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Alireza Najigivi - One of the best experts on this subject based on the ideXlab platform.
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Study on mechanical properties of ternary blended concrete containing two different sizes of nano-SiO2
Composites Part B: Engineering, 2019Co-Authors: Amin Nazerigivi, Alireza NajigiviAbstract:Abstract The aim of this study was to investigate the influences of combination of the two different SiO2 nanoparticles (15 nm and 80 nm) on compressive, flexural and tensile strength of ternary blended concrete. SiO2 nanoparticles with two different sizes of 15 and 80 nm have been used as a partial cement replacement by 0.5, 1.0, 1.5 and 2.0 wt.% in 16 different proportions of mixture followed by curing in Lime Solution for 7, 28 and 90 days. The results indicate that in all curing ages in Lime Solution specimens with 2.0% of 15 nm plus 1.5% of 80 nm cement replacement achieved higher mechanical properties. The continuous cement paste with the lowest delicate zones might be due to the fact of quick formation of C–S–H gel in the existence of ultra-high dynamic nanosized SiO2 in both average particle sizes together with their high filler effect. It was concluded that the use of novel ternary blended concrete provides significant improvement in the all mechanical properties of concrete. In other words, increasing in the strength could be due to this fact that the nucleus of strengthening gel might merely reach to the critical volume of nucleation.
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Investigating the effects of using different types of SiO2 nanoparticles on the mechanical properties of binary blended concrete
Composites Part B: Engineering, 2013Co-Authors: Alireza Najigivi, Alireza Khaloo, Azam Iraji Zad, Suraya Abdul RashidAbstract:The aim of this study was to assess the effects of two different types of SiO2 nanoparticles (N and M series) with different ratios on the workability and compressive strength of developed binary blended concretes cured in water and Lime Solution as two different curing media. N and M series SiO2 nanoparticles with an average size of 15 nm were used as obtained from the suppliers. Fresh and hardened concretes incorporating 0.5%, 1.0%, 1.5% and 2.0% of N and 2% of M series nanoparticles with constant water to binder ratio and aggregate content were made and tested. Fresh mixtures were tested for workability and hardened concretes were tested for compressive strength at 7, 28 and 90 days of curing. Fresh concrete test results showed that the workability of binary blends was reduced in the presence of both types of SiO2 nanoparticles. Hardened concrete test results revealed that the optimal replacement level of cement by N series of SiO2 nanoparticles for producing concrete with considerably improved strength was set at 1.0 wt.% after curing in water. However, the ultimate strengths of binary blended concretes were gained at 2.0 wt.% replacement of cement by both series after curing in Lime Solution. It is concluded that SiO2 nanoparticles play significant roles in mechanical properties of concrete by formation of additional calcium silicate hydrate gel during treatment, which played an important role in raising highly the compressive strength of binary blends. The current study sheds light on the implications of nanotechnology in nano-engineering of concrete.
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Water absorption control of ternary blended concrete with nano-SiO_2 in presence of rice husk ash
Materials and Structures, 2012Co-Authors: Alireza Najigivi, Suraya Abdul Rashid, Farah Nora A. Aziz, Mohamad Amran Mohd SallehAbstract:In the current study, the effects of SiO_2 nanoparticles as additive with two different sizes of 15 and 80 nm on water absorption of rice husk ash (RHA) blended concrete have been investigated. Concrete samples were prepared by replacing 10, 15 and 20 wt% of cement with RHA and 0.5, 1.0, 1.5 and 2.0% of cement with SiO_2 nanoparticles followed by curing in Lime Solution for 7, 28 and 90 days. The results indicated that the resistance to water absorption of Portland cement–nano SiO_2–rice husk ash (PC–NS–RHA) ternary blended concrete was considerably improved with respect to the control concrete. This improvement was observed at all curing ages and replacement levels but the optimal point was reached for 20% of RHA incorporating 2% of 80 nm SiO_2 particles at 90 days of curing. Fast formation of C–S–H gel in the presence of ultra high active nano-sized SiO_2 and micron level RHA particles together with their high filler effect may result in a continuous cement paste with the lowest weak zones. It has been concluded that the use of novel ternary blended concrete (PC–NS–RHA) provides significant reduction in the water absorption of concrete.
