Ash Silica Research Articles

Research on the Configuration of Multi-Component Solid Waste Cementitious Materials and the Strength Characteristics of Consolidated Aeolian Sand

Developing green, low-carbon building materials has become a viable option for managing bulk industrial solid waste. This paper presents a kind of all solid waste cementitious material (SWCM), which is made entirely from six common industrial wastes, including carbide slag and silica fume, that demonstrate strong mechanical properties and effectively stabilize aeolian sand (AS). Initially, we investigated the mechanical strength of waste-based cementitious materials in various mix ratios, focusing on their ability to stabilize river sand (RS) and aeolian sand. The results show that it is necessary to use alkaline solid waste carbide slag to provide a suitable reaction environment to achieve the desired strength. In contrast, the low reactivity of coal gangue powder did not contribute effectively to the strength of the cementitious material. Further orthogonal experiments determined the impact of different waste dosages on the strength of stabilized AS. It was found that increasing the amounts of carbide slag, silica fume, and blast furnace slag powder improved strength, while increasing fly ash first increased and then decreased strength. In contrast, higher additions of desulfurization gypsum and coal gangue powder led to a continuous decrease in strength. The optimized mix is carbide slag—desulfurization gypsum—fly ash—silica fume—blast furnace slag powder in a ratio of 4:2:2:3:3. The experimental results using SWCM to stabilize AS indicated a proportional relationship between strength and SWCM content. When the content is ≥20%, it meets the strength requirements for road subbases. The primary hydration products of stabilized AS are C-(A)-S-H, AFt, and CaCO3. Increasing the SWCM content enhances the reaction degree of the materials, thereby improving mechanical strength. This study highlights the mechanical properties of cementitious materials made entirely from waste for stabilizing AS. It provides a reference for the large-scale utilization of industrial solid waste and practical applications in desert road construction.

The influence of selected grain size fractions of coal fly ash on properties of clay-cement mortars used for the flood levees construction

This study examines the influence of different grain size fractions of coal fly ash on the properties of clay-cement mortars used in flood levee construction. Dry aerodynamic separation and mesh sieving were used to obtain ultrafine, fine, and medium fractions of high-calcium and silica fly ash. The experimental results reveal that the rheological properties of fresh mortars are significantly influenced by these fractions. High-calcium fly ash mortars exhibit high reactivity and rapid increase in viscosity, with finer fractions showing the highest reactivity. Silica ashes show increased reactivity in the later stages of suspension hardening. Their spherical shape contributes to reducing internal friction during flow in initial technological operations. Furthermore, the compressive strength of hardened mortars improves as the particle size decreases for both ashes, resulting in a dense and uniform microstructure. The separation and fractionation of fly ashes contribute to the obtaining of fractions that influence the parameters of clay-cement suspension application on different scales. The results show the potential benefits of ash separation, which can bring advantages in terms of economic viability, engineering performance, and ecological sustainability.

SURFACE MODIFICATION OF FLY ASH FROM ASAM-ASAM COAL POWER PLANT USING STEARIC ACID AS HYDROPHOBIC INORGANIC MATERIAL

Abundant coal reserves make this material a substitute fuel choice, especially for industry. The use of coal carries a high risk due to incomplete combustion and produces fly ash products. Fly ash cause pollution and health risks as well as environmental contamination when they are released, deposited, or leached into the ecosystem over short or long periods of time. The high content of silica and alumina in fly ash can be utilized and modified into new materials with added value. This research aims to modify the surface of fly ash using stearic acid as a hydrophobic inorganic material. Fly ash from Asam-asam Coal Power Plant was characterized by using XRD and modified by immersing in stearic acid (2,4,6, and 8%) and 98% ethanol. The result showed that the contact angle increases when fly ash is modified on the surface using stearic acid. The contact angle increases with increasing stearic acid concentration. The highest contact angle was obtained at a stearic acid concentration of 8%, and the lowest at 2% was about 112.9 and 102.2, respectively. The fly ash composition was primarily silica and alumina, which were crystalline, as confirmed by XRD. These findings provide several aspects of fly ash and its potential as a candidate material for environmental remediation and waste management.

