Use Of Metakaolin Research Articles

Physical and Mechanical Properties of Concrete with Locally Produced Metakaolin and Micro-silica as Supplementary Cementitious Material

Malaysia is among the countries that have abundant reserves of raw material to be used to form metakaolin (MK). Only a few studies are available in the literature, which examines the potential of the development of metakaolin through calcination and its use as supplementary cementitious material (SCM). The use of MK as SCM is essential to utilise the local resources and to reduce the carbon footprint and embodied energy in the use of cement. Thus, MK developed at laboratory scale, produced through using local source, is compared with the commercially available micro-silica by investigating their properties in this paper. The concrete made of MK and micro-silica was tested under compression, split tension and bending. The comparison of the phase difference between MK and micro-silica had carried out through X-ray diffraction pattern. Besides, an interfacial transition zone of concrete made of MK and micro-silica had observed through field emission scanning electron microscopy. A total of three mixes of concrete had prepared, out of which one was without cement replacement and served as control mix. The remaining two mixes were 10% cement replacement with micro-silica and MK. The results showed that MK has high reactivity with portlandite in concrete due to its irregular structure and the amorphous phase. The compressive strength was 4% higher with MK as compared to micro-silica at an early age. MK concrete displayed a higher split tensile strength of approximately 14% and 35% and a higher load-carrying capacity of approximately 15% compared to micro-silica and competitive with control concrete at ages 7–90 days.

High-temperature effects on white cement-based slurry infiltrated fiber concrete with metakaolin and fly ash additive

In this present study, the high flexural parameter properties of SIFCON were examined, while the use of metakaolin and fly ash with PC 52.5 CEM I R was examined. 5 series were prepared and replaced with metakaolin and fly ash 25% and 50%. 5% of steel fiber was used in all series and the results of 7 and 28 days flexural and compressive strengths, and ultrasonic pulse velocity were examined. Given the 28-day test period, strength increase was observed in metakaolin-added samples, while lower results were obtained in fly ash-added samples since fly ash has not yet been completely hydrated. When the 28-day compressive and flexural strength results were examined, the highest results were achieved with 57.39 MPa and 44.53 MPa in series 4 with the pozzolans’ hydration. SIFCON is a material that can be used in different areas, such as military buildings. In these buildings, it is necessary to examine the circumstances after the impact of the explosion and fire. For this purpose, high-temperature testing is required. After the 200, 400 and 600 oC of temperature test, the results of flexural and compressive strengths, ultrasonic pulse velocity and weight loss were examined. The increase in strength after the 300 oC temperature can be caused by drying shrinkage of the matrix, whose C-S-H structure is not yet intact, and compression of the fiber wall. The conversion from Ca(OH)2 to Cao begins at about 400 oC, and the C-S-H structure is quickly destroyed as it approaches 600 oC. Cracks in the distribution, similar to the branching of cracks in non-fiber samples, were much narrower on the surface of SIFCON samples

Evaluation of the mechanical properties of high-strength cement paste at elevated temperatures using metakaolin

This paper presents a wide experimental study, in which it evaluates the performance of high-strength paste exposed to elevated temperatures up to 900 °C. Several factors have been investigated at the age of 90 days, i.e. metakaolin (MK) dosages, water to binder ratio (w/b) as well as elevated temperatures. Results proved that MK improves the relative residual compressive strength and relative residual bending strength showing a gain up to 52% and of 71% at 500 °C, respectively, compared to the pure cement paste in case of 0.3 w/b. The maximum use of MK is not more than 12%, and the optimum dosages were 9, 12, and 12% of MK replacements for 0.3, 0.35, and 0.4 w/b, respectively. The optimum dosage could change with changing w/b ratio and this up to the density of the microstructure which is controlled by the amount of w/b ratio and the packing effect of MK amount. In addition to the mechanical properties, the adoption of MK decreases the cracking of the specimens at elevated temperatures. SEM investigations show the positive physical morphology contribution of MK, specific surface area as well as its chemical composition for decreasing the Ca(OH)2 effect. Different phases that formed during temperatures elevation are illustrated by TG analysis. Results showed the reason behind using MK on the cracking enhancement and mechanical properties improvement after high temperatures exposure. Meanwhile, the obtained optimum MK dosages at ambient temperature are not similar to that obtained at elevated temperatures.