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Development of High Strength Cement-Based Concrete Utilizing Silicon Dioxide Nanoparticles and Rice Husk Ash
2011Co-Authors: Alireza NajigiviAbstract:Nano-engineering of concrete is a relatively new but rapidly growing area in concrete research. This study deals with development of high strength concrete incorporating agrowaste rice husk ash (RHA) and SiO2 nanoparticles as supplementary cementing materials replacing cement particles in order to improve sustainability of concrete constructions as fundamental need. Various binary and ternary blended concrete mixtures were produced using two sizes of RHA (5 and 95 μm) and SiO2 nanoparticles (15 and 80 nm). Fresh and hardened concretes incorporating 5, 10, 15 and 20% of RHA and 0.5, 1, 1.5, and 2% of SiO2 nanoparticles with constant water to binder ratio and aggregate content were prepared and tested. Fresh mixtures were tested for workability and hardened concretes were tested for compressive strength and water absorption at 7, 28 and 90 days of curing. Additionally,the effects of two different curing media, water and Lime Solution on compressive strength and water absorption of concretes were tested. Finally, using Artificial Neural Network (ANN) a model was proposed for the design procedure of concrete mixture proportioning with different sizes and contents of the utilized materials. Fresh concrete test results showed that workability of binary blends was improved in the presence of up to 20% of RHA in both particle sizes; however, workability was reduced in the presence of both sizes of SiO2 nanoparticles. In ternary blends, workability was improved in the presence of up to 20% of RHA and 2% of SiO2 nanoparticles (in both sizes). Hardened concrete test results revealed that in water-cured binary mixes compressive strength was enhanced with incorporation of both sizes of RHA up to 10%. Compressive strength of Lime-cured mixtures, on the other hand, showed an increase up to 15% with coarser RHA blends but in finer RHA blends the highest strength was obtained at 20%. Similarly, the overall compressive strengths of concretes incorporating SiO2 nanoparticles were enhanced both in water-cured and Limecured mixes, however, concretes comprising larger particles with contents up to 1.5% and 2% in water and Lime Solution, respectively, improved the compressive strength. Smaller SiO2 nanoparticles, on the other hand, improved compressive strength up to 1% and 2% in water and Lime Solution, respectively. In ternary blends, compressive strengths were enhanced with incorporation of RHA up to 20% and SiO2 nanoparticles (with both sizes) up to 2%. In binary blends, the lowest water absorption for water-cured RHA blends for both sizes was obtained at 10%. In Lime-cured mixes, 15% of coarser RHA and 20% of finer RHA replacement yielded the lowest values at 90 days of curing. Similarly, for SiO2 nanoparticles in binary blends the lowest water absorption in both curing media across all percentages was obtained with 2% of both particle sizes at later curing ages. In ternary blends, the lowest water absorption was obtained at 90 days of curing at 2% of SiO2 nanoparticles (both sizes) in combination with 20% of RHA replacement. The overall results confirmed that ternary blends have better contributions to the mechanical and physical properties of concert due to the effects of SiO2 nanoparticles. The results also indicated that ANN is an efficient model to predict unlimited number of necessary proportions for the mixtures by conducting a limited number of experiments. The employment of the model to predict the behavior of output variables saves a lot of library trials and computational efforts carried out in conventional methods. The implications of the study for concrete engineering in general and nano-engineering of concrete in particular have been discussed.
Paulo Roberto Cetlin - One of the best experts on this subject based on the ideXlab platform.
