Partial Replacement Of Metakaolin Research Articles

Strength Assessment of RCC Beam With Partial Replacement of Metakaolin and Marble Dust

The most popular and adaptable building material is concrete, which is typically used to withstand compressive stress. A few pozzolanic elements can be added as admixtures to improve the various qualities of concrete. Calcified clay, or metakaolin, is widely accessible in Gujarat, Maharashtra, Bombay, and other places. It is the clay mineral kaolinite in a dehydroxylated state. Metakaolin particles are smaller than cement particles in size. Marble dust is produced by the industries that cut and manufacture marble. Approximately 3500 metric tons of marble dust slurry is produced daily in India. Therefore, marble dust may be found extremely cheaply and simply. Because marble dust has some advantages over cement, it is recommended to utilize it in part. The current study details an experimental program designed to explore the flexural behavior of reinforced concrete beams where river sand was partially replaced with marble powder in preparation for concrete and metakaolin was used in place of some of the cement. In this work, partial cement replacement has been carried out using MK (Metakaolin) at 5% and 10% and MP (Marble Powder) at 5%, 10%, 15%, and 20%. Concrete manufactured with MK-MP has been compared to conventional concrete of grade M30 in terms of both compressive and tensile strength. The Rapid Chloride Migration Test, or RCMT, was also used to examine the durability of concrete.

Sustainable activation of pumice with partially variable substitutions of metakaolin and/or fumed silica

AbstractSustainable alkali activation of pumice from Turkish origin was studied by a partial replacement of metakaolin and/or fumed silica additives. Following the characterization of as‐received pumice by X‐ray fluorescence spectroscopy, x‐ray diffraction, and nuclear magnetic resonance spectroscopy, a series of powder mixtures were prepared by introducing metakaolin and/or fumed silica (8, 14, and 20 M) into 1 M of the pumice. The mixtures were then dissolved in 11 M NaOH or sodium silicate solutions. The slurries were poured into polyacetal molds to obtain geopolymer samples for mechanical testing and cured in a constant 50°C temperature in a humidity oven for 48 h and then left for 1 week to undergo additional curing at ambient temperature. The microstructural, mechanical, and thermal properties of the final geopolymer samples were determined by XRD, scanning electron microscopy, Weibull analysis of 3‐point flexural and compressive tests and thermal conductivity measurements. Results showed that all the Weibull values were best for 14 M of metakaolin and/or fumed silica. The metakaolin‐added pumice yielded higher compressive strengths of (53.78 ± 33.30 MPa) than fumed silica (10.87 ± 4.04 MPa) and fumed silica plus metakaolin (41.22 ± 5.16 MPa). Thermal conductivities (0.19–0.46 Wm–1K–1) were also comparable to the thermal conductivity of metakaolin‐based geopolymers.

Strength Studies on Concrete with Recycled Aggregates and Cement with Metakaolin

Concrete is one of the most widely used construction material in the world. Recent technology has greatly improved the recycling process for waste concrete. Due to the critical shortage of natural aggregate, the availability of demolished concrete for use a recycled concrete aggregate is increasing. The study presents on the natural aggregates and recycled aggregates and also the effect of mineral admixture (metakaolin) on the strength studies. The use of metakaolin in concrete to achieve high strength and durable of concrete. The experimental work on the recycled aggregate and natural aggregates are replaced of 0%,50,100%, replacement of natural aggregate of recycled aggregates were casting in respectively the concrete mixed designed using M30 grade. In the cement partial replacement of metakaolin in 15% used for all mixtures. In the cement partial replacement of metakaolin in 5%,10%, 15%,20% used for all mixtures. The compressive strength of concrete has been determined after 7&28 days are curing compared with the results of concrete. The result shows the 15% of metakaolin and 50% recycled aggregates is high strength in concrete. The compressive strength and split tensile strength of the concrete.

Synergic effect of millet husk ash and wheat straw ash on the fresh and hardened properties of Metakaolin-based self-compacting geopolymer concrete

This experimental work explored the synergic effect of millet husk ash (MHA) and wheat straw ash (WSA) on the fresh and hardened properties of metakaolin-based self-compacting geopolymer concrete. An equal amount of MHA and WSA contents at 2.5%, 5%, 7.5% and 10% were utilized as a partial replacement of metakaolin in the mixes. The filling ability (slump flow, V-Funnel, and T50 flow) and passing ability (J-Ring and L-box) of fresh SCGC mixture were determined. The study further determined the density, compressive, split tensile and flexural strength and permeability of hardened SCGC mixes. The results showed that both MHA and WSA addition somewhat reduced in workability of fresh SCGC mixes. However, the hardened properties were significantly enhanced, a development that was more pronounced in the mix having 5% each of MHA and WSA with compressive strength, split tensile strength, and flexural strength of 53.80 MPa, 4.82 MPa, and 5.15 MPa, respectively. The water penetration depth and density of SCGC mixes lessen as the MHA and WSA contents were increased beyond 10%. Overall, the study recommends a combined use of 5% each of MHA and WSA for metakaolin-based geopolymer SCC production to ensure optimal performance.

