Search

To develop a practical alternative to classic cement materials, alkali-activated materials were manufactured from industrial wastes (fly and bottom ash). Microstructural behavior of these blends was investigated through X-ray diffraction, scanning electron microscope, thermal analysis, Fourier-transform infrared spectroscopy and surface response methodology. Natrolite, phillipsite, and calcium aluminum silicate hydrate and sodium carbonate newly formed after alkali activation. Empirical ternary diagrams as well as modeling equations were united to predict the physico-mechanical evolution of the prepared specimens. The used model described well the evolution of the studied properties against the processing factors; temperature, NaOH concentration and curing time. The weight of the effect of each parameter was estimated and factor to factor interaction was considered. NaOH concentrations and ageing temperature had a considerable positive effect on density and mechanical strength, respectively. Water absorption and electrical conductivity were influenced differently by the factors, the electrical conductivity increases as the NaOH concentrations increase, and time and temperature decrease. The response surfaces and their results were correlated with the microstructure of the hardened samples. Overall, alkali activated binders with good engineering properties could be synthesized in the considered conditions. The optimal alkali activation conditions were ∼12 M and the corresponding final properties were as follows: 50 MPa for the compressive strength and 20% for water absorption while density was recorded at a 1.75 g/cm3 value. [ABSTRACT FROM AUTHOR]

Pervious concrete is a special type of concrete consisting of cement, coarse aggregate and water. Cement is a widely used raw material for construction including pervious concrete and had led to the release of huge amounts of CO2 to the environment. Therefore, there is lot of research interest in finding supplementary cementitious materials. The present study examined and compared the feasibility of using industrial waste fly ash (FA) and agricultural waste rice husk ash (RHA) for sustainable pervious concrete production. An experimental program was performed with substitution of FA and RHA contents of 5%, 10%, 15% and 20% as cement replacement and water to binder ratio of 0.3, 0.35, 0.4 and 0.45. The characteristics of pervious concrete and sustainability analysis were compared for both FA and RHA replacement with control concrete mortar. The results showed that both FA and RHA have a negative effect on permeability. The compressive strength was optimum for FA content lies between 10% and 15% replacement level and RHA content of 5% replacement level. Furthermore, the utilisation of FA and RHA decreased production cost, the total embodied energy and carbon emission, resulting in cost-effective and eco-friendly pervious concrete. [ABSTRACT FROM AUTHOR]

Granular blast furnace slag (GS) is a glassy substance formed when the slag melted in blast furnace ironmaking is not crystallized within time. An alkaline activator can show high hydraulic hardness in an alkaline environment. Using industrial wastes such as GS and fly ash (FA) to solidify dredged sludge (DS) is an economical and environmentally friendly solution. This study investigates the effectiveness of sodium hydroxide (SH) on the strength development of cement-bound industrial waste to stabilize DS. The effects of SH content on strength, atterberg limits, cohesion, and internal friction angle were analyzed. In addition, microstructural analysis was carried out by scanning electron microscopy (SEM) and x-ray diffraction experiments (XRD). Thermal gravimetry (TG) and derivative thermal gravimetry (DTG) was carried out to analyze the decomposition properties of the stabilized soil. The results show that SH's content significantly affects the solidified DS, and the UCS of stabilized soil increases with the increase in SH content. In addition, the SH content had no noticeable effect on the cohesion between particles. However, with the increase of SH content, the internal friction angle increased significantly, improving the solidified DS's shear strength. [ABSTRACT FROM AUTHOR]

Geopolymers are amorphous, quasi-crystalline, three-dimensional networked gel structures formed by the reaction of aluminosilicate raw materials and alkali activators and are composed of silicon-oxygen tetrahedrons and aluminum-oxygen tetrahedrons. They have excellent mechanical properties, durability and environmental friendliness and can be used as a substitute for Portland cement in civil engineering. In this paper, the current research achievements of geopolymers are reviewed, including the structure type, preparation process, mechanical performance, durability and application of geopolymers in civil engineering. When compared with those of ordinary Portland cement, the mechanical properties of geopolymers not only meet the specification requirements but also show carbonation resistance, acid resistance and high temperature resistance. In addition, the raw materials of geopolymers, such as fly ash and blast furnace slag, are all derived from industrial waste; the use of geopolymers can realize waste recycling, which has extremely high economic benefits. This paper introduces its applications in soil stabilization and silt solidification, curing heavy metals, pavement repair materials and so on. The shortcomings in the current research of geopolymer are also briefly analyzed. This article reviews geopolymers from multiple perspectives, trying to give a more comprehensive understanding of geopolymers. [ABSTRACT FROM AUTHOR]

