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This study focuses on the development of an alkali-activated lightweight foamed material (AA-LFM) with enhanced density. Several mixes of tungsten waste mud (TWM), grounded waste glass (WG), and metakaolin (MK) were produced. Al powder as a foaming agent was added, varying from 0.009 w.% to 0.05 w.% of precursor weight. Expanded granulated cork (EGC) particles were incorporated (10% to 40% of the total volume of precursors). The physical and mechanical properties of the foamed materials obtained, the effects of the amount of the foaming agent and the percentage of cork particles added varying from 10 vol.% to 40% are presented and discussed. Highly porous structures were obtained, Pore size and cork particles distribution are critical parameters in determining the density and strength of the foams. The compressive strength results with different densities of AA-LFM obtained by modifying the foaming agent and cork particles are also presented and discussed. Mechanical properties of the cured structure are adequate for lightweight prefabricated building elements and components.
Imed Beghoura; Joao Castro-Gomes. Enhancing Density-Based Mining Waste Alkali-Activated Foamed Materials Incorporating Expanded Cork. CivilEng 2021, 2, 523 -540.
AMA StyleImed Beghoura, Joao Castro-Gomes. Enhancing Density-Based Mining Waste Alkali-Activated Foamed Materials Incorporating Expanded Cork. CivilEng. 2021; 2 (2):523-540.
Chicago/Turabian StyleImed Beghoura; Joao Castro-Gomes. 2021. "Enhancing Density-Based Mining Waste Alkali-Activated Foamed Materials Incorporating Expanded Cork." CivilEng 2, no. 2: 523-540.
The development of alternative binders to Portland Cement has become a critical factor in decreasing the Portland cement industry’s carbon footprint, which nowadays represents about 7% of CO2 emissions worldwide. Thereby the seek for the development of alternatives binders led to a recent and growing interest in carbonate-based binders due to their ability to capture and store CO2 into their cementitious matrix and, consequently, leading to the rise of the research related to the scope of this work, Carbonated Reactive Magnesia Cement, which has as the main property the capability to adsorb CO2 into its cementitious matrix when subject to favourable carbonation curing conditions. Thus, this paper describes the Magnesia carbonation mechanism to subsequently review and enumerate the influencing factors over the carbonation curing of Carbonated Reactive Magnesia Cement-based materials. Afterwards, it summarizes recent works on this binding technology that don’t use Portland cement in their composition. Besides that, the carbonation curing conditions used in these studies are highlighted along with this work. Therefore, the main goal of this review is to bring a starting point of the carbonation curing influencing factors of Carbonated Reactive Magnesia Cement-based materials. Thereby, this review may help future research on this field and some issues to be overcome by this material group.
Erick Grünhäuser Soares; João Castro-Gomes. Carbonation curing influencing factors of Carbonated Reactive Magnesia Cements (CRMC) – A review. Journal of Cleaner Production 2021, 305, 127210 .
AMA StyleErick Grünhäuser Soares, João Castro-Gomes. Carbonation curing influencing factors of Carbonated Reactive Magnesia Cements (CRMC) – A review. Journal of Cleaner Production. 2021; 305 ():127210.
Chicago/Turabian StyleErick Grünhäuser Soares; João Castro-Gomes. 2021. "Carbonation curing influencing factors of Carbonated Reactive Magnesia Cements (CRMC) – A review." Journal of Cleaner Production 305, no. : 127210.
Alkali-activated materials have the potential to replace Portland cement in certain applications. To better understand these binders’ properties, it is relevant to study their rheological behaviour at early ages, like in the case of Portland cement paste. There are already many studies on the rheological behaviour of these materials in the available literature, using fly ash, metakaolin, and ground granulated blast furnace slag as precursors. However, this study discusses the rheological behaviour, mechanical properties, and porosity of ternary alkali-activated binders based on mining mud waste, waste glass, and metakaolin. The precursor consisted of a volume mix of 70% of tungsten mining waste mud, 15% glass waste, and 15% of metakaolin. The activator was a combination of sodium hydroxide and sodium silicate solution. Five activator/precursor (A/P) ratios (0.37, 0.38, 0.39, 0.40, and 0.4) were studied. The result showed that the activator/precursor ratio affects the rheology of paste and their rheological behaviour fit the Bingham model. The relative yield stress (g) and plastic viscosity (h) increased inversely with the A/P ratio, while the workability increased proportionally. Furthermore, some empirical models are proposed to describe the characteristic of yield stress: plastic viscosity and spread diameter versus the A/P ratio and time with a correlation between the rheological parameters and the spread diameter. The increase in A/P ratio has also followed a decrease in compressive strength in all tested samples for all the ages. As expected, an increase of the porosity accompanied the increase of the A/P ratio.
