Rice Husk Ash Research Articles

Salt slag and rice husk ash as raw materials in zeolite synthesis: Process optimization using central composite rotational design

The growing demand of zeolites for many industrial applications has led to a search for eco-friendly alternatives for their production, in an attempt to reduce costs, save natural resources and alleviate the associated environmental impacts. In the present study, hazardous aluminum salt slag (aluminum source) and rice husk ash (silicon source) were used as secondary raw materials to synthesize sustainable NaP-type zeolites through a hydrothermal process. A central composite rotational experimental design was applied to evaluate the effect of the reaction time and hydrothermal temperature on the obtained zeolites crystallinity. Using the proposed experimental design, temperatures between 85 and 115 °C and different reaction times (2–28 h) were tested. It was found that the interaction between the variables (time and temperature) and both variables, independently, exerted a significant influence on the crystallinity of the zeolites. The optimal experimental conditions (105 °C and 20 h), statistically determined, enabled a high degree of crystallinity (>73%) to be achieved. Thus, the use of hazardous aluminum and agri-food wastes as unconventional precursors for the production of zeolites represents a sustainable alternative to manage these wastes, by transforming them into secondary raw materials.

Mesoporous silica aerogels for sunflower oil refining and investigation of their adsorption performance

AbstractInvolving a succession of oil refining stages for edible oil production, a notable constraint lies in the necessity to employ diverse adsorbents at various steps within these processes. This study investigates the synthesis of mesoporous silica aerogels from rice husk ash, comparing their efficacy in physical sunflower oil refining with earth clay (Bentonite) and commercial silica (Trisyl). Tetraethyl orthosilicate (TEOS) impact during aging was analyzed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and N2 adsorption-desorption analyzer to examine alterations in the structure of silica aerogels. The surface areas of TEOS-doped silica aerogel (TSA) and non-TEOS-doped silica aerogel (NTSA) were 296.18 and 267.06 m²/g. Mesoporous silica aerogels were evaluated for their ability to reduce free fatty acids (FFA), peroxide value (PV), phosphorus, and color pigments in sunflower oil. TSA and NTSA demonstrated significant FFA removal, with TSA at 3 wt.% achieving the highest performance of 32.2%. TSA also effectively reduced PV and phosphorus compared to NTSA, Bentonite and Trisyl, exhibiting performance similar to Bentonite in the bleaching process. TEOS-doped silica aerogels have shown promise as adsorbents for impurity removal in sunflower oil and has emerged as the potential adsorbent that can comprehensively and effectively meet the requirements of many edible oil physical refining applications in a singular step. Graphical Abstract

Eco-friendly building materials: full-scale replacement of mineral aggregates with rice husk

In a context where sustainable construction and ecology are increasingly central, the construction industry is constantly seeking alternative materials that are both economical and eco-friendly. Concurrently, global rice production generates significant amounts of rice husks, often considered as low-value waste. This study deviates from traditional approaches that favor the use of rice husk ash (RHA) as a mineral additive, to explore the potential of rice husks themselves as a complete substitute for sand in concrete formulations. After meticulous characterization of the physicochemical properties of rice husks, several concrete formulations were designed and subjected to a battery of tests. The results are promising. They show that concrete based on rice husks exhibits satisfactory mechanical properties for a wide range of applications, from slabs to load-bearing walls. The compressive strength varies between 0.56 MPa and 5.41 MPa depending on the composition, while the thermal conductivity falls within a range of 0.070 W m−1 K−1 to 0.129 W m−1 K−1, which is comparable to other agro-concretes. This research highlights the promising potential of rice husks as a sand substitute material in concrete. It thus paves the way for more ecologically responsible and economically viable construction alternatives, while proposing a value-added solution for a widely available agricultural byproduct.

Quaternary blended eco high performance concrete utilizing high volumes of siliceous additives

