Compaction and strength characteristics of Lime activated flyash with GGBS as an admixture

A very fine by-product generated through coal combustion process at thermal power plants is known as flyash and a part of ash falls down at the bottom of the boiler is known as bottom ash. Out of the total production of waste material flyash generated is approximately 80% whereas bottom ash generated is 20% (by weight of total generated waste). In India, the total production of flyash was 184.14MT in the year of 2014-2015. Out of which total utilization of flyash was 102.59MT or 60.94% and in the year of 2015-16, the production of flyash was 176.74MT. Out of which total utilization of flyash was 107.77MT or 60.97%. Here it can be seen that the production and utilization both are increasing but there is still 40% of flyash that producing as a waste. The flyash that remained unused will deposited as landfills and brings environmental problems. From these landfills, some of the heavy metals like mercury, cadmium and boron and the very fine particles of flyash leach to groundwater and cause the ground water contamination. And also unused flyash is the major cause of air pollution. In the present study, a try has been made for effective utilization of flyash as a geoengineering material. Material that has been used in the study was class-F flyash and brought up from Adhunik Metaliks Limited, Sundergarh. The geotechnical properties like specific gravity, OMC, MDD, and UCS strength has been evaluated, of this virgin flyash. To enhance the properties of the flyash, it was mixed with lime and slag at different proportion. Lime was mixed with flyash at 0%, 2%, 4%, 8% and 12% whereas slag was mixed at 0%, 5%, 10%, 15%, and 20%. A number of combinations of flyash, lime, and slag have been made for testing. The light compaction test has been done to determine the OMC and MDD of different mixes of flyash-GGBS-lime. In total 25 numbers of compaction test has been conducted to find out the OMC and MDD of the above mixes. Further UCS test has been done with different combinations of flyash-GGBS-lime compacted to their respective MDD at OMC. These samples were cured under an average temperature of 28ºC with samples sealed in wax for curing periods of 0, 7, 14 and 28 days and the UCS values were determined. In the hydrometer analysis, it was found that the flyash particles are uniformly graded and the size of the particles lies between fine sand to silt size. The MDD determined was low at higher OMC. After treatment of flyash with lime and slag, the OMC reduced and MDD increased. The UCS determined for virgin flyash was very less and when treated with lime, it increased immediately marginally. UCS for the lime treated flyash samples were increased with increase in curing period. UCS for the slag-treated flyash samples was very low when tested immediately and with increasing curing periods the UCS values increased up to some extent. The strength of flyash treated with lime and slag was found to be highest when cured for 28 days of curing period. At a given curing period flyash samples mixed with slag and lime shows a higher UCS value then flyash treated with the same percentage of lime without slag. This indicates a defiant advantage in adding slag to flyash. Slag which is rich in pozzolanic material like silica and alumina and it also contains a substantial amount of lime. However GGBS possess latent hydraulic properties which have to be activated by an alkali environment, here lime has used to provide an alkali environment to initiate the pozzolanic reaction of slag

Penetrating Ionizing Radiation Levels Observed in the Lower Arkansas and White River Valleys of Arkansas

Environmental levels of penetrating ionizing radiation were measured in the lower Arkansas and White River valleys of Arkansas. Measurements of environmental gamma and cosmic rays were made using a portable high pressure ionization chamber. The surveyed area encompassed a large coal-fired industrial plant. Observed exposure rates ranged from 5.9 microRoentgens per hour (μR/h) to 13.4 μR/h. The average exposure rate for the region was 8.8 μR/h. This value corresponds to 77 millirem (mrem) or 0.77 milliSieverts (mSv) per year. In comparison, a prior state-wide survey reported an average dose equivalent rate of 78.2 mrem (0.782 mSv) per year in Arkansas

Physiochemical Characterization and Dematerialization of Coal Class F Flyash Residues from Thermal Power Plant

Class F flyash has a low percentage content of lime and is considered as a leading category of flyash generated in India with an average utilization of nearly 55% of flyash produced by the coal-burning power plant. The coal Class F flyash residue sample has been collected from Harduaganj, Thermal Power Station India. The paper illustrates the outcome of the study carried out to examine all the relevant features of the chemical and physical properties of Class F flyash sample. Elementary quantitative results from point analysis, SEM/EDS, FTIR, and pH analysis have been done in the chemical analysis of the study. The physical characterization of the sample is done by several experimental approaches to compare all the relevant features of Class F flyash sample and common soil. The main objective of this study is to evaluate whether the locally available Class F flyash from Harduaganj Thermal Power Station India, will provide satisfactory performance in fully or partially replacement of common soil. The performance evaluation of flyash and soil in different test results included bulk density, specific gravity, plasticity, maximum dry density, optimum moisture content, and permeability in accordance with the relevant IS or ASTM standards. Finally, the reported research recommended the selection of Class F flyash sample with low-lime content that provided the close correlation of its physical properties to the common soil

Mechanical, Electrical and Thermal Properties of Nylon-66/Flyash Composites: Effect of Flyash

In the current study, the effect of flyash (FA) on the physic-mechanical, electrical, thermal and morphological behavior of nylon-66 (PA) was investigated. PA/FA composites were prepared by melt mixing via twin screw extruder, with varying weight percent (5 wt %, 10 wt %, 15 wt % and 20 wt %) of flyash. The results of composites were optimized and compared with virgin nylon-66. Mechanical and electrical properties of composites improved up to 10 wt% of FA loading without compromising the properties. The flyash filled nylon-66 composites showed a low abrasive wear rate. Increase the heat distortion temperature of composites with an increase in weight percent of flyash while opposing the melt flow rate. Flyash filler enhances the stiffness of plastics but significantly reduces the impact properties. Dispersion of flyash was examined by impact fracture surface of composites using a scanning electron microscope

