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1.
Investigation of sewage sludge stabilization potential by the addition of fly ash and lime 总被引:5,自引:0,他引:5
Samaras P Papadimitriou CA Haritou I Zouboulis AI 《Journal of hazardous materials》2008,154(1-3):1052-1059
The aim of this work was the examination of stabilization potential of sewage sludge by the addition of fly ash and/or lime and the investigation of the effect of stabilization time on the properties of produced mixtures. Five samples were prepared by mixing fly ash, sewage sludge and lime in various ratios and the mixtures were stabilized for a period of 35 d. The addition of alkaline agents resulted in the increase of sample pH up to 12, the increase of total solids content to about 50% and the reduction of the organic fraction of the solids. The produced samples presented inhibition effects to seed germination and root length growth of three higher plants (one monocotyl and two dicotyls); however, samples with high sludge content resulted in negligible seed germination inhibition at prolonged stabilization times. The standard TCLP leaching procedure was applied in all the produced samples in order to evaluate the extraction potential of certain metallic elements; the content of metals in the eluates was varied, depending upon their speciation and form. Eluates presented significant inhibition to the marine photobacterium Vibrio fischeri bioluminescence, while the lowest inhibition was detected for the samples containing higher sludge content. These samples potentially could be applied as soil amendment, offering an efficient method for the combined utilization of two different solid wastes; however, low dosages of fly ash should be used for the production of a stabilized material presenting negligible effects with respect to its phytotoxic and ecotoxic properties. 相似文献
2.
A. Basumajumdar A. K. Das N. Bandyopadhyay S. Maitra 《Bulletin of Materials Science》2005,28(2):131-136
The reaction between fly ash (FA) and lime is extensively exploited for the manufacture of building bricks, blocks and aggregates.
To get a better idea of this reaction, FA from different sources were mixed in different ratios with lime and compacted. The
compacts were treated both by ordinary water and hydrothermal curing to promote lime bearing hydrate bond formation e.g. CaO-
SiO2-H2O (C-S-H), CaO-Al2O3-H2O (C-A-H) etc. The decrease in free lime content in these compacts was measured as a function of curing time and curing process.
This drop in this content was correlated to the chemical composition of the fly ashes. The mathematical relationships between
free lime remaining in the compacts after its maximum decrease in concentration and lime binding modulus (a ratio between
the amount of added lime and the total amount of lime binding constituents present in FA) for both types of curing were developed.
Further, the rate of decrease in free CaO content under both types of curing conditions was compared from kinetic study. From
this study the orders of the reactions and rate constants were found out. 相似文献
3.
Geopolymers prepared from a class C fly ash (CFA) and a mixed alkali activator of sodium hydroxide and sodium silicate solution were investigated. A high compressive strength was obtained when the modulus of the activator viz., molar ratio of SiO2/Na2O was 1.5, and the proper content of this activator as evaluated by the mass proportion of Na2O to CFA was 10%. The compressive strength of these samples was 63.4 MPa when they were cured at 75 °C for 8 h followed by curing at 23 °C for 28 d. In FTIR spectroscopy, the main peaks at 1036 and 1400 cm?1 have been attributed to asymmetric stretching of Al–O/Si–O bonds, while those at 747 cm?1 are due to the Si–O–Si/Si–O–Al bending band. The main geopolymeric gel and calcium silicate hydrate (C–S–H) gel co-exist and bond some remaining unreacted CFA spheres as observed in XRD and SEM–EXDA. The presence of gismondine (zeolite) was also observed in the XRD pattern. 相似文献
4.
Lime–fly ash mixtures are exploited for the manufacture of fly ash bricks finding applications in load bearing masonry. Lime–pozzolana
reactions take place at a slow pace under ambient temperature conditions and hence very long curing durations are required
to achieve meaningful strength values. The present investigation examines the improvements in strength development in lime–fly
ash compacts through low temperature steam curing and use of additives like gypsum. Results of density–strength–moulding water
content relationships, influence of lime–fly ash ratio, steam curing and role of gypsum on strength development, and characteristics
of compacted lime–fly ash–gypsum bricks have been discussed. The test results reveal that (a) strength increases with increase
in density irrespective of lime content, type of curing and moulding water content, (b) optimum lime–fly ash ratio yielding
maximum strength is about 0.75 in the normal curing conditions, (c) 24 h of steam curing (at 80°C) is sufficient to achieve
nearly possible maximum strength, (d) optimum gypsum content yielding maximum compressive strength is at 2%, (e) with gypsum
additive it is possible to obtain lime–fly ash bricks or blocks having sufficient strength (>10 MPa) at 28 days of normal
wet burlap curing. 相似文献
5.
