initial surface absorption while increasing water absorption. The optimal replacement of cement with metakaolin to enhance strength and transport properties in high-strength concrete under steam curing regimes is between 10% and 15%. Future research could examine the effects of long-term steam curing on the durability and performance of concrete incorporating an optimal proportion of metakaolin.

Statistical Model for Compressive Strength of Metakaolin Concrete

In the present research work, investigations were carried out to improve the performance of concrete in terms of strength by incorporating metakaolin (MK) as mineral admixture in concrete. Parametric study was carried out by considering w/c ratio, various percentage of MK and age of concrete as parameters to understand the effect of each parameter. The study was conducted for different w/c ratios of 0.32, 0.35, 0.4 and 0.5. The MK proportion was varied from 0 to 15% with an increment of 5% and age of concrete from 3 to 90 days were considered and experiments performed accordingly. The effects of above said parameters on the various properties of concrete such as workability, compressive strength and pH of concrete were investigated, and the results of metakaolin concrete were compared with the conventional concrete. From the results, it was observed that MK concrete showed greater strength for higher water cement ratios (0.4 & 0.5). A Multiple non-linear regression analysis was used to develop a statistical model to predict the strength and found to have good correlation between the observed and predicted values. It was concluded that the concrete developed in this study have significant potential for use on real time projects.

Recycled Incineration Bottom Ash and Metakaolin as Sustainable Materials for Cement Replacement in Cementitious Composites

Study was related to the influence of the concrete properties by using different percentages of metakaolin and fixed percent of incineration bottom ash to partially replace the cement. Cement is a well-known building material and used for the construction in the world. Moreover, the used of metakaolin (MK) and incineration bottom ash (IBA) in this research would give significance to our environment as it can reduce the usage of cement in concrete. By using bottom ash, it could reduce the land filling space. The X-Ray Fluorescence (XRF) test was used to determine the chemical composition of IBA and MK. Four series of concrete have been examined, including control, IBA and MK were used as partial replacement for cement at 10%IBA + 10%MK, 10%IBA + 15%MK and 10%IBA + 20%MK of concrete mixes by volume. The curing period for the samples is 7 days and 28 days. To determine the properties of concrete, the tests such as slump test, density test, water absorption test, pulse velocity test, rebound hammer test and compression test were performed. The results proved that the strength development of 10%IBA + 10%MK concrete sample shows the highest compressive strength after 28 days of curing.

Effect of Metakaolin on Properties of Lightweight Porcelinate Aggregate Concrete

Research in Iraq has expanded in the field of material technology involving the properties of the lightweight concrete using natural aggregate. The use of the porcelinate aggregate in the production of structural light concrete has a wide objective and requires a lot of research to become suitable for practical application. In this work metakaolin was used to improve compressive strength of lightweight porcelinate concrete which usually have a low compressive strength about 17 MPa . The effect of metakaolin on compressive, splitting tensile, flexure strengths and modulus of elasticity of lightweight porcelinate concrete have been investigated. Many experiments were carried out by replacing cement with different percentages of metakaolin. The metakaolin was replaced by 5%, 10%, 15% and 20%. A control reference mix without metakaolin was made for comparison purpose. For all mixes, compressive, splitting tensile, flexure strengths and modulus of elasticity were determined at 28-day. The results showed that the using of metakaolin improve the compressive, splitting tensile, flexure strengths and modulus of elasticity of lightweight porcelinate concrete. The higher compressive, splitting tensile, flexure strengths and modulus of elasticity were found for 15% metakaolin.

A comprehensive GEP and MEP analysis of a cement-based concrete containing metakaolin