The growing disposal of industrial waste materials and high CO2 emission of cementitious materials production are serious concerns since they can globally pose critical environmental problems. Therefore, the environmental impacts besides the mechanical properties of materials are one of the major factors that should be considered. This study aims to investigate the mechanical, microstructural, environmental and economic impacts of red mud (RM)- and fly ash-based geopolymer concrete (GPC) containing waste tire rubber. The mechanical characteristics of rubberized GPC were evaluated by destructive and nondestructive tests. The scanning electron microscopy and X-ray diffraction were used for microstructural investigations. The response surface method was adopted to determine the optimum concrete mixture based on desirable goals. The results indicate that the low content of rubber did not significantly change the mechanical properties of rubberized GPC. A slight enhancement in strength was observed by increasing the RM from 20% to 30% at 60% and 90% of rubber. Based on this study, rubberized GPC can be considered to be suitable and beneficial as a medium to low and controlled low strength material, since the incorporation of wastes led to the reduction of both CO2 emission and cost with desirable mechanical properties. [ABSTRACT FROM AUTHOR]

Zinc tailing waste material is generated during the extraction of zinc metal. Its deposit is increasing year after year posing a threat to the environment and occupying large precious land. The present research explores the possibility of its application in road construction and filling. Physical and chemical tests were carried out, viz. SEM, EDS, X-ray diffraction and toxicity characteristics leachate procedure. The geotechnical characterisation was carried out and compared with similar types of materials, viz. soil and industrial wastes (fly ash and jarofix). Stress-settlement behaviour was studied by using a small scale physical model and validated by a numerical model test. Tailing was further mixed with cement to improve its properties for application in stabilised layers. Tailing is a porous, multi-phase and non-swelling cohesionless fine-grained material. It contains mainly oxides of silica, alumina, magnesium, calcium and less concentration of heavy metals. It has a high dry density (18.62 kN/m3), California Bearing Ratio (11%) and angle of internal friction (34°) compared to soil which makes it suitable for road construction. Cement stabilised tailing can be used in sub-base layer and can save about 170 mm thickness of the aggregate layer. Modulus value (18.17 MPa) indicates that it is a stiff material which leads to less settlement as a structural fill. [ABSTRACT FROM AUTHOR]

The mix design procedure for geopolymer concrete has not been standardised as there are so many variables to consider. Industrial wastes primarily fly ash, metakaolin, silica fume, GGBS and rice husk ash were used in this study individually and in combination along with sodium-based alkaline solutions. By taking into account of numerous elements that affect the qualities of geopolymer concrete, 243 geopolymer concrete blends were developed. The percentage of coarse aggregate and combined aggregate, sodium hydroxide to sodium silicate ratio, concentration of NaOH, curing temperature are all the factors taken into account of this study to arrive a mix design procedure for geopolymer concrete. Based on the findings, an approach for determining the mix proportion for geopolymer concrete was derived. These data can be used to produce geopolymer concrete grades ranging from 15 to 80 MPa. [ABSTRACT FROM AUTHOR]

