Particle Size Of Rice Husk Ash Research Articles

Durability of alkali-activated slag concrete incorporating silica fume and rice husk ash

To improve the mechanical properties and durability of alkali-activated slag concrete (AASC), as well as to reduce carbon emissions and exploitation of natural resources. This paper attempts to introduce rice husk ash (RHA) and silica fume (SF) into the AASC system. The effects of RHA and SF on the physical properties (water absorption and density), mechanical properties (flexural strength and compressive strength), and durability properties (dry shrinkage, resistance to sulfuric acid attack and carbonation) of AASC are examined. The optimization mechanisms are also explored from the points of pore structure and microstructure analysis. The experimental results suggest that RHA and SF can substantially reduce water absorption and improve the mechanical and durability properties of AASC. Remarkably, adding 10 wt% RHA into concrete can reduce the water absorption by 42%, increase the strength by 9.7–20%, the resistance to sulfuric acid attack by 26.91%, and the resistance to carbonization by 54.4%. Unfavorably, its dry shrinkage increases by 3.2–33%. Microstructural investigations demonstrate that the addition of RHA and SF to the AASC system provides an additional source of silica, which could have a filler effect, pore refinement, and pozzolanic nature. Moreover, RHA has more silica content than SF, and the particle size of RHA is finer and the reaction is more adequate, so the effect is more remarkable. The findings of the study suggest that RHA and SF demonstrate promising prospects in improving the durability and sustainability of AASC.

Effect of Rice Husk Ash on the Properties of Alkali-Activated Slag Pastes: Shrinkage, Hydration and Mechanical Property.

In this paper, rice husk ash (RHA) with different average pore diameters and specific surface areas was used to replace 10% slag in the preparation of alkali-activated slag (AAS) pastes. The effect of RHA addition on the shrinkage, hydration, and strength of AAS pastes was studied. The results show that RHA with a porous structure will pre-absorb part of the mixing water during paste preparation, resulting in a decrease in the fluidity of AAS pastes by 5-20 mm. RHA has a significant inhibitory effect on the shrinkage of AAS pastes. The autogenous shrinkage of AAS pastes decreases by 18-55% at 7 days, and the drying shrinkage decreases by 7-18% at 28 days. This shrinkage reduction effect weakens with the decrease in RHA particle size. RHA has no obvious effect on the type of hydration products of AAS pastes, whereas RHA after proper grinding treatment can significantly improve the hydration degree. Therefore, more hydration products are generated and fills the internal pores of the pastes, which significantly improves the mechanical properties of the AAS pastes. The 28 day compressive strength of sample R10M30 (the content of RHA is 10%, RHA milling time is 30 min) is 13 MPa higher than that of blank sample.

Experiment study on the mechanical properties and alkali silica reaction (ASR) of mortar blended rice husk ash (RHA)

To ensure the serviceable popularization of RHA and avoid the alkali silica reaction of mortar blended RHA, the impact of RHA particle size and dosage on the mechanical strength and alkali silica reaction expansion of the mortar prepared with nonreactive silica sand and river sand has been evolutionarily investigated. The hydrates products of the mortar containing RHA were conducted by thermogravimetric (TG) and X-ray diffraction analysis (XRD). The microstructure of the mortar containing RHA was also explored by scanning electron microscope with an energy-dispersive X-ray spectroscopy analysis (SEM-EDX). The experiment results demonstrate that the compressive strength of mortar could be maximum enhanced by 21.1 % when RHA8.8 substituted 20 % of cement due to the pozzolanic effect and physical filling effect of RHA. Moreover, RHA with massive amorphous silica could react with Na ions in pore solution to form alkali-silica gel, thereafter resulting in expanding and destroying the microstructure of the mortar. The real ASR expansion value fabricated by RHA increased as the RHA particle size increased, which was mostly up to 0.0177 % when 20 % cement was replaced by RHA with a mean particle of 27.6 µm. Cracks noticeably emerged on the surface and edge of the mortar containing RHA with the particle size from 8.8 µm to 27.6 µm when RHA substituted 20 % of cement (by mass). Overall, the RHA particle size should be lower than 8.8 µm, while the substitution of cement by RHA also be below 10 % of cement, which can safely avoid the destructive expansion of RHA in an alkali environment.

