Leaching of elements from cement activated fly ash and slag amended soils

Mahedi, Masrur; Çetin, Bora

doi:10.1016/j.chemosphere.2019.06.178

Cited by 36 publications

(3 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Chen et al [ 14 ] explored the variations in the leached ion concentration of a cement-phosphypsum filling paste with temperature and found that hydration products such as AFt and C-S-H gels inside the filling paste had an adsorptive effect on ions, and temperature affected ion leaching by changing the type and quantity of hydration products. Mahedi et al [ 15 ] conducted four kinds of leaching tests to study the leaching characteristics of cement-activated fly ash and slag–treated soil and found that the ion leaching mechanism mainly involved the dissolution and precipitation of oxides and hydroxides. Yang et al [ 16 ] used slag, steel slag and cement as cementing materials combined with fly ash and mine tailings to prepare a filling paste and found that the filling paste immobilized Cd 2+ significantly under the optimal mixing ratio.…”

Section: Introductionmentioning

confidence: 99%

Changes in the Strength and Leaching Characteristics of Steel Slag-Oil Shale Residue-Based Filling Paste in a Complex Erosive Environment

Lian

Meng

2023

Materials

View full text Add to dashboard Cite

Our research group prepared a new filling paste consisting of steel slag–oil shale residue and no admixtures. It was used as the research object to explore the combined effect of chloride and dry–wet cycling-driven erosion on the long-term stability of a cemented filling paste made of total solid wastes. Macroscopic experiments and microscopic analyses methods were employed. The influence of solutions with different mass fractions of chloride salts and different cycling periods on the uniaxial compressive strength and toxicity of the steel slag–oil shale residue-based filling paste was studied, and the deterioration mechanisms of the steel slag–oil shale residue-based filling paste under combined erosion from chloride and dry–wet cycling were investigated. The test results showed that in the same cycling conditions, the strength of the steel slag-oil shale residue-based filling paste increased first with the increase in the mass fraction of the chloride solution and then decreased with the increase in the mass fraction of the chloride solution after reaching the peak value; the leached concentrations of heavy metal ions decreased with increasing chloride salt mass fraction. With an increase in the number of dry–wet cycles, the compressive strength of the specimens in the chloride salt solution with a mass fraction of 0 (pure water) first increases and then tends to be stable. The strength of samples in 5% and 10% chloride salt solutions increased first and then decreased with an increase in the number of dry–wet cycles. The leached concentrations of heavy metal ions from the samples in all three solutions first decreased and then stabilized. The prehydration products of the steel slag–oil shale residue-based filling paste were C-S-H gels, AFt and Friedel’s salt, and these increased with increasing chloride salt mass fraction and the number of dry–wet cycles. However, the hydration reactions of the samples in the 0% chloride solution nearly stopped in the later stages of cycling, and the samples in 5% and 10% chloride salt solutions developed local cracks due to the accumulation of hydration products. The results showed that the number of dry–wet cycles and the chloride salt mass fraction affected the strength and leaching characteristics of the steel slag–oil shale residue-based filling paste by changing the type and amount of erosion products. The test results provide a scientific basis for the promotion and application of backfilling pastes made from total solid wastes.

show abstract

Section: Introductionmentioning

confidence: 99%

Changes in the Strength and Leaching Characteristics of Steel Slag-Oil Shale Residue-Based Filling Paste in a Complex Erosive Environment

Lian

Meng

2023

Materials

View full text Add to dashboard Cite

show abstract

“…FA is the main waste product of coal-fired power generation, which is more harmful to the environment and can pollute groundwater and soil if disposed of by backfilling [ 7 ]. Mohanty et al [ 8 , 9 , 10 ] found through their study that fly ash-modified soil has the characteristics of low early strength and poor water stability, and a single external admixture exposed many problems, but together with cement, these phenomena can be alleviated. In recent years, polymeric synthetic materials have been favored by the building materials market for their superior properties and low prices, of which fibers are one of the typical representatives.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties, Curing Mechanism, and Microscopic Experimental Study of Polypropylene Fiber Coordinated Fly Ash Modified Cement–Silty Soil

