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This research study evaluated the effects of adding Scottish canal sediment after calcination at 750 °C in combination with GGBS on hydration, strength and microstructural properties in ternary cement mixtures in order to reduce their carbon footprint (CO2) and cost. A series of physico-chemical, hydration heat, mechanic performance, mercury porosity and microstructure tests or observations was performed in order to evaluate the fresh and hardened properties. The physical and chemical characterisation of the calcined sediments revealed good pozzolanic properties that could be valorised as a potential co-product in the cement industry. The results obtained for mortars with various percentages of calcined sediment confirmed that this represents a previously unrecognised potential source of high reactivity pozzolanic materials. The evolution of the compressive strength for the different types of mortars based on the partial substitution of cement by slag and calcined sediments showed a linear increase in compressive strength for 90 days. The best compressive strengths and porosity were observed in mortars composed of 50% cement, 40% slag and 10% calcined sediment (CSS10%) after 90 days. In conclusion, the addition of calcined canal sediments as an artificial pozzolanic material could improve strength and save significant amounts of energy or greenhouse gas emissions, while potentially contributing to Scotland’s ambitious 2045 net zero target and reducing greenhouse gas emissions by 2050 in the UK and Europe.
Rachid Hadj Sadok; Walid Maherzi; Mahfoud Benzerzour; Richard Lord; Keith Torrance; Agnes Zambon; Nor-Edine Abriak. Mechanical Properties and Microstructure of Low Carbon Binders Manufactured from Calcined Canal Sediments and Ground Granulated Blast Furnace Slag (GGBS). Sustainability 2021, 13, 9057 .
AMA StyleRachid Hadj Sadok, Walid Maherzi, Mahfoud Benzerzour, Richard Lord, Keith Torrance, Agnes Zambon, Nor-Edine Abriak. Mechanical Properties and Microstructure of Low Carbon Binders Manufactured from Calcined Canal Sediments and Ground Granulated Blast Furnace Slag (GGBS). Sustainability. 2021; 13 (16):9057.
Chicago/Turabian StyleRachid Hadj Sadok; Walid Maherzi; Mahfoud Benzerzour; Richard Lord; Keith Torrance; Agnes Zambon; Nor-Edine Abriak. 2021. "Mechanical Properties and Microstructure of Low Carbon Binders Manufactured from Calcined Canal Sediments and Ground Granulated Blast Furnace Slag (GGBS)." Sustainability 13, no. 16: 9057.
The disposal of waste slurry from construction engineering is attracting more and more attention due to the thorny issues related to high water content (dewatering is difficult and time-consuming). The use of chemical flocculants is proposed in this study, and organic, inorganic, and composite flocculant are designed to identify the characteristics and efficiency of slurry-water separation. The influence of flocculant type and dosage on slurry settlement and its associated mechanisms are studied by a set of sedimentation column, particle size distribution, and scanning electron microscopy (SEM) tests. The experimental results prove that organic, inorganic, and composite flocculants can promote the efficiency of slurry-water separation, although inorganic flocculants may perform relatively worse in comparison with organic and composite flocculants. The conditioning performance of organic flocculants is sequentially anionic polyacrylamide (APAM) > polyacrylamide (PAM) > amphoteric polyacrylamide (ACPAM) > cationic polyacrylamide (CPAM), while their optimum dosage is 300, 300, 400, and 400 mg/L, respectively. The combined formulation of APAM+FeCl3 improves the conditioning of slurry owing to the charge neutralization, net capturing, and sweeping ability. The flocculating effect causes an aggregation of fine particles, and this induces a decrease in the amount of fine particles and an increase in the fraction of coarse flocs. The SEM results prove that the slurry particles tend to be arranged in a parallel manner and the flocculant induces an agglomeration of fine particles owning to a series of physicochemical reactions. The previous discussions can provide an experimental framework for the development of slurry-water separation technology on waste slurry from construction works.
Dongxing Wang; Shengjie Di; Linfeng Wu; Yunzhi Tan; Yikai Tang. Sedimentation Behavior of Organic, Inorganic, and Composite Flocculant-Treated Waste Slurry from Construction Works. Journal of Materials in Civil Engineering 2021, 33, 04021134 .
AMA StyleDongxing Wang, Shengjie Di, Linfeng Wu, Yunzhi Tan, Yikai Tang. Sedimentation Behavior of Organic, Inorganic, and Composite Flocculant-Treated Waste Slurry from Construction Works. Journal of Materials in Civil Engineering. 2021; 33 (7):04021134.
Chicago/Turabian StyleDongxing Wang; Shengjie Di; Linfeng Wu; Yunzhi Tan; Yikai Tang. 2021. "Sedimentation Behavior of Organic, Inorganic, and Composite Flocculant-Treated Waste Slurry from Construction Works." Journal of Materials in Civil Engineering 33, no. 7: 04021134.
Few studies focus on the co-valorization of river dredging sediments (DS) and residual waste glass (RWG) in alkali-activated binders. This study investigates the use of DS as an aluminosilicate source by substituting a natural resource (metakaolin (MK)), while using RWG as an activator (sodium silicate source). Suitable treatments are selected to increase the potential reactivity of each residue. The DS is thermally treated at 750 °C to promote limestone and aluminosilicate clays’ activation. The RWG (amorphous, rich in silicon, and containing sodium) is used as an alkaline activator after treatment in 10 M NaOH. Structural monitoring using nuclear magnetic resonance (29NMR and 27NMR), X-ray diffraction, and leaching is conducted to achieve processing optimization. In the second stage, mortars were prepared and characterized by determining compressive strength, water absorption, mercury porosimetry and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). Results obtained show the great advantage of combining RWG and DS in an alkali-activation binder. The treated RWG offers advantages when used as sodium silicate activating solution, while the substitution of MK by calcined sediments (DS-750 °C) at 10%, 20%, and 30% leads to improvements in the properties of the matrix such as an increase in compressive strength and a refinement and reduction of the pore size within the matrix.