Valorization of agriculture waste: Preparation of alkoxysilanes from mixed rice straw and rice husk ash

Synthesis of alkoxysilanes from renewable silica resources could promote their sustainability but remain grand challenges. Herein, we present a simple, effective strategy to synthesize tetraethyl orthosilicate (TEOS) directly from bio-derived silica through supercritical ethanol processing, where no catalyst nor additives are required. Crucially, calcination temperature is demonstrated to play a critical role in altering the structure of silica in rice husk ash (RHA), which directly influences its conversion activity to alkoxysilanes. Specifically, under optimized conditions at 280 °C and 1 h, RHA obtained at 400–625 °C calcination allows for an amorphous silica structure and as high as 85 mol% yield to alkoxysilanes. Moreover, the ash obtained from mixed rice straw and rice husk yields over 94 mol% alkoxysilanes, demonstrating the self-catalytic potential of the natural complexity of the ash. The effects of typical minerals contained in ash on the reaction are probed. It is revealed that potassium oxide is the main catalytic species in ash, which provide a suitable alkaline strength. The concentration of potassium ion exhibits a pronounced positive effect on catalyzing the synthesis of alkoxysilanes, and the co-existed phosphorus species exhibits promotional effect to TEOS selectivity. Furthermore, 29Si MAS NMR and Laplacian bond order analysis reveal that the cleavage of Si-O-Si bond predominates in the supercritical ethanol environment, providing a viable path for the production of TEOS.

Invitro Activity of Mineral Trioxide Aggregate Modification from Rice Hull Ash Silica and Calcium Oxide from Clamshells

The impact of SrO particles and hydroxyapatite (HA) on the characteristics of Mineral Trioxide Aggregate (MTA) from silica Rice Husk Ash (RHA) and Precipitated Calcium Carbonate (PCC) from clam shell has been studied in this research. Silica and calcium oxide are used as material to form tricalcium silicate (C3S) and dicalcium silicate (C2S) in MTA. Bi2O3 and SrO were added in MTA with 18% (w/w) total percentage. MTA was made with a sol-gel process and used catalyst NH3. After synthesis, material was calcined at 1000 oC for 3 h. HA was added at percentages of 3, 6, and 9% in 5% SrO modified MTA to see the effect of its addition on the material. The modified MTA (MTA-SrO-HA) were hydrated water using water to powder method with ratio of 3:1. The MTA-SrO5/HA6 showed higher compressive strength and dentine interaction to the commercial MTA (Proroot brand) in days 3 and 7. This material had potential as a root canal filling in dental endodontic treatment.

Comparison the adsorption of Pb with Ecofriendly Bio-Adsorbent From Rice Husk Ash and Boiler Fly Ash

The amount of environmental pollution is in line with the increasing of industry. Industry can generate waste in the form of solid, liquid or gas. Utilization of waste as an adsorbent is a solution that can be done in dealing with waste such as metal waste contained in water. Therefore, this research aims to make a bio-adsorbent in the form of silica from rice husk ash and boiler fly ash and know the comparison of the Pb absorbed. The research method used is an experimental method by synthesizing the manufacture of silica. Then testing of Pb based on contact time was 30 minutes, 60 minutes, 90 minutes and 120 minutes. The results showed that the two silica-based bio-adsorbents could adsorb Pb. Bio-adsorbent from rice husk ash absorbed 56.51% of Pb in 30 minutes, 52.93% in 60 minutes, 48.65% in 90 minutes and 43.55% in 120 minutes. The bio-adsorbent from the fly ash boiler absorbed 50.15% of Pb in 30 minutes, 44.28% in 60 minutes, 38.48% in 90 minutes and 36.45% in 120 minutes. Bio-adsorbent from rice husk ash absorbs more Pb ions than from boiler fly ash. Because the silica in the rice husk ash forms a collection in the pores, whereas in the fly ash boiler there is silica that is spread out. This research can be a basis for further research in the form of dye bio-adsorbent products based on their short use time.