Due to the detrimental environmental consequence of cement formation, studies has concentrated on decreasing the environmental influence and expense of cement containing products. It is crucial to conduct research on the mechanical characteristics of cement additive/replacement products such as metakaolin (MK). To serve the said purpose, the importance of developing predictive machine learning (ML) models is growing as ecological concerns intensify. Since there are few ML approaches for them, it is imperative to develop techniques to improve the mechanical properties of such products. In order to overcome these issues, this research examines ML methods for forecasting the compressive strength (fc') of concrete containing MK. Gene expression programming (GEP) and multigene expression programming (MEP), two distinct ML predictive models, are provided in detail along with the most useful variables, enabling effective analysis and forecasting of the fc' of concrete containing MK. An important component of any prediction or simulation endeavor is model generalization, and the researchers of this study used a data set of MK concrete mechanical properties for this purpose. The database has 405 data points with pertinent model parameters to calculate the fc' of concrete containing MK. Cement, percentage of metakaolin by binder, coarse and fine aggregate by binder, water by binder, coarse aggregates by fine aggregates, percentage of superplasticizer by binder, and age are among the factors in the database that influence concrete's fc' yet still previously infrequently regarded as crucial input attributes. The effectiveness of the models is then examined in order to choose and implement the best predicted model for the mechanical properties of MK-based concrete. According to the findings of this research, the optimal ML algorithms for forecasting MK-based concrete fc' is MEP with R2 value of 0.96. Additionally, the sensitivity analysis shows that water-by-binder, percentage of superplasticizer-by-binder and age have the significant effect on the development of compressive strength of metakaolin based concrete. GEP and MEP models develop empirical expression for the outcome to forecast future databases' features to promote the usage of sustainable MK concrete. Moreover, detrimental effects caused by intensive and costly labor work can be overcome by utilizing these environmental-friendly techniques.

Suitability of ceramic industrial waste recycling by alkaline activation for use as construction and restoration materials

Ceramic is one of the prominent sources of waste in Europe. Its aluminosilicate composition, together with the relatively high amount of amorphous phase, makes it suitable as a potential precursor for alkali activated products. The technical characteristics of these kinds of materials, as well as the aesthetic appearance, determine a good applicability in the field of construction and for restoration purposes. This research aimed to investigate the suitability of ceramic industrial tiles waste through the alkaline activation process for the production of novel and eco-friendly materials. The applicative goal was the implementation of binder formulations to be used for the production of eco-sustainable bricks, tiles, mortars and decorative elements. The results showed that pure ceramic based geopolymers and binary mixtures obtained by adding few percentages of metakaolin can be produced at room temperature by only using sodium hydroxide and waterglass, reaching efficient technical characteristics for their employment in restoration. This work represents a starting point for future development of ceramic based geopolymeric products to be employed in construction and restoration field.

Prediction of rapid chloride penetration resistance of metakaolin based high strength concrete using light GBM and XGBoost models by incorporating SHAP analysis

• Light GBM and XGBoost prediction models for estimating RCPT of metakaolin-containing concrete. • Accuracy Analysis of the developed models using statistical evaluation. • Optimization of water-binder ratio and percentage of metakaolin using interpretable machine learning SHAP analysis. • Light GBM surpasses in accuracy compared to XGBoost. This study investigates the non-linear capabilities of two machine learning prediction models, namely Light GBM and XGBoost, for predicting the values of Rapid Chloride Penetration Test (RCPT). Chloride penetration is one of the most significant issues affecting reinforced concrete (RC) structures, which necessitate frequent maintenance and repair. The mix design of concrete play a vital role in the formation of pore structure that is relatively more resistant to chloride attacks. For estimating the chloride resistance of concrete, 201 experimental records, incorporating aging of concrete, binder content, water-binder ratio, percentage of metakaolin, and content of fine and coarse aggregates as input variables. The models were trained using grid search optimization for tuning setting parameters to yield the best performance for the models. The performance of the models using statistical indices indicated LightGBM surpasses in prediction accuracy as compared to XGBoost model. The coefficient of determination (R 2 ) values revealed 0.9738 and 0.9379 for LightGBM and XGBoost models, respectively. The minimum value of MAE was recorded for the training data of the LightGBM model equalling 172.7 C. The best fit model, i.e., the LightGBM model, was used for SHAP analysis to see the relative importance of contributing attributes and optimization of input variables. The SHAP analysis revealed f c ’, aging, and W/B ratio as most significant in yielding RCPT, whereas individual interpretation of Shapley values showed that W/B ratio of 0.30 – 0.35 and 15% MK replacement highly resisted chloride penetration at higher compressive strength values.

