Fly Ash Powder Research Articles

Characterization of high-performance concrete using limestone powder and supplementary fillers in binary and ternary blends under different curing regimes

Although the dumping of waste generated by industries in the environment poses a hazard, it is feasible to use waste and unused materials to manufacture high-performance concrete. By recycling these wastes in binary and ternary blends, sustainable and durable concrete mixtures can be created, resulting in the development of sustainable concrete structures. Therefore, a research project was undertaken to develop high-performance concrete (HPC) using available supplementary and waste materials, such as fly ash (FA), silica fume (SF), Quartz filler (QF), and limestone powder (LSP), as partial replacements for cement in binary and ternary blends under various curing conditions. Different percentages (5, 8, 10, 15, 20%) of the supplementary materials were mixed in binary and ternary combinations to determine the optimal dosage for high-performance concrete. The fresh and hardened properties of the concrete were evaluated using various tests, including slump, compressive strength, rapid chloride ion permeability, porosity, and drying shrinkage tests. The prepared concrete specimens were tested using various concentrations of binder replacement in binary, ternary, and quaternary combinations. The results showed that incorporating quartz filler as a partial replacement of cement up to 8% yielded positive results regarding mechanical properties. However, all mixtures containing different dosages of SF, QF, FA, and LSP demonstrated significant improvement in durability-related properties under normal and high-temperature curing conditions. Interestingly, the porosity of mixtures incorporating fly ash and LSP showed a slight increase compared to identical specimens under normal curing conditions. Moreover, the drying shrinkage behavior of ultrafine fillers (QF, SF, LSP, FA) indicated that their incorporation led to an increase in the shrinkage of high-performance mixtures under normal and high-temperature curing conditions. Binary and ternary blends incorporating QF, LSP, and SF showed an increase of around 5–8% in shrinkage under high-temperature curing compared to identical specimens under normal curing conditions. Therefore, it can be concluded that QF, LSP, SF, and FA can be efficiently used to produce high-performance cementitious composites, leading to sustainable concrete material.

Effect of fly ash and waste glass powder as a fractional substitute on the performance of natural fibers reinforced concrete

Stockpiling and landfilling of waste glass (WG) is becoming a severe environmental issue around the World as hundreds of tons of WG are dumped on the land. The present research assesses the behavior of WG in a concrete mixture as a partial replacement of sand to attain the optimal percentage of waste glass. Due to the production of ordinary Portland cement (OPC), the natural reserves of limestone are depleting fast, and the production of OPC also leads to a high proportion of carbon dioxide (CO2), so it is essential to utilize industrial by-products such as fly ash (FA) to replace cement partially. In the current study, the WG is used as a fractional substitute of sand in different proportions (14 %, 15 %, 16 %, 17 %, 18 %, 19 %, 20 %), with 20 % FA as a replacement for OPC, with 2.5 % coconut fibers (CFs) to improve the flexural strength of concrete. Engineering properties such as compressive and flexural strength, water permeability, sorptivity, density, voids ratio, resistance against fire, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) spectra were assessed. The outcomes showed that the M4 mixture (WG16-FA20-CFs2.5) had the utmost optimal performance, as 15.8 % and 9.57 % compression strength and flexural strength were improved at the curing of 90 days. During exposure of samples to fire, concrete with 16 % WG lost only 38.7 %, 44.2 % mass and compressive strength at 600 °C, which was the most lowered among other mixtures. Because of the utilization of FA, the concrete’s matrix gets denser, leading to improved water-related characteristics of concrete. It was observed that adding more than 16 %, WG led to reduced strength and durability properties of concrete. The current research confirmed that the 16 % WG, 20 % FA, and 2.5 % CFs could be replaced in concrete to produce improved, eco-friendly concrete.