One-step functionalization and polymer grafting potential of green silica derived from rice husk ash

Green silica has been synthesized from rice husk ash which exempts the landfilling of agricultural waste and the requirement of higher temperature for digestion, unlike the conventional mode of silica synthesis making the process of precipitation and functionalization sustainable. An energy-efficient method of functionalization has been optimized for the synthesis of functionalized silica from rice husk ash via co-condensation. The potential for providing better reinforcement leads silica to be used as filler in composite manufacturing. To obtain a better silica-polymer interaction, nitroxide functionalized silica has been synthesized over three different types of silica samples using different processes. The nitroxide functionalities were introduced by thiol-ene reaction between 4-acryloyloxy(2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) and mercaptopropyl functionalized silica particles. The mercaptopropyl functionalized silica was synthesized by post-modification as well as co-condensation over commercial precipitated silica, commercial rice husk ash silica, and silica synthesized in the lab from sodium silicate obtained from rice husk ash. By comparing mercaptopropyl and nitroxide grafting density, it has been observed that the nitroxide loading highly depends on the method of functionalization and the co-condensed samples show higher nitroxide loading compared to the post-modified samples. The nitroxide functionalized samples were further subjected to polystyrene grafting, and the efficiency of surface nitroxide radicals in capturing the polymer radicals with respect to nitroxide loading was determined. The grafting density was observed to increase with the increase in conversion and the increase in the initiator-to-monomer ratio. However, the grafting density was observed to be saturated at some point despite having a higher surface area and surface nitroxide radicals. The study can be used to tune the surface nitroxide radical concentration and surface area for optimum polymer grafting for engineering applications.

Freeze–thaw damage analysis and life prediction of modified pervious concrete based on Weibull distribution

An assessment of the freeze–thaw durability of pervious concrete was conducted using a rapid freezing method to investigate the durability of modified pervious concrete within a freeze–thaw environment. The optimal proportion of the modified material was determined by evaluating the mass-loss rate and the relative dynamic elastic modulus as indicators of freeze–thaw performance. Scanning electron microscopy (SEM) was employed to observe microcrack propagation and reaction products. A freeze–thaw damage model, based on the Weibull probability distribution, was formulated. Freeze–thaw damage analysis and life prediction assessment were carried out using curves such as freeze–thaw damage velocity curves, freeze–thaw damage acceleration curves, failure rate curves, and reliability life curves. The outcomes revealed that the inclusion of polyacrylonitrile (PAN) and silica ash had a favourable impact on improving the frost resistance of pervious concrete at later stages. The optimal proportions for PAN fibre and silica ash were determined as 0.6 % and 8 %, respectively. As the number of freeze–thaw cycles approached approximately 52.03 times, the freeze–thaw cycle velocity peaked. Subsequently, the freeze–thaw damage velocity was categorised into three stages based on the freeze–thaw damage acceleration curve. The degradation of pervious concrete due to freeze–thaw cycles followed a typical loss-type failure pattern. Notably, a 50 % increase in PAN fibre content resulted in a 62.92 % reduction in failure rate. Furthermore, a predictive analysis was conducted to estimate the lifespan of pervious concrete in a representative freeze–thaw region in China was performed.

Development of Rheology in the Area of High-Performance Concrete – A Review

Abstract The rheological or flow quality high-performance concrete (HPC) are significant as they affect several parameters, including ease of placing, compatibility, durability and strength. For the selection of component materials and prediction of the fresh and hardened characteristics of HPC, an adequate understanding of rheology is required. This literature review gives a gist of the works done in the field of rheological study of HPC. The flow models and equations to explain the flow behaviour of HPC mixes as proposed by the researchers are presented. Yield stress and plastic viscosity are the basic rheological parameters that are used in these equations. Various rheometers developed to measure and estimate these rheological parameters of HPC are also presented in this paper. This review provides a thorough analysis of the effects of various constituent materials on the rheological properties of HPC. This includes aggregates, cement, various supplementary cementitious materials like fly ash silica fume, slag etc. Also, the effect of mineral admixtures like superplasticizers and viscosity modifying agents along with the synergic effects is discussed. Finally, the prospects of the study on the unexplored areas and future challenges in the field of study are discussed.