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Comparing the pozzolanic behavior of sugar cane bagasse ash to amorphous and crystalline SiO2
Cement and Concrete Composites, 2016Co-Authors: Marcela M.n.s. De Soares, Roberto B. Figueiredo, Maria Teresa Paulino Aguilar, Dayana C.s. Garcia, Paulo Roberto CetlinAbstract:Abstract The present paper aims to clarify the pozzolanic behavior of sugar cane bagasse ash-SCBA by comparing it to amorphous and crystalline silica. It is shown that calcium silicate hydrate is formed in Lime Solution with SCBA but the reaction is slow and does not consume all the material. Comparing its results with the obtained in tests with silica fume and with crushed quartz show a better agreement with the latter. Characterization of cement pastes shows 20% of cement replacement by sugar cane bagasse ash leads to only a minor reduction in the amount of calcium hydroxide formed. This behavior is also closer to the observed in quartz than in silica fume. The results suggest SCBA should be used as a replacement for inert constituents in cement composites rather than pozzolanic addition. Analysis of the microstructure of the cement pastes revealed the presence of calcium hydroxide in samples prepared with partial replacement by silica fume, quartz and sugar cane bagasse ash. The presence of this phase in the sample prepared with silica fume was attributed to agglomeration of the particles that affected the reactivity of this material.
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Evaluation of Pozzolanic Activity of Siliceous Materials Using the Method of Variation of Conductivity in Lime Solution
Materials Science Forum, 2014Co-Authors: Marcela Maira Nascimento De Souza Soares, Roberto B. Figueiredo, Maria Teresa Paulino Aguilar, Paulo Roberto CetlinAbstract:Pozzolanic materials react with Lime produced during curing of cement forming a hard phase similar to hardened cement. There are multiple methods to evaluate the pozzolanic activity of materials and one of these methods is the evaluation of the conductivity in Lime Solution. This method does not follow a standard procedure and there are multiple parameters that affect the results. The present paper summarizes some of the variations in this method reported in the literature and shows experimental results from tests in siliceous materials with crystalline (sand) or amorphous (silica fume) structure. The test is also used to evaluate the pozzolanic activity of sugar-cane bagasse ash. The effects of temperature, sample size and Solution agitation are reported. The results indicates this method permits a rapid evaluation of pozzolanic activity but the testing parameters must be rigorously controlled.
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The effect of calcination conditions on the physical and chemical characteristics of sugar cane bagasse ash
Rem: Revista Escola de Minas, 2014Co-Authors: Marcela Maira Nascimento De Souza Soares, Roberto B. Figueiredo, Maria Teresa Paulino Aguilar, Flávia Spitale Jacques Poggiali, Augusto Cesar Da Silva Bezerra, Paulo Roberto CetlinAbstract:The effect of calcination temperature and air flow on the content of organic material, morphology of particles, degree of crystallinity and the reactivity with Lime Solution of the sugar cane bagasse ash is evaluated. The results show that the long fibers of the bagasse and organic material are retained when calcination occurs without sufficient air flow. Calcining with forced air-flow breaks the fibers, removes organic material and produces fine particles at a temperature of 600oC. The non-organic material observed in the ash displays a high degree of crystallinity. Experiments show that the crystalline structure observed in the ashes is due to adhered sand which was not previously washed away. The reduction on the conductivity in Lime Solution and X-rays diffraction pattern suggest that amorphous silica is formed at temperatures lower than 600oC and cristobalite is formed at higher temperatures.
Suraya Abdul Rashid - One of the best experts on this subject based on the ideXlab platform.