Effect of modified nano‐titanium and fly ash on ultra‐high‐performance concrete properties

AbstractThis paper aims to study the effect of using modified nano‐TiO2 with fly ash (FA) on ultra‐high performance concrete's (UHPC) mechanical, transport, and microstructure properties (UHPC). A ball mill was used to disband the nano‐TiO2 and distribute it uniformly within the FA powder. In this research, 20% of the cement weight was replaced by FA, and nano‐TiO2 was added by 0.4%, 0.8%, 1.2%, 1.6%, and 2% of the FA weight. To investigate the effect of the ball mill period on the UHPC properties, periods of 10, 20, 30, and 40 min were applied to a binder of 20% FA and with 6% nano‐TiO2. In addition, a 30‐min ball mill period on a binder of 20% FA and 0.4%, 0.8%, 1.2%, 1.6%, and 2% nano‐TiO2 was also investigated. Tests of compressive strength after 1, 7, 28, and 91 days of curing in tap water, splitting tensile strength, flexural strength, and modulus of elasticity were performed after 28 days of curing in tap water. Tests of chloride permeability, sorptivity coefficient, water permeability, and microstructure were also performed after 28 days of curing in tap water. The results showed that the addition of higher percentages of nano‐TiO2 led to a decrease in workability. The addition of nano‐TiO2 improved the mechanical properties. The highest compressive strength of 208.9 MPa was achieved for the mixture of 20% FA with 1.2% nano‐TiO2 at the age of 28 days. The 30‐min period of application of the ball mill achieved the best performance compared with the other periods. The results of using a ball‐mill to re‐mix nano‐TiO2 between 1.2% and 2% by weight with FA showed impressive comparative results.

Durability assessment of quaternary blended recycled aggregate concrete under chloride environment

This article describes the durability of Normally Vibrated Concrete (NVC) containing Recycled Coarse Aggregate (RCA) using different mineral admixtures under extreme chloride environment. Further, to make concrete more sustainable by replacing cement and Natural Coarse Aggregates (NCA) with supplementary cementitious materials and RCA respectively without compromising the performance of concrete. For this, cement is replaced partially with Fly Ash (FA), Silica Powder (SP) and Ground Granulated Blast Furnace Slag (GGBS). The percentage of admixtures (FA, GGBS and silica powder) are decided based on the fresh) and hardened (compressive - strength) properties. M30 concrete is prepared using binary mix (OPC + FA), (OPC + GGBS), ternary mix (OPC + FA + GGBS) and quaternary mix (OPC + FA + GGBS + silica powder). Fresh and mechanical properties of concrete prepared from these mixes are determined. Further the best result of the outcomes based on the above mechanical properties is opted as optimum proportion of (FA, GGBS and silica powder) and is replaced in conventional mix to make concrete more sustainable. This optimum proportion is now used as a new conventional mix for replacing natural coarse aggregate with RCA by % weight varying in proportion 0%, 20%, 40%, 60%, 80% and 100%. For the assessment of durability of concrete Rapid Chloride Permeability Test (RCPT) is carried out. Charge passed through the concrete mix, ingress depth, migration coefficient is noted and relationship between compressive - strength and total charge passed for varying percentage of RCA with optimum proportion of admixtures is analysed. From experimental results it is observed that fly ash, GGBS and silica powder significantly improve the mechanical and durability properties of concrete. Moreover, it is also concluded that up to some extent RCA can be used as alternative of coarse aggregate.

Investigation on properties of autoclave aerated concrete using different pre-curing and curing techniques

AAC (Autoclave aerated concrete) is a porous and lightweight concrete that is produced through the molding process and can be used to make blocks, cladding, and flooring by autoclaving a variety of raw materials. The primary focus of this work is to assess various pre-curing and curing methods for AAC blocks. Autoclave curing is used in the conventional process of manufacturing AAC blocks, which increases the overall manufacturing cost of AAC blocks. For the production of AAC block, coarse aggregates are not used. The density of the AAC block ranges from 600 to 800 kg/m3. For achieving lesser density, cement, fly ash, sand, and aluminum powder was used. The chemical reaction between aluminum powder and lime in presence of water is exothermic and releases hydrogen gas in the form of bubbles, which results in a lower density. In the present study, various mixture design of AAC block was developed consisting of fly ash, cement, lime, aluminum powder, and water. Samples for determining the mechanical properties of AAC were developed using various mixing methods such as hand mixing, pan mixing, and high-speed hand-drill mixing. The impact of several curing techniques, including air drying and water curing, on the compressive strength and density of the AAC block was examined. Sodium chloride and calcium nitrate were used to increase the setting time of the AAC block. The compressive strength of the AAC block was obtained in the range of 0.2 to 1.5 Mpa and the density of the block was obtained between 512.3 kg/m3 to 750.2 kg/m3. The compressive strength of AAC obtained after autoclave curing is more than the compressive strength obtained after air curing as well as water curing. An attempt has been made in the present investigation to develop AAC blocks without using an autoclave process, so that overall production cost of AAC blocks can be reduced.