Effect of microbial solution on compressive strength, water absorption and sorptivity of cement mortar incorporated with metakaolin

Recent researches in literature have established that the overall life of mortar used in plastering works can be improved by the self-healing processes. Cracking of mortar plasters is a common hurdle due to the intrinsic brittleness of the material. This will result in severe loss of durability and water tightness. There are various methods to prevent this problem, such as adding glass fibers to the mortar mix which prevents shrinkage cracks is one among them and another way to do it is with the help of microorganisms that precipitates calcium carbonate which fills the cracks. But not all kinds of bacteria will precipitate calcium carbonate. Even if it does it should survive under extreme conditions present in mortar. The species called bacillus is a kind which fulfills those conditions is used in this project. The two bacteria namely “Bacillus Subtilis” and “Bacillus Megaterium” were isolated by taking 10g rhizosphere soil and they are cultured. The objective of this project is to compare the productivity of two bacteria. Along with this, a material called metakaolin is also used in combination with bacteria and its efficiency is also checked. The use of metakaolin (kaolinite) in this project increases compressive strength, decreases the heat of hydration which in turn increases the efficiency of calcium carbonate (CaCO3) precipitation along with bacteria. Mortar cubes are cast in different combinations to observe the compressive strength by Compression Test, healing capacity of mortar through Ultrasonic Pulse Velocity (UPV) Test and the precipitated amount of calcium carbonate via X-ray Diffraction Test. Also, the durability of mortar cubes has been identified using Water Absorption Test and Sorptivity Test.

Valorization of calcined kaolinitic clay used in high performance mortar

In this work, an experimental investigation was carried out to evaluate the potential of an industrial pozzolan, the metakaolin, on the behavior of mortar. The aim is to use metakaolin as a 10% partial replacement of cement. Its effect on the physico-mechanical properties of the mortar has been analyzed. The results show that the incorporation of metakaolin decreases the density of the dried mortar and increases that of the wet mortar but these remain lower than those of the control mortar. Moreover, thermal analysis ATD / ATG shows that in the heat flow curve appears two endothermic peaks which correspond to the loss of mass of the cement pastes. Heat flux of these pastes increases when metakaolin is used into the cement. In addition, metakaolin increases the compressive and flexural strengths of wet and dry mortars by approaching without exceeding those of the control mortar. The use of metakaolin as a cement substitution has shown its potential to be a pozzolanic material that can offer economic, environmental and technical benefits.

Evaluating the mechanical performance of hot asphalt mixtures modified with metakaolin as filler

Filler has an essential effect on the behavior of the hot asphalt pavement mixtures (HMA) through reducing the voids in the aggregate skeleton and reducing the temperature susceptibility of the asphalt binder layer. Recently the use of Metakaolin as a Pozzolanic admixture has been investigated to enhance the strength of cement concrete mixture. In this study, an experimental assessment of the mechanical properties of the HMA modified by Metakaolin as partial replacement of cement mineral filler was conducted. Five mixtures containing 0, 25, 50, 75, and 100 Metakaolin replacements percentages of ordinary cement were prepared at their optimum asphalt content. The Marshall properties, temperature susceptibility, and moisture damage are investigated for these mixtures. It was found that the addition of different proportions of Metakaolin filler as replacement of cement has a significant influence on the mechanical behavior of the HMA. The result illustrated that The Marshall's Stability, Flow and, density grow as the Metakaolin content grows until 50%, then the value starts to decrease at 75 and 100%. The air voids and voids in mineral aggregate decrease with increase the Metakaolin content to the lowest value at 50% of Metakaolin. The indirect tensile strength increases continuously as the Metakaolin content increases at 25, 40, and 60 oC, while temperature susceptibility decreases as Metakaolin content increases. The resistance to moisture damage has been improved by adding Metakaolin filler. It is concluded that the hot asphalt mixture can be modified by using Metakaolin as partial replacement mineral filler at 50% and optimum asphalt content of 5.2 %.

Bond behaviour in rubberised concrete filled circular steel tubes

Rubberised concrete filled steel tube (CFST) is a potential method to utilise the crumb rubber as partial replacement of aggregate, however previous researches show weaker interfacial bond between the rubber and concrete. The aim of this research is to investigate the bond behaviour between the steel tube and the concrete in CFST. Push-out and mechanical tests were conducted on circular specimens, and the variables were: 1) different thicknesses of steel tube; 2) concrete types (normal, rubberised concrete and presence of metakaolin as pozzolan). The results indicated that the use of rubber gives adverse effect on the compressive and splitting tensile strengths, and the modulus of elasticity. However, the use of metakaolin as cement replacement improves its mechanical properties. Based on push-out test, the rubberised concrete shows lower bond strength, and the bond strength increases with increasing section thickness. The presence of metakaolin yielded higher bond strength compared with other mixes.