By-product fly ash from coal combustion generally contains a high percentage of active silica and smaller amounts of alumina,
although some coals can have higher alumina contents (30 to 40%). During our experimental tests on the utilization f fly ash
in road and highway foundation sheets, we have found a fly ash poor in silica, having an exceptionally high alumina content.
This material has shown a good reactivity towards lime paste, giving hardened mixtures with high mechanical properties. 相似文献
6.
Xiaolu Guo Huisheng Shi Liming Chen Warren A. Dick 《Journal of hazardous materials》2010,173(1-3):480-486
Processes that maximize utilization of industrial solid wastes are greatly needed. Sodium hydroxide and sodium silicate solution were used to create alkali-activated complex binders (AACBs) from class C fly ash (CFA) and other Ca-containing admixtures including Portland cement (PC), flue gas desulfurization gypsum (FGDG), and water treatment residual (WTR). Specimens made only from CFA (CFA100), or the same fly ash mixed with 40 wt% PC (CFA60–PC40), with 10 wt% FGDG (CFA90–FGDG10), or with 10 wt% WTR (CFA90–WTR10) had better mechanical performance compared to binders using other mix ratios. The maximum compressive strength of specimens reached 80.0 MPa. Geopolymeric gel, sodium polysilicate zeolite, and hydrated products coexist when AACB reactions occur. Ca from CFA, PC, and WTR precipitated as Ca(OH)2, bonded in geopolymers to obtain charge balance, or reacted with dissolved silicate and aluminate species to form calcium silicate hydrate (C-S-H) gel. However, Ca from FGDG probably reacted with dissolved silicate and aluminate species to form ettringite. Utilization of CFA and Ca-containing admixtures in AACB is feasible. These binders may be widely utilized in various applications such as in building materials and for solidification/stabilization of other wastes, thus making the wastes more environmentally benign. 相似文献
7.
Over 15 million tons of fly ash (FA) and 3 million tons of phosphogypsum (PG) are produced in Turkey every year. The utilization of these industrial by-product materials is important in terms of environmental and economical issues are concerned. The main purpose of this study is to evaluate the technical possibilities of incorporating FA and PG in production of building blocks. Various mixtures were prepared by incorporating these industrial wastes by replacing clay with seven different weight proportions (0%, 5%, 10%, 15%, 20%, 25% and 30%). All specimens were fired at 1000°C peak temperature. The physical and mechanical properties of all specimens such as; unit weight, compressive strength, flexural strength, dimensional stability and water absorption values were recorded. The effect of PG incorporation on the properties of samples seems to be more dominant than the effect of FA incorporation. The test results showed that; PG incorporation increased the unit weight and mechanical strength values while lowering the water absorption values. Utilization of these wastes additives is not only for conservation of clay resources, but also an alternative solution to a difficult and expensive waste disposal problems. 相似文献
8.
9.
Batch adsorption studies were carried out for the sorption of C.I. Reactive Black 5, a reactive dye, onto high lime fly ash, obtained from Soma Thermal Power Plant (Turkey), to be low cost adsorbent. The effect of various experimental parameters such as contact time, adsorbent dose and initial dye concentration were investigated. Determination of the adsorption equilibrium concentrations was determined by UV-vis spectrophotometry analytical method. Equilibrium data were fitted to the Freundlich and Langmuir isotherm equations and the equilibrium data were found to be well represented by the Freundlich isotherm equation. The adsorption kinetics of C.I. Reactive Black 5 onto high lime fly ash were also studied to characterize of the surface complexation reaction. A pseudo-second-order mechanism has been developed to predict the rate constant of the adsorption, the equilibrium capacity and initial adsorption rate with the effect of initial concentration. A single-stage batch adsorber design of the adsorption of C.I. Reactive Black 5 onto high lime fly ash has been studied based on the Freundlich isotherm equation. 相似文献
10.
The reduction in Portland cement consumption means lower CO2 emissions. Partial replacement of Portland cement by pozzolans such as fly ash has its limitations due to the quantity of calcium hydroxide generated in the mix. In this work we have studied the contribution of the addition of hydrated lime to Portland cement + fly ash systems. We have also studied several levels of cement replacement, ranging from 15% to 75%.The best mechanical results were obtained replacing 50% of Portland cement by the same amount of fly ash plus the addition of hydrated lime (20% respect to the amount of fly ash). In these systems, an acid-base self-neutralization of the matrix has occurred through a pozzolanic reaction of fly ash with portlandite liberated in the hydration of Portland cement and the added hydrated lime. It has been identified for these mixtures a significant amount of hydrated gehlenite, typical reaction product from rich-alumina pozzolans. 相似文献
11.