Environmental impact assessment and potentials of material efficiency using by-products and waste materials

As sustainability is becoming a priority in the construction industry, concerns associated with the environmental impacts of the production and use of Portland cement (PC) are being raised. To respond to this challenge and among different strategies of material efficiency, the potential of by-products and recycling wastes to produce eco-friendly cement-based or cement-less construction materials is given greater emphasis. This research investigates the environmental assessment and carbon footprint of different building envelope walls using by-product and waste materials of energy-intensive processes including power plants, and steel and glass industries. Four different products that can be used in the concrete as the replacement of Portland cement including fly ash, ground granulated blast-furnace slag (GGBS), Glass powder, and mix design of these materials are compared with the regular concrete mix to be used as an envelope wall. After that, the potentials of production and consumption of these materials in the concrete are assessed in Canada. Results show that GGBS concrete with 287 kg CO2 eq per m3 has the lowest CO2 emissions compared with other by-products/waste-used concrete. The CO2 emissions of fly ash concrete are 37% higher than GGBS and glass powder concrete has 50% higher CO2 emissions compared with GGBS concrete. Also, among different environmental damages that concrete would be responsible for, damage to human health has the highest impact on the environment. Fly ash and glass powder concrete have also the highest environmental damage to human health even than regular mix. GGBS concrete has the lowest environmental impact compared with other products that can be considered as a great replacement for PC. Due to the concrete demand exist in Canada, all studied by-products and waste can be fully used in the concrete industry.

Physical and mechanical properties of pozzolanic materials blended cement mortars before and after the freeze-thaw cycles

Today, Portland cement (PC) production causes a significant release of carbon dioxide (CO2) gas into the atmosphere. The CO2 gases released into the atmosphere create environmental pollution worldwide and prevent current and future generations from living in a cleaner nature. One of the most effective ways of restricting PC use in concrete mixes is to use different types of industrial wastes by replacing them with PC. Using industrial wastes such as fly ash (FA), SF, and MP in concrete mixtures by replacing cement in specific proportions is vital in terms of sustainability. The primary purpose of this study is to examine comparatively the effects of fly ash (FA), silica fume (SF), and marble powder (MP) replaced with cement at the rate of 10%, 20%, and 30% on the flowability, mass loss, and residual compressive strength (RCS) of mortars before and after F-T cycles. According to the results, the effects of FA, SF, and MP on mortars' fresh and hardened properties vary considerably. However, using FA, SF, and MP instead of cement significantly improves the matrix's weak cement/aggregate interface transition zones (ITZ) by showing the filler effect. They contribute considerably to reducing mass losses and increasing the RCS capacities of mortars. Compared to room conditions, the reduction in RCS capacities of the control mortar was 21.32% after 200 F-T cycles, while the decrease in RCS capacities of FA-, SD-, and MP-added mortars was between 7.86 and 19.85%. While the mass loss of the control sample after the 200 F-T cycle is 1.23%, the mass loss of mortars with FA, SF, and MP additives is lower and varies between 0.44% and 1.02%.