Optimization Design of Mix Proportion for Fly Ash-Silica Fume-Basalt Fiber-Polypropylene Fiber Concrete under Steam Curing Condition.

To enhance the physical and mechanical characteristics of steam-cured concrete, an orthogonal experimental design was utilized to examine the effects of varying contents of fly ash (0 wt%, 10 wt%, 15 wt%, 20 wt%), silica fume (0 wt%, 5 wt%, 10 wt%, 15 wt%), basalt fiber (0 vol%, 0.05 vol%, 0.1 vol%, 0.2 vol%), and polypropylene fiber (0 vol%, 0.05 vol%, 0.1 vol%, 0.2 vol%) on its mechanical properties. Utilizing range and variance analyses, this study identified four preliminary optimized compositions of concrete incorporating fly ash, silica fume, basalt fiber, and polypropylene fiber. On this basis, in order to determine the optimal mix proportion, the mechanical performances, the pore characteristics, and the microstructure of four optimized mix proportions were analyzed. According to the results of macroscopic, fine, and microscopic multi-scale tests, the addition of 15 wt% fly ash, 10 wt% silica ash, 0.2 vol% basalt fiber, and 0.1 vol% polypropylene fiber to the steamed concrete is the best to improve the performance of the steamed concrete. Compared to ordinary concrete, the compressive strength increases by 28%, the tensile strength increases by 40%, and the porosity decreases by 47.2%.

Effects of chemical treatment on natural (rice straw/neem saw dust) fiber morphology and mechanical properties of its composite material

Recent years have seen an increase in the use of natural fibers. Rice straw/natural fiber hybrid composites can recycle agricultural waste easily and eliminate fine silica ash pollution. Composite specimens are created by hand lay-up as per ASTM standards. Unsaturated polyester resins and rice straws are studied using scanning electron microscopy. Hybrid composites reinforced with rice straw and neem powder perform better. The optimal fiber content for impact and flexural strength is 50 % by volume fraction. RSNWP6 fibers with hybrid properties have more significant impact strength, hardness, and flexural strength than other fibers at 516.86 J/m, 45 BIU, and 80.03 MPa.

COD’s Level Reduction of Tofu Industrial Wastewater by Using Activated Coal Fly Ash as Adsorbent

Tofu wastewater contained a high concentration of COD and will be dangerous if directly discharged into the environment without any pre-processing. In this research, tofu wastewater is processed using an adsorption process to determine the amount of COD reduction in tofu wastewater using coal fly ash. To maximize the adsorption process by enlarging the fly ash’s pores and removing the impurities, fly ash is activated first by using 2 M of H2SO4 100 mL. Fly ash was tested with XRD (X-Ray Diffraction) to know its crystal structure and tested with XRF (X-Ray Fluorescence) to determine the difference in the elemental composition of fly ash before and after the activation process. The research on the effect of time on the adsorption process was carried out with time variations of 15, 30, 45, 60, 75, 90, 105, and 120 minutes. The results showed that the intensity of silica in the fly ash after the activation process was more significant than before the activation process. The optimum time for fly ash to adsorb tofu wastewater was 105 minutes with eficiency of 79,71%.