Rheological properties of self compacting concrete with partial replacement of metakaolin in cement and plastic fibre

This work deals with the experimental study of SCC with plastic fibre and metakaolin. Metakaolin with 20% replacement for cement and also addition of plastic fibre in SCC are tested. The influence of mineral admixture and the addition of plastic fibre in physical and mechanical properties in SCC are investigated. Plastic fibre is added to SCC with five various ratio are 0%, 0.25%, 0.5%, 0.75% and 1%respectively. The fresh concrete is tested by L – box test, V – funnel test and U – box test. The hardened concrete is tested by compressive test, flexural strength test and split tensile test. The properties of fresh concrete demonstrated that filling and passing capability of SCC are weak because of introduction of plastic fibre but are not greatly affected the properties. The hardened concrete properties show that metakaolin and plastic fibre has an impact on the strength of SCC.

Feasibility study of MK-based geopolymer binder for RAC applications: Effects of silica fume and added CaO on compressive strength of mortar samples

The results of a preliminary case study of the effects of silica fume and additional calcium oxide (CaO) on the compressive strength of a metakaolin-based geopolymer binder developed to exhibit appropriate properties for use in recycled aggregate concrete (RAC) are presented. Using recycled aggregates in new concrete has significant environmental benefits but also presents significant challenges to the applicability of the technology, and using geopolymer binders in place of ordinary Portland cement (OPC) has the potential to solve some of these challenges. The study presented in this paper suggests that partial replacement of metakaolin with silica fume results in increased strength while additional CaO may only have limited effectiveness in certain applications. Additionally, it was observed that the activator-to-binder ratio has a much more significant effect on the strength than the water-to-binder ratio. It is concluded that, with some optimization, a geopolymer binder with appropriate strength can be developed for use in RAC applications.

Characteristics of Eco-Friendly Metakaolin Based Geopolymer Concrete Pavement Bricks

The purpose of this work is to investigate the possibility to recycled and reused of waste clay brick and waste plastic as constituents in the production of green Geopolymer concrete paving bricks. Powder of clay brick waste (WBP) was used as a partial replacement of Metakaolin (MK) in Geopolymer binder. Moreover, recycled clay brick waste aggregate (BA) and plastic waste aggregate (PL) were incorporated as coarse aggregate in mixtures of Metakaolin based Geopolymer concrete (MK-GPC) pavement bricks. Six types of mixtures were prepared and cast as pavement bricks with dimensions of 150×150×100 mm. All samples have been tested for compressive strength, water absorption and abrasion resistance at age of 28 days; and compared the results with the requirements of Iraqi specification No.1606-2006. The MK-GPC pavement bricks present a compressive strength of 31-47MPa, water absorption of 3.66% to5.32% and abrasion resistance with groove length between 21.78mm to 18.91 mm. These types of pavement bricks are classified as a medium to light capacity for weight loading, and it is possible to be used in wide range of paving applications, especially in aggressive wearing environment.

Partial replacement of metakaolin with red ceramic waste in geopolymer

Metakaolin was incrementally replaced (33.3%, 50% and 66.6%) by red ceramic waste in geopolymer formulation to study the effect on geopolymerisation and its resultant properties. The geopolymer binders composed of two calcined aluminosilicates (viz. Metakaolin and Red ceramic waste), NaOH and sodium silicate. In the experimental compositions, metakaolin was replaced gradually up to 66.6% in the clay fraction, the Si/Al increased from 3.36 to 5.16 and Na/Al increased from 0.93 to 1.38. The FTIR spectroscopic studies of geopolymer pastes along with XRD analysis indicated that the red ceramic waste partly reacts with alkali and takes part in geopolymer formation. Replacement of 33.3% metakaolin by the red ceramic waste in geopolymer binder did not reduce the compressive strength with respect to the pure metakaolin geopolymer here. Additional replacement resulted in a drastic decrease in the compressive strength of the geopolymer binder. However, the compressive strength of geopolymer mortars revealed interesting synergy between the amount of binder and particle packing in the mortar. Despite having a lower amount of binder phase, mortars with 33% and 50% red ceramic waste exhibited maximum compressive strength values. This has been attributed to improved particle packing through incorporation of red ceramic waste particles.