Alternative cleaner production of masonry mortar from fly ash and waste concrete powder

Experimental studies involving the use of waste concrete powder (WCP) or fly ash (FA) as cement replacement in mortar production are available in the literature. However, studies on the combined effect of WCP and FA in cement mortar, together with their environmental impacts (EI) and cost analyses, are yet to be found in the literature. Hence, the current study aims to achieve this objective. The study was done in two phases. Mortars were made using binder to sand ratio of 1:3. The cement was substituted with WCP at 0%, 15%, 40%, 60% and 100% levels in Phase I. Based on the strength property results obtained in Phase I, a mortar mixture made with 40% cement and 60% WCP was selected for the Phase II study. Mortars were prepared by replacing cement with FA at 0%, 5%, 10%, 15%, 20%, and 25%.It was found that the performance of the mortars was improved when FA was employed. For instance, the 28-day compressive strength of the control mortar was increased from 15.8 MPa to 17.3 MPa when 10% of the cement was replaced with FA. The experimental results show that the produced mortars could be used for masonry works. Also, cost and EI analyses of the mortars were conducted. It was observed that the incorporation of FA in the WCP-cement mortars resulted in reducing the costs and EI of the mortars. Hence, the produced mortars met the strength requirements for masonry works as well as providing economic and environmental benefits.

In-situ Remediation Effect of Cadmium-polluted Agriculture Land Using Different Amendments Under Rice-wheat Rotation

Exploring the effects of one-time amendment treatments on cadmium (Cd)-contaminated farmland soils is beneficial for providing a theoretical basis to effectively prevent Cd pollution in farmland soils and ensure the safe production of crops. Five amendments, including straw biochar, fly ash, sepiolite, white marble powder, and shale (particle size <0.2 mm, application rate 2.25 kg·m-2), were applied to the Cd-contaminated farmland soils. The soil nutrients, pH, soil available Cd, and Cd chemical forms in the soils and grain Cd concentration in the planted crops were determined to investigate the effects and persistence of one-time applications of the five amendments. The results showed that:① the application of the five amendments had little effect on soil nutrient content, but all of them could increase soil pH. Amendment treatments improved the transfer of Cd from the acid extraction fraction to residue fraction and further reduced the Cd availability in the soil. The decreasing amplitudes of straw biochar and white marble powder soil conditioner were 20.42%-22.53%, which was higher than those in the other treatments. ② The grain Cd concentrations in rice and wheat were significantly decreased under the amendment treatments with the decreasing amplitudes of 19.88%-48.77% and 5.06%-24.00%, respectively. The Cd concentrations in rice grains under the treatments of straw biochar, fly ash, and white marble powder soil conditioner were 0.195, 0.196, and 0.223 mg·kg-1, respectively, which were lower than those under the other treatments and were close to or approached the National Standard of Food Safety(GB 2762-2017)(0.2 mg·kg-1). ③ The immobilization effects on Cd in farmland soils were decreasing with time under one-time application of the amendments. The available Cd concentrations in the soil and Cd concentrations in crop grains were still lower than those in the control after three rounds of rice-wheat rotation. The straw biochar and white marble powder soil conditioner had a good and long-term effect on reducing Cd availability in soils and Cd concentrations in crop grain, making them ideal materials for safe production in Cd-contaminated soils.

Chloride Penetration Resistance, Electrical Resistivity, and Compressive Strength of Concrete with Calcined Kaolinite Clay, Fly Ash, and Limestone Powder

This study aims to examine the chloride penetration resistance, chloride binding capacity, electrical resistivity, and compressive strength of multibinder systems, including ordinary portland cement (OPC), calcined kaolinite clay (C), fly ash (F), and limestone powder (L). At all tested ages, the results revealed that calcined kaolinite clay concrete had better chloride penetration resistance and chloride binding ability compared with the control OPC concrete. Moreover, at all tested ages, calcined kaolinite clay concrete had greater compressive strength compared with the control OPC concrete and fly ash concrete. At the curing age of 91 days, improved performance of fly ash concrete was observed. The overall performance of the ternary binder system of cement-fly ash-calcined kaolinite clay surpassed that of the binary binder systems. Among the tested combinations of binders, the ternary binder C30F15 (55% OPC+30% C+15% F) demonstrated the best overall performance. The test results also indicate that fly ash can be beneficially integrated into the cement-calcined kaolinite clay binder system to obtain a ternary binder system, which is better than the ternary binder system of cement, calcined kaolinite clay, and limestone powder, at both tested early and later ages.