Effects of Milling Time on Nano Rice Husk Ash Particle Size

This research focuses on the manufacture of nano Rice Husk Ash (nRHA) by ball milling technique and critically analyzes the effect of milling time on particle size. The process starts with collection of raw rice husk from a local rice mill factory, followed by controlled incineration at a temperature of 700°C for 5 hours to get the amorphous RHA. Finally, the nano RHA is prepared by subjecting the RHA to grinding for the different period like 10, 20, 30, and 40 hrs. The particle size was analyzed with FESEM, and it was found that particles got smaller as grinding proceeded, reaching an optimal size of 28 nm following 30 h grinding. Nonetheless, prolonged grinding resulted into particle agglomeration that was caused by Van der Waal forces. Therefore, these findings are significant in that they help to comprehend the morphology changes and particle size alterations in nRHA that may be applied for different uses such sustainable construction materials.

Effect of particle size of rice husk ash on aluminium/graphene composites

Aluminium/graphene (Al/G) composite has gained wider engineering applications because of its unique properties such as lightweight, excellent corrosion resistant, improved strength and enhanced thermal conductivity. However, difficulty in dispersing graphene in molten aluminium remains one of the major optimization challenges. This study developed, by stir casting technique, composites of aluminium alloy from recycled aluminium can, 0.4 wt. % graphene (G) and 1.6 wt.% rice husk ash (RHA) with particle sizes of 150, 300 and 600 μm. The tensile, hardness, impact and fatigue properties were analyzed using Instron Extensometer, Vickers hardness tester, Charpy Impact machine and rotating fatigue machine respectively. Furthermore, the cast samples were characterized using scanning electron microscope (SEM) and X-ray diffractometer (XRD). The morphology of the microstructure of all composites showed the retention and uniform distribution of G and RHA particles in the Al matrix devoid of presence of harmful aluminium carbide with improved mechanical properties. The study established a new approach of dispersing graphene in molten aluminium through a stir cast method with 150 μm particle size of RHA given the best mechanical and morphological properties.

Alkali silica reactivity of rice husk ash in cement paste

The aim of this study is to investigate alkali silica reactivity of rice husk ash (RHA) in cement paste. Scanning electron microscope in combination with Energy-dispersive X-ray spectroscopy was used to analyse the mechanism of alkali silica reactivity of RHA. The results indicate that RHA has paradoxical effect on alkali silica reaction (ASR) in cement paste, especially with coarse RHA particles and at high temperatures. RHA particles indeed act as micro-reactive aggregates and react with alkali hydroxide to generate expansive ASR products even when particle size of RHA is in range of 5.7–22.6 µm. The pozzolanic reaction and ASR take place successively from the exterior to interior of RHA particles. The mechanism for the successive reactions of RHA is proposed. The C-S-H phases as pozzolanic products of RHA contain an amount of sodium and potassium, whereas the ASR products of RHA contain an amount of calcium. The Ca/Si and (Na + K)/Si ratios of pozzolanic products are much higher and lower than those of ASR products, respectively. To mitigate ASR, RHA should be ground to very fine particles, at least finer than 5 µm.

Effect of particle size, porous structure and content of rice husk ash on the hydration process and compressive strength evolution of concrete

Compressive strength evolution of high strength concrete with rice husk ash (RHA) was evaluated as a function of RHA particle size, porous structure and replacement content. RHA porous structure was investigated by N2 absorption isotherm and its effect on hydration evaluated using isothermal calorimetry and thermogravimetry. Results indicated that RHA particle size influenced compressive strength until 28 days, whereas at 91 days replacement content became the significant factor. Preserved porous structure of RHA particles besides improving hydration kinetics enabled its action as internal curing agent improving compressive strength at late age.