Flyash as a Resource Material in Construction Industry: A Clean Approach to Environment Management

The maximum amount of electricity is produced by most of the thermal power plants by burning coal at their operating facilities. Due to this activity, various types of secondary materials are generated. Any material resulting from coal-combustion processes may be called as a coal-combustion product (CCP). Among different CCPs reported worldwide by coal-burning power plants, flyash is the most common one. As per the characterization report, flyash is considered as a powdery material being collected by dust collectors installed in the thermal power plants with the use of coal as fuel. There are different problems related to flyash like requirement of large area of land for disposal and toxicity caused by flyash which leach to groundwater. The study has established flyash as air and water pollution source. It is considered as waste that may act as a resource material in construction industry, thereby acting as a resource for waste and environment management. Till a decade back, flyash was treated as waste material worldwide, but now it is developed as an environment savior

Effluent characterization from a conical pressurized fluid bed

To obtain useable corrosion and erosion results it was necessary to have data with several levels of particulate matter in the hot gases. One level of particulate loading was as low as possible so that ideally no erosion and only corrosion occurred. A conical fluidized bed was used to obtain some degree of filtration through the top of the bed which would not be highly fluidized. This would minimize the filtration required for the hot gases or conversely the amount of particulate matter in the hot gases after a given level of filtration by cyclones and/or filters. The data obtained during testing characterized the effluent from the bed at different test conditions. A range of bed heights, coal flows, air flows, limestone flows, and pressure are represented. These tests were made to determine the best operating conditions prior to using the bed to determine erosion and corrosion rates of typical turbine blade materials

Utilisation of Waste Plastics in Flexible Pavement Construction Laid on Expansive Soil Subgrade

This paper investigates the performance of model flexible pavement on expansive soil subgrade using gravel / flyash as subbase course with waste plastics as a reinforcing material. It was observed that from the laboratory test results of direct shear and CBR, the optimum percentage of waste plastics is equal to 0.3% and 0.4% for gravel and flyash materials. Cyclic load tests were carried out in the field on the reinforced and unreinforced model flexible pavements laid on expansive soil subgrades. It is observed that the maximum load carrying capacity associated with less value of rebound deflection is obtained for gravel/flyash reinforced subbase compared to unreinforced gravel/flyash subbase

Growth of Biodiesel Plant in Flyash: A sustainable approach Response of Jatropha curcus, a Biodiesel Plant in Fly Ash Amended Soil with Respect to Pigment Content and Photosynthetic Rate

AbstractFly-ash, an inevitable waste of coal-fired thermal power plant has great potential in the area of plant growth due to its efficacy in modification of soil health and thereby the plant performance. In this study we analyze the effects of flyash on pigment content and photosynthetic rate in Jatropha curcus. The observations and results of the study indicate that Jatropha curcus grown in different amendments of soil and flyash showed an increase in chlorophyll content at 20% flyash in soil, but further declined with the increase in concentration of flyash (40%, 60%, 80% and 100%) in soil than control. Similar trends of the increase in photosynthetic rate of Jatropha curcus in 20% flyash amended soil and thereby decreased results at higher concentrations have also been observed which can thereby be directly correlated with the chlorophyll content of the plant. Thus the increase in both the parameters at low dose of flyash indicates the healthy growth status of Jatropha curcus Hence through the present venture we are utilizing a waste that is fly ash and using it for the growth of Jatropha curcus, a biodiesel plant which also helps in absorbing the greenhouse gases (CO2 AND CH4)

The first 20 hours of geopolymerization: An in situ WAXS study of flyash-based geopolymers

This study followed the first 20 h of flyash geopolymerization at 70 °C using time resolved Wide Angle X-ray Scattering (WAXS). The extent of dissolution of the amorphous phase of the flyash was determined to range from 29% to 54% for the different formulations trialed. The dissolution rate of the flyash significantly reduced after the first 5 h for all samples. During the formation stage of the geopolymer there were significant temporal variations in the chemistry of the dissolved solution due to the rate of flyash dissolution, with a relative standard deviation of 20%, 57% and 24% for the Si/Al, Na/Al and H/Si ratios, respectively. Utilizing the Power Law, scattering in the low angle region of the WAXS pattern combined with the geopolymer peak area yielded a measure which correlated with the compressive strength-providing a new method to measure the flyash dissolution and geopolymer formation processes independently. The evolution of several zeolite-like phases was followed, noting there are different formation mechanisms involved even within the same sample. Four samples were examined with compressive strengths ranging from 14(2)-50(9) MPa, each was synthesized with flyash from Collie Power Station (Western Australia) activated with sodium silicate solution of varying concentrations

Effect of Flyash and Waste Rubber on Properties of Concrete composite

Increasing use of waste materials like flyash, scrap tyre rubber etc, in construction industry has reduced the handling and disposal problems of these wastes. Flyash and scrap tyre rubbers are generally, employed to develop light weight and low strength concrete composites. The present work discusses the influence of flyash and waste tyre rubber particles on the behaviour of concrete composite. The rubber content has been taken in the range of 0 to 40% as replacement of fine and coarse aggregates while the flyash has been varied from 0 to 30% for cement. Testing of the concrete specimen prepared under different percentage of flyash and rubber waste was performed at 28 days of age for workability, density, compressive and bond strength. Experimental results show that the density, compressive strength and bond strength decreases while workability increases with increasing rubber content. Addition of flyash also decreases the density and compressive strength