Increase in industrial and construction activities has led to an enormous rise in waste generation and its hazardous impacts on the environment. Quarrying of rocks and manufacturing of artificial sands for civil engineering projects leads to the dumping of rock waste dust, which is a source of landfill problems. Further, excessive energy requirements for cement manufacturing, higher greenhouse gas emissions and rapid depletion of natural resources have focused the research towards the development of environment friendly and sustainable materials such as geopolymers. In this paper, a novel geopolymer has been developed from industrial wastes such as basalt rock fines considering partial replacement with ground granulated blast furnace slag up to 30%. After a detailed mix-design investigation, the optimum molarity (M) of the sodium hydroxide solution was found to be 8 M whereas the optimum ratio (R) of sodium silicate to sodium hydroxide solution as 0.75. Unconfined compressive strength evaluation showed 7-day strengths up to 34 MPa, comparable to geopolymers based on conventional precursor materials. The scanning electron microscopy imaging of the specimens revealed a dense geopolymer gel formation resulting in a homogeneous microstructure. As a result, this innovative material produced can be used as an alternative, sustainable and cost-effective construction material. [ABSTRACT FROM AUTHOR]

In the current work, a novel combination of discharge plasma and industrial wastes has been proposed to explore the possibility of treating the oxides of nitrogen (NOX) in diesel exhaust through plasma-activation of abundant and freely available industrial wastes. Five industrial wastes have been selected for testing as potential catalysts, namely fly ash, foundry sand, bagasse, mulberry residue, and oyster shells. The diesel exhaust was treated using plasma catalysis, by allowing it to flow through a dielectric barrier discharge plasma reactor packed with industrial waste pellets, at ambient temperature and atmospheric pressure. An increase in NOX removal during plasma catalysis, in comparison to plasma-only treatment, was observed through experiments conducted using the pellets. Maximum removal of NOX (70%) was obtained during plasma catalysis using oyster shell pellets. The results have been discussed in detail along with the possible reaction pathways and explanations for the NOX removal during plasma catalysis. [ABSTRACT FROM AUTHOR]

In this research, the performance of fly ash/GGBS geopolymer mortars made with different quarry waste powder as filler materials by substituted the river sand fine aggregate with different ratios was evaluated based on the mechanical, physical, durability properties and microstructural analysis. Limestone waste, marble waste and basalt waste powder were used as filler materials developing eco-friendly and economical geopolymer from industrial waste as a promising sustainable area of research. A series of tests were conducted such as on strength properties, ultrasonic pulse velocity (UPV), physical properties, abrasion resistance test, splitting tensile strength and microstructure analysis (SEM). The samples were elevated at the high-temperatures of 200 °C, 400 °C, 600 °C and 800 °C. Results conducted that the use of limestone waste powder and marble waste powder up to 50% ratio improved the geopolymer composite's strength. The three filler geopolymer composites positively affected water absorption, strength properties and abrasion ratio results. The current article's finding has indicated a potential solution, presenting another geopolymer class followed by the successful use of fly ash and quarry waste as significant asset materials. The output of this study is commercially expected to be effective intercession for waste recycled and friendly environmental management conclusions. [ABSTRACT FROM AUTHOR]

Every year nearly 100 million tons of fly ash is being generated in India and its disposing consumes large land volumes. Fly ash can be used as a good adsorbent to clean flue gases as well as wastewater treatment for effluents containing phenolic compounds. In the present work, fly ash from different sources (coal and bagasse based) was evaluated for wastewater treatment. The work involves (i) batch kinetic studies for adsorption of phenols viz. phenol, catechol, resorcinol, hydroquinone, 2-aminophenol and 3-aminophenol, on fly ash; (ii) the effect of initial solute concentration, initial mass of adsorbent, temperature, contact time and pH on removal of phenols from solution; (iii) determination of adsorption isotherm parameters for three isotherm models namely Freundlich, Langmuir and Fritz–Schlunder; and (iv) mathematical model for packed bed adsorption process using fly ash as an adsorbent for industrial-scale capacity (∼10,000 L/day). The results show that bagasse-based fly ash has much more adsorption capacity (∼80% phenol removal) as compared to coal-based fly ash. [ABSTRACT FROM AUTHOR]

