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Recycling Silicate-Bearing Waste Materials

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A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Inorganic Crystalline Materials".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 24269

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Special Issue Editors

Prof. Dr. Nichola Coleman

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Guest Editor

School of Science, University of Greenwich, London SE10 9LS, UK
Interests: cements and silicate materials for biomedical; environmental; civil engineering
Special Issues, Collections and Topics in MDPI journals

Dr. Samantha E. Booth

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Guest Editor

School of Science, Univerisity of Greenwich, London, UK
Interests: silicate cements, glasses for medical and marine applications

Special Issue Information

Dear Colleagues,

A world in which we are no longer dependent upon processed silicate materials is unimaginable. Silicates in civil engineering underpin our built environment and transport infrastructure to such an extent that water is the only commodity used in greater quantity than cement. Similarly, our daily encounters with silicate glasses and ceramics in the forms of windows, containers, cookware, sanitary fittings, and electronic devices are innumerable. Many of our various industrial, engineering, and agricultural activities are responsible for the generation of large volumes of silicate-bearing waste materials for which further reprocessing and redeployment are necessary.

In tandem with waste minimisation strategies, technological advances in the recycling and reuse of silicate waste streams are essential to environmental sustainability. To date, studies to convert silicate wastes into value-added materials such as secondary aggregates, construction blocks, geopolymers, sorbents, ion exchangers, and catalysts have been reported in the literature.

This Special Issue focusses on the current initiatives in the recycling of silicate-bearing waste materials. The potential topics for original research articles and critical reviews include, but are not limited to, the recycling, reprocessing, or redeployment of the following waste streams:

- Silicate Glasses: containers, windshields, flat screens, liquid crystal displays, borosilicates;

- Incineration Ashes arising from coal, paper-making, oil shale, rice husk, bagasse;

- Construction: brick-, stoneware- and cement-based demolition materials, cement kiln dust;

- Mining and Metallurgical Residues: mineral tailings, slags, red mud, spent foundry sand, stone powder, granite fines, opal waste; and

- Ceramics: sanitary ware, chamotte, and various porcelain- and clay-based residues.

Dr. Nichola J. Coleman
Dr. Samantha E. Booth
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Reprocessing
Glass
Cement and concrete
Ceramic
Clay
Zeolite
Geopolymer
Aggregate
Incineration ash
Slag
Construction and demolition waste
Tailings

Published Papers (9 papers)

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Research

16 pages, 8791 KiB

Open AccessArticle

Interactions of Cr³⁺, Ni²⁺, and Sr²⁺ with Crushed Concrete Fines

by Andrew P. Hurt, Aimee A. Coleman and Nichola J. Coleman

Crystals 2022, 12(5), 717; https://doi.org/10.3390/cryst12050717 - 18 May 2022

Viewed by 1783

Abstract

The underutilized cement-rich fine fraction of concrete-based demolition waste is a potential sorbent for aqueous metal ion contaminants. In this study, crushed concrete fines (CCF) were found to exclude 33.9 mg g⁻¹ of Cr³⁺, 35.8 mg g⁻¹ of Ni²⁺, and 7.16 mg g⁻¹ of Sr²⁺ from ~1000 ppm single metal nitrate solutions (CCF:solution 25 mg cm⁻³) under static batch conditions at 20 °C after 3 weeks. The removal of Sr²⁺ followed a pseudo-second-order reaction (k₂ = 3.1 × 10⁻⁴ g mg⁻¹ min⁻¹, R² = 0.999), whereas a pseudo-first-order model described the removal of Cr³⁺ (k₁ = 2.3 × 10⁻⁴ min⁻¹, R² = 0.998) and Ni²⁺ (k₁ = 5.7 × 10⁻⁴ min⁻¹, R² = 0.991). In all cases, the principal mechanism of interaction was the alkali-mediated precipitation of solubility-limiting phases on the surface of the CCF. Four consecutive deionized water leaching procedures (CCF:water 0.1 g cm⁻³) liberated 0.53%, 0.88%, and 8.39% of the bound Cr³⁺, Ni²⁺, and Sr²⁺ species, respectively. These findings indicate that CCF are an effective sorbent for the immobilization and retention of aqueous Cr³⁺ and Ni²⁺ ions, although they are comparatively ineffectual in the removal and sustained exclusion of Sr²⁺ ions. As is commonly noted with Portland cement-based sorbents, slow removal kinetics, long equilibrium times, the associated release of Ca²⁺ ions, high pH, and the formation of loose floc may preclude these materials from conventional wastewater treatments. This notwithstanding, they are potentially suitable for incorporation into permeable reactive barriers for the containment of metal species in contaminated groundwaters, sediments, and soils. Full article