Abdelhadi Bouchikhi; Walid Maherzi; Mahfoud Benzerzour; Yannick Mamindy-Pajany; Arne Peys; Nor-Edine Abriak. Manufacturing of Low-Carbon Binders Using Waste Glass and Dredged Sediments: Formulation and Performance Assessment at Laboratory Scale. Sustainability 2021, 13, 4960 .
AMA StyleAbdelhadi Bouchikhi, Walid Maherzi, Mahfoud Benzerzour, Yannick Mamindy-Pajany, Arne Peys, Nor-Edine Abriak. Manufacturing of Low-Carbon Binders Using Waste Glass and Dredged Sediments: Formulation and Performance Assessment at Laboratory Scale. Sustainability. 2021; 13 (9):4960.
Chicago/Turabian StyleAbdelhadi Bouchikhi; Walid Maherzi; Mahfoud Benzerzour; Yannick Mamindy-Pajany; Arne Peys; Nor-Edine Abriak. 2021. "Manufacturing of Low-Carbon Binders Using Waste Glass and Dredged Sediments: Formulation and Performance Assessment at Laboratory Scale." Sustainability 13, no. 9: 4960.
The feasibility and performance of eco-friendly and sustainable magnesium potassium phosphate cement (MKPC) to solidify urban river sludge are innovatively evaluated. To probe exhaustively into the mechanical performance and micromechanism of MKPC solidified dredged sludge, the effect of binder content, Mg/P molar ratio, retarder (borax) content and curing age are analyzed through unconfined compressive strength (UCS), mercury intrusion porosimetry (MIP), X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests. The experimental findings indicate the compressive strength is raised owing to an increase in MKPC amount and curing age. The isolation effect of sludge matrix weakens the retarding effect of borax, but reasonable borax content is beneficial to the strength improvement at longer curing age. The UCS of solidified samples with lower molar ratio (Mg/P = 3) increases rapidly at the early age while limitedly in later stage. The UCS reaches the maximum at the molar ratio of Mg/P = 4–5. The XRD and MIP analysis demonstrates that MgKPO4·6H2O (struvite-k) is the major hydration phase produced along with unreacted dead burned magnesia. Struvite-k can effectively fill the large pores (1–10 μm) and cause the transformation of large pores into small pores (0–0.1 μm), which has a good refinement performance for pore structure. The SEM images show that the prismatic or layered struvite-k forms preferentially and its final morphology is intimately connected with the Mg/P molar ratio. When the MKPC dosage and curing age increase, the struvite-k crystals are significantly densified and some microcracks appear due to the surface tension effect during the hydration heat-associated dehydration in crystal growth process. The synthesized crystal is fully developed and the crystal grows more completely under appropriate reaction conditions and reasonable relative concentration of reactants, which produces stronger interconnection between sludge particles and denser microstructure within matrix, contributing to the strength development of solidified sludge. In summary, the mechanical, eco-friendly and cost-efficient benefits could be highly anticipated from substituting MKPC for Portland cement (PC) in sludge solidification.
Dongxing Wang; Jiaye Zhu; Ruihong Wang. Assessment of magnesium potassium phosphate cement for waste sludge solidification: Macro- and micro-analysis. Journal of Cleaner Production 2021, 294, 126365 .
AMA StyleDongxing Wang, Jiaye Zhu, Ruihong Wang. Assessment of magnesium potassium phosphate cement for waste sludge solidification: Macro- and micro-analysis. Journal of Cleaner Production. 2021; 294 ():126365.
Chicago/Turabian StyleDongxing Wang; Jiaye Zhu; Ruihong Wang. 2021. "Assessment of magnesium potassium phosphate cement for waste sludge solidification: Macro- and micro-analysis." Journal of Cleaner Production 294, no. : 126365.
Stabilization/solidification (S/S) of dredged sediments is an environmentally friendly, low-cost and time-efficient way to manage this waste (according to the European waste classification) in the context of valorization as novel resources. In this study, the main objective was to evaluate the efficiency of using a novel and green binder Calcium Sulfo-Aluminate (CSA) cement to solidified Dunkirk sediments. For comparison, the Ordinary Portland Cement (OPC) binder was used as a reference. For this purpose, several tests were performed on samples containing various types and amounts of binders. The experimental program included: modified Proctor compaction tests, immediate Californian Bearing Ratio (I-CBR) index tests, unconfined compressive strength tests, splitting tensile strength tests, measurements of elastic and secant modulus, and mineral and micropore structure analysis. It is realistic to conclude that the compaction performance of the CSA-/OPC-solidified sediments is significantly improves. The mechanical performance of compressive, tensile strength and elastic modulus increases with binder content and curing time. The simple model obtained to relate the compressive and tensile strength with elastic modulus allows predicting easily, for a given suitable set of characteristics, the type or the amount of binder needed. This model allows optimizing the amount of binder to reach a given properties of solidified sediments and hence improves the cost of developed material. The results also demonstrate the ability of solidified sediment to be valorized in road construction.
Rachid Zentar; Hongwei Wang; Dongxing Wang. Comparative study of stabilization/solidification of dredged sediments with ordinary Portland cement and calcium sulfo-aluminate cement in the framework of valorization in road construction material. Construction and Building Materials 2021, 279, 122447 .
AMA StyleRachid Zentar, Hongwei Wang, Dongxing Wang. Comparative study of stabilization/solidification of dredged sediments with ordinary Portland cement and calcium sulfo-aluminate cement in the framework of valorization in road construction material. Construction and Building Materials. 2021; 279 ():122447.