Lu¹,

Ma²,

et al. 2021

Materials

View full text Add to dashboard Cite

Silty soil has the characteristics of low natural moisture content and poor viscosity, and the strength and deformation required for foundation engineering can be satisfied by reinforcing and improving the silt. In order to study the reinforcement and improvement effects of polypropylene (PP) fiber and fly ash (FA) on cement–silty soil, an unconfined compressive strength (UCS) test, scanning electron microscope (SEM) test, and X-ray diffraction (XRD) analysis test were carried out. Cement (mixed amounts are 4%, 8%, 12%, and 16% of dry soil mass) was used as the basic modifier, and PP fiber (mixed amounts are 0%, 0.15%, 0.3%, and 0.45% of dry soil mass) compounded with FA (adding amounts of 0%, 5%, 10%, and 15% of dry soil mass) were used as an external admixture of cement–silty soil to study the mechanical properties, curing mechanism, and microstructure of the modified soil in different ages of 7 d, 14 d, 28 d, and 60 d. The test results show that with the increase in cement and curing age, the UCS of the modified soil increases, and with the increase in the PP fiber and FA, the UCS of the modified soil first increases and then decreases; there is an optimal content of FA and PP fiber, which are 10 and 0.15%, respectively. A large amount of C-S-H and AFt substances are produced inside the modified soil to cover the surface of soil particles or fill in the pores between soil particles, forming a tight spatial network structure and improving the mechanical properties of the cement–soil. The intensity of the diffraction peaks of the mineral components within the modified soils is more influenced by the cement and age, and the effect of FA is weaker. The stress–strain curve of the modified soil is divided into elastic stage, plastic deformation stage, and strain-softening stage, and the specimens in each stage have corresponding deformation characteristics. By analyzing the behavioral characteristics and curing improvement mechanism of modified soil from the duo perspective of macro-mechanical properties and microstructural composition, it can provide some basis for the engineering application of silty soil.

show abstract

“…In recent decades, several onestep methods have been reported, in which the calculated leaching content (determined through leaching tests) is used to represent the risk value of remediated soils (Ding et al, 2019). These methods mainly include the toxicity characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP) and multiple extraction procedure (MEP), which were issued by the US Environmental Protection Agency (USEPA) and are widely used in the current methods to evaluate the effect of soil remediation technologies (Abbas et al, 2018;Mahedi and Cetin, 2019). If the leaching contents of heavy metals are lower than the relevant toxicity standards under specific experimental conditions, the method is considered to be in accordance with the remediation requirements (Gupta et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Two-step calculation method to enable the ecological and human health risk assessment of remediated soil treated through thermal curing

Xie

Ning

et al. 2021

Soil Ecol. Lett.

View full text Add to dashboard Cite

The centralized utilization of heavy-metal-contaminated soil has become the main strategy to remediate brownfield-site pollution. However, few studies have evaluated the ecological and human health risks of reusing these remediated soils. Considering Zn as the target metal, systematic pHdependent leaching and the Community Bureau of Reference (BCR) extraction were conducted at six pH values (pH = 2, 4, 6, 8, 10, 12) for the remediated soil treated through thermal curing. The pHdependent leaching results showed that with the formation of ZnCr 2 O 4 spinel phases, the remediated soil exhibited strong inherent resistance to acidic attack over longer leaching periods. Furthermore, the BCR extraction results showed that the leaching agent pH value mainly affected the acid-soluble fraction content. Moreover, a strong complementary relationship was noted between the leaching and acid-soluble fraction contents, indicating that the sum of these two parameters is representative of the remediated soil risk value. Therefore, we proposed a two-step calculation method to determine the sum of the two heavy metal parameters as the risk value of remediated soil. In contrast to the traditional one-step calculation method, which only uses the leaching content as the risk value, this two-step calculation method can effectively avoid underestimating the risk of remediated soil.

show abstract

Leaching of elements from cement activated fly ash and slag amended soils

Cited by 36 publications

References 41 publications

Changes in the Strength and Leaching Characteristics of Steel Slag-Oil Shale Residue-Based Filling Paste in a Complex Erosive Environment

Changes in the Strength and Leaching Characteristics of Steel Slag-Oil Shale Residue-Based Filling Paste in a Complex Erosive Environment

Mechanical Properties, Curing Mechanism, and Microscopic Experimental Study of Polypropylene Fiber Coordinated Fly Ash Modified Cement–Silty Soil

Two-step calculation method to enable the ecological and human health risk assessment of remediated soil treated through thermal curing

Contact Info

Product

Resources

About