An experimental study on self compacting geo-polymer concrete containing Metakaolin at ambient curing condition

The production of cement consumes considerable energy and releases a huge amount of CO2 which is not eco-friendly. One of the possible alternatives is to use alkaline activated binders with the by-products obtained from industries such as fly ash and Ground Granulated Blast Furnace Slag which includes the silicate materials. Accordingly, the worlds suggested innovative concrete; Geopolymer Concrete exhibits mechanical and durability properties against the OPC. Special concretes should possess the ability to flow, pass through small spaces and should be able to fill the narrow gaps of the congested spaces in the structural elements. Self Compacted Concrete is one such special concrete, originally developed in Japan which can handle the workability and durability issues without sacrificing the strength. In the following study, detail investigation of experimental studies is carried out to derive Self Compacting Geopolymer Concrete (SCGPC) with powder content of Fly ash, GGBS and Metakaolin (MK). Superplasticizer is used to improve the workability. Different percentages of GGBS and MK are individually and combinedly added to the constant amount of Fly ash to study the varying results. The Fresh property of concrete are analysed by conducting Slump flow, V Funnel T50 sec, L- box test procedures. Hardened properties are derived by tensile, flexural and compressive strength tests. The study resulted that after the addition of Superplasticizer and presence of Mk shows good workability and the hardened properties improved with increase in percentages of MK and GGBS.

Metakaolin Addition to Improve Geopolymerization Process and Properties of Waste Clay-Based Materials

The exploitation of different kind of clayey waste (halloysitic, smectitic/illitic, kaolinitic) for the production of geopolymers in the view of a circular economy of mines is the main goal of this study. In particular, the addition of low percentages of metakaolin (5-15%) was evaluated to improve the chemical-physical properties and the consolidation degree of geopolymeric formulations produced with clays classified as mine’s by-products. In fact, these secondary raw materials are often not sufficient alone to obtain chemically stable formulations with acceptable mechanical properties but require the addition of reactive fillers. All samples contained thermally treated clays (600°C-700°C) and metakaolin as aluminosilicate precursors, alkaline solution of NaOH and Na2SiO3, and were cured at room temperature. The influence on the final products with MK addition was monitored with the evaluation of the chemical stability in water (pH and ionic conductivity measures), the comparison of setting times (Vicat needle) and mechanical performance.

Influence of metakaolin as a partial replacement of cement on characteristics of concrete exposed to high temperatures

The ever-increasing construction demand for the human and high energy consumption of the production of the raw material has a significant impact on environmental pollution. One of the challenges facing civil engineers is to understand the behavior of concrete during exposure to elevated temperatures, and their service life performance after exposure. In this study, the possibility of partial replacement of cement with metakaolin on the improvement of concrete properties is investigated. The dosage of metakaolin is 10, 15, and 20% of cement weight. After determining the optimum percentage of metakaolin at ambient temperature, the specifications of the specimens are tested at temperatures of 28–800 °C. Although high temperatures damage the mechanical and durability characteristics of normal concrete, the substitution of 15% of cement weight with metakaolin can be recommended as a practical solution to improve the mechanical and durability properties of concrete exposed to elevated temperatures.

Use of Nondestructive Testing of Ultrasound and Artificial Neural Networks to Estimate Compressive Strength of Concrete

The work presents the results of an experimental campaign carried out on concrete elements in order to investigate the potential of using artificial neural networks (ANNs) to estimate the compressive strength based on relevant parameters, such as the water–cement ratio, aggregate–cement ratio, age of testing, and percentage cement/metakaolin ratios (5% and 10%). We prepared 162 cylindrical concrete specimens with dimensions of 10 cm in diameter and 20 cm in height and 27 prismatic specimens with cross sections measuring 25 and 50 cm in length, with 9 different concrete mixture proportions. A longitudinal transducer with a frequency of 54 kHz was used to measure the ultrasonic velocities. An ANN model was developed, different ANN configurations were tested and compared to identify the best ANN model. Using this model, it was possible to assess the contribution of each input variable to the compressive strength of the tested concretes. The results indicate an excellent performance of the ANN model developed to predict compressive strength from the input parameters studied, with an average error less than 5%. Together, the water–cement ratio and the percentage of metakaolin were shown to be the most influential factors for the compressive strength value predicted by the developed ANN model.

Effect of MK and SF on the concrete mechanical properties

This paper inspects the impact of MK and SF on the mechanical properties of concrete. In this study the replacement percentage of cement with Meta-kaolin was ranged from (7–8%) and the addition of silica fume by (15%). The results showed that the obtained compressive strengths, split tensile strengths and flexural strengths for the concrete have been determined that all results of the tests have been increased while increasing the meta kaolin ratio up to 7%. later there is a little decreasing in the strength for overflowing use of meta kaolin up to 7.5% and 8% which decreases the ratio of w/c and postponement the activity of a pozzolan. The maximum value of strength with the 7% ratio of meta kaolin addition is sufficient because the meta kaolin amount reacts with the calcium hydroxide which speeds up the hydration of cement and creates gel of C-SH. From the results the best percentage of Meta-kaolin can be replaced with cement is (7%) with addition of silica fume by (15%).