This research examines the optimal feasibility of incorporating siliceous additives as an adjunct material for cement in the formulation of environmentally sustainable high-performance concrete (Eco-HPC). Siliceous materials, including Nano silica (NS), Rice Husk Ash (RHA), and Fly Ash (FA), were fine-tuned within the cementitious system in order to achieve the amplified performance of Eco-HPC by reducing the required cement content from 370 kg/m3 to 273 kg/m3. This is achieved by employing the Modified Andreasen and Andreasen (MA&A) particle packing model, with ‘q’ (distribution factor) as ‘0.3’. The Levenberg Marquardt algorithm (curve fitting) was utilized to validate the packing density of each concrete blends. Initially, the dry NS agglomerates are synthesized into stabilized aqueous dispersion through High shear mixing (10 min/1750 rpm) followed by probe sonication (15 min/(1/3) s/s) with anionic surfactant dosage of 0.1 g/10 g. Incorporating secondary siliceous binders into the cement matrix led to an enhancement in the packing density, increasing from 0.94 (nullary) to 0.96 (quaternary) which in turn alters the reactivity and cohesiveness of the matrix. Compressive strength values for Binary (NS2), Ternary (RN15, FN20), and quaternary mix (FRN25) were observed as 57.42 MPa, 56.83 MPa, 55.34 MPa, and 52.58 MPa, respectively, for primary binder contents of 362 kg/m3, 314 kg/m3, 296 kg/m3, and 273 kg/m3 without compromising durability parameters. An assessment on reduced carbon dioxide emissions indicated that increasing the cement replacement percentages in Eco-HPC by up to 30% for binder contents of 358 kg/m3, 296 kg/m3, 259 kg/m3, and 273 kg/m3 resulted in a reduction of CO2 emissions by 2.98%, 18%, 27%, and 23.33%, respectively. Among the twelve formulated mixes, FRN25, FRN20, FRN15 and FN30 are identified as Eco-HPC mix through a computational framework which integrates the packing density, carbon emission, strength and diffusion coefficient.

Exploring the Impact of Rice Husk Ash Masonry Blocks on Building Energy Performance

Operational building energy consumption accounts for 55% of global energy consumption. Most of this is attributed to residential buildings, as they make up the largest building type when compared to the total building stock worldwide. As the building envelope is a major contributor to building energy performance, especially the external walls, its optimisation is therefore imperative to reduce energy consumption and carbon emissions. This study set out to assess the effects of waste material additions to external walls and their effect on building energy performance. This research aimed to critically investigate the effect of rice husk ash (RHA) masonry blocks on building energy performance when compared to conventional masonry blocks in tropical climates. A mix of methods, including experimental investigation and simulation studies, were employed for this study. Three variations of RHA block samples were created for this investigation: RHA 5%, RHA 10%, and RHA 15%. Using prototype buildings from the study context, the building simulation results helped quantify the impact on building energy performance from the reuse of rice waste. The largest improvement to the building fabric was recorded with the RHA15% blocks, which resulted in a 9.9% and 11.3% reduction in solar heat gains through the external walls for the selected bungalow and duplex/storey building, respectively. This resulted in a 6.55% and 4.2% reduction in cooling loads and a 4.1% and 2.8% reduction in carbon emissions, respectively, for the bungalow and duplex/storey building. The findings of this research will prove valuable to householders, researchers, architects, and policymakers in their decision-making processes. The findings will also be useful in introducing new methods that can be adopted for similar studies, bridging the knowledge gap while promoting a circular economy through the reuse of landfilled waste.

Exploration of rice husk ash as a green corrosion inhibitor immersed in NH4Cl 7.5 % solution

The study reports the development of a liquid smoke solution of rice husk ash (RHA) as a green corrosion inhibitor in NH4Cl solution in approaching corrosion protection for refinery facilities. The recent utilization of RHA has a partial solution to address the possible chemical to form a filming layer to disconnect bare metal and their environment. This work prepared the RHA solution by condensing the RHA vapor before adding it to various concentrations. The corrosion test of potentiodynamic and electrochemicals intends to discover the inhibitor's corrosion resistance before examining the electronic transition corresponding to the contribution of several functional groups using Ultraviolet Visible (UV–Vis) and Fourier-Transform Infrared Spectroscopy (FTIR). Surface evaluation intends to unveil the nature of the corrosion by utilizing the Scanning Electronic and Atomic Force Microscope. The corrosion test result shows the depression of corrosion rate to 0.120 mmpy with high efficiency beyond 96 % in the addition of 7.5 ppm RHA inhibitor. The greater Nyquist semicircle diameter at high concentrations increases the adsorption of the RHA on the surface of C1018. The electronic transition of n–π* and π –π* shows an extensive contribution of CC, CO, and –OH based on the UV–Vis and FTIR test. The formation of a complex compound of Fe-(NH4Cl-RHA)n blocks the corrosion active sites to reduce the corrosion. This study paves the way for using RHA as an organic compound under NH4Cl conditions, such as in a refinery process facility.