Modeling Heterogeneous Grades of Aggregate on Partial Replacement of Metakaolin on Compressive Strength of Concrete

The pursue for high strength by experts to monitor the growth rate of high-performance concretes has definitely improved...

Thermal Insulation Enhancement of Metakaolin-Based Geopolymer Concrete Using Waste Clay Brick

Geopolymer concrete is one of the sustainable building materials that has a low energy production and a minimum carbon footprint. In this study, the effect of utilization waste clay brick on the thermal conductivity (TC) of Metakaolin geopolymer concrete (MK-GPC) was investigated. The waste of clay brick was used in two series of mixes, first one included clay brick waste powder (BP) as partial replacement of Metakaolin (MK) at weight dosage 10%, 15%, and 20%, while the second group of mixes contained crushed clay brick waste aggregate (CBA) at replacement level of 10%, 20% and 30% by volume of natural coarse aggregate. In addition to (TC), all the specimens were tested to determine the ultrasonic pulse velocity (UPV), and voids content at 7 and 28 days. The results of the samples with 10% and 15% BP have shown higher UPV and less voids content, while the incorporation of CBA aggregate at 20% and 30% caused reduction in UPV and increased the voids in MK-GPC mixture. Furthermore, the addition of the waste clay brick in both forms (powder and aggregate) has improved the results of thermal insulation. Conclusively, reusing of waste clay brick as ingredients in MK-GPC will provide a super-sustainable geopolymer concrete with advanced thermal insulation properties.

Effect of alkali-mixed content and thermally untreated phosphate sludge dosages on some properties of metakaolin based geopolymer material

In the present work we investigate the possibility of reusing phosphate sludge, which is considered as a mining by-product from beneficiation plants of the Moroccan phosphate rocks (OCP, Youssoufia), through the geopolymerization process. This process allows to evaluate the alkaline behaviour of thermally untreated phosphate sludge (UPS) as a partial replacement of metakaolin. The geopolymers were synthesized with various activator modulus (Ms = 1.40, 1.30, 1.24, 1.20, and 1.15) made from a mixture of different alkaline (NaOH and KOH) solutions and sodium silicate. The effect of 0–60% untreated sludge (UPS) powder in metakaolin based geopolymer materials cured at 60 °C was investigated. Compressive strength and apparent porosity were determined after 28 days of curing and the reaction products were tested by different techniques including: X-Ray Diffraction (XRD), Fourier Transformed Infrared spectroscopy (FTIR), thermal gravimetric analyses (TGA) and Electron microscope scanning coupled with energy dispersive spectroscopy (SEM-EDX). For up to 50% of UPS, physical properties of the hardened products are induced, especially when the activator modulus (Ms = 1.30) is used. In these blends, the presence of UPS is favorable to ensure the better connectivity between grains in the system. In fact, the sludge has been suggested to have a dual role, it has a filler effect and/or a small precipitation of Ca-bearing phases co-existing with (Na, K)-A-S-H-type gel.

Partial replacement of metakaolin with thermally treated rice husk ash in metakaolin-based geopolymer

The influences of rice husk ash (RHA) on the reaction kinetics, mechanical property, and microstructure of metakaolin-based geopolymer (MG) were investigated. Geopolymer pastes containing different contents of RHA were prepared by sodium silicate activation. Analysis results show that both metakaolin and rice husk ash are involved in the geopolymerization, contributing to the development of mechanical properties and formation of compact microstructure. The longer reaction duration of setting time in the group incorporated RHA was ascribed to the procedure of SiO2 dissolution. The geopolymers added with RHA have a compact pore structure, which show a relatively high compressive strength. The replacement of metakaolin by RHA did not cut the total quantity of gel phase formation, but changed the form of partial gels existence and an optimal mixed point was reached at the 20% replacement level. The abundant in gel along with the pore channel and secondary filling effects make a significant contribution to the development for refinement of pore and improvement of strength. This study can be used as an indicator for the application of RHA in geopolymer, which is of great value in urging RHA towards realization in recycling.