Chicago/Turabian StyleRachid Zentar; Hongwei Wang; Dongxing Wang. 2021. "Comparative study of stabilization/solidification of dredged sediments with ordinary Portland cement and calcium sulfo-aluminate cement in the framework of valorization in road construction material." Construction and Building Materials 279, no. : 122447.
Due to huge carbon emissions associated with the production of Portland cement (PC), the pursuit of sustainable and efficient cementitious materials is a major challenge to manage solid wastes including urban river sludge. As an eco-friendly alternative to PC, granulated blast furnace slag (GBFS)-modified magnesium oxychloride cement (MOC) is innovatively introduced in sludge solidification. The slag modification to MOC and their synergistic efficiency on sludge treatment is systematically evaluated by unconfined compressive strength (UCS), durability and microstructural tests, considering slag dosage, molar ratio of MgO/MgCl2 and curing age. The obtained results suggest that MOC-slag mixture is efficient in sludge solidification and the inclusion of slag overcomes the strength retraction of MOC solidified sludge. The mechanical behaviour is closely concerned with the formation of phase 5, brucite and C–S–H gels, which imposes a dominant impact on the morphology and microstructure of solidified sludge. Especially, the physic-chemical effect of slag is able to improve the durability of MOC solidified sludge, and induces an enhancement of its long-term stability. The C–S–H gels formed by alkaline activation of slag are the crucial cause of improvement in long-term strength and durability of MOC-slag solidified sludge. In brief, the combined agent of slag-modified MOC shall be deemed as an effective and eco-friendly approach for urban sludge disposal.
Dongxing Wang; Xiangyun Gao; Xiqi Liu; Gang Zeng. Strength, durability and microstructure of granulated blast furnace slag-modified magnesium oxychloride cement solidified waste sludge. Journal of Cleaner Production 2021, 292, 126072 .
AMA StyleDongxing Wang, Xiangyun Gao, Xiqi Liu, Gang Zeng. Strength, durability and microstructure of granulated blast furnace slag-modified magnesium oxychloride cement solidified waste sludge. Journal of Cleaner Production. 2021; 292 ():126072.
Chicago/Turabian StyleDongxing Wang; Xiangyun Gao; Xiqi Liu; Gang Zeng. 2021. "Strength, durability and microstructure of granulated blast furnace slag-modified magnesium oxychloride cement solidified waste sludge." Journal of Cleaner Production 292, no. : 126072.
Acid/alkali contamination of expansive soils, which has been probed in recent years, gives rise to unexpected structural failure when exposed. However, a systematic research aiming at evaluating volumetric behavior of natural illitic clays when subjected to acid/alkali solution as pore fluid and its microlevel analysis is not well established. A series of oedometer tests and microanalytical experiments (X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy) have been carried out to investigate the effects of acid and alkali contamination on swelling and compressibility of natural expansive clays from Heilongjiang province in China and to identify the underlying controlling mechanisms. Distilled water, sulfuric acid of pH 3, and caustic soda of pH 13 were selected as three different pore fluids. The results show that compared to samples inundated with water, specimens exhibit greater swelling and lower compressibility after being exposed to acid solution, and lower swelling and greater compressibility after being subjected to alkali solution. In three different soaking solutions, all samples present an increasing tendency for swelling deformation with dry density from 1.4 to 1.8 g/cm3, while the highest compressibility occurs at dry density around 1.5 g/cm3. The microanalysis revealed that soils undergo reactions, including desiliconization and cation exchange, due to the acid and alkali erosion, which correspondingly leads to changes in soil mineralogy and texture. Acid and alkali contamination results in disintegration and loose structure, and acid exerts more destructive impacts than alkali do. The sulfuric acid promoted the dissolution of tetrahedral cations, while the caustic soda improved the dissolution of octahedral cations.
Dongxing Wang; Yiying Du; Leena Korkiala-Tanttu; Zengfeng Zhao. Volume Change Behavior of Natural Expansive Soils Subjected to Acid and Alkali Contamination. International Journal of Geomechanics 2020, 20, 06020030 .
AMA StyleDongxing Wang, Yiying Du, Leena Korkiala-Tanttu, Zengfeng Zhao. Volume Change Behavior of Natural Expansive Soils Subjected to Acid and Alkali Contamination. International Journal of Geomechanics. 2020; 20 (11):06020030.
Chicago/Turabian StyleDongxing Wang; Yiying Du; Leena Korkiala-Tanttu; Zengfeng Zhao. 2020. "Volume Change Behavior of Natural Expansive Soils Subjected to Acid and Alkali Contamination." International Journal of Geomechanics 20, no. 11: 06020030.
Waste glass based geopolymers have a high potential in the future as an eco-friendly inorganic binder. However, limited studies are available on the use of the residue of waste glass recycling in this type of binder. This work investigates the valorization of Residual Waste Glass (RWG) (the final waste of glass recycling centers) crushed at d90 < 13 μm in a geopolymer activating solution. RWG is thus used as source of free silicon with metakaolin (MK) as source of aluminosilicates. The activating solution from RWG was prepared in four ratios with a sodium hydroxide solution of 10M: R1 (10M-NaOH + 10g RWG), R2 (10M-NaOH + 20g RWG), R3 (10M-NaOH + 30g RWG) and R4 (10M-NaOH + 40g of RWG). The effect of these treatments on the mobility of metallic and metalloid trace elements (MMTE) and major elements (Si4+ and Al3+) was measured. The structure of the solid phases produced after drying at 120°C/24h was studied using Fourier Transformed Infrared (FTIR) spectroscopy, Nuclear Magnetic Resonance (NMR) and XRD analyses. From these analyses, activating solution R3 was deemed optimal. The formulation of geopolymer mortars using MK and three activator sources: The optimized activating solution from RWG (R3), Commercial Sodium Silicate solution (CSS) and a reference activator formed by NaOH with RWG blended with the MK to obtain the same molar ratios in the geopolymer mixture. The mechanical and environmental performance results both highlight the interest of dissolving the RWG in NaOH first before insertion into the matrix. This study shows that treated glass R3 becomes an activating solution with good reactivity for obtaining a geopolymer binder and enhanced properties compared to the CSS source.