Realization of mechanical and tribological properties of hybrid banana, sisal, and pineapple fiber epoxy composites using naturally available fillers

In recent days the use of Natural fiber-reinforced composites in all sorts of consumer goods. A wide variety of technologies necessitate the use of materials with unusual property combinations, such as high strength-to-weight and stiffness ratios. Traditional metal alloys fall short of these quality standards, which has led to a significant increase in the applications of natural fibers. Hence, an effort has been made to investigate the effect of fillers like Coconut shell (CS), Saw dust (SD), Kolam (KP), and Fly ash powder (FA) on the mechanical and wear properties of Epoxy reinforced hybrid Sisal, Banana, and Pineapple fiber composites in this work. The Natural fibers weight percent was taken around 45 wt%, with the same quantity of epoxy blended with 10 wt% Naturally available fillers. The findings revealed that the CS fillers in the composite have a more positive influence on tensile strength and modulus than the composite with other fillers which are used in this study. SEM analysis of tensile-fractured CS specimens also reveals an improved fiber-matrix bonding. Similarly, the CS-filled composite also exhibits better flexural strength, modulus, and Impact strength maximum of up to 18% higher than the BS, SD, KP, and FA-filled Hybrid composites. Further, CS-filled composite has reduced weight loss against wear and friction due to higher lignin content.

THE EFFECT OF ADDING FLY ASH AND GLASS POWDER ON THE COMPRESSION STRENGTH OF CONCRETE

The purpose of this study was to determine the effect of the use of fly ash waste and glass powder on the compressive strength of concrete. 17.5% at the age of 3 days, 7 days, 14 days, and 28 days. for the specimens used measuring with a diameter of 10 cm and a height of 20 cm as many as 36 test samples by making variations of the day as many as 3 samples of the test object, After testing the compressive strength of concrete, the compressive strength of the characteristic concrete with the addition of 7% fly ash and glass powder 5%, the maximum compressive strength at the age of 7 days was 23.35 Mpa, the age of 14 days was 28.93 Mpa, and the age of 28 days was 33.85 Mpa. These results exceed the value of the compressive strength of normal concrete characteristics and indicate that fly ash and glass powder increase the compressive strength of concrete. There is a strong influence from the addition of fly ash and glass powder with variations in the addition and certain age of concrete&#x0D;

Effect of composition of geopolymer composites containing fly ash and waste glass powder on their durability and resistivity demonstrated in presence of a nanocarbon additive in a form of graphene

The objective of this study was to obtain a geopolymer composite with semi-conductive or conductive properties for self-control of abnormal symptoms caused by damages to its microstructure. For that purpose effects of different content of fly ash, waste glass powder, as well as two types of graphene and hydrophilic and hydrophobic nanosilica on electrical, physical and mechanical properties were tested. Measurements of resistivity showed the capacity for electrical charge flow in composites, which depended on their composition and products of the geopolymer hardening process. Based on results of the electrical charge flow intensity and observations of geopolymer composite microstructure by means of XRD and scanning microscopy, a possible course of the electrical conductivity mechanism in geopolymer materials was indicated. It was found that geopolymer composites containing fly ash, as well as addition of graphene and hydrophobic nanosilica, showed the most favourable electrical charge conductivity parameters and the highest strength gain.

Zeolite A powder and beads from sugarcane bagasse fly ash modified with iron(III) oxide-hydroxide for lead adsorption