Improving insulation in metakaolin based geopolymer: Effects of metabauxite and metatalc

To improve the thermal stability of porous geopolymers, metabauxite and metatalc were used as partial replacement of metakaolin. The results of optical microscopy, Scanning Electron Microscopy (SEM), thermal sintering, mercury intrusion porosimetry (MIP) and hot disk investigations, were used to establish the effective stability of the porous composites up to 800 °C. At 1000 °C, the metabauxite based composites showed microcracks into the larger pores and small microcracks into the matrix as the results of residual poorly bounded Alumina oligomers. Metatalc based porous composites showed microcracks only inside larger pores. Those microcracks can be eliminated with the optimization of the mix-design. Despite those microcracks, the specimens maintained their integrity and stability. Above 800 °C it can be seem that the thermal conductivity of the matrices with only metakaolin increases more rapidly compared to matrices containing metatalc or metabauxite. The combination of high volume of porosity (60–65%), low thermal conductivity ( ̴ 0.30 W/m/K) and good thermal stability gives to porous refractory geopolymers a large scale of intrinsic properties that can be positively exploited in the field of incinerators, anti flames, kilns and building constructions.

Response of Refractory Cement Based Composite to Gradual Temperature Loading

This paper deals with the experimental study of the response of refractory concrete mixture to gradual thermal loading, up to 1000 °C. A binding system based on calcium aluminate cement (CAC) modified by the partial replacement of metakaolin was used. Short ceramic fibers were applied in a dose of 4% by volume in the studied mixture. Material transformations due to thermal loading were monitored in terms of residual mechanical, fracture and basic physical properties-compressive strength, flexural strength, fracture energy, dynamic modulus of elasticity, and bulk density in the study. The results obtained corresponded well with the mineral transformations monitored using the thermogravimetric analysis performed on the binder paste. Residual values of compressive and flexural strength were approximately 40% of the initial values after exposure to a temperature of 1000°C; however, the dominant part of the total loss was monitored up to 400°C, due to decomposition of the hydrates. Fiber employment contributed considerably to the resistance against thermal loading up to 400°C, which was demonstrated by the fracture energy results (a loss of 25% was monitored). An additional increase of the temperature load led to micro crack propagation, which was obvious in the results of dynamic modulus of elasticity determination, in which the short fiber incorporation was noticeably limited.

The effect of matrix composition and calcium content on the sulfate durability of metakaolin and metakaolin/slag alkali-activated mortars

The work in hand presents the results of an experimental research on the effect of different precursors (binders) used in alkali-activated materials (AMM) and its composition (i.e. SiO2/Al2O3 molar ratio) on their sulfate durability. A reference matrix is formed from the activation of metakaolin (MK); this matrix was modified by the partial replacement of MK with either 20wt% silica fume (SF) or 20 and 40wt% blast furnace slag (BFS), so that the SiO2/Al2O3 molar ratio of calcium-free and calcium-rich AAM changed from 3.0 to 3.9. The properties assessed prior to the durability testing were: density (pycnometry), compressive strength, capillary sorption and oxygen permeability. The sulfate durability was investigated by exposing the matrices to a magnesium sulfate solution for 30, 90 and 180 days of attack, after which the residual compressive strength was determined. The reductions in strength after each period of testing were correlated with variations in the pH of the sulfate solutions and with geometry changes (expansion) measured in cylinders exposed to the durability tests. X-Ray diffraction was used to determine the minerals formed onto the surface of the samples after magnesium sulfate attack. The results show that the MK-based AAM present a higher resistance to magnesium sulfate attack. Furthermore, the partial replacement of MK with BFS is responsible for reductions in the mechanical properties after attack to sulfate. This is associated with the formation of ettringite and gypsum in the presence of calcium from BFS, besides the loss of alkalinity from the migration of alkali (Na+) to the solution.

Production of Geopolymeric Mortars Containing Forest Biomass Ash as Partial Replacement of Metakaolin

Geopolymers are a new class of binders based on alkali activation of natural and by-products raw materials. Their properties and eco-compatibility highly depends on the reaction system. The (Na,K)2O-Al2O3-SiO2-H2O system shows a distinguishing pseudo-zeolitic network structure, but reaction requires a high amount of activators. The aim of this work is to investigate how the use of forest biomass ash (FBA), as partial replacement material in the production of metakaolin (MK) based geopolymeric mortar, and affect its properties. FBA is a by-product of the combustion process of forest biomass in thermal power plants. Mortars with a FBA content of 0%, 10%, 20%, and 30% wt have been tested for workability, flexural, and compressive strength. Capillary absorption, micro-morphological features, thermal, and shrinkage behavior have been investigated. The addition of FBA allowed for a decrease in the use of alkaline activator up to 20%, while preserving the characteristic broad hump centered at approximately 28° 2θ Mechanical properties of the geopolymeric mortars decrease proportionally with metakaolin replacement, even if a compression strength of more than 35 MPa is still obtained with a FBA content of 30% wt. After thermal cycles of up to 700 °C, all of the mortars still retain their cohesiveness, with an overall loss of mechanical strength of about 80% of the initial value that can be attributed to the formation of microcracks as a consequence of the network strain and distortion due to dehydration and shrinkage.