Enhanced hydrogen generation from biodiesel-waste glycerol using Ni/SBA-15 catalyst synthesized from boiler ash

The successful synthesis of the mesostructured SBA-15 derived from extracted boiler ash silica (BA) with distinct Ni loading (15 wt%, 20 wt%, and 25 wt%) towards H2 production from CO2 and C3H8O3 was explored. The catalysts prepared by the ultrasonic-assisted method were subjected to 8 h of GDR at 800 °C. The XRD and N2 sorption revealed reduced area and crystallinity in 25 wt% Ni versus 15 wt% Ni catalyst. 20 Ni/SBA-15(BA) exhibited a larger area (234 m2/g), aperture (8.99 nm), and small NiO crystallite (18.34 nm), implying well-dispersed Ni species on SBA-15(BA) surface. 20 Ni/SBA-15(BA) displayed the highest GDR catalytic activity (57 %), credited to its accessible structure, strong Ni–O–Si bonding, and good Ni dispersion that reduced coke formation (9.8 % carbon). This discovery highlights the excellent performance of 20 wt% of Ni loaded on SBA-15 by using green silica source extracted from waste material for H2 fuel production.

Silica ash from waste palm fronds used as an eco-friendly, sustainable adsorbent for the Removal of cupper (II).

Silica ash from waste palm fronds used as an eco-friendly, sustainable adsorbent for the Removal of cupper (II).

Rice husk fibers and their extracted silica as promising bio-based fillers for EPDM/NBR rubber blend vulcanizates

Bio-based natural wastes could be considered eco-friendly alternatives to conventional fillers for enhancing the properties and reducing the cost of final rubber products. Thus, in the present research, EPDM/NBR rubber blend composites filled with kaolin and mixed with rice husk fibers (RHFs) were prepared. Homogeneity of the EPDM/NBR blends was improved by the incorporation of maleic anhydride (MAH) as a compatibilizing agent (1 phr), as evidenced by scanning electron microscopy (SEM). Of all EPDM/NBR blend ratios investigated, the 25/75 blend revealed good mechanical properties, thermal stability, and the least weight swell at equilibrium (Q%) in motor oil and brake fluid. EPDM/NBR/kaolin (25/75/30) blend vulcanizates containing RHFs at various loadings demonstrated a significant improvement in swelling resistance, primarily in motor oil and brake fluid, accompanied by a slight reduction in the mechanical properties at high RHFs content. That was complemented by the enhancement of thermal stability of the rubber blends, as demonstrated by TGA analysis. Among the filler types investigated (RHFs, silica ash (SA), rice husk silica (RHS), and kaolin), RHFs exhibited the best swelling resistance of the composite vulcanizates in motor oil and brake fluid. In addition, RHS could be used successfully as a supporting filler for carbon black-reinforced EPDM/NBR composite vulcanizates because it enhanced their thermal stability and swelling resistance in the motor oil.Graphical

Preparation and properties of rice husk ash silica filled natural rubber

AbstractRice husk ash silica obtained from the chemical purification of rice husk ash is a bio‐based silica. As a sustainable raw material, the bio‐based silica has attracted much attention in recent years. It can be used to replace traditional carbon black and silica in tire rubbers. Our experimental results show that the bio‐based silica can bring similar mechanical properties and higher wet grip to natural rubber in comparison with traditional silica. The wet mixing method is successfully used to disperse the bio‐based silica in natural rubber latex, obtaining a bio‐based silica/natural rubber composite with higher abrasion resistance and lower rolling resistance than the composite prepared by traditional dry mixing. The mechanical properties of bio‐based silica/natural rubber composites depend on the silica loading and mixing methods. Mixing natural rubber and bio‐based silica through wet‐mixing method is a green and sustainable approach to the tread rubbers with excellent mechanical properties, low rolling resistance, high abrasion resistance, and wet grip.