Sarah Jamil P.C. Abhilash Nandita Singh P.N. Sharma 《Journal of hazardous materials》2009,172(1):599-275
A greenhouse pot experiment was conducted to test the heavy metal phytoremediation capacity of Jatropha curcas from fly ash. Both natural accumulation by J. curcas and chemically enhanced phytoextraction was investigated. Plants were grown on FA and FA amended with fertile garden soil, in presence and absence of chemical chelating agent EDTA at 0.1 g kg−1 and 0.3 g kg−1 of soil. EDTA enhanced the uptake of all five elements (Fe, Al, Cr, Cu and Mn) tested. Fe and Mn were retained more in roots while Cu, Al and Cr were translocated more to the shoot. Metal accumulation index indicates that the effect of EDTA at 0.3 g kg−1 was more pronounced than EDTA at 0.1 g kg−1 in terms of metal accumulation. Biomass was enhanced up to 37% when FA was amended with GS. Heavy metal uptake was enhanced by 117% in root, 62% in stem, 86% in leaves when EDTA was applied at 0.3 g kg−1 to FA amended with GS. Study suggest that J. curcas has potential of establishing itself on FA when provided with basic plant nutrients and can also accumulate heavy metals many folds from FA without attenuating plant growth. 相似文献
12.
The resistance of class C fly ash belite cement (FABC-2-W) to concentrated sodium sulphate salts associated with low level wastes (LLW) and medium level wastes (MLW) is discussed. This study was carried out according to the Koch and Steinegger methodology by testing the flexural strength of mortars immersed in simulated radioactive liquid waste rich in sulphate (48,000 ppm) and demineralised water (used as a reference), at 20 degrees C and 40 degrees C over a period of 180 days. The reaction mechanisms of sulphate ion with the mortar was carried out through a microstructure study, which included the use of Scanning electron microscopy (SEM), porosity and pore-size distribution and X-ray diffraction (XRD). The results showed that the FABC mortar was stable against simulated sulphate radioactive liquid waste (SSRLW) attack at the two chosen temperatures. The enhancement of mechanical properties was a result of the formation of non-expansive ettringite inside the pores and an alkaline activation of the hydraulic activity of cement promoted by the ingress of sulphate. Accordingly, the microstructure was strongly refined. 相似文献
13.
K. Wesche I. L. Alonso I. Bijen P. Schubert W. Vom Berg R. Rankers 《Materials and Structures》1989,22(4):299-308
The texts presented hereunder are drafts which are submitted for comment, particularly relating to the reference material
in section 7.2.2 and 7.4.1. The final recommendations will be drawn up by the committee with respect to the possible comments
that should be sent to the Chairman of the committee: Professor Dr.-Ing. K. Wesche, Institute of Building Research, Aachen
University of Technology, Schinkelstr. 3, D-5100 Aachen, Germany, before December 31, 1989. 相似文献
14.
Durability of class C fly ash belite cement in simulated sodium chloride radioactive liquid waste: influence of temperature 总被引:1,自引:0,他引:1
This work is a continuation of a previous durability study of class C fly ash belite cement (FABC-2-W) in simulated radioactive liquid waste (SRLW) that is very rich in sulphate salts. The same experimental methodology was applied in the present case, but with a SRLW rich in sodium chloride. The study was carried out by testing the flexural strength of mortars immersed in simulated radioactive liquid waste that was rich in chloride (0.5M), and demineralised water as a reference, at 20 and 40 degrees C over a period of 180 days. The reaction mechanism of chloride ions with the mortar was evaluated by scanning electron microscopy (SEM), porosity and pore-size distribution, and X-ray diffraction (XRD). The results showed that the FABC mortar was stable against simulated chloride radioactive liquid waste (SCRLW) attack at the two chosen temperatures. The enhancement of mechanical properties was a result of the formation of non-expansive Friedel's salt inside the pores; accordingly, the microstructure was refined. 相似文献
15.