Synthesis of silica from rice husk as cement substitution for high strength concrete

This research was conducted to determine the effect of adding the rice husk ash (RHA) from mechano-chemical process as cement replacement for concrete. Mechano-chemical process was carried out using planetary ball mill with the rational speed at 22 rpm for 15 minutes and adding the 1M Hydrochloric Acid. This process aims to reduce the particle size of RHA. RHA will be used as cement replacement material with the composition that will be displayed in this study. concrete was made on 10 x 10 cm cube mold and a compressive strength test was carried out after 28 days curing. Beside RHA, in this study silica fused is used as cement replacement material. Concrete with the addition of RHA from mechano-chemical process has higher compressive strength than concrete with addition of silica fused.

Comparative study of pozzolanic and filler effect of rice husk ash on the mechanical properties and microstructure of brick aggregate concrete

The aim of this study was to investigate the pozzolanic effect (PE) and filler effect (FE) of rice husk ash (RHA) on the mechanical properties and microstructure of brick aggregate concrete (BAC). For this, concrete cylinders (100 mm × 200 mm) were prepared with 0–25% RHA with water-to-binder ratios of 0.50 at a constant mix-ratio of 1:1.5:3 and cured in water. Test results revealed that the mean particle size of RHA decreases with increasing grinding time. The compressive strength (fc') of BAC due to filler effect are 58.56–94.62% less compared to the pozzolanic effect of RHA for the 10%–25% replacement of cement. Meanwhile, the 15% RHA showed the maximum fc' of BAC due to pozzolanic effect of RHA. The tensile strength (fsp) and flexural strength (fr) of BAC due to pozzolanic effect are 60%–150% and 25%–150% higher than that of filler effect of RHA for the 10%–25% replacement of cement respectively. The modulus of elasticity (Ec) and Poisson's ratio(ν) of BAC due to pozzolanic effect are 2%–29% and 27%–43% greater than that of filler effect of RHA for the 10%–25% replacement of cement respectively. BAC with 10–20% RHA shows a dense and homogeneous microstructure. Therefore, inclusion of RHA as a partial replacement of cement possesses a significant pozzolanic effect than the filler effect on the mechanical properties and microstructure of BAC.

Preparation and characterization of rice husk ash for using as a filler in natural rubber

Abstract In this study, rice husk ash (RHA) and commercial silica were used as reinforcing fillers in natural rubber (NR). XRF, FTIR, SEM and particle size analysis were used to characterize RHA and commercial silica. Silica contents in RHA and commercial silica were 91.413% and 98.693%, respectively. Particle size of RHA was larger than that of commercial silica. Cure characteristics, mechanical properties and morphology of NR reinforced with RHA and commercial silica were compared. RHA/NR composite showed shorter scorch time and cure time when compared to silica/NR composite. Mechanical properties of commercial silica/NR composite were higher than those of RHA/NR composite. Silane coupling agent (Si69) increased mechanical properties but reduced scorch time and cure time of the NR composites. SEM results revealed that Si69 improved the compatibility between the filler and NR matrix.

Physical, chemical and electric characterization of thermally treated rice husk ash and its potential application as ceramic raw material

Rice husk ash (RHA) is composed essentially by carbon and high levels of silica that justify the economically viable use of RHA in production of ceramic materials. Therefore, this study presents the physical, chemical, and electric characterization of two RHAs submitted to thermal treatment at different temperatures. Grain size, specific weight, specific surface area, total carbon analysis as well as X-ray fluorescence spectrometry, scanning electron microscopy, X-ray diffraction, and complex impedance spectroscopy were carried out. The results indicate that the thermal treatments afforded to produce high-silica RHA with cristobalite and tridymite crystalline phases that indicate the potential of RHA to be used as raw material to obtain advanced silica-based ceramic products. RHA particle size increased with treatment temperature, followed by a slight increase in specific weight and a drastic drop in surface area. Electrical characterization showed that silica particles are closely packed to a carbon film.