Abdelhadi Bouchikhi; Yannick Mamindy-Pajany; Walid Maherzi; Cyrille Albert-Mercier; Hamza El-Moueden; Mahfoud Benzerzour; Arne Peys; Nor-Edine Abriak. Use of residual waste glass in an alkali-activated binder – Structural characterization, environmental leaching behavior and comparison of reactivity. Journal of Building Engineering 2020, 34, 101903 .
AMA StyleAbdelhadi Bouchikhi, Yannick Mamindy-Pajany, Walid Maherzi, Cyrille Albert-Mercier, Hamza El-Moueden, Mahfoud Benzerzour, Arne Peys, Nor-Edine Abriak. Use of residual waste glass in an alkali-activated binder – Structural characterization, environmental leaching behavior and comparison of reactivity. Journal of Building Engineering. 2020; 34 ():101903.
Chicago/Turabian StyleAbdelhadi Bouchikhi; Yannick Mamindy-Pajany; Walid Maherzi; Cyrille Albert-Mercier; Hamza El-Moueden; Mahfoud Benzerzour; Arne Peys; Nor-Edine Abriak. 2020. "Use of residual waste glass in an alkali-activated binder – Structural characterization, environmental leaching behavior and comparison of reactivity." Journal of Building Engineering 34, no. : 101903.
The solidification of construction waste slurry draws much attention today due to the increasing awareness of environmental protection. Magnesium oxychloride cement (MOC) was first incorporated to solidify slurry in combination with industrial residue, which has the potential to be used as roadbed material. Three types of binding materials including MOC, industrial residue, and industrial residue modified MOC were proposed to evaluate their performance in the solidification of construction slurry with high water content. The unconfined compressive strength (UCS) and coefficient of permeability were investigated, taking into account factors including MOC content, molar ratio of MgO/MgCl2, mass ratio of MOC to industrial residue, industrial residue content, and curing time. The microstructure was identified to reveal the intrinsic mechanisms by scanning electron microscopy (SEM). The results showed that the mechanical behavior of solidified slurry was largely influenced by these factors, and the industrial residue proved effective in improving the strength and permeability of MOC solidified slurry by impeding the decomposition of phase 5 and phase 3 and absorbing a certain amount of water. The industrial residue modified MOC solidified slurry showed higher water resistance and a lower coefficient of permeability due to the generation of amorphous calcium silicate hydrate (C-S-H) gels, phase 5 and phase 3 that could form a much stronger interlocking network.
Dongxing Wang; Mahfoud Benzerzour; Xu Hu; Bin Huang; Zhengguang Chen; Xueyong Xu. Strength, Permeability, and Micromechanisms of Industrial Residue Magnesium Oxychloride Cement Solidified Slurry. International Journal of Geomechanics 2020, 20, 04020088 .
AMA StyleDongxing Wang, Mahfoud Benzerzour, Xu Hu, Bin Huang, Zhengguang Chen, Xueyong Xu. Strength, Permeability, and Micromechanisms of Industrial Residue Magnesium Oxychloride Cement Solidified Slurry. International Journal of Geomechanics. 2020; 20 (7):04020088.
Chicago/Turabian StyleDongxing Wang; Mahfoud Benzerzour; Xu Hu; Bin Huang; Zhengguang Chen; Xueyong Xu. 2020. "Strength, Permeability, and Micromechanisms of Industrial Residue Magnesium Oxychloride Cement Solidified Slurry." International Journal of Geomechanics 20, no. 7: 04020088.
The objective of our work was to develop a software for the optimization of the processes of treatment and formulation of dredged sediments for utilization in civil engineering applications. The software proposes an optimal solution that meets the different technical and environmental requirements of sediment utilization at a lower cost. The software development consisted of defining the technical and environmental constraints that the sediments must comply with to be used in one of the four applications targeted in this work: road technique, dikes, concrete, and agricultural spreading. Boundary values were determined according to the current national regulations (France, Belgium, the Netherlands, and the United Kingdom) for each type of application. The constraints were modeled by equations, and then introduced into the software. Economical aspects were also taken into account in the optimization process, with an assessment of costs related to dredging operations, natural materials, treatment, and transportation. In order to validate the computation model of the software, a simulation of the construction of a road based on three sediments was performed. The aim of this work was to provide decision makers with simple and interactive software which will facilitate the management and the utilization of dredged sediments in civil engineering. The software proposed the mixture of three types of dredged sediments (30.29%) and sand (69.69%). The software also proposed treatments to reduce the organic matter content of the sediment and the amount of chemical elements that exceed the environmental thresholds defined by regulations. An estimate of the overall cost and of the detailed cost related to the sediment utilization was also proposed by the software. The presented software is a tool for optimizing the utilization and treatment of dredged sediments in civil engineering works. The technical and environmental constraints were modeled as well as the costs of each step of the sediment utilization. This allowed proposing the optimal solution that meets different technical and environmental requirements at a lower cost. The software has been tested during a road construction in Lille, France, and results confirmed the reliability of the solution proposed by the software.
Ahmed Zeraoui; Mahfoud Benzerzour; Walid Maherzi; Raid Mansi; Nor-Edine Abriak. New software for the optimization of the formulation and the treatment of dredged sediments for utilization in civil engineering. Journal of Soils and Sediments 2020, 20, 2709 -2716.