Water treatment sludge and rice husk ash to sustainable geopolymer production

Water Treatment Sludge (WTS) comes from a basic sanitation service and has increased generation. In Brazil, WTS is widely discarded into watercourses, or when it is treated to increase the solids content, the residue is landfilled. The objective of this research was to produce geopolymer using non-calcined WTS as partial replacement of metakaolin (MK). The alkali source was an alternative sodium silicate solution made from the mixture of NaOH and rice husk ash (RHA). MK was partially replaced by WTS in the proportions of 0%, 15%, 30%, and 60% in mass. Additional RHA was used in the geopolymer mixtures to keep SiO2/Al2O3 molar ratio constant. Geopolymer mortars were cured at room temperature. Mechanical properties and durability characteristics were investigated. WTS replacement decreased the flow, flexural and compressive strengths, and increased porosity and permeability of geopolymer mortar. The replacement of 15% of MK by WTS had 25 MPa of compressive strength at 28 days, which is a good result to make concrete or building components. The results show that the use of non-calcined WTS and sodium silicate solution from RHA in geopolymer is technically feasible, resulting in a sustainable and environmentally friendly alternative for WTS and RHA disposal.

Experimental Investigation of Compressive Behaviour of Pier by Partial Replacement of Metakaolin

Objectives:The main focus of our experimental investigation is to study the behavior of a pier based on variations in compressive strength due to partial replacement of cement with metakaolin in order to attain maximum stiffness and strength, so as to withstand the shear forces, bending moments and other related structural response parameters efficiently. Analysis: The round and rectangular specimens were prepared by replacing cement with metakaolin up to 15%. The samples were tested after 7 and 28 days. Findings: Study reveals that with the replacement of 10% metakaolin in both circular as well as rectangular moulds, there is an increase in the load carrying capacity approximately about 19%, when compared with plain reinforced concrete moulds after 28 days. The most important finding is that the replacement of cement by metakaolin up to 10% helped us to attain higher strength after 7 as well as 28 days hence providing us a simple and efficient method of preventing the pier failure by attaining higher strengths. Improvement/Applications: Based on the test results there is remarkable increase in the load carrying capacity of pier which enhances the rigidity of pier in terms of strength and stiffness.

Recycled natural wastes in metakaolin based porous geopolymers for insulating applications

The effectiveness of two amorphous silica based wastes, rice husk ash and volcanic ash powders, used to act as structural reinforcement and partial replacement of metakaolin in porous matrices for thermal isolation was assessed. Both wastes produced colloidal phase that contributed to improve the reactivity and homogeneity of the matrices enhancing the mechanical strength. Rounded pores were obtained in relation with significant reduction of the interpore partitions under controlled addition of the blowing agent. The bulk thermal conductivity decreased from 0.6 to less than 0.15Wm−1K−1 with the increase of the concentration of blowing agent. The final matrix presented pore size distribution and pore connectivity that allows analytical description and prediction of their effective thermal conductivity.Results demonstrated that clear relations can be established among the viscosity of the pastes, chemical composition, amount of blowing agent and the volume expansion/pore size distribution.

Using fly ash to partially substitute metakaolin in geopolymer synthesis

Metakaolin-based geopolymers containing between 0 and 40% fly ash were prepared, to study the influence of fly ash substitution on the reaction process and products. At constant liquid/solid ratio, the partial replacement of metakaolin by fly ash reduces the rate of reaction, but the reaction continues for an extended duration and so is still able to achieve a relatively high extent of reaction and provide a comparable 28-day compressive strength when the replacement is less than 30%. The replacement of 10% of the metakaolin by fly ash gives an increased reaction extent (as measured by isothermal conduction calorimetry), and also a higher 28-day compressive strength, by 15%. The porosity of the geopolymer increases with the level of fly ash replacement, and pore refinement and ongoing reaction of fly ash particles during the first month of curing are also apparent.