(This article belongs to the Special Issue Recycling Silicate-Bearing Waste Materials)

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17 pages, 4977 KiB

Open AccessArticle

Predicting the Splitting Tensile Strength of Recycled Aggregate Concrete Using Individual and Ensemble Machine Learning Approaches

by Yongzhong Zhu, Ayaz Ahmad, Waqas Ahmad, Nikolai Ivanovich Vatin, Abdeliazim Mustafa Mohamed and Dina Fathi

Crystals 2022, 12(5), 569; https://doi.org/10.3390/cryst12050569 - 19 Apr 2022

Cited by 22 | Viewed by 2509

Abstract

The application of waste materials in concrete is gaining more popularity for sustainable development. The adaptation of this approach not only reduces the environmental risks but also fulfills the requirement of concrete material. This study used the novel algorithms of machine learning (ML) to forecast the splitting tensile strength (STS) of concrete containing recycled aggregate (RA). The gene expression programming (GEP), artificial neural network (ANN), and bagging techniques were investigated for the selected database. Results reveal that the precision level of the bagging model is more accurate toward the prediction of STS of RA-based concrete as opposed to GEP and ANN models. The high value (0.95) of the coefficient of determination (R²) and lesser values of the errors (MAE, MSE, RMSE) were a clear indication of the accurate precision of the bagging model. Moreover, the statistical checks and k-fold cross-validation method were also incorporated to confirm the validity of the employed model. In addition, sensitivity analysis was also carried out to know the contribution level of each parameter toward the prediction of the outcome. The application of ML approaches for the anticipation of concrete’s mechanical properties will benefit the area of civil engineering by saving time, effort, and resources. Full article

(This article belongs to the Special Issue Recycling Silicate-Bearing Waste Materials)

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13 pages, 5683 KiB

Open AccessArticle

Experimental Study of the Thermophysical Properties of the Red Earth Composite Stabilized with Cement Containing Waste Glass Powder

by Oumaima Nasry, Abderrahim Samaouali, Hanane Sghiouri El Idrissi, Nora Bouhaddour and Adil Hafidi Alaoui

Crystals 2022, 12(3), 396; https://doi.org/10.3390/cryst12030396 - 15 Mar 2022

Cited by 6 | Viewed by 1761

Abstract

The aim of this study was to measure the thermophysical properties (thermal conductivity, volumetric thermal capacity, thermal diffusivity, and thermal effusivity) of red earth stabilized with cement and substituted with waste glass powder. Several samples (red earth) were stabilized with 6% and 12% cement and incorporated with different percentages of waste glass powder, which varied from 10% to 30%. The bulk density of the 12 samples was measured in the dry state and at room temperature. All samples were analyzed by a scanning electron microscope (SEM). The thermal conductivity and specific heat of the composite materials were measured experimentally with a thermal conductivity device (CT meter) in the dry state and at ambient temperature. The experimental results showed a decrease in the thermophysical parameters of stabilized red earth containing 12% cement and substituted by 30% glass powder. The following results were obtained: 53.97% for thermal conductivity, 45.42% for volumetric specific heat, 15.66% for thermal diffusivity, and 49.88% for thermal effusivity. The bulk density of the red earth also decreased by 13.66% in the dry state at ambient temperature. Stabilization with 6% and 12% cement played an important role in the compactness of the material and, consequently, improved its thermophysical performance. The composition of this new ternary material significantly affected the thermophysical properties of the red earth. Full article

(This article belongs to the Special Issue Recycling Silicate-Bearing Waste Materials)

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20 pages, 6808 KiB

Open AccessArticle

Effect of Rheology of Fresh Paste on the Pore Structure and Properties of Pervious Concrete Based on the High Fluidity Alkali-Activated Slag

by Haining Geng, Qing Xu, Saiful B. Duraman and Qiu Li

Crystals 2021, 11(6), 593; https://doi.org/10.3390/cryst11060593 - 24 May 2021

Cited by 10 | Viewed by 1909

Abstract

Pervious concrete is made of cementitious materials, coarse aggregate, water and additives, with characteristic macro- and meso-connected pore structure, which enables the acceptable mechanical properties and high water permeability for pavement and road applications. In this study, the effect of rheology of fresh alkali-activated slag paste on the sedimentation of paste on the bottom of pervious concrete, meso-structure, connected porosity, mechanical properties and water permeability was investigated by a range of analytical techniques through varying the equivalent alkali content to control the rheology of fresh paste in the pervious concrete. The compressive strength of pervious concrete was related to the percentage area of paste and the average thickness of paste on the surface of coarse aggregate. The tensile strength and water permeability were correlated to the connected porosity of pervious concrete and the rheology of fresh paste. A relative lower fluidity, higher viscosity and shear stress of fresh alkali-activated slag paste favoured lower sedimentation of paste on the bottom of pervious concrete, higher connected porosity, tensile strength and water permeability. There was no correlation between compressive strength and tensile strength of pervious concrete. Full article