Use of metakaolin as supplementary cementitious material in concrete, with focus on durability properties

Numerous research efforts on metakaolin as a supplementary cementitious material (SCM) have been undertaken in the past 20 years. This material, while relatively expensive mainly due to low production volumes worldwide, nevertheless has a significantly lower production cost than Portland cement. However, industry remains tentative in considering metakaolin in concrete. This paper takes the view that industry should consider investing in the production and application of metakaolin in appropriate concrete projects, particularly in aggressive environments where plain Portland cement may be inadequate, and where other SCMs may not readily be available. The main contribution of the paper is a global review of recent studies on the use of metakaolin in different types of concrete. This international experience is then compared with results from a study on the durability performance of metakaolin concrete using local materials in the Western Cape province of South Africa, as a means of concrete performance improvement. The study investigates concrete durability properties: penetrability (sorptivity, permeability, conductivity and diffusion), mitigation of Alkali-Silica Reaction (ASR), and carbonation resistance. The concretes were prepared with three water-binder ratios (0.4, 0.5 and 0.6), and with metakaolin replacement levels of 0% (control), 10%, 15% and 20%. Performance results show that, with increasing metakaolin content, the transport properties of concrete are considerably improved, ASR expansion due to a highly reactive local aggregate decreases to non-deleterious levels, while no detrimental effect on carbonation is observed. Thus, metakaolin could serve as a valuable SCM to enhance the durability performance of concrete in local aggressive environments.

Effect of supplementary cementitious material on chemical resistance of concrete

Recently the supplementary cementitious materials are used in the world widely in ready-mixed concrete because of it is economic and environmental benefits; they focusing on them has been increase in the recent years. Whether they come from industrial waste, agro wasted or with products, the SCM may be varied involving loose fasten to improve cement strength. SCM may contain slag cement, rice husk, fly ash, silica fume, and common pozzolans, to name a few. These components are used in combining with ordinary Portland cement (OPC). The use of those materials in concrete will part cut back the consumption of cement¸ which, in turn, will reduce construction prices, providing materials suppliers, contractors and engineers with substantial blessings. This paper is reviewed the use of metakaolin (MK) and rice husk as fractional alteration of cement in mortar and concrete has been extensively widely in lately years. (SCM; Metakaolin, Rice husk ash) is investigated.

Autogenous Shrinkage, Pozzolanic Activity and Mechanical Properties of Metakaolin Blended Cementitious Materials

In the literature, there are some conflicting results regarding the influence of metakaolin (MK) addition on autogenous shrinkage behavior of cementitious materials. In this study, with the aim of identifying how the use of MK changes the properties of cementitious materials, cement was partially replaced by MK in different proportions (8%, 16%, and 24%) in pastes produced with variable water/binder ratios (w/b; 0.28, 0.35 and 0.42). The temperature development and calcium hydroxide consumption by thermogravimetric analysis were observed to better characterize the effects of MK on the autogenous shrinkage behavior. The mechanical properties such as compressive strength and flexural strength were experimentally investigated. The results show that the addition of MK has contrasting effects on autogenous shrinkage during early ages depending on the w/b ratio. Thermogravimetric analysis showed that the amount of stratlingite was smaller in pastes with low w/b ratios than in pastes with high w/b ratio. The calcium hydroxide consumption with the pozzolanic reaction of MK was significant even at 2 days, but consumption ratios with respect to the reference paste slowed down at 7 to 28 days.

Cyclic uniaxial stress-strain test and rheological behavior of carbon black/metakaolin dual-filler system used in nitrile rubber compounds

Abstract Dual-filler systems may promote synergetic effects to mechanical properties in rubber compounds. The use of metakaolin (M) and carbon black (C) in nitrile rubber (NBR) compounds was studied with respect to rheological and non-obvious mechanical tests. The reaction order of the curing process was not influenced by the filler system, however, carbon black presented a slowdown effect in the vulcanization process. Cyclic uniaxial tests indicated that stress softening was observed even for unfilled compound; however, notably only-carbon black filled compound experienced the highest values for decrease in stress softening after second cycle. Although the polymer chains alone are the main driving force of hysteresis, it was more negatively affected by carbon black than by metakaolin. Moreover, dual filler composites experienced balanced results for stress softening, and other properties as Payne effect and complex viscosity.