Insulating refractories based on rice husk ashes functionalized by flame-sprayed alumina coatings for steel ingot casting

This study investigates a new insulating refractory material based on rice husk ashes (RHA) for its application in the steel ingot casting process. The excellent insulating properties of this material may improve heat- and energy balance during ingot casting. A flame-sprayed alumina coating is applied to provide chemical inertness of the substrate material against the steel melt. The refractoriness, oxidation resistance, phase evolution and thermal expansion of four different grades of RHA materials and phase evolution and thermal expansion of flame-sprayed alumina coatings are studied. The refractoriness of the RHA materials increased with increasing silica content, showing sufficient refractoriness up to 1600°C for SiO2>94wt%. Immersion tests with composite materials made from RHA substrate and a flame-sprayed alumina coating were successfully performed in a steel casting simulator. No deformation of the substrate material nor spalling of the flame-sprayed alumina coating was observed despite an immersion without preheating.

Investigating the effects of biofilm, biopolymer, and enzymatic treatment methods on natural fiber for improving concrete strength properties

In today's age, finding harmony between construction endeavors and safeguarding the environment is of utmost importance. Consequently, there is a substantial requirement to explore the feasibility of utilizing waste materials as a replacement for traditional construction substances. Unfortunately, there is a lack of information regarding the possibilities of incorporating recycled glass, rice husk, and sugarcane bagasse ash into concrete production. This study investigated the viability of integrating recycled glass fibres and agricultural waste ash into concrete to bolster its strength and sustainability. When evaluating mechanical and durability properties across five mixtures, the concrete formulations ranged in fibre content percentages from 1% to 3% and in ash content percentages from 10% to 20%. Specifically, Mixtures 1, 2, 3, 4, and 5 contained 1% fibre and 10% ash, 2% fibre and 15% ash, 2.5% fibre and 20% ash, 3% fibre and 12% ash, and 1.5% fibre and 18% ash respectively. Mixture 2 and Mixture 5, boasting heightened fibre and ash content, showcased outstanding compressive strength at 38.5 MPa and 37.2 MPa, respectively, indicating a positive correlation between these materials and concrete strength. Conversely, Mixture 3, burdened with excessive fibre and ash content, witnessed diminished strength, underscoring the necessity for meticulous optimization. In terms of tensile and flexural strength, Mixture 2 and Mixture 5 displayed commendable performance, while Mixture 3 suffered setbacks from excessive content. Durability assessments unveiled Mixture 1 and Mixture 4's superior freeze-thaw resistance, with minimal mass loss (1.5% and 1.8%, respectively) and no visible damage, rendering them favorable choices for sustainable construction. Contrastingly, Mixture 3 exhibited poorer freeze-thaw resistance and higher environmental impact, highlighting the need for careful consideration in material selection. Overall, this study underscores the importance of optimizing concrete formulations through the integration of recycled materials, paving the way for stronger, more durable, and environmentally friendly construction practices.

Data-guided for discovering high-strength, cost-effective, and low-carbon rice husk ash concrete

This study aims to present a data-guided intelligent design framework for discovering high-strength, cost-effective, and low-carbon rice husk ash concrete (RHC). First, gradient boosting (GB) models were developed to predict compressive strength of RHC based on a dataset with 1150 samples. The CatBoost model outperforms XGBoost and LightGBM models on the test set, and its determination of coefficient (R2), root mean squared error (RMSE), and mean absolute error (MAE) are 0.984, 3.270 MPa, and 2.290 MPa respectively. With the best prediction model, SHapley Additive exPlanations (SHAP) was utilized to shed light on the model outputs. The curing age is the most dominant features effecting the compressive strength of RHC, and the next two are the contents of cement and water. Then, a computational design framework was proposed by integrating the machine learning-based model and the evolutionary algorithm. Considering compressive strength, materials cost, embodied carbon, and embodied energy, the multi-objective optimization was conducted leveraging the improved adaptive geometry estimation based many-objective evolutionary algorithm (AGE-MOEA II). The optimal solutions of the different design scenarios were achieved using the multi-criteria decision-making method. The research can provide a theoretical reference for the capability of developing RHC mixture using data-guided approachesto promote the sustainable development of concrete industry.