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Influence of 15 and 80 nano-SiO2particles addition on mechanical and physical properties of ternary blended concrete incorporating rice husk ash
Journal of Experimental Nanoscience, 2013Co-Authors: Alireza Naji Givi, Suraya Abdul Rashid, Farah Nora Aznieta Abd. Aziz, Mohamad Amran Mohd SallehAbstract:This study demonstrates the effects of SiO2 nanoparticles as additives with two different sizes of 15 and 80 nm on compressive strength and porosity of rice husk ash (RHA) blended concrete. Up to 20% of ordinary Portland cement (OPC) was replaced by RHA with average particle size of 5 micron. Also, SiO2 nanoparticles were added to the above mixture at four different weight percentages of 0.5, 1.0, 1.5 and 2.0 and cured in Lime Solution. The results indicated that compressive strength of Portland cement–nano SiO2–rice husk ash (PC–NS–RHA) ternary blended concrete was considerably increased. Moreover, the total amount of porosity decreased to a minimum with respect to the control concrete. This improvement was observed at all the curing ages and replacement levels, but there was a gain in the optimal point with 20% of RHA plus 2% of 80 nm SiO2 particles at 90 days of curing.
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Investigating the effects of using different types of SiO2 nanoparticles on the mechanical properties of binary blended concrete
Composites Part B: Engineering, 2013Co-Authors: Alireza Najigivi, Alireza Khaloo, Azam Iraji Zad, Suraya Abdul RashidAbstract:The aim of this study was to assess the effects of two different types of SiO2 nanoparticles (N and M series) with different ratios on the workability and compressive strength of developed binary blended concretes cured in water and Lime Solution as two different curing media. N and M series SiO2 nanoparticles with an average size of 15 nm were used as obtained from the suppliers. Fresh and hardened concretes incorporating 0.5%, 1.0%, 1.5% and 2.0% of N and 2% of M series nanoparticles with constant water to binder ratio and aggregate content were made and tested. Fresh mixtures were tested for workability and hardened concretes were tested for compressive strength at 7, 28 and 90 days of curing. Fresh concrete test results showed that the workability of binary blends was reduced in the presence of both types of SiO2 nanoparticles. Hardened concrete test results revealed that the optimal replacement level of cement by N series of SiO2 nanoparticles for producing concrete with considerably improved strength was set at 1.0 wt.% after curing in water. However, the ultimate strengths of binary blended concretes were gained at 2.0 wt.% replacement of cement by both series after curing in Lime Solution. It is concluded that SiO2 nanoparticles play significant roles in mechanical properties of concrete by formation of additional calcium silicate hydrate gel during treatment, which played an important role in raising highly the compressive strength of binary blends. The current study sheds light on the implications of nanotechnology in nano-engineering of concrete.
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The effects of Lime Solution on the properties of SiO2 nanoparticles binary blended concrete
Composites Part B: Engineering, 2011Co-Authors: Alireza Naji Givi, Suraya Abdul Rashid, Farah Nora Aznieta Abd. Aziz, Mohamad Amran Mohd SallehAbstract:In this study, the effects of SiO2 nanoparticles on both mechanical properties (compressive, split tensile and flexural strength) and physical properties (water permeability, workability and setting time) of binary blended concrete have been investigated. SiO2 nano-particles have been used as a partial cement replacement by 0.5, 1.0, 1.5 and 2.0 wt.%. Curing of the specimens has been carried out in water and Lime Solution for 7, 28 and 90 days after casting. For the specimens cured in water, the optimal replacement level of cement by SiO2 nanoparticles for producing concrete with improved strength, was set at 1.0 wt.%. However, by curing the specimens in Lime Solution, Portland cement could be advantageously replaced by 2.0 wt.% of SiO2 nanoparticles. It was concluded that the SiO2 nanoparticles can improve the filler effect and its ultra high pozzolanic activity causes more C–S–H gel formation when cured in Lime Solution. Although curing in the Lime Solution can reduce the strength of control concrete, Curing the specimens containing SiO2 nanoparticles in Lime Solution causes faster setting time together with higher strength and residence to water absorption.
Mohamad Amran Mohd Salleh - One of the best experts on this subject based on the ideXlab platform.