Increasing amounts of residues and waste materials coming from industrial activities in different processes have become an increasingly urgent problem for the future. The release of large quantities of heavy metals into the environment has resulted in a number of environmental problems. The present study investigated the safe disposal of the zinc leach residue waste using industrial residues such as fly ash, phosphogypsum and red mud. In the study, leachability of heavy metals from the zinc leach residue has been evaluated by mine water leaching procedure (MWLP) and toxicity characteristic leaching procedure (TCLP). Zinc removal from leachate was studied using fly ash, phosphogypsum and red mud. The adsorption capacities and adsorption efficiencies were determined. The adsorption rate data was analyzed according to the pseudo-second-order kinetic, Elovich kinetic and intra-particle diffusion kinetic models. The pseudo-second-order kinetic was the best fit kinetic model for the experimental data. The results show that addition of fly ash, phosphogypsum and red mud to the zinc leach residue drastically reduces the heavy metal content in the leachate and could be used as liner materials. 相似文献
16.
This paper presents the performance of 7-year fly ash concrete exposed to hot and high humidity climate in marine conditions. Control concrete and fly-ash concrete cube specimens of 200 mm were cast and steel bars of 12 mm in diameter and 50 mm in length were embedded at various cover depths. The concrete specimens were exposed to tidal zone of marine environment in the Gulf of Thailand. The concrete specimens were tested for chloride penetration profile, chloride content at the position of embedded steel bar, and corrosion of embedded steel bar after being exposed to tidal zone of sea water up to 7 years. Consequently, these experimental data were used to generate the empirical equation for predicting long term required cover depth of cement and fly ash concretes to protect against the initial corrosion of reinforcing steel in a marine environment. 相似文献
17.
Nasim Heidari Bateni Mohd Nizar Hamidon Khamirul Amin Matori Soodkhet Pojprapai Puripat Kantha 《Journal of Materials Science: Materials in Electronics》2014,25(12):5491-5495
In this work, Polarization–Electric field (P–E) hysteresis loop was evaluated and dielectric studies of the ceramic obtained from white rice husk ash (WRHA) and soda lime silica (SLS) glass was reported for electronic applications. Dielectric properties and hysteresis loop of the specimens were measured using a LCR meter and Sawyer–Tower circuit, respectively. The dielectric analysis clearly shows that the different amount of SLS glass content gives the different value of dielectric constant and loss to the ceramic. Sample with 2.5 wt% SLS glass content includes the lowest dielectric constant (11.13) among others, at 100 kHz, when sintered at 1,200 °C. The results show dielectric constant and loss of the specimens decrease with increasing applied frequency. P–E loop measurement indicates that the WRHA ceramic, generally, had capacitor capability and became more “resistor-like” than “capacitor-like”, with addition of SLS glass content. 相似文献
18.
Improved geopolymerization of bottom ash by incorporating fly ash and using waste gypsum as additive
Kornkanok Boonserm Vanchai Sata Kedsarin Pimraksa Prinya Chindaprasirt 《Cement and Concrete Composites》2012,34(7):819-824
This research studied the improvement of the geopolymerization of bottom ash (BA) by incorporating fly ash (FA) and using flue gas desulfurization gypsum (FGDG) as additive. The BA:FA ratios of 100:0, 75:25, 50:50, 25:75, and 0:100 were used as the blended source materials. The source materials were then replaced with 0%, 5%, 10%, and 15% of FGDG. NaOH, sodium silicate and temperature curing were used to activate the geopolymer. Test results indicated that the increase in FA content in the BA–FA blends improved the strengths of geopolymer mortars owing to the high glassy phase content and high reactivity of FA compared to those of BA. The use of up to 10% of FGDG as additive also significantly increased the strengths of geopolymer. In this case, the compressive strength enhancement was due to the increase in the Al3+ leached from BA in the presence of and the formation of additional calcium silicate hydrate. 相似文献
19.
K. S. Rebeiz J. W. Rosett S. M. Nesbit A. P. Craft 《Journal of Materials Science Letters》1996,15(14):1273-1275
20.
This is a full article that overcomes such some negative side effects as rapid coagulation and reduced early strength in class F fly ash-substituted cement (FFA-SC) by serving nano graphite particle (nG). This study uses class F fly ash (FFA), nG, and ASTM type I cement as constituent materials to prepare proper pulverized fly ash–Portland cement combinations (35% FFA + 65% ASTM I + 1.1% nG i.e.). Pastes include lime and/or lime + nG, and tap water to examine ups and downs in Ca(OH)2 content. Mortars also contain these prepared cements, tap water and/or tap water + super plasticizer (SP), and mortar sand in order to measure fluidity, flexural strength, and compressive strength according to present standard methods. Results indicate for FFA-SC system that the nano graphite particle increases the reduced early strength gain at early age, and the SP reduces the rapid coagulation. The use of nG also shows to be favorable in terms of the Ca(OH)2 content, the fluidity and the flexural strength gain, and compressive strength gain in FFA-SC system when compared to the pure Portland cement with and without nano graphite particle. 相似文献