Potential of rice husk ash as cement alternative in constructing bricks: Utilization for “Gulayan sa Paaralan” program

This research aims to investigate the “Potential of Rice Husk Ash as Cement Alternative in Constructing Bricks: Utilization for ‘Gulayan sa Paaralan’ Program”. The success of this study provides cheaper option of construction materials. The pandemic experience of the Philippines, economic deterioration became a challenge. Prices of prime commodities continuously increases, including the construction industry. Nowadays, there are various cement alternative being utilized inside and outside of the country. Some part here in the Philippines use fly ash as a cement alternative. But fly ash is not readily available in Laguna. That is why the researchers look for an alternative that is readily available, inexpensive and do not harm the environment. In this study, the researchers examine the potential of rice husk ash and they constructed bricks in which they plan to use for the beautification of school’s garden. In accordance with the governing specification of American Standard of State Highway and Transportation Officials (AASHTO) and American Society for Testing and Materials (ASTM), the researchers conducted a standardized laboratory test. After series of test, researchers concluded that rice husk ash is not a significant alternative to cement as it reduce the strength and durability of the brick made out of it. However, since the chemical composition, fineness test, and water absorption test of rice husk ash and rice husk ash bricks passed the requirements of American Society for Testing and Materials, the researchers inferred that rice husk ash could still be used as additive in creating a decorative bricks.

Investigation on Partial Replacement of Cement with Rice Husk Ash

Investigation on Partial Replacement of Cement with Rice Husk Ash

Investigational Study on the Influence of Sisal Fiber and Rice Husk Ash in the Stabilisation of Clayey Soil

The process of improving and enhancing the engineering qualities of soil so that it can support large loads without failing is known as "soil stabilization" in the realm of civil engineering. The behavior of the soil was examined in the current work at various proportions following the addition of Rice Husk Ash (fixed at 15%) and sisal fiber (varying at 1.5%, 2.0%, and 2.5%; length 40 mm). Various soil properties, such as OMC, MDD, CBR value, and UCS values, were then quantified. Utilizing Sisal Fiber and Rice Husk Ash together can enhance the diverse engineering features of soil, according to the conclusion of this experimental research project. Laboratory tests such Atterberg's Limits, Specific Gravity, Particle Size Distribution, Standard Proctor test, Unconfined Compressive Strength (UCS), and California Bearing Ratio (CBR) were carried out to examine the engineering qualities of the soil and its mixtures. The results showed that the engineering qualities of clayey soil were significantly enhanced by the addition of Sisal Fiber and Rice Husk Ash. As a result, Sisal Fiber and Rice Husk Ash may act as soil stabilizing agents, making clayey soil a better choice for building foundations. All testing were carried out in accordance with Indian standards regulations. Key Words: Compaction test, CBR, UCS, Rice Husk Ash, Sisal Fiber

Ternary geopolymer synthesized using self-made rice husk ash-based water glass for removing Cu2+ and Cr3+ from wastewater

In this study, a ternary microsphere geopolymer composed of fly ash, calcium carbide slag, and rice husk ash was synthesized, with homemade rice husk ash-based water glass employed as a substitute for industrial water glass. Through a series of characterizations, it was confirmed that calcium carbide slag and rice husk ash promote geopolymerization and produce more hydrated calcium silicate (C-S-H) gels. The ternary microsphere adsorbent demonstrates potential cost-effective and efficient applications in heavy metal adsorption.

Enhancing Soil with Low-Cost Pozzolanic Materials: Rice Husk Ash and Groundnut Shell Ash Compared to Cement

Enhancing Soil with Low-Cost Pozzolanic Materials: Rice Husk Ash and Groundnut Shell Ash Compared to Cement

Synergistic effects of limestone powder and unground rice husk ash additions on performances of slag-cement based self-compacting concrete

Synergistic effects of limestone powder and unground rice husk ash additions on performances of slag-cement based self-compacting concrete

Durability of Ternary Blended Concrete Incorporating Rice Husk Ash and Calcined Clay

Research on the combined substitution of supplementary cementitious materials (SCMs) has already demonstrated that it might be one of the few viable options to produce low-carbon concrete at scale. This paper presents an experimental investigation on the performance and durability of rice husk ash (RHA) and calcined clay (CC) in ternary blended concrete exposed to chloride attacks under wet/dry cycles. Portland cement (PC) was replaced by RHA and CC up to 50% by weight to produce low-carbon concrete. Samples were subjected to wet/dry cycles in 3.5% NaCl water, with mineralogical composition and microstructure development before and after exposure analysed by TGA-DSC, MIP, XRD, and SEM. The durability of the concrete against wet/dry cycles was investigated in terms of compressive strength, water absorption, open porosity, density, thermal conductivity, and electrical resistivity. The results showed that concrete mixes with CC and RHA up to 60% exhibited an increase of 33% in compressive strength, followed by minimal changes in water absorption. While a decrease in electrical resistivity was measured in all samples with RHA and CC, increasing the CC content to 50% resulted in improved resistance to chloride penetration. Increasing the CC content resulted in a more refined microstructure, with an overall decrease in porosity of up to 32% compared to the control series. While RHA alone did not contribute to significant improvements after wet/dry cycles, the combined substitution of RHA and CC at SCM replacement levels of 60% showed an overall improvement in hardened properties and durability. This investigation provides valuable insights into the long-term performance and strength of innovative low-carbon concrete.