(This article belongs to the Special Issue Recycling Silicate-Bearing Waste Materials)

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12 pages, 3890 KiB

Open AccessArticle

Thermophysical Properties of Cement Mortar Containing Waste Glass Powder

by Oumaima Nasry, Abderrahim Samaouali, Sara Belarouf, Abdelkrim Moufakkir, Hanane Sghiouri El Idrissi, Houda Soulami, Younes El Rhaffari, Mohamed Hraita, Saïf Ed Dîn Fertahi and Adil Hafidi-Alaoui

Crystals 2021, 11(5), 488; https://doi.org/10.3390/cryst11050488 - 27 Apr 2021

Cited by 22 | Viewed by 2511

Abstract

This study aims to provide a thermophysical characterization of a new economical and green mortar. This material is characterized by partially replacing the cement with recycled soda lime glass. The cement was partially substituted (10, 20, 30, 40, 50 and 60% in weight) by glass powder with a water/cement ratio of 0.4. The glass powder and four of the seven samples were analyzed using a scanning electron microscope (SEM). The thermophysical properties, such as thermal conductivity and volumetric specific heat, were experimentally measured in both dry and wet (water saturated) states. These properties were determined as a function of the glass powder percentage by using a CT-Meter at different temperatures (20 °C, 30 °C, 40 °C and 50 °C) in a temperature-controlled box. The results show that the thermophysical parameters decreased linearly when 60% glass powder was added to cement mortar: 37% for thermal conductivity, 18% for volumetric specific heat and 22% for thermal diffusivity. The density of the mortar also decreased by about 11% in dry state and 5% in wet state. The use of waste glass powder as a cement replacement affects the thermophysical properties of cement mortar due to its porosity as compared with the control mortar. The results indicate that thermal conductivity and volumetric specific heat increases with temperature increase and/or the substitution rate decrease. Therefore, the addition of waste glass powder can significantly affect the thermophysical properties of ordinary cement mortar. Full article

(This article belongs to the Special Issue Recycling Silicate-Bearing Waste Materials)

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26 pages, 1483 KiB

Open AccessArticle

Application of General Full Factorial Statistical Experimental Design’s Approach for the Development of Sustainable Clay-Based Ceramics Incorporated with Malaysia’s Electric Arc Furnace Steel Slag Waste

by Pao Ter Teo, Siti Koriah Zakaria, Nurulakmal Mohd Sharif, Anasyida Abu Seman, Mustaffa Ali Azhar Taib, Julie Juliewatty Mohamed, Mahani Yusoff, Abdul Hafidz Yusoff, Mardawani Mohamad, Arlina Ali and Mohamad Najmi Masri

Crystals 2021, 11(4), 442; https://doi.org/10.3390/cryst11040442 - 19 Apr 2021

Cited by 13 | Viewed by 2764

Abstract

This study aims to optimize the composition (body formulation) and firing temperature of sustainable ceramic clay-based ceramics incorporated with electric arc furnace (EAF) steel slag waste using general full factorial design (GFFD). The optimization is necessary to minimize drawbacks of high iron oxide’s fluxing agent (originated from electric arc furnace, EAF steel slag waste), which led to severe surface defects and high closed porosity issue of the ceramics. Statistical analysis of GFFD including model adequacy checking, analysis of variance (ANOVA), interaction plots, regression model, contour plot and response optimizer were conducted in the study. The responses (final properties of ceramics) investigated were firing shrinkage, water absorption, apparent porosity, bulk density and modulus of rupture (MOR). Meanwhile, the factors employed in experimental parameters were weight percentage (wt.%) of EAF slag added and firing temperature. Upon statistical analysis, GFFD has deduced that wt.% amount of EAF slag added and firing temperatures are proven to significantly influence the final properties of the clay-based ceramic incorporated with EAF slag. The results of conducted statistical analysis were also highly significant and proven valid for the ceramics. Optimized properties (maximum MOR, minimum water absorption and apparent porosity) of the ceramic were attained at 50 wt.% of EAF slag added and firing temperature of 1180 °C. Full article

(This article belongs to the Special Issue Recycling Silicate-Bearing Waste Materials)

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16 pages, 7400 KiB

Open AccessArticle

Axial Compressive Behavior of Reinforced Concrete (RC) Columns Incorporating Multi-Walled Carbon Nanotubes and Marble Powder

by Abdul Jalil Khan, Liaqat Ali Qureshi, Muhammad Nasir Ayaz Khan, Akhtar Gul, Muhammad Umar, Aneel Manan, Yasir Irfan Badrashi, Asim Abbas, Usman Javed and Rashid Farooq