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Influence of 15 and 80 nano-SiO2particles addition on mechanical and physical properties of ternary blended concrete incorporating rice husk ash
Journal of Experimental Nanoscience, 2013Co-Authors: Alireza Naji Givi, Suraya Abdul Rashid, Farah Nora Aznieta Abd. Aziz, Mohamad Amran Mohd SallehAbstract:This study demonstrates the effects of SiO2 nanoparticles as additives with two different sizes of 15 and 80 nm on compressive strength and porosity of rice husk ash (RHA) blended concrete. Up to 20% of ordinary Portland cement (OPC) was replaced by RHA with average particle size of 5 micron. Also, SiO2 nanoparticles were added to the above mixture at four different weight percentages of 0.5, 1.0, 1.5 and 2.0 and cured in Lime Solution. The results indicated that compressive strength of Portland cement–nano SiO2–rice husk ash (PC–NS–RHA) ternary blended concrete was considerably increased. Moreover, the total amount of porosity decreased to a minimum with respect to the control concrete. This improvement was observed at all the curing ages and replacement levels, but there was a gain in the optimal point with 20% of RHA plus 2% of 80 nm SiO2 particles at 90 days of curing.
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The effects of Lime Solution on the properties of SiO2 nanoparticles binary blended concrete
Composites Part B: Engineering, 2011Co-Authors: Alireza Naji Givi, Suraya Abdul Rashid, Farah Nora Aznieta Abd. Aziz, Mohamad Amran Mohd SallehAbstract:In this study, the effects of SiO2 nanoparticles on both mechanical properties (compressive, split tensile and flexural strength) and physical properties (water permeability, workability and setting time) of binary blended concrete have been investigated. SiO2 nano-particles have been used as a partial cement replacement by 0.5, 1.0, 1.5 and 2.0 wt.%. Curing of the specimens has been carried out in water and Lime Solution for 7, 28 and 90 days after casting. For the specimens cured in water, the optimal replacement level of cement by SiO2 nanoparticles for producing concrete with improved strength, was set at 1.0 wt.%. However, by curing the specimens in Lime Solution, Portland cement could be advantageously replaced by 2.0 wt.% of SiO2 nanoparticles. It was concluded that the SiO2 nanoparticles can improve the filler effect and its ultra high pozzolanic activity causes more C–S–H gel formation when cured in Lime Solution. Although curing in the Lime Solution can reduce the strength of control concrete, Curing the specimens containing SiO2 nanoparticles in Lime Solution causes faster setting time together with higher strength and residence to water absorption.
Maria Teresa Paulino Aguilar - One of the best experts on this subject based on the ideXlab platform.
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Investigations on the Pozzolanic Effect of Sugar Cane Bagasse Ashes Used in Cementitious Composites
The Open Construction and Building Technology Journal, 2016Co-Authors: Paula Gisele Lamezon De Pádua, Roberto B. Figueiredo, Túlio Hallak Panzera, A. M. Gomes, Maria Teresa Paulino AguilarAbstract:Brazil is a major producer of alcohol from sugar cane, a fuel with low environmental impact. The production of alcohol generates a large amount of bagasse, the biggest waste of Brazilian agriculture. This bagasse is usually burned for energy production providing nearly 3% of residual ashes. The potential use of these ashes like mineral admixture of cementitious composites depends on calcination conditions. The present work identifies the physical and chemical characteristics of ashes from the furnace exhauster, obtained in an industry located at southeast region of Brazil. The ashes were obtained from bagasse of sugar cane harvest in two different seasons. Chemical composition analysis, X-ray diffraction, grain size distribution, loss on ignition, thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), specific surface measurements (BET) and Fourier transform infrared spectroscopy (FTIR) tests were used to characterize the ashes. The pozzolanic activity was estimated by pozzolanic activity index tests with cement and Lime, by the modified Chapelle test, electrical conductivity in Lime Solution tests, TGA and FTIR. The ashes presented different chemical compositions and degree of amorphicity. The ashes with a higher content of silica, the lower organic material content and high degree of crystallinity (1st harvest), for the same size, have higher pozzolanic on electrical conductivity in Lime Solution tests than the ashes with lower silica content and higher amorphicity (2nd harvest). However, the results of differential scanning calorimetry (DSC) and modified Chapelle method would indicate the pozzolanicity of the ashes of the 2nd harvest. The results of pozzolanic activity index (with cement or Lime) indicated the ashes were not pozzolanic.