Effect on Compressive Strength of Concrete by The Use of Metakaolin, Laterite Sand and Quarry Dust

Effect on Compressive Strength of Concrete by The Use of Metakaolin, Laterite Sand and Quarry Dust

Use of metakaolin or coal gangue as a partial substitution of cement in mechanical performance of PC mortars

This work investigates the feasibility of the use of high temperature pozzolan such as metakaolin (Mk) and other industrial waste, such as coal gangue without burned, mortars were made with the aim of improving, through various dosages, their physical and mechanical properties and durability. Mortars were subjected to destructive tests as well as non-destructive tests in hardened state: electrical resistivity (ER), with trial ages of 14, 28, 45, 90, 180 and 360 days. The percentages of the substitutions were 5, 10, 15, 20 and 30% with respect to the weight of Portland cement and a control mixture (cement–sand–water) was produced as a reference parameter. A comparative study was carried out with the results of the aforementioned tests, to estimate the quality and porosity of each mixture. It is observed that the tests of ER indicate indirectly the porosity of the material, the mixtures elaborated with Mk improved the mechanical properties with respect to the control mixture. With the partial replacement of the cement and according to the tests carried out, it can be observed that the problem of durability and CO2 emissions to the atmosphere is reduced significantly diminishing the attack on our planet.

Synergistic Effect of Marble Powder and Green Sand on the Mechanical Properties of Metakaolin-Cement Concrete.

The aim of this paper is to study experimentally the effect of marble powder and green sand as partial substitute for fine aggregate on the strength and durability of M40 grade concrete. The use of metakaolin as a pozzolanic admixture by using as binder replacement is also studied to assess the properties with respect to fresh and hardened state. Several formulations were prepared with constant water-binder ratio 0.4 and varying percentages of marble powder and green sand. The results indicated that the properties of concrete were much enhanced by extent incorporation of marble powder and green sand as fine aggregate and metakaolin for cement when compared to normal concrete. The microscopic studies also confirmed the viability of using green sand and marble powder as fine aggregates.

The Effect of Substituting Metakaolin for Sand on the Thermomechanical Behaviour of Reactive Powder Concrete (RPC)

The weakening of the behavior of reactive powder concrete (RPC) under high temperature is a major drawback; therefore, it is necessary to find an ingredient that improves their resistance under rising temperatures. The present work involves the use of metakaolin as a substitute for sand in a reactive powder concrete (RPC) in order to assess its effect on the mechanical strength at high temperatures. The test specimens are preheated up to 100°, 300°, 500°, 700° and 900°C, respectively following a well-defined cycle, thereafter subjected to a three-point bending followed by compression tests. Samples of the tested specimens were used for thermal, mineralogical and microstructural analyses using the thermogravimetric and differential thermal analysis (TG / DTA), the X-ray diffraction (XRD) and the scanning electron microscopic Analysis (SEM).The heating tests revealed that all the specimens exploded before reaching 500°C. However, they can withstand 300°C before exploding for different exposure durations depending on the metakaolin substitution ratio. Therefore, the mechanical tests were applied only on unheated specimens and those heated up to 100°C. The results showed that the use of metakaolin improves the mechanical strength of the RPC, both at room temperature (25°C±1°C) and at 100°C. This result is confirmed by the microstructure analysis, which revealed the absence of portlandite. The latter did react with the metakaolin silica to form new calcium silicate hydrates (CSH) enhancing the mechanical strength.

Mechanical Properties of Concrete incorporating natural Pozzolanic Material Subjected to Crude Oil

The paper shows the final findings of the effect of metakaolin on the strengths properties of concrete exposed to crude oil. Sulfate resistance Portland cement of V type was used and specimens of concrete were adjusted and subjected to a solution of concentrated crude oil. However, the samples are cured in a control media at immersion ages of (28, 56 & 120 days) with ambient temperature, then samples have been kept in curing water for comparisons purpose as well. The results explain that the use of metakaolin reinforces compressive, flexural and splitting resistance of concrete which is exposed to crude oil. The compressive strength reduction increased from 8.0% at (28 days) to 37.7% at (120 days) curing for normal weight concrete (NW) whereas the concrete incorporating metakaolin (MC) has a reduction of 6.0% at (28 days) & 29.3% at (120 days). .

Investigation into effect of metakaolin-based additives incorporation on formation of cement stone structure

The paper presents studies on the evaluation of the effect of complex additives, including metakaolin, microsilica and superplasticizer on the formation of the phase composition of cement stone. The change in the structure of the modified cement stone was studied and the dependencies were established. A comparative analysis of two complex additives to evaluate the effect of metakaolin on the change in the phase composition of cement stone was carried out. The possibility of obtaining high-performance concrete with low porosity, high early and vintage strength, durability, using additive accelerators and structure modifiers has been investigated. It is established that the use of metakaolin leads to the formation of a cement stone structure, mainly consisting of metastable calcium hydroalumates. It is necessary to use metakaolin together with microsilica and superplasticizer to create a dense structure of cement stone with low capillary porosity from stable low-basic weakly crystallized hydrate phases that are stable when the medium pH is changed.

