Hydration and solidification of hazardous wastes containing heavy metals using modified cementitious materials

Park, Choon‐Keun

doi:10.1016/s0008-8846(99)00272-0

Cited by 111 publications

(62 citation statements)

References 4 publications

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“…It has been reported that HA whiskers are formed by adding an acetic acid solution to amorphous calcium phosphate (Toyama et al, 2001). In Portland cement, the formation of ettringite, which shows whisker-like crystals, promotes solidification and increases strength (Park, 2000, Sakai et al, 2004. These results suggest that the strength of the test pieces subjected to CA treatment in this study might increase if whisker-like HA crystals are formed within them.…”

Section: Compressive Strength Imparted By Cpcsupporting

confidence: 50%

Novel grout material comprised of calcium phosphate compounds: In vitro evaluation of crystal precipitation and strength reinforcement

Akiyama¹,

Kawasaki

2012

Engineering Geology

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Calcium phosphate compounds (CPCs) have unique physicochemical properties. As grout material, they afford many advantages such as adequate physical strength, self-setting property, pH dependence of precipitation, non-toxicity, and recyclability. To apply CPCs to the permeability control and reinforcement of ground soil and rock, we explored suitable conditions for in vitro CPC precipitation, conducted unconfined compressive strength (UCS) tests of Toyoura sand test pieces cemented by CPC, and carried out observations and elemental analysis of precipitated CPC crystals.Two kinds of phosphate stock solution and two kinds of calcium stock solution were used to prepare the reaction mixtures, and CPC precipitation was detected in all reaction mixtures. The volume of CPC precipitation in the reaction mixture increased as the pH rose from strongly acidic to around neutral. The UCS of Toyoura sand test pieces cemented by 1.5 M diammonium phosphate and 0.75 M calcium acetate tended to increase with time, reaching a maximum of 63.5 kPa after 14 days of curing. Conversely, the UCS of test pieces cemented by using calcium nitrate was below 20 kPa and showed no significant increase in strength. CPC precipitation with calcium nitrate induced the formation of plate-like crystals, whereas that with calcium acetate induced whisker-like crystals.Elemental analysis of the cemented test pieces showed that the distributions of phosphorus and calcium were similar. The results indicate the practical feasibility of using novel CPC grouts as chemical grouts because of their self-setting property, and as biogrouts because of their crystal 3 structure and pH dependence of precipitation.

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Section: Compressive Strength Imparted By Cpcsupporting

confidence: 50%

Novel grout material comprised of calcium phosphate compounds: In vitro evaluation of crystal precipitation and strength reinforcement

Akiyama¹,

Kawasaki

2012

Engineering Geology

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“…Its disposal in hydrologic environment can cause environmental risk due to the mobility of metal ions. These metal ions get mixed in surface water and ground water system, which may be detrimental to human being as well to the environment [1][2][3][4][5][6][7][8][9][10]. Various technologies have been developed which purport to render a waste or to reduce the potential for the release of toxic species into the environment.…”

Section: Introductionmentioning

confidence: 99%

Solidification/Fixation of Nickel Ions in Ordinary Portland Cement

Ak¹,

Goyal²

2014

J Chem Eng Process Technol

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In this research article we represented the results of the studies of addition of varying concentrations of Nickel ions on the physical, chemical and engineering properties of 43 grade ordinary Portland cement. The studies regarding different physical & chemical parameters of OPC like initial and final setting time of cement, bulk density, and compressive strength, microscopic and spectroscopic properties have been carried out and the result of these studies are presented and discussed in the manuscript. Different building products containing varying concentrations of added nickel ions were prepared and subjected to hydrologic environment to investigate the leaching behavior of nickel ions. The efforts have also been made to establish a quantitative co-relation between the concentration of added Nickel ions and the intensity of any effect in above properties of the cement also the possible fixation mechanism of Nickel ions in cement was suggested. Scanning electron microscopy and X-Ray diffraction study of nickel containing cement samples show that nickel have no greater effect on the cement properties. Ni does not show any effect on the hydration of cement & its main compounds but it slightly retards the setting process. Some amount of Nickel is found to distributed throughout to the C-S-H gel phase Nickel get adsorbed the interstitial phases of the cement and formed the insoluble nickel compound. The C-S-H phase of Nickel containing samples found denser than that of control samples.

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“…The addition and accumulation of such unwanted materials or things into the environment causes destruction and degradation in ecology. The knowledge of environmental chemistry serves as a key to the understanding of water, land, air and soil pollution that may be caused through biological, chemical and physical activities [1,2].…”

Section: Environmental Pollutionmentioning

confidence: 99%

“…Cement provides a strongly alkaline internal environment. Ca(OH) 2 and calcium silicate hydrogel (C-S-H) are available to buffer the pH to about 12.4 at 18°C in the short term any alkali in the cement or waste tends to raise the pH above 12.4 because counter ions other than OH -are relatively insoluble: chloride and nitrate are the main exceptions. Hence the pH of the lime or cement conditioned matrix is likely to be within the range 12.4-14.0 and is well buffered by the cement solids [44][45][46][47].…”

Section: Solidification/stabilization For the Fixation Of Toxic Wastementioning

confidence: 99%

Environmental Pollution Remediation through Solidification/Fixation of Heavy Metal Ions in Portland Cement

Goyal¹,

Chauhan²

2015

J Environ Anal Toxicol

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Hydration and solidification of hazardous wastes containing heavy metals using modified cementitious materials

Cited by 111 publications

References 4 publications

Novel grout material comprised of calcium phosphate compounds: In vitro evaluation of crystal precipitation and strength reinforcement

Novel grout material comprised of calcium phosphate compounds: In vitro evaluation of crystal precipitation and strength reinforcement

Solidification/Fixation of Nickel Ions in Ordinary Portland Cement

Environmental Pollution Remediation through Solidification/Fixation of Heavy Metal Ions in Portland Cement

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