AMA StyleAhmed Zeraoui, Mahfoud Benzerzour, Walid Maherzi, Raid Mansi, Nor-Edine Abriak. New software for the optimization of the formulation and the treatment of dredged sediments for utilization in civil engineering. Journal of Soils and Sediments. 2020; 20 (6):2709-2716.
Chicago/Turabian StyleAhmed Zeraoui; Mahfoud Benzerzour; Walid Maherzi; Raid Mansi; Nor-Edine Abriak. 2020. "New software for the optimization of the formulation and the treatment of dredged sediments for utilization in civil engineering." Journal of Soils and Sediments 20, no. 6: 2709-2716.
Eco-friendly magnesium oxychloride cement (MOC) is incorporated to reduce the disposal obstacles and mitigate the environmental impacts related to the urban river sludge. Three major factors including MOC content, molar ratio of MgO/MgCl2 and curing time are examined by unconfined compressive strength (UCS) tests. The microscopic effect caused by the MOC-hydration process is identified using X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) technique to reveal the intrinsic mechanisms. The results show that MOC content, molar ratio of MgO/MgCl2 and curing time strongly affects the UCS of MOC-solidified sludge. The suitable parameter values for sludge treatment by MOC turn out to be molar ratio of MgO/MgCl2 of 8–10, MOC content of 10% and curing time of 60 d. The UCS and strength retention coefficient of MOC-solidified sludge present an important decreasing trend with water immersion time due to the gradual decomposition of phase 5 – 5 Mg(OH)2·MgCl2·8H2O into Mg(OH)2 phase, some soluble ions and H2O molecules. The UCS development is directly related to the formation of phase 5 and brucite, which induces a transformation of pore structure and boosts to develop a much stronger interlocking microstructure in solidified matrix. The identification of brucite with a significant volumetric expansion and phase 5 provides an insightful interpretation for the strength evolution of MOC-solidified sludge. Overall, the innovative incorporation of MOC treatment is supposed to be an efficient and sustainable approach on sludge solidification.
Dongxing Wang; Shengjie Di; Xiangyun Gao; Ruihong Wang; Zhengguang Chen. Strength properties and associated mechanisms of magnesium oxychloride cement-solidified urban river sludge. Construction and Building Materials 2020, 250, 118933 .
AMA StyleDongxing Wang, Shengjie Di, Xiangyun Gao, Ruihong Wang, Zhengguang Chen. Strength properties and associated mechanisms of magnesium oxychloride cement-solidified urban river sludge. Construction and Building Materials. 2020; 250 ():118933.
Chicago/Turabian StyleDongxing Wang; Shengjie Di; Xiangyun Gao; Ruihong Wang; Zhengguang Chen. 2020. "Strength properties and associated mechanisms of magnesium oxychloride cement-solidified urban river sludge." Construction and Building Materials 250, no. : 118933.
The management of dredging sediments and plastic waste is of increasing environmental, societal, and economic importance. To address this, we produced lightweight aggregates composed of 70% sediment based mineral filler and 30% thermoplastic waste containing polypropylene, polyethylene, and polystyrene. When tested, the aggregates satisfied the requirements of the European Standard EN 13055-1 for lightweight aggregates and exhibited good mechanical properties and low water absorption compared to natural aggregates. Based on these results, the formulated lightweight aggregates were found to be suitable for use as a partial replacement for up to 30% of the natural sand in mortar formulations.
İlyas Ennahal; Walid Maherzi; Mahfoud Benzerzour; Yannick Mamindy; Nor-Edine Abriak. Performance of Lightweight Aggregates Comprised of Sediments and Thermoplastic Waste. Waste and Biomass Valorization 2020, 12, 515 -530.
AMA Styleİlyas Ennahal, Walid Maherzi, Mahfoud Benzerzour, Yannick Mamindy, Nor-Edine Abriak. Performance of Lightweight Aggregates Comprised of Sediments and Thermoplastic Waste. Waste and Biomass Valorization. 2020; 12 (1):515-530.
Chicago/Turabian Styleİlyas Ennahal; Walid Maherzi; Mahfoud Benzerzour; Yannick Mamindy; Nor-Edine Abriak. 2020. "Performance of Lightweight Aggregates Comprised of Sediments and Thermoplastic Waste." Waste and Biomass Valorization 12, no. 1: 515-530.
The polypropylene fibers, which are currently attracting enormous attention in various geotechnical applications, carry a risk of aging under an integrated effect of heat, oxygen, light and other environmental factors, causing potentially infrastructure failure. An eco-friendly and biologically inactive material – basalt fiber, which has excellent natural resistance to aging and can eliminate aging-associated disasters, deserves more attention in geotechnical field. However, quite few studies are available on the beneficial reuse of basalt fibers to improve the engineering performance of soils. Therefore, this study aims to incorporate the sustainable basalt fiber and clarify how its inclusion impacts the mechanical properties and microstructure of cemented kaolinite. The experimental programs are comprised of three types of tests, i.e. two to examine the compressive strength and triaxial shear behavior and one to evaluate the microstructure properties. The results indicate that the basalt fiber reinforcement plays an essential role in enhancing the compressive strength and peak deviatoric stress of cemented and uncemented kaolinite. The inclusion of basalt fibers improves the ductility and weakens the brittleness of cemented kaolinite. The compressive strength increases with basalt fiber content and curing time, and reaches the peak at the fiber content of 0.2%, followed by a reduction due to the formation of weak zone at higher fiber content. The peak deviatoric stress is elevated until reaching the maximum at the basalt fiber content of 0.4%, after which further addition of basalt fiber tends to reduce its reinforcing effect. The peak deviatoric stress increases as the basalt fiber length is shortened and the confining pressure is raised. The strength gain of cement-basalt fiber inclusion is much more than the sum of strength increase induced by them individually. The combination of basalt fiber and cement has the virtues of both cement-stabilized and basalt fiber-reinforced kaolinite. The SEM analysis reveals that the mechanical interaction in the form of interface bonding and friction between kaolinite particle, cement hydration product and basalt fiber is the dominant mechanism controlling the reinforcement-cementation benefits. The bridging effect (reinforcement) of basalt fibers and binding effect (cementation) of hydration products make a major contribution to the formation of stable and interconnected microstructure, which results in an evident improvement in the mechanical behaviour of cemented kaolinite. The combination of basalt fiber and cement stabilization would be an innovative and effective method for geotechnical engineering works such as soft ground improvement.