Effect of incorporation of metakaolin and recycled coarse aggregate on properties of concrete

The present research work investigates the utilization of metakaolin as a mineral admixture in improving the properties of concrete mixes, containing varying percentages of recycled coarse aggregates (RCA). For this, fifteen concrete mixes have been designed by substituting natural coarse aggregates (NCA) with 0%, 50% and 100% RCA and cement with 0%, 5%, 10%, 15% and 20% metakaolin. Nine different properties of concrete including workability, compressive strength at three different curing ages (3, 7 and 28 days), splitting tensile strength, flexural strength, ultrasonic pulse velocity, rebound number, water absorption, density and volume of voids have been experimented to examine the effect of metakaolin and RCA on the properties of concrete. The outcomes of the study reveal that the workability becomes higher with higher percentage of RCA; however it slightly reduces when metakaolin is used. The mechanical properties like compressive strength, splitting tensile strength, flexural strength and dry density get reduced when quantities of RCA increases. The non-destructive parameters like ultrasonic pulse velocity and rebound number of concrete follows similar pattern as that of compressive strength. The water absorption and volume of voids shows higher values for recycled aggregate concrete (RAC) mixes. However, the use of metakaolin in RAC significantly reduces the water absorption and volume of voids. The optimum replacement percentage of metakaolin is found to be 15% as the RAC mixes shows best performance at this replacement level. Furthermore, the properties of concrete mix containing 100% RCA and 15% metakaolin are similar to that of normal concrete. Therefore, it is feasible to produce sustainable concrete by using maximum waste concrete i.e. 100% RCA and 15% metakaolin without much affecting the strength criteria.

The Effect of Recycled Concrete Aggregates and Metakaolin on the Mechanical Properties of Self-Compacting Concrete Containing Nanoparticles

Nowadays, finding appropriate solutions for reducing the environmental pollutions as a consequence of buildings is important. Using recycled concrete from demolished buildings as an aggregate in new concrete preparation can have a significant role in the sustainable development of the concrete industry; therefore, in this research work, the effect of employing different percentages (i.e., 20, 40, 60, 80 and 100%) of recycled concrete aggregates and the impact of using metakaolin as pozzolan in self-compacting concrete containing SiO2 nanoparticles were investigated. Hence, some properties of hardened self-compacting concrete such as compressive strength, tensile strength, modulus of elasticity, water absorption, density and apparent porosity of the samples were studied. The results demonstrate that construction of self-compacting concrete with complete replacement of recycled aggregates is possible. Although the strength of recycled self-compacting concretes is almost 11% less than the control samples, the use of metakaolin with optimum percentage as additives of cement leads to improvement in the recycled concretes properties.

Performance evaluation of silica fume and metakaolin with identical finenesses in self compacting and fiber reinforced concretes

Partial replacement of cement by metakaolin (MK) increases the strength of concrete, but since the properties of MK are important parameters it is not entirely clear whether MK is more effective than silica fume (SF) in enhancing the properties of concrete. In this study, in high-performance self-compacting concretes (SCC) with two different water/binder (w/b) ratios (0.28 and 0.35), cement was replaced by MK or SF at the weight fraction of 10%. In order to provide a meaningful comparison, the pozzolans with similar particle sizes were used. The effectiveness of MK and SF on the autogenous shrinkage, calcium hydroxide (CH) consumption, flowability, mechanical properties and fracture behavior of SCC was examined. In addition, the performances of these two types of mineral additives in fiber reinforced concrete under four-point bending were documented. It was shown that both MK and SF had an increasing effect on autogenous shrinkage of paste with 0.35 w/b ratios, while at 0.28 w/b ratio the mixtures with MK showed a lesser amount of autogenous shrinkage at 48 h. CH consumption was found to be slightly higher in the pastes containing MK compared to those with SF. The long-term autogenous shrinkage of SCCs with MK was lower than those with SF. The use of MK and SF as mineral additives caused a decrease in fracture energies of concretes, and this effect is more pronounced in SF blended concretes, while no significant change was observed in the compressive strength developments of the mixtures. Fiber reinforced concretes containing MK were found to have much higher fracture energy than that with SF, indicating that the MK addition improves the matrix/steel fiber bonding properties.