Mechanical properties of green concrete

The engineering properties inspection of green concrete resulted from using Metakaolin to replace cement and crushed tiles as waste coarse aggregates is the main aim in this work study. Different concrete mixtures were prepared in order to obtain 30 MPa target strength for concrete in compression. The crushed tile as waste aggregates is used to substitute crushed gravel as natural aggregate with ratios of 0 to 100% in the concrete mixtures and the mixture properties were inspected. It is revealed that employing Metakaolin in the replacement of cement and crushed tile to substitute a ratio of crushed gravel affects all concrete properties such as; elastic modulus, tensile strength, and compressive strength. The difference relies on the percentages of Metakaolin and aggregate substituted. The optimum percentages for both Metakaolin and waste aggregate were found to be 20% and 25% respectively which can be used to produce green concrete with acceptable properties and solve a very important environmental problem. The ACI 318 code equations for estimating the spilt cylinder and modulus of elasticity are used and it is revealed that these equations give overestimated values for green concrete having waste aggregate with percentage exceeding 25%.

An Experimental work on Reactive Powder Concrete using Quartz Sand and Metakaolin

Reactive Powder Concrete is a Concrete which does not have fine &coarse aggregate in it. It is due to the high cost in coarse aggregate and at the same time scarcity of the fine aggregate. RPC is also consists of fully a partially replacement of cement .so we are using partially replacement of cement. Where it is a special concrete and the microstructure is optimized by precise degree of all particles in the mix yield to maximum density. It consists of metakaolin, quartz-sand and cement. Here we are replacing coarse and fine aggregate by quartz-sand, and cement is partially replaced by metakaolin. And the percentage of meta kaolin is identified by trial and error method. In this we get the compressive, flexural & split tensile strength of RPC for 28 days.

Numerical Investigation on Flexural Beams Made with Metakaolin and Shredded Plastic Waste

Among various building materials, concrete is the most widely used conventional material. Nowadays many scientists are on a hunt for a substitute material for constructionthat is eco-friendly and made from industrial waste products and offer sustainable development. In this study, cement was partially substituted by metakaolin of varying percentage as 0%, 2.5%, 5%, 7.5% and 10% by weight of cement. Shredded plastic waste of 0.5% by weight was added to concrete by replacing coarse aggregate in the concrete. M20 grade concrete is used for beams. Optimum replacement percentage of metakaolin was determined from the tests. Ultimate load carrying capacity of beams produced with the optimum replacement percentage was compared with the numerical investigation done by finite element modelling package ANSYS 12.0.

Use of extended finite element method and statistical analysis for modelling the corrosion-induced cracking in reinforced concrete containing metakaolin

This study presents an improved technique to predict the time for corrosion-induced cracking in concrete containing metakaolin (MK) based on combining extended finite element model (XFEM) and statistical analysis. The prediction model was developed based on the percentage of MK in the mixture, binder content, water-to-binder (W/B) ratio, and concrete cover thickness. The developed model was also validated experimentally using an accelerated corrosion test. Moreover, design charts were developed in this study using statistical analysis to facilitate and simplify the use of the prediction model. The results indicated that the corrosion pressure required to crack the concrete cover increased with higher percentages of MK, higher binder content, and (or) lower W/B ratio. The most significant factors affecting the time for corrosion-induced cracking was found to be the concrete cover, W/B ratio, MK replacement, and binder content, respectively, in order of significance. The results also indicated that the time required for corrosion-induced cracking obtained from the developed prediction model showed a good agreement with the experimental results of the accelerated corrosion samples. Also, the cracks predicted by the XFEM showed a similar trend of variation with that found in the accelerated corrosion samples.

Setting up the production process of diatomite-based ceramic foams

ABSTRACTThe design of the production process of diatomite-based ceramic foams, starting from different percentages of metakaolin, diatomite, and sodium silicate solution as reactive ingredients and vegetable surfactant and silicon powder as blowing agents, has been set up. The foams were obtained using the double effect of different foaming approaches: mechanical stirring and chemical foaming. Six systems were prepared fixing the amount of diatomite (100%) and adding in the starting mixture of different percentages (0.05, 0.1, 0.25, 0.5, 0.75, and 1 wt%) of silicon metal. Once the optimal percentage of silicon metal (0.05%) is chosen thanks to XRD analysis, other three systems were prepared only changing the amount of diatomite (50, 70, and 100 wt%) in starting formulation. The foam obtained with 100% of diatomite results to be the optimized final formulation, as it shows a hierarchical porosity with a high homogeneity of the matrix at the same time. The results highlighted that the best performances in terms of lightness, high porosity as well as homogenous microstructure were obtained using, with respect to the total amount, 6 wt% of mechanical stirred vegetable surfactant together with 0.05 wt% of Si as physical and chemical blowing agents, respectively.