Crystals 2021, 11(3), 247; https://doi.org/10.3390/cryst11030247 - 28 Feb 2021

Cited by 6 | Viewed by 2304

Abstract

In this study, Multiwalled Carbon Nanotubes (MWCNTs) and Marble Powder (MP) have been utilized in reinforced concrete columns to assess their structural behavior. The nanotubes from 0.025% to 0.20% and 5% MP by weight of cement were used. The compressive strength of reinforced concrete columns and cubes was analyzed as the main property. The incorporation of MWCNTs and marble powder was able to increase the compressive strength of columns by 72.69% and mortar by 42.45% as compared to reference concrete. The ductility was noted to be improved by 42.04%. The load-deformation and stress-strain behaviors were also analyzed. The Scanning Electron Microscopy (SEM) analysis revealed the formation of a strong compact bridge (90–100 layers), Calcium Silicate Hydrate (C-S-H) gel, evenly dispersion, and bridging effect caused by MWCNTs. The incorporation of 0.20% MWCNTs by weight of cement was recommended to be effectively used as a reinforcing agent in concrete. Full article

(This article belongs to the Special Issue Recycling Silicate-Bearing Waste Materials)

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18 pages, 4547 KiB

Open AccessArticle

Alkali-Activated Hybrid Concrete Based on Fly Ash and Its Application in the Production of High-Class Structural Blocks

by Oriana Rojas-Duque, Lina Marcela Espinosa, Rafael A. Robayo-Salazar and Ruby Mejía de Gutiérrez

Crystals 2020, 10(10), 946; https://doi.org/10.3390/cryst10100946 - 17 Oct 2020

Cited by 6 | Viewed by 3474

Abstract

This article reports the production and characterization of a hybrid concrete based on the alkaline activation of a fly ash (FA) of Colombian origin, which was added with 10% Portland cement (OPC) in order to promote the compressive strength development at room temperature. The alkali-activated hybrid cement FA/OPC 90/10 was classified as a low heat reaction cement (type LH), according to American Society of Testing Materials, ASTM C1157; the compressive strength was of 31.56 MPa and of 22.68 MPa (28 days) at the levels of paste and standard mortar, respectively, with an initial setting time of 93.3 min. From this binder, a hybrid concrete was produced and classified as a structural type, with a compressive strength of 23.16 MPa and a flexural modulus of rupture of 5.32 MPa, at 28 days of curing. The global warming potential index (GWP 100), based on life cycle analysis, was 35% lower than the reference concrete based on 100% OPC. Finally, its use was validated in the manufacture of a solid block-type construction element, which reached a compressive strength of 21.9 MPa at 28 days, exceeding by 40.6% the minimum strength value established by the Colombia Technical Standard, NTC 4026 (13 MPa) to be classified as high class structural blocks. Full article

(This article belongs to the Special Issue Recycling Silicate-Bearing Waste Materials)

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17 pages, 4066 KiB

Open AccessArticle

Effects of Highly Crystalized Nano C-S-H Particles on Performances of Portland Cement Paste and Its Mechanism

by Yuli Wang, Huijuan Lu, Junjie Wang and Hang He

Crystals 2020, 10(9), 816; https://doi.org/10.3390/cryst10090816 - 15 Sep 2020

Cited by 26 | Viewed by 3551

Abstract

In order to improve the early age strength of ordinary Portland cement-based materials, many early strength agents were applied in different conditions. Different from previous research, the nano calcium silicate hydrate (C-S-H) particles used in this study were synthesized through the chemical reaction of CaO, SiO₂, and H₂O under 120 °C using the hydrothermal method, and the prepared nano C-S-H particles were highly crystalized. The influences of different amounts of nano C-S-H particles (0%, 0.5%, 1%, 2% and 3% by weight of cement) on the setting time, compressive strength, and hydration heat of cement paste were studied. The hydration products and microstructure of the cement paste with different additions of nano C-S-H particles were investigated through thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction (XRD), and scanning electron microscope (SEM) tests. The results show that the nano C-S-H particles could be used as an early strength agent, and the early strength of cement paste can be increased by up to 43% through accelerating the hydration of tricalcium silicate (C₃S). However, the addition of more than 2% nano C-S-H particles was unfavorable to the later strength development due to more space being left during the initial accelerated hydration process. It is suggested that the suitable content of the nano C-S-H particles is 0.5%−1% by weight of cement. Full article

(This article belongs to the Special Issue Recycling Silicate-Bearing Waste Materials)

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