Eco-friendly polyurethane composites with rice husk ash residue to remove petroleum hydrocarbons from aqueous media

Eco-friendly polyurethane composites with rice husk ash residue to remove petroleum hydrocarbons from aqueous media

Properties of ultra lightweight foamed concrete utilizing agro waste ashes as an alkaline activated material

In the present investigation, rice husk ash (RHA), bamboo leaf ash (BLA) and palm oil fuel ash (POFA) known as agricultural-waste materials locally available were used to produce ultra lightweight foamed concretes (ULFCs). BLA, RHA, and POFA were used as replacements for cement in ULFCs at different weight percentages of 0 %, 5 %, 10 %, 15 %, and 20 %. To achieve the target density of 350 kg/m3, cement was substituted with agricultural wastes, and a protein foaming agent was added. The properties of ULFCs were examined including, slump test, setting time, fresh density, splitting tensile, compressive and flexural strengths, thermal insulating, microstructural and transport properties, permeability and pore's structure. The experimental results demonstrated that BLA and POFA ashes significantly outperforms in terms of efficiency and improved the mechanical and transport qualities of ULFCs than RHA ash. By increasing the weight fractions of BLA, RHA, and POFA from 5 % to 20 % in ULFC mixes resulted in an improvement in slump, porosity, capillary sorption, water absorption, bulk density, intrinsic air permeability, and specific heat. The ideal results were seen in terms of compressive strength, bending strength, splitting tensile strength, and UPV when 15 % POFA and BLA, and 10 % RHA were used as substitutes for cement. The increase in weight fraction of BLA, RHA, and POFA resulted in a rise in both thermal conductivity and thermal diffusivity of ULFCs. SEM studies revealed that incorporating different agricultural wastes positively affects the pore size distribution within the microstructure decreasing with increased content of ashes related to the development of ULFCs with stronger matrix. As a result, the formulated ULFCs met the masonry strength criteria while also providing economic and environmental benefits.

Shear Strength and Durability of Expansive Soil Treated with Recycled Gypsum and Rice Husk Ash

Expansive soil underlying structures pose a significant risk to the integrity of superstructures. Chemical soil stabilization can be used to strengthen soils due to the cost and impracticality of mechanical approaches. Waste materials such as recycled gypsum and rice husk ash have been considered alternatives because of their sustainable and economic advantages. A combination of these additives was used to address the high absorption of gypsum and the lack of cohesion of the pozzolan. The study assessed the short-term and long-term performance of expansive soil treated with recycled gypsum and rice husk ash under normal and fluctuating moisture conditions. Direct shear tests indicated ductile and compressive soil behavior with improved shear strength. A good approximation of stress–strain response was made with a modified hyperbolic model for treated soils that exhibited strain hardening and compressive volumetric strain. Durability and water immersion tests were performed for samples after varying curing periods and cycles of capillary soaking to assess the behavior when exposed to varied environmental conditions. Samples under the modified durability test experienced significant strength loss, with decreasing compressive strength as curing durations increased. Specimens in the modified water immersion test experienced significant strength loss; however, it was determined that curing durations did not contribute to the change in the strength of the sample. Expansion index tests also determined that the treatment effectively mitigated expansivity and collapsibility in all samples. Despite improvement in shear strength and expansion potential, further investigation is needed to enhance the durability of soil treated with gypsum and rice husk ash.

Strength Properties of Blended Cement Mortar with Metakaolin and Rice Husk Ash

This study investigates the feasibility of using rice husk ash (RHA) and metakaolin as substitutes for Ordinary Portland Cement (OPC) in mortar production to reduce greenhouse gas emissions associated with construction. The study employs MM3 grade mortar, with RHA replacing cement at varying percentages (0%, 5%, 10%, and 15%), while metakaolin consistently substitutes 10% of the cement. Compressive strength tests are conducted on specimens cured for 7, 14, and 28 days to assess performance. The study utilizes OPC 53-grade cement with a water-cement ratio of 0.4. In total, four mortar mixes are prepared, and each mix comprises nine specimens, totaling 45 specimens. Initially, conventional mortar is evaluated for its physical and mechanical properties. The study aims to contribute to ongoing efforts in the construction industry to explore sustainable alternatives to conventional materials, such as RHA and metakaolin, while ensuring the requisite strength properties of mortar are maintained. Key Words: Rice husk ash, metakaolin, cement, sand, mortar and compressive strength