Performance of Rice Husk Ash as a Partial Cement Replacement in Fine Grained Mortar

This paper investigates the performance of rice husk ash (RHA) in a fine grained mortar. RHA produced from control combustion of rice husk. Fine grained mortar (FGM) is a mortar containing fine sand with a maximum size of 1mm. Chemical composition of RHA and Ordinary Portland Cement (OPC) were investigated using XRF in order to know the silica content in these materials. The particle size of RHA was analyzed to make sure it fineness is same with OPC after grinding. Compressive and flexural strength of FGM were tested on mortar prism for size 40mm x 40mm x 160mm with replacement of RHA 10%, 20% and 30% by weight of cement at 7 days and 28 days ofcuring. All 24 specimens of FGM were caste and tested. The flexural strength, compressive strength of FGM have shown quite encouraging and interesting results. The optimum replacement of RHA in FGM from compressive and flexural strength is 20% by weight of cement.

Alkali silica reaction in mortar formulated from self-compacting high performance concrete containing rice husk ash

In the present study, the resistance of mortar formulated from self-compacting high performance concrete containing rice husk ash (RHA)/silica fume (SF) and reactive/non-reactive aggregates to alkali silica reaction (ASR) was assessed.For the mortar containing greywacke reactive aggregate, SF is significantly more effective than RHA in reducing expansion of the mortar under accelerated testing conditions (NaOH 1M at 80°C). The increase in particle size of RHA increased the expansion of mortar. Surprisingly, the mortars containing coarse RHA, i.e. 15.6 and 7.7μm, were disrupted after 28 and 56days of immersion. However, the increase in the fine RHA (5.7μm) content decreased the expansion of mortar.For the mortar containing non-reactive basalt aggregate, the incorporation of RHA increased the expansion, and the samples containing the coarse RHA (15.6μm) cracked substantially. This indicates that RHA had paradoxical effect on ASR. The results from microscopic investigations show that RHA particles cracked substantially. The cracks also radiated from the RHA particles into the matrix, and ASR gels formed inside the RHA particles. It is suggested that to mitigate ASR by using RHA, RHA should be ground to very fine particle sizes of at least 5.7μm.

PENGARUH UKURAN PARTIKEL DAN KOMPOSISI ABU SEKAM PADI HITAM TERHADAP SIFAT KEKUATAN TARIK KOMPOSIT POLIESTER TIDAK JENUH

This research was aimed to investigate the effect of black rice husk ash particle size and black rice husk ash composition as filler in tensile strength of unsaturated polyester composites. The composites were made with open mixing method by mixing unsaturated polyester with black rice husk ash with particle size variation of 100 mesh and 250 mesh, and volume fraction ratio between filler and matrix 95/5 : 90/10 : 85/15 : 80/20 then added with 1% methyl ethyl ketone peroxide as catalizer into mixture of unsaturated polyester and black rice husk ash. Tests performed are tensile, elongation at break, and Young’s modulus. The result of obtained at a ratio 95/5 with a particle size of 100 and 250 mesh was 24,413 MPa and 24,689 MPa.

Prediction of tribological behaviour of rice husk ash reinforced aluminum alloy matrix composites using artificial neural network

Artificial Neural Network (ANN) model was developed to predict the wear rate and coefficient of friction for the Rice Husk Ash (RHA) reinforced aluminum alloy composite. The composite was fabricated using the stir cast route and their tribological behavior was tested using Pin-on-Disc wear tester. The experiments were conducted based on Orthogonal array (L27) generated through the Taguchi Technique and their results were used to train the ANN model. The input parameters assigned to develop an ANN model are applied load, sliding speed, RHA particle size and weight percentage of RHA reinforcement. A four layer perception network having 4-7-8-2 architecture was found to be the optimum network. Finally, confirmation test was done to verify the predictive model with the experimental results and also the wear surface morphology of the wear pin was analyzed using the scanning electron microscope.