Dongxing Wang; Hongwei Wang; Stefan Larsson; Mahfoud Benzerzour; Walid Maherzi; Mouhamadou Amar. Effect of basalt fiber inclusion on the mechanical properties and microstructure of cement-solidified kaolinite. Construction and Building Materials 2020, 241, 118085 .
AMA StyleDongxing Wang, Hongwei Wang, Stefan Larsson, Mahfoud Benzerzour, Walid Maherzi, Mouhamadou Amar. Effect of basalt fiber inclusion on the mechanical properties and microstructure of cement-solidified kaolinite. Construction and Building Materials. 2020; 241 ():118085.
Chicago/Turabian StyleDongxing Wang; Hongwei Wang; Stefan Larsson; Mahfoud Benzerzour; Walid Maherzi; Mouhamadou Amar. 2020. "Effect of basalt fiber inclusion on the mechanical properties and microstructure of cement-solidified kaolinite." Construction and Building Materials 241, no. : 118085.
Several studies have shown the potential of upgrading sediments in the civil engineering field. However, the complexity of sediments represents a scientific challenge in terms of their management. This study presents the river sediments recovery in a thermosetting matrix. The characterization results epoxy mortars show the feasibility of incorporating dredged sediments up to 50% substitution rate of natural sand. Moreover, according to the physic, mechanical, thermal and chemical evaluations of the thermosetting matrices, it appears that the performances depend on the factors of the rate of resin and the rate of sediments used. Indeed, the difference between the performances of resin mortars containing sediments and mortars without sediments is reduced by a resin content equal to 18%. In comparison with cementitious matrix mortars, the performances of polymeric mortars are well above. Finally, the SEM observations of different formulations made it possible to explain the results observed at the macroscopic scale.
Walid Maherzi; İlyas Ennahal; Mahfoud Benzerzour; Yannick Mammindy-Pajany; Nor-Edine Abriak. Study of the polymer mortar based on dredged sediments and epoxy resin: Effect of the sediments on the behavior of the polymer mortar. Powder Technology 2019, 361, 968 -982.
AMA StyleWalid Maherzi, İlyas Ennahal, Mahfoud Benzerzour, Yannick Mammindy-Pajany, Nor-Edine Abriak. Study of the polymer mortar based on dredged sediments and epoxy resin: Effect of the sediments on the behavior of the polymer mortar. Powder Technology. 2019; 361 ():968-982.
Chicago/Turabian StyleWalid Maherzi; İlyas Ennahal; Mahfoud Benzerzour; Yannick Mammindy-Pajany; Nor-Edine Abriak. 2019. "Study of the polymer mortar based on dredged sediments and epoxy resin: Effect of the sediments on the behavior of the polymer mortar." Powder Technology 361, no. : 968-982.
An innovative approach combining CO2 accelerated carbonation with industrial by-products is systematically investigated to produce low-carbon and sustainable cementing materials, in which reactive MgO-CaO-FA (fly ash) blends are introduced to replace traditional Portland Cement (PC) with high energy consumption, mineral resources demand and CO2 emissions. The effect of initial water content, carbonation time, binder amount and mass ratio of MgO/CaO on the mechanical and microstructural properties of carbonated solidified soils is analyzed through unconfined compressive strength (UCS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. The carbonation efficiency and carbon footprint of cementitious materials are evaluated under different schemes. The test results indicate that CO2 carbonation combined with reactive MgO-CaO-FA blends is proved highly effective and reliable to improve the strength performance of soil samples. The compressive strength of carbonated soils increases with binder content and mass ratio of MgO/CaO, which is related to the densification of pore system by carbonation products. An optimum UCS is reached at 6 h of carbonation, followed by a plateau or an important decrease with carbonation time. Water content controls the diffusion and permeability rate of CO2, affecting the chemical contact between Ca2+/Mg2+ released from MgO-CaO-FA blend and dissolved CO2 and further the strength of carbonated samples. XRD and SEM results demonstrate that the strength gain is mainly attributed to the formation of carbonation products (CaCO3, MgCO3), facilitating the densification and cementation of solidified materials. High-Ca FA promotes the carbonation efficiency by reducing porosity and providing nucleation sites for carbonate precipitation, while reactive MgO plays a more important role than CaO in developing binding capacity and building skeleton structure. The carbon footprint analysis reveals that compared with PC, the net CO2 emissions of MgO-CaO-FA blends are effectively reduced by 38.8–64.7%. The coupling technique of CO2 carbonation with industrial by-products is proved a feasible alternative to traditional PC in soil solidification.
Dongxing Wang; Jiaye Zhu; Fujin He. CO2 carbonation-induced improvement in strength and microstructure of reactive MgO-CaO-fly ash-solidified soils. Construction and Building Materials 2019, 229, 116914 .
AMA StyleDongxing Wang, Jiaye Zhu, Fujin He. CO2 carbonation-induced improvement in strength and microstructure of reactive MgO-CaO-fly ash-solidified soils. Construction and Building Materials. 2019; 229 ():116914.
