Environmental behavior of construction and demolition waste as recycled aggregates for backfilling in mines: Leaching toxicity and surface subsidence studies

Liu, Hengfeng; Zhang, Jixiong; Li, Baiyi; Zhou, Nan; Xiao, Xilong; Li, Meng; Zhu, Cunli

doi:10.1016/j.jhazmat.2019.121870

Cited by 48 publications

(14 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Its annual production is huge, while the recycling rate is less than 5% [1]. e main components of construction waste are bricks and concrete blocks [2][3][4][5]. In recent years, many studies have been focused on investigating the properties and reuse methods of waste concretes, and correspondingly the recycling rate of waste concretes is high [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Analysis on the Strength of Cement Mortar Mixed with Construction Waste Brick Powder

Xue

Huang

Feng

et al. 2021

Advances in Civil Engineering

View full text Add to dashboard Cite

The pile-up of massive construction waste causes serious challenges to environment and engineering practice. In order to promote the reuse rate of construction waste bricks, the effects of the content and fineness of construction waste brick powder and of brick powder-silica flour mixture on the strengths of cement mortar were experimentally investigated. Based on the test results, the significance of the particle characteristics of brick powder on mortar strength was analyzed by grey entropy method. The experimental results show that the early strength of cement mortar decreases due to the addition of brick powder; the reduction is, however, not significant when the content of brick powder is less than 10%; the 28 d strength of cement mortar increases with a proper content of brick powder. The grey entropy analysis indicates that the particle characteristics have strong influence on the activity of brick powder and mortar strength; the strength is significantly dependent on specific surface area and the fraction of particles smaller than 20 μm. Fine brick powder and silica flour can improve the macroscopic strengths of cement mortar by affecting the type and quantity of hydration products and the structure of interfacial transition zone between cement paste and sand.

show abstract

Section: Introductionmentioning

confidence: 99%

Analysis on the Strength of Cement Mortar Mixed with Construction Waste Brick Powder

Xue

Huang

Feng

et al. 2021

Advances in Civil Engineering

View full text Add to dashboard Cite

show abstract

“…Leaching tests are widely used for the determination of contaminant release rates from soils [ 1 , 2 , 3 , 4 ], recycling materials [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ], construction products [ 12 , 13 , 14 , 15 , 16 ], radioactive and other waste materials [ 17 , 18 ]. Compared to traditional batch shaking tests, column tests are preferred for assessing the risk of release of potential pollutants into groundwater or surface waters because they are closer to natural conditions [ 19 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

Mass Transfer Principles in Column Percolation Tests: Initial Conditions and Tailing in Heterogeneous Materials

2021

View full text Add to dashboard Cite

Initial conditions (pre-equilibrium or after the first flooding of the column), mass transfer mechanisms and sample composition (heterogeneity) have a strong impact on leaching of less and strongly sorbing compounds in column percolation tests. Mechanistic models as used in this study provide the necessary insight to understand the complexity of column leaching tests especially when heterogeneous samples are concerned. By means of numerical experiments, we illustrate the initial concentration distribution inside the column after the first flooding and how this impacts leaching concentrations. Steep concentration gradients close to the outlet of the column have to be expected for small distribution coefficients (Kd<1 L kg−1) and longitudinal dispersion leads to smaller initial concentrations than expected under equilibrium conditions. In order to elucidate the impact of different mass transfer mechanisms, film diffusion across an external aqueous boundary layer (first order kinetics, FD) and intraparticle pore diffusion (IPD) are considered. The results show that IPD results in slow desorption kinetics due to retarded transport within the tortuous intragranular pores. Non-linear sorption has not much of an effect if compared to Kd values calculated for the appropriate concentration range (e.g., the initial equilibrium concentration). Sample heterogeneity in terms of grain size and different fractions of sorptive particles in the sample have a strong impact on leaching curves. A small fraction (<1%) of strongly sorbing particles (high Kd) carrying the contaminant may lead to very slow desorption rates (because of less surface area)—especially if mass release is limited by IPD—and thus non-equilibrium. In contrast, mixtures of less sorbing fine material (“labile” contamination with low Kd), with a small fraction of coarse particles carrying the contaminant leads to leaching close to or at equilibrium showing a step-wise concentration decline in the column effluent.

show abstract

“…After coal mining, many mined-out spaces are formed underground, which causes strata movement, damage, surface subsidence, and collapse [1][2][3][4][5]. Simultaneously, a large quantity of solid wastes such as gangue is discharged in the coal mining process [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Effects of Water Immersion on the Long-Term Bearing Characteristics of Crushed Gangue in Goaf

Ning

Yin

et al. 2021

Geofluids

View full text Add to dashboard Cite

To study the long-term bearing characteristics of crushed gangue in goaf under water immersion conditions, the creep test of the crushed gangue in the water immersion state was performed by using the self-developed large-scale deformation-seepage test system of crushed rock. The effects of the rock lithology, axial stress, and grain composition on the long-term bearing deformation characteristics and fractal characteristics of crushed gangue under water immersion were analysed. The results show that under certain conditions of axial stress and grain composition of the gangue, a greater uniaxial compressive strength of water-saturated rock corresponds to a greater deformation resistance of the rock, smaller strain and crushing expansion in the corresponding creep stage, and greater fractal dimension increments of the crushed gangue after compression, and the gangue will have more serious crushing. With identical grain compositions and with the increase in the axial stress in the creep stage, the strain increases, the crushing expansion decreases, the fractal dimension increments of the crushed gangue after compression increase, and the gangue will have more serious crushing. Under identical axial stress conditions, when the Talbol power index n is 0.5, the differentials of the strain and crushing expansion for the crushed sandstone sample in the creep stage are minimal. When n is 0.3 or 0.7, these quantities are basically equal. With the increase in the Talbol power index, the fractal dimension increments of the crushed sandstone sample during compression gradually increase, and the crushed sandstone sample will have more serious crushing.

show abstract

Environmental behavior of construction and demolition waste as recycled aggregates for backfilling in mines: Leaching toxicity and surface subsidence studies

Cited by 48 publications

References 40 publications

Analysis on the Strength of Cement Mortar Mixed with Construction Waste Brick Powder

Analysis on the Strength of Cement Mortar Mixed with Construction Waste Brick Powder

Mass Transfer Principles in Column Percolation Tests: Initial Conditions and Tailing in Heterogeneous Materials

Effects of Water Immersion on the Long-Term Bearing Characteristics of Crushed Gangue in Goaf

Contact Info

Product

Resources

About