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Comparing the pozzolanic behavior of sugar cane bagasse ash to amorphous and crystalline SiO2
Cement and Concrete Composites, 2016Co-Authors: Marcela M.n.s. De Soares, Roberto B. Figueiredo, Maria Teresa Paulino Aguilar, Dayana C.s. Garcia, Paulo Roberto CetlinAbstract:Abstract The present paper aims to clarify the pozzolanic behavior of sugar cane bagasse ash-SCBA by comparing it to amorphous and crystalline silica. It is shown that calcium silicate hydrate is formed in Lime Solution with SCBA but the reaction is slow and does not consume all the material. Comparing its results with the obtained in tests with silica fume and with crushed quartz show a better agreement with the latter. Characterization of cement pastes shows 20% of cement replacement by sugar cane bagasse ash leads to only a minor reduction in the amount of calcium hydroxide formed. This behavior is also closer to the observed in quartz than in silica fume. The results suggest SCBA should be used as a replacement for inert constituents in cement composites rather than pozzolanic addition. Analysis of the microstructure of the cement pastes revealed the presence of calcium hydroxide in samples prepared with partial replacement by silica fume, quartz and sugar cane bagasse ash. The presence of this phase in the sample prepared with silica fume was attributed to agglomeration of the particles that affected the reactivity of this material.
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Evaluation of Pozzolanic Activity of Siliceous Materials Using the Method of Variation of Conductivity in Lime Solution
Materials Science Forum, 2014Co-Authors: Marcela Maira Nascimento De Souza Soares, Roberto B. Figueiredo, Maria Teresa Paulino Aguilar, Paulo Roberto CetlinAbstract:Pozzolanic materials react with Lime produced during curing of cement forming a hard phase similar to hardened cement. There are multiple methods to evaluate the pozzolanic activity of materials and one of these methods is the evaluation of the conductivity in Lime Solution. This method does not follow a standard procedure and there are multiple parameters that affect the results. The present paper summarizes some of the variations in this method reported in the literature and shows experimental results from tests in siliceous materials with crystalline (sand) or amorphous (silica fume) structure. The test is also used to evaluate the pozzolanic activity of sugar-cane bagasse ash. The effects of temperature, sample size and Solution agitation are reported. The results indicates this method permits a rapid evaluation of pozzolanic activity but the testing parameters must be rigorously controlled.
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The effect of calcination conditions on the physical and chemical characteristics of sugar cane bagasse ash
Rem: Revista Escola de Minas, 2014Co-Authors: Marcela Maira Nascimento De Souza Soares, Roberto B. Figueiredo, Maria Teresa Paulino Aguilar, Flávia Spitale Jacques Poggiali, Augusto Cesar Da Silva Bezerra, Paulo Roberto CetlinAbstract:The effect of calcination temperature and air flow on the content of organic material, morphology of particles, degree of crystallinity and the reactivity with Lime Solution of the sugar cane bagasse ash is evaluated. The results show that the long fibers of the bagasse and organic material are retained when calcination occurs without sufficient air flow. Calcining with forced air-flow breaks the fibers, removes organic material and produces fine particles at a temperature of 600oC. The non-organic material observed in the ash displays a high degree of crystallinity. Experiments show that the crystalline structure observed in the ashes is due to adhered sand which was not previously washed away. The reduction on the conductivity in Lime Solution and X-rays diffraction pattern suggest that amorphous silica is formed at temperatures lower than 600oC and cristobalite is formed at higher temperatures.