Chicago/Turabian StyleDongxing Wang; Jiaye Zhu; Fujin He. 2019. "CO2 carbonation-induced improvement in strength and microstructure of reactive MgO-CaO-fly ash-solidified soils." Construction and Building Materials 229, no. : 116914.
The combined use of CO2 and industrial by-products offers a novel alternative to traditional Portland cement in soil stabilization, sequestering permanently CO2 emissions and producing low-carbon cementitious materials in an accelerated carbonation environment. This study attempts to propose two approaches to evaluate the CO2 uptake amount of reactive magnesia-lime-fly ash/slag solidified soils, rather than soil improvement proved by previous findings. The CO2 uptake efficiency, pore structure and micro-mechanisms are examined, and the carbon footprint of each designed mixture is evaluated based on life cycle assessment. The key outcomes from accelerated carbonation, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) tests reveal that: (i) CO2 uptake amount and uptake efficiency estimated by direct weight gain are largely greater than that defined by indirect thermogravimetric analysis, (ii) CO2 uptake amount and uptake efficiency tend to increase with carbonation duration, binder content and mass ratio of magnesia/lime, (iii) accelerated carbonation induces reduced total pore volume, smaller pore size and denser microstructure and reactive magnesia contributes more than lime in filling pore spaces, (iv) magnesium and calcium carbonates are formed in magnesia-lime-fly ash/slag solidified soils storing permanently CO2, and (v) carbon emissions for magnesia-lime-fly ash/slag blends are greatly reduced during their whole product life cycle in comparison to Portland cement.
Dongxing Wang; Jiaye Zhu; Fujin He. Quantification and micro-mechanisms of CO2 sequestration in magnesia-lime-fly ash/slag solidified soils. International Journal of Greenhouse Gas Control 2019, 91, 102827 .
AMA StyleDongxing Wang, Jiaye Zhu, Fujin He. Quantification and micro-mechanisms of CO2 sequestration in magnesia-lime-fly ash/slag solidified soils. International Journal of Greenhouse Gas Control. 2019; 91 ():102827.
Chicago/Turabian StyleDongxing Wang; Jiaye Zhu; Fujin He. 2019. "Quantification and micro-mechanisms of CO2 sequestration in magnesia-lime-fly ash/slag solidified soils." International Journal of Greenhouse Gas Control 91, no. : 102827.
This study investigates the physico-chemical, mineralogical and thermal characteristics of three natural Tunisian clays collected from Gafsa (A1), Zeramdine (A2) and Nabeul (A3). The aim was to promote an appropriate formulation of materials and to obtain optimal compacted earth blocks (CEB). Results of mineralogical analysis of clays revealed the dominance of kaolinite (>13.58%), illite (>25.7%), quartz (>18%) and a minor fraction of smectite phases. Chemical analysis of the clays major elements showed a SiO2 content exceeding 50% and a percentage of Al2O3 higher than 18%. Particle size distribution showed that clay fractions varied from 10 to 20%. Plasticity index defined a plastic character while the values of specific surface area were around 60 m2/g. This discrepancy has an effect on the behavior of these clays in CEB, notably their mechanical properties. From this characterization, it appears that all the sampled clays are suitable as raw material for CEB application. The prepared CEB formulations varied according to compaction energy and binder dosages. In this work, lime served as a binder at different rates (4, 6, 8 and 10%) to ameliorate the quality of CEB. Unconfined Compressive Strength values were determined by Static method test. Then bulk density, shrinkage and porosity values of samples were determined. Compressive strength could reach 7 MPa with lime supplementation in sample A1. The static compaction onto the sand-clay mixture achieved a value of density superior to 2 g cm−3 with lime supplementation in sample A1. Overall, the Gafsa clay was the most suitable for CEB preparation. Also, lime improved the compressive strength of the matrix, in addition to its ecological merits.
Safa Mkaouar; Walid Maherzi; Patrick Pizette; Hicham Zaitan; Mourad Benzina. A comparative study of natural Tunisian clay types in the formulation of compacted earth blocks. Journal of African Earth Sciences 2019, 160, 103620 .
AMA StyleSafa Mkaouar, Walid Maherzi, Patrick Pizette, Hicham Zaitan, Mourad Benzina. A comparative study of natural Tunisian clay types in the formulation of compacted earth blocks. Journal of African Earth Sciences. 2019; 160 ():103620.
Chicago/Turabian StyleSafa Mkaouar; Walid Maherzi; Patrick Pizette; Hicham Zaitan; Mourad Benzina. 2019. "A comparative study of natural Tunisian clay types in the formulation of compacted earth blocks." Journal of African Earth Sciences 160, no. : 103620.
Alkali-activated industrial by-products (granulated blast furnace slag, Class F fly ash) by traditional alkali activator (such as NaOH and Na2SiO3) serves as a partial replacement for Portland cement in soil stabilization projects and suffers from environmental and technical problems. Reactive MgO – a greener and more practical alternative has recently emerged as a potential activator for slag and fly ash, but its micromechanisms of alkaline activation still need to be deeply investigated for strength improvement of soils. Hence, this study focuses on the strength and hydration properties of reactive MgO-slag and MgO-fly ash solidified soils, especially incorporating the impact of elevated curing temperature. Reactive MgO is proved to be excellent as a novel activator for activation of slag and fly ash, and their activating efficiency increases with elevated curing temperature that helps to remarkably enhance the compressive strength of soils. The major hydration products for reactive MgO-slag solidified soils, detected jointly by X-ray diffraction, scanning electron microscopy and thermogravimetric/differential thermogravimetric tests, are calcium silicate hydrate gels and hydrotalcite-like phases. The primary hydration products for MgO-fly ash solidified soils are magnesium silicate hydrate gels and Mg(OH)2. That is just the intrinsic reason why the microstructure of solidified soils becomes much denser and the mechanical behavior is significantly improved. The minor carbonate phases such as magnesium carbonate and/or calcite are also observed in reactive MgO-slag and MgO-fly ash solidified soils, depending on the period of exposure to air. The curing temperature and binder amount are proved to be the two major factors governing the hydration process of reactive MgO-slag and MgO-fly ash blends. A higher curing temperature and binder amount can generate more hydration products, but their chemical compositions such as accurate element ratios need to be investigated in the future study.