The discharging of lead-contaminated wastewater is a concern because of its toxicity to living organisms and water quality resulting in dangerous water consumption, so it is highly recommended to remove lead from wastewater to be below water quality standards for a safe environment. Zeolite A sugarcane bagasse fly ash powder (ZB), zeolite A sugarcane bagasse fly ash powder mixed iron(III) oxide-hydroxide (ZBF), zeolite A sugarcane bagasse fly ash beads (ZBB), zeolite A sugarcane bagasse fly ash powder mixed iron(III) oxide-hydroxide beads (ZBFB), and zeolite A sugarcane bagasse fly ash beads coated iron(III) oxide-hydroxide (ZBBF) were synthesized and characterized in various techniques. Their lead removal efficiencies were investigated by batch experiments, adsorption isotherms, and kinetics. The specific surface area, pore volume, and pore size of ZB were close values to zeolite A standard (STD), and ZBF had the highest specific surface area and the smallest pore size than others. ZB and ZBF demonstrated crystalline phases whereas ZBB, ZBFB, and ZBBF were amorphous phases. The surface morphology of ZB was a cubic shape similar to STD. ZBF demonstrated an agglomerated formation of ZB and iron(III) oxide-hydroxide whereas ZBFB and ZBBF had sphere shapes with coarse surfaces. Si, Al, O, Fe, Na, Ca, O–H, (Si, Al)–O, H2O, and D4R were detected in all materials. The surface charges of all zeolite A materials had negatively charged at all pH values, and their surfaces increased more negatively charged with increasing pH value which pH 5 illustrated as the highest negatively charged in all materials. Their lead removal efficiencies were higher than 82%. Langmuir isotherm and pseudo-second-order kinetic models were well explained for their adsorption patterns and mechanisms. Finally, ZBBF is a good offer for applying in industrial wastewater treatment systems because of its easy operation and saving costs than ZBF.

Synthesis and adsorption performance of fly ash/steel slag‐based geopolymer for removal of Cu (II) and methylene blue

AbstractIn order to realize the value‐added resource utilization of solid waste, geopolymer particle adsorbents were prepared at low temperatures using silica‐aluminum‐rich fly ash and steel slag powders as raw materials. In order to investigate the mechanism of their adsorption of dyes and heavy metal ions from wastewater, the effects of steel slag/fly ash ratio, adsorbent dosage, initial concentration of methylene blue (MB) and Cu2+ solution, adsorption time and temperature on the adsorption performance of the fly ash/steel slag‐based geopolymer adsorbents were investigated, systematically. Results presented that the adsorption capacities of MB and Cu2+ were 33.30 and 24.15 mg/g, and the removal efficiencies were 99.90% and 96.59% with the dosages of 3 and 4 g/L geopolymer adsorbents (steel slag/fly ash ratio of 20 wt.%), respectively. The adsorption processes of MB and Cu2+ on the adsorbents were in accordance with the proposed pseudo‐second‐order and Langmuir isotherm models, which mainly included physical and chemical adsorption mechanisms. The adsorption was a spontaneous endothermic process. The fly ash/steel slag‐based geopolymer had good removal ability for dyes and heavy metal ions, and it could maintain good adsorption performance after three cycles of regeneration. It had potential application in wastewater treatment.

Physico-Antibacterial Feature and SEM Morphology of Bio-Hydraulic Lime Mortars Incorporating Nano-Graphene Oxide and Binary Combination of Nano-Graphene Oxide with Nano Silver, Fly Ash, Zinc, and Titanium Powders

The study evaluated the impact of graphene powders used as additives in the recipe of the experimental lime mortar to a mixture ratio of 1:2.5 of NHL3.5 hydraulic lime:fine sand. The content of binder, aggregate and water was kept constant, varying only the amount and the type of the added additives in relation to the amount of natural hydraulic lime NHL3.5. The following five types of experimental mortars were prepared as follows: reference mortar (without additive); mortars containing 1 wt.% GO and 5 wt.% GO powder; mortar with the following GO powders mixture: GO powder functionalized with silver nanoparticles and with fly ash (GO-Ag + GO-fly ash); mortar with the following GO powders mixture: GO with zinc oxide and with titanium oxide (GO-ZnO + GO-TiO2). The influence of the GO-based additive addition on the porosity, surface microstructure, and water sorption coefficient of the mortar samples was evaluated. The antibacterial effect of the mortar samples against three bacterial strains was also investigated. The best results were obtained for the experimental mortar containing GO-ZnO -TiO2, which showed improved experimental properties that potentially allow its use for the rehabilitation of heritage buildings.