The copper flue dust is an important secondary source for various metals and also a potential threat to the environment. In this study, a process was developed to convert a local copper flue dust containing 20.60% copper, 21% iron and 2.88% zinc into value-added products via a hydrometallurgical route. The response surface methodology was applied for the optimization of base metals leaching by sulfuric acid. Maximum recoveries of 96% for zinc and 76.7% for copper were achieved under the optimum conditions, whereas only 23.92% of the iron content was dissolved. Moreover, various parameters effective on Zn/Fe separation factor were assessed, and favorable separation obtained at pH 3, 2:1 A/O ratio, 20% V/V of D2EHPA in kerosene during 15 minutes. Stripping experiments also showed that 96.35% of zinc was successfully stripped at 1 M sulfuric acid and 2:1 A/O. The mathematical prediction models for leaching, solvent extraction and stripping were proposed and confirmed by statistical analysis and experiments. The proposed process in this study, enhances the copper production in the current leaching plant and makes it possible to recover zinc from industrial waste as a by-product. [ABSTRACT FROM AUTHOR]

The demand for bricks in South Asia is increasing significantly due to growth in the construction sector. Bricks produced using traditional firing technique and fertile clay contribute significantly to some of the worst air pollution in the world. Therefore, the utilisation of other environment-friendly alternative to conventional bricks is considered an urgent need to conserve a clean environment and help in saving its fertile soil. This research aimed to explore geopolymerisation technique with ternary combined industrial waste/by-products as binders including high volume Ladle Furnace Slag (LFS), Fly ash and Ground Granulated Blast Furnace Slag (GGBS) to produce non-fired and clay-free brick alternatives. The first two byproducts are locally produced in the related iron and power industry while GGBS are being imported by the cement industry. The results indicated that all the prepared samples conform to the minimum compressive strength requirement of 20.7 MPa and maximum water absorption rate of 17% for common brick with severe weathering as per ASTM C62. This highly promising performance pronounced the use of locally available high volume LFS and other industrial waste/by-products materials in non-fired building block production to achieve a cleaner, environmental-friendly sustainable society as well as a sustainable route for industrial waste management. [ABSTRACT FROM AUTHOR]

High value-added NaHS zeolite was prepared using the microwave-assisted alkali fusion hydrothermal method from industrial solid waste coal fly ash as raw material without adding silicon and aluminum sources. The effect of mass ratio of alkali to coal fly ash, crystallization temperature, and crystallization time on the preparation of NaHS zeolite was investigated. The NaHS zeolite was characterized using XRD, SEM, BET, and FT-IR. The experimental results showed that the NaHS zeolite with complete crystal structure could be synthesized at m(sodium hydroxide):m(coal fly ash) = 2:1, crystallization temperature of 140°C, and crystallization time of 48 h. The prepared HS zeolite had high purity, complete crystal structure, and uniform grain size (2 μm). The NaHS zeolite was beneficial for CO2 adsorption properties with 110.9 cm3/g at 25°C. [ABSTRACT FROM AUTHOR]

Cenospheres are the main component of industrial waste of fly ash and taking full advantage of them has good economic and environmental values. In this paper, cenospheres sensitized emulsion explosive was prepared by adding cenospheres into the emulsion matrix as the sensitizers. The effects of content and particle size of cenospheres on detonation performance of emulsion explosives were studied, and the optimum formula was determined by comparing its detonation performance with glass microspheres (GMs) sensitized emulsion explosive. The optimum content and particle size of cenospheres were 12 mass% and 83 μm, and the brisance and detonation velocity were 18.34 mm and 4970 m/s, respectively, which were close to the maximum values of the traditional GMs sensitized emulsion explosive. Air blast experiments indicated that the influence of particle size of cenospheres on the work capability of emulsion explosive was consistent with its explosion power. Shelf-life test and optical microscope results showed that cenospheres sensitized emulsion explosives had good storage stability. Therefore, cenospheres could be a promising physical sensitizer for emulsion explosives. [ABSTRACT FROM AUTHOR]