Chemical Transformation of Rice Husk Ash Morphology

Rice husk ash (RHA) has significant potential to be used as a supplementary cementing material (SCM). However, RHA contains a cellular, honeycomb-like morphology of amorphous silica and this morphology results in high water absorption. Due to this morphology, the use of RHA in concrete results in reduced workability and higher water demands. Reduced workability and higher water demands can be mitigated by using smaller RHA particles. These smaller particles can be obtained by mechanical grinding. However, this grinding requires significant energy. This paper presents a novel method to transform RHA morphology using a chemical transformation process; specifically, an alkali transformation method. Results indicate that the process can effectively reduce RHA particle size and eliminate the cellular and honeycomb-like morphology.

Mechanical Behaviors and Chloride Permeability of Rice Husk Ash Concrete

Rice husk ash (RHA) was used as a mineral additive in concrete and replaced the ordinary cement by 0-30% in this study. The fresh concrete properties, compressive strength, split tensile strength, and elastic modulus as well as the chloride permeability of concretes mixed with different RHA contents was tested. The experimental results reveal that the fluidity, the mechanical behaviors and the chloride ion resistance of rice husk ash concrete decrease with the increasing replacement rate of RHA. The particle size of RHA limits its pozzolanic activity, which indicates that the controlled burning temperature and the fineness of RHA have significant impact on the properties of rice husk ash concrete.

Assessment of the effects of rice husk ash particle size on strength, water permeability and workability of binary blended concrete

This study develops the compressive strength, water permeability and workability of concrete by partial replacement of cement with agro-waste rice husk ash. Two types of rice husk ash with average particle size of 5 micron (ultra fine particles) and 95 micron and with four different contents of 5%, 10%, 15% and 20% by weight were used. Replacement of cement up to maximum of 15% and 20% respectively by 95 and 5 μm rice husk ash, produces concrete with improved strength. However, the ultimate strength of concrete was gained at 10% of cement replacement by ultra fine rice husk ash particles. Also the percentage, velocity and coefficient of water absorption significantly decreased with 10% cement replacement by ultra fine rice husk ash. Moreover, the workability of fresh concrete was remarkably improved by increasing the content of rice husk ash especially in the case of coarser size. It is concluded that partial replacement of cement with rice husk ash improves the compressive strength and workability of concrete and decreases its water permeability. In addition, decreasing rice husk ash average particle size provides a positive effect on the compressive strength and water permeability of hardened concrete but indicates adverse effect on the workability of fresh concrete.

Characterization of mesoporous rice husk ash (RHA) and adsorption kinetics of metal ions from aqueous solution onto RHA

The present study deals with the characterization of low-cost rice husk ash (RHA) for its various physico-chemical properties and adsorption characteristics of metal ions. The average particle size of RHA was 150.47 μm. Proximate analysis showed the presence of high amount of ash in RHA. Bulk density and the heating value of RHA were 104.9 kg/m 3 and 9.68 MJ/kg, respectively. The pore size distribution results showed that the RHA was predominantly mesoporous. The BET surface area was 36.44 m 2/g. The average pore diameter by BET was 42.603 Å. The BJH pore area showed 80% of the pore area due to the mesopores. The polar groups present on the RHA surface imparted considerable cation exchange capacity to it. RHA was found to be an effective adsorbent for the removal of cadmium (Cd(II)), nickel (Ni(II)) and zinc (Zn(II)) metal ions from aqueous solutions. The pH 0 ≈6.0 is found to be the optimum for the removal of individual cations from the aqueous solutions by RHA at an optimum dose of 10 kg/m 3. The kinetics of adsorption showed that the metal ions adsorption on RHA is a gradual process with quasi-equilibrium being attained in 5 h. The pseudo-second-order kinetics represents the equilibrium data well. The effective diffusion coefficient of the cations onto the RHA is of the order of 10 −13 m 2/s.