Dongxing Wang; Xiangyun Gao; Ruihong Wang; Stefan Larsson; Mahfoud Benzerzour. Elevated curing temperature-associated strength and mechanisms of reactive MgO-activated industrial by-products solidified soils. Marine Georesources & Geotechnology 2019, 38, 659 -671.
AMA StyleDongxing Wang, Xiangyun Gao, Ruihong Wang, Stefan Larsson, Mahfoud Benzerzour. Elevated curing temperature-associated strength and mechanisms of reactive MgO-activated industrial by-products solidified soils. Marine Georesources & Geotechnology. 2019; 38 (6):659-671.
Chicago/Turabian StyleDongxing Wang; Xiangyun Gao; Ruihong Wang; Stefan Larsson; Mahfoud Benzerzour. 2019. "Elevated curing temperature-associated strength and mechanisms of reactive MgO-activated industrial by-products solidified soils." Marine Georesources & Geotechnology 38, no. 6: 659-671.
The reactive MgO-fly ash blends are employed for stabilizing lacustrine sludge through absorbing gaseous CO2, which is a prospective and sustainable technique combined of carbonation and solidification. The mechanical and microstructural variation of carbonated MgO-fly ash solidified sludge subjected to three durability tests (i.e. water immersion, cyclic dry-wet, cyclic freeze–thaw) is investigated through unconfined compressive strength (UCS), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) tests. The obtained results demonstrate that the CO2 carbonation reaction can greatly enhance the resistance of MgO-fly ash solidified sludge to environmental changes, and the stress–strain behaviour depends mainly on types of durability tests, damage period and carbonation mode. The main carbonation products detected in CO2-MgO-fly ash-sludge system are the elongated prismatic hydromagnesite (skeleton constructing), flower-/bone-like and flaky dypingite and nesquehonite (pore filling and particle cementing). The coupled action of skeleton constructing-filling-cementing enables the CO2 carbonated specimens to be qualified with higher strength, better water stability, and stronger resistance to dry-wet and freeze-thaw cycles. Especially, the continuous immersion in water leads to transition of some interparticle pores into intra-aggregate pores and phase transformation of dypingite and nesquehonite to hydromagnesite. The cyclic dry-wet exposure causes partial transition of intra-aggregate pores into interparticle pores and phase transformation from dypingite and nesquehonite to hydromagnesite. However, no visible transformation between carbonation products can be recognized for specimens under freeze-thaw cycles, except an increased amount of large pores with radius around 10 μm.
Dongxing Wang; Jie Xiao; Fujin He; Yadong Zhou. Durability evolution and associated micro-mechanisms of carbonated reactive MgO-fly ash solidified sludge from East Lake, China. Construction and Building Materials 2019, 208, 1 -12.
AMA StyleDongxing Wang, Jie Xiao, Fujin He, Yadong Zhou. Durability evolution and associated micro-mechanisms of carbonated reactive MgO-fly ash solidified sludge from East Lake, China. Construction and Building Materials. 2019; 208 ():1-12.
Chicago/Turabian StyleDongxing Wang; Jie Xiao; Fujin He; Yadong Zhou. 2019. "Durability evolution and associated micro-mechanisms of carbonated reactive MgO-fly ash solidified sludge from East Lake, China." Construction and Building Materials 208, no. : 1-12.
The onshore management of marine and river sediments represents economic, environmental, and societal issues; these materials are considered as wastes after dredging. In the framework of the SEDIPLAST regional project, dredged sediments, which are considered as non-inert waste according to European regulation, are recovered as mineral aggregates in thermosetting polymeric matrix to formulate polymer mortars in the field of floor coverings. The formulations are optimized using the Packing Density Model, to determine the optimum density of the mixtures, thus allowing having the high mechanicals characteristics of material. These formulations are evaluated by mechanical, thermal, and chemical tests according to the French classification of durability which characterizes the soil of a locality according to its use (UPEC). The results showed that the polymer mortars including dredged sediments have excellent physical, mechanical, and thermal properties, such as low voids content and excellent chemical resistance properties. Finally, SEM observations of different mixtures allowed to give an explanation of the results observed in macroscopic scale.
İlyas Ennahal; Walid Maherzi; Yannick Mamindy-Pajany; Mahfoud Benzerzour; Nor-Edine Abriak. Eco-friendly polymers mortar for floor covering based on dredged sediments of the north of France. Journal of Material Cycles and Waste Management 2019, 21, 861 -871.
AMA Styleİlyas Ennahal, Walid Maherzi, Yannick Mamindy-Pajany, Mahfoud Benzerzour, Nor-Edine Abriak. Eco-friendly polymers mortar for floor covering based on dredged sediments of the north of France. Journal of Material Cycles and Waste Management. 2019; 21 (4):861-871.
Chicago/Turabian Styleİlyas Ennahal; Walid Maherzi; Yannick Mamindy-Pajany; Mahfoud Benzerzour; Nor-Edine Abriak. 2019. "Eco-friendly polymers mortar for floor covering based on dredged sediments of the north of France." Journal of Material Cycles and Waste Management 21, no. 4: 861-871.