Pentachlorobenzene (PeCB) and hexachlorobenzene (HCB) are unintentionally produced persistent organic pollutants. To date, control and management of PeCB and HCB emissions from residual ash in developing countries are lacked. In this study, the levels, emission of PeCB, HCB, and their correlation in bottom ash and fly ash from different thermal industrial facilities have been studies. The results indicated that the concentrations of PeCB, HCB and their emission factors (EFs) were different from investigated facilities, nevertheless, the highest concentrations and emission factors of PeCB, HCB were observed in residual ash from industrial waste incinerator and municipal waste incinerator. Using line regression and statistical analysis such as Pearson correlation, we found strongest correlation of EFs between PeCB and HCB in industrial waste incinerator (r2 = 0.98, p <.001) and municipal waste incinerator (r2 = 0.76, p <.001). The analyses of correlations of EFs between PeCB and HCB in fly ash and bottom ash indicated that emission of PeCB and HCB has similar formation mechanism in fly ash. Total exposure values for worker were much lower than the acceptable level. Our results can contribute the database on PeCB and HCB emissions in Vietnam, and could be used in the update data in the Toolkit for source categories and/or classes. [ABSTRACT FROM AUTHOR]

River-dredged sludge has a high water content and minimal bearing capacity and strength. Adding cement, fly ash, and slag to dredged sludge as a combined curing agent can quickly reduce its water content and improve its strength. This study experimentally investigates the solidification effectiveness of different proportions of curing agents using methods including electron microscopy, particle size analysis, water ratio limit, and water content and direct shear tests. The water content and shear strength of different combined curing agents are obtained at different ages. We find that an optimum curing agent combination exists. With increases in fly ash and slag content, test results indicate that the water content of solidified sludge first decreases and then increases, whereas the shear strength first increases and then decreases, allowing an optimal combination curing agent to be obtained. When using industrial waste residue as curing agent, it is necessary to consider the negative effects of the curing agent to better control the dosage so as to achieve better curing effect. [ABSTRACT FROM AUTHOR]

The utilization of industrial waste as a partial replacement in construction materials has been increasing rapidly in recent years. This Paper investigates the performance of reinforced concrete columns comprising of recycled aggregates, fly ash and synthetic fibres in varying percentage, under monotonic and thermal loads. Ten full scale reinforced concrete columns of size 150 x 150 x 750 mm were experimentally studied under compressive loads. Results of the experiment showed that the polypropylene (PP) fibre reinforced fly ash column with recycled aggregate consisting of 1.5% PP fibre, 15% fly ash and 25% recycled aggregates exhibited better load carrying and deflection capacities and was further considered for numerical analysis. The conventional column was modelled as a control specimen and the behaviour of polypropylene fibre-reinforced fly ash column with recycled aggregate was comparatively studied under the action of thermal loads in ABAQUS. In order to understand the effect of fibre-reinforced polymer (FRP) rebar reinforcement in columns under thermal loads, a parametric study was carried out by varying the type of reinforcement, using carbon fibre-reinforced polymer rebar (CFRP) and glass fibre-reinforced polymer rebar (GFRP). The polypropylene fibre-reinforced fly ash column with recycled aggregate reinforced with CFRP rebars exhibited better performance under thermal loads. [ABSTRACT FROM AUTHOR]

At present, it is necessary to develop low cost adsorbents to remove copper (Cu(II)) from the environment. In this study, adsorbents were produced by pyrolyzing a mixture of pinewood and industrial solid wastes (5:1). The physicochemical characteristics of the resulting adsorbents were assessed using instruments including XRD, BET, SEM and FTIR. The adsorbents had significant effects on the removal rate under a pH of 6 through electrostatic interactions. The maximum adsorption capacities of the three different samples at an initial Cu(II) concentration of 30 mg/L were 1.846 mg/g with BC, 2.166 mg/g with BC-FA, and 2.260 mg/g with BC-CG. The equilibrium data on these adsorbents were accurately represented by the Freundlich model and the pseudo-second-order kinetic equation. [ABSTRACT FROM AUTHOR]

This study focuses on the creation of artificial soils from waste products, such as overburden, leftover brown coal, fly ash and compost, for rehabilitation of degraded mine sites acknowledging acid mine drainage. It was found that with the increase in the amount of compost from 2 to 2.5 g in artificial soils, there was an increase in the moisture holding capacity and load bearing capacity from 7.47 to 16.5% and 2.5 to 5.7 kN, respectively. Metals leached from artificial soils under different conditions were found to be below standards limits set by USEPA for leachate in the environment. [ABSTRACT FROM AUTHOR]