Shear strength characteristic of geopolymer fly ash and egg shell powder stabilized clay soil

The clay soil can present various issues as a construction and infrastructure material. Clay soil is susceptible to shrinkage and swelling, limited bearing capacity, poor drainage, and erosion. Several techniques, including soil stabilization, drainage systems, and excavation techniques, may alleviate these issues and control the risks associated with clay soil. There is a growing interest in soil stabilization and developing environmentally friendly alternatives to Portland cement. Alternative utilization of waste with pozzolanic properties as a stabilizing material to replace cement and lime is increasing. In this field, the use of waste materials such as fly ash and eggshell powder is increasing. This study examines the properties of clay soil shear strength treated with a mixture of fly ash and eggshell powder geopolymer. The unconsolidated, undrained triaxial test was performed to determine the shear strength of the treated soil. In addition, the effects of sample variation, such as NaOH molarity, curing duration, and the ratio of eggshell powder to replaced fly ash, were studied. The results demonstrated that 5% eggshell powder might boost the shear strength of treated soil. In addition, increasing the NaOH molarity resulted in higher shear strength values, showing that the geopolymer has a more substantial binding effect. However, extending the curing period impacts the shear strength of stabilized soil. This study established the viability of eggshell powder geopolymer as a stabilizing agent for clay soil. Including 5% eggshell powder in the fly ash geopolymer mixture can enhance the shear strength of the soil.

Fly Ash and Slag as Partial Replacement of Cement for the Synthesis of Low Carbon Cementitious Materials

Tailings known as solid waste are generated by the mining industry. The development of tailings as wet shotcrete aggregates has significant economic and environmental benefits. The fine particle size of the tailings results in a large consumption of traditional cement as a cementitious material and insignificant improvement in strength. Therefore, a composite cementitious system of cement and solid waste resources (fly ash and slag powder) is explored for this study. In this paper, the response surface methodology (RSM) is used to optimize the experimental design and a multivariate nonlinear response model with cement, fly ash and slag powder contents as variables are constructed, which can investigate the effect of the composite cementitious system on the strength of tailing wet shotcrete (TWSC). In addition, the information entropy (IE) is introduced and combined with the RSM to evaluate the composite cementitious system. Finally, the desirability function (DF) combined with RSM is used to optimize the composite cementitious system. The results show that the response model constructed in this paper has R2 = 0.96 and P-value < 0.01 (the test result of the model is P-value < 0.01), which indicates that the model has high reliability. The higher the content of slag powder and cement in the composite cementitious system, the higher the strength and comprehensive score of the TWSC. There is a critical value of fly ash content, which makes the maximum cementation of the composite cementing system. The optimal mix proportion of the composite cementitious system is obtained based on RSM-DF, which leads to the strength of TWSC at different curing time to achieve the expected index.

The effect of natural fiber ratio on mechanical properties of kaolin/fly–ash at low temperature ceramics

This study aims to increase the feasibility of ceramics at low temperature using natural fibers. The ceramics (Ce) were prepared by mixing a powder of kaolin and fly–ash at an equal ratio of 50:50 wt.%. The mixture was milled by ball–milling technique. The natural fibers ceramics (CeNF) were created by adding local pineapple leaves to kaolin and fly–ash powder. Scanning electron microscopy (SEM) was used to amorphous observation and particle size determination. The compositions of Ce and CeNF were investigated by using X–ray diffraction (XRD) technique. The mechanical properties of ceramics were determined by hardness and density test. The results showed that the grinding of kaolin and fly–ash for 4 h produced the highest strength Ce. For the addition of local pineapple leaves at 2 wt.%, the strength could be increased from 92.9 kgf to 118.3 kgf.

Analysis of a Cashew Shell and Fly Ash Rich Brake Liner Composite Material

Hybrid materials collected from organic and inorganic sources, which are traditionally used as brake lining materials, generally include fly ash, cashew shell powder, phenolic resins, aluminium wool, barites, lime powder, carbon powder and copper powder. The present research focuses on the specific effects produced by fly ash and aims to provide useful indications for the replacement of asbestos due to the health hazards caused by the related fibers. Furthermore, the financial implications related to the use of large-volume use of fly ash, lime stone and cashew shell powder, readily available in most countries in the world, are also discussed. It is shown that many manufacturing and automotive industries, which are currently experiencing difficulties in meeting the increasing demand for brake lining material, may take advantage from the proposed solution.