Extraction of Silica from Different Solid Wastes and Its Application as Catalyst Support for Vapour Phase Oxidation of Aromatic Hydrocarbon

In present study, the research work has been divided into two sections viz. Firstly, amorphous silica was extracted from different silica rich agricultural and industrial waste materials (fly ash, perlite and rice husk ash) via sol-gel method. The extracted silica (RHA-Si, Perlite-Si, FA-Si) was characterized using BET surface area, FESEM, EDS, XRD, NMR and FTIR techniques. The surface area and particle size of extracted silica was found to be 23.06-255.5 m2/g and 61-267 nm. Secondly, fly ash silica was used as catalyst support and modified desirably by loading different molybdenum weight percentages via acid impregnation method. The presence of MoO3 on the surface of extracted silica were confirmed by different characterization techniques. The kinetic studies of the FASi/Mo-15 catalyst for the vapour phase oxidation of benzene was also investigated by employing the Mars Van Krevelen model to analyze the reaction mechanism and rate of the process. The vapour phase oxidation reaction follows zero order kinetics, with faster benzene conversion occurring at lower intake concentrations and higher reaction temperatures.

TEMPERATURE IMPACT ON THE HYDRATION AND SETTING MECHANISM OF C-S-H BONDING ON NANO-BIOMASS SILICA WITH POLY-CARBOXYLATE ETHER

<p>Pozzolanic material and a chemical admixture have been used in the current investigation; Nano Biomass Silica (NBS) and Poly-Carboxylate Ether (PCE). NBS produces 20% of the 590 million tonnes of paddy produced globally. Amorphous silica, a mineral component used in concrete, is present in sizable levels in these by-products (NBS). A binary and ternary of NBS with partial replacement of Ordinary Portland Cement (OPC) and the addition of PCE with varying dosage by weight of cement were used. This study's goal is to determine how they affect paste Setting time (ST) and Standard consistency (SC), and hydration temperature evaluation conducted in hot weather with various percentage at NBS from 6, 12 and 18% and PCE with varying dosage from 0.8, 0.9 and 1%. The chemical bond & structure of pozzolanic and chemical admixture in the FTIR were analysed. While PCE showed very little impact on consistency, higher w/b ratios with higher NBS levels were required for the maintenance of OPC-NBS paste consistency standards. The Initial setting time (IST) & Final setting time (FST) for binary OPC-NBS pastes significantly raise to 6% NBS, followed by a decrease at 12% and 18% NBS. However, for OPC-PCE pastes, the IST increased to 0.8%PCE followed by decrease at 0.9% and 1% PCE. In cement paste, PCE can be added as an additive, but the FST increases with an increase in the PCE percentage. At the same time, the mineral admixtures NBS can be used as a cement paste to decrease the FST and also reduce agricultural waste. NBS will effectively use silica ash as a microstructure filler as an additive in manufacturing to produce a certain form of cement with specific IST and FST, in particular for the sustainability of building materials and in hot weather.</p>

Investigation of rice husk semi-continuous combustion in suspension furnace to produce amorphous silica in ash

Investigation of rice husk semi-continuous combustion in suspension furnace to produce amorphous silica in ash

ACID WASH INFLUENCES ON PHYSICOCHEMICAL CHARACTERISTICS OF BAMBOO LEAVES ASH

Silica production from sandstone requires tremendous fossil resources that threaten our environment. Hence, greener resources from biomass should be utilized. One of them is from bamboo leaves which contain rich silica in ash. Even so, acid wash should be applied to achieve higher silica purity. This work aims to investigate the acid wash influences on the physicochemical characteristics of bamboo leaves ash (BLA). The treatment used 1 mol/L HCl under 1-h, 2-h, and no acid wash as a control. The BLA crystallography indicates a fully amorphous phase of silica. Interestingly, 1-h acid wash precisely reduces the silica purity from 95.35% to 94.74%, but it then increases to 96.06% under 2-h acid wash. It is also notified that the longer acid wash duration could alleviate leaves’ mechanical strength. After calcination, consequently, a smaller average particle size of BLA was nominated under 2-h acid wash (6.32 mm). It was then followed by 1-h acid wash (21.32 mm) and no acid wash (149.44 mm). The 2-h acid wash is concluded able to intensify silica purity as well as reduce the particle size of BLA. Finally, acid wash treatment becomes important to facilitate further BLA extraction in order to achieve high purity of silica.