Time-dependence of chloride diffusion for concrete containing metakaolin

Chloride diffusion coefficient depends on many variables including concrete quality, environmental conditions, and time. In this investigation, the concrete quality and time were studied while maintaining the environmental conditions constant. Fifty-three concrete mixtures were tested based on a refined statistical analysis. Enhanced response surface method (RSM) was used to present the most significant factors affecting the chloride diffusion at different ages. The tested mixtures contained various water-to-binder (W/B) (ratios 0.3–0.5), metakaolin (MK) replacement (0–25%), and total binder content (350–600kg/m3). Bulk diffusion test was adopted for two years to determine the time-dependent coefficient m of chloride diffusion for all mixtures based on the error function solution to Fick's law. This coefficient was calculated based on two different bulk diffusion test methods: total and average methods. Design charts were developed to facilitate the optimization of mixture proportions for designers/engineers. The investigation also included some experimental relationships between the rapid chloride permeability test (RCPT), chloride diffusion coefficient, and compressive strength results. The results showed that the values of the chloride diffusion indicated a general reduction from 28 days to 760 days of testing. As the percentage of MK or binder content increased or as the W/B ratio decrease, the chloride diffusion reduction coefficients, mtotal and mavr, were found to increase. Based on the analysis of variance (ANOVA) from the statistical model, MK was found to be the most significant factor affecting the chloride diffusion at late ages (360 and 720 days), while the W/B ratio was the most significant factor affecting early ages of chloride diffusion (28 and 90 days). The developed models and design charts in this paper can be of special interest to designers/engineers by aiding prediction of service life of concrete containing MK.

Refined statistical modeling for chloride permeability and strength of concrete containing metakaolin

An experimental investigation was conducted to develop design tools using refined statistical analysis to optimize chloride permeability and strength of concrete containing metakaolin (MK). The study adopts the design of experiments (DOEs) to test 53 concrete mixtures based on enhanced response surface method (RSM). Three factors were considered: total binder content (binder), percentage of metakaolin (MK%), and water-to-binder ratio (W/B). The mixtures were examined based on the rapid chloride permeability test (RCPT), chloride diffusion test, compressive strength (fc), modulus of elasticity (MOE), splitting tensile strength (STS), flexural strength (FS), and cost of mixture per cubic meter. The developed statistical models and design charts are valid for concrete with W/B ratios ranging from 0.3 to 0.5, MK from 0% to 25%, and total binder content from 350kg/m3 to 600kg/m3. The results endorse that the obtained derived models and design charts are useful for understanding the influence of the key factors on concrete mechanical and durability properties. These models and design charts are beneficial for predicting and selecting the optimum mixture proportions for a given application in a simple and accurate way. This paper’s recommendations can be of special interest to designers considering the use of concrete containing MK in structural applications.

Properties of blended cement using metakaolin and hydrated lime

Thermal activation of Ga'ara kaolin is used to produce a good quality metakaolin. Portland cement clinker is ground and blended with 3% gypsum. In this study, two types of mixes are made: the first using 10% hydrated lime and different percentages of metakaolin as replacement by weight of the blended cement; in the second type, only metakaolin is used, without hydrated lime, in mixes as a replacement by weight of the blended cement. The aim of this study is to make a new type of environmentally friendly, blended cement with good fresh and hardened properties. Energy savings can be achieved by using materials produced as industrial by-products (metakaolin, hydrated lime). The compressive strength is 42·1 MPa for the mix with 12% metakaolin and 0% hydrated lime, and 38·8 MPa for 12% metakaolin with 10% hydrated lime, as compared to the reference mix value of 37·9 MPa at age 90 d. Blended cement can be made with 86% Portland cement fineness, adding 22% metakaolin + hydrated lime as a replacement by weight of the blend, to give almost the same compressive strength as the reference mix, with excellent soundness properties. This could reduce the annual production of cement, as well as the associated emission of gaseous pollutants from factories during the cement production process.