Abdelhakim Benhamouda; João Castro-Gomes; Luiz Pereira-De-Oliveira. Rheology, Mechanical Properties and Porosity of Ternary Alkali-Activated Binders Based on Mining Mud Waste with Waste Glass and Metakaolin. CivilEng 2021, 2, 236 -253.
AMA StyleAbdelhakim Benhamouda, João Castro-Gomes, Luiz Pereira-De-Oliveira. Rheology, Mechanical Properties and Porosity of Ternary Alkali-Activated Binders Based on Mining Mud Waste with Waste Glass and Metakaolin. CivilEng. 2021; 2 (1):236-253.
Chicago/Turabian StyleAbdelhakim Benhamouda; João Castro-Gomes; Luiz Pereira-De-Oliveira. 2021. "Rheology, Mechanical Properties and Porosity of Ternary Alkali-Activated Binders Based on Mining Mud Waste with Waste Glass and Metakaolin." CivilEng 2, no. 1: 236-253.
The valorization and reusing of mining waste has been widely studied in recent years. Research has demonstrated that there is great potential for reusing mining waste for construction applications. This work experimentally investigated the strength development, pore structure, and microstructure of a binary alkali-activated binder. This is based on tungsten mining waste mud (TMWM) and electric-arc-furnace slag (EAF-Slag) using different proportions of TMWM (10, 20, 30, 40, and 50 vt.%). The precursors were activated using sodium silicate (Na2SiO3) and potassium hydroxide (KOH 8M) as alkaline activator solution with solid:liquid weight ratio = 3. Pastes were used to assess the compressive strength of the blended binder and their microstructure. The reaction products were characterized by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infra-red (FT-IR) spectroscopy, while the porosity and the pores size properties were examined by mercury intrusion porosimetry (MIP). The results show that the partial replacement of TMWM with EAF-Slag exhibited better mechanical properties than the 100TM-AAB. A maximum strength value of 20.1 MPa was obtained in the binary-AAB sample prepared with 50 vt.% TMWM and EAF-Slag. The pastes that contained a higher dosage of EAF-Slag became more compact with lower porosity and finer pore-size distribution. In addition, the results obtained by SEM-EDS confirmed the formation of different types of reaction products in the 100TM-AAB, 100FS-AAB, and the binary-AABs mixtures such as N-A-S-H, C-A-S-H and (N, C)-A-S-H gels frameworks in the system as the major elements detected are Si, Al, Ca, and Na.
Naim Sedira; João Castro-Gomes. Alkali-Activated Binders Based on Tungsten Mining Waste and Electric-Arc-Furnace Slag: Compressive Strength and Microstructure Properties. CivilEng 2020, 1, 154 -180.
AMA StyleNaim Sedira, João Castro-Gomes. Alkali-Activated Binders Based on Tungsten Mining Waste and Electric-Arc-Furnace Slag: Compressive Strength and Microstructure Properties. CivilEng. 2020; 1 (2):154-180.
Chicago/Turabian StyleNaim Sedira; João Castro-Gomes. 2020. "Alkali-Activated Binders Based on Tungsten Mining Waste and Electric-Arc-Furnace Slag: Compressive Strength and Microstructure Properties." CivilEng 1, no. 2: 154-180.
The goal of this study is to collect and validate relevant information on the degradation of reinforced concrete exposed to aggressive environments, such as chlorides or sulfates, for later incorporation in maintenance management systems compatible with the BIM methodology (Building Information Modeling). To achieve this, two simultaneous monitoring systems were used, one that allows measuring the ionic resistivity of the concrete and another that measures the corrosion potential and polarization resistance of the reinforcement. With the first monitoring system, it is intended to monitor the changes occurring in the concrete at the level of its ionic conductivity during the contamination process. The second system allows, at a later stage of the concrete degradation process, to detect signs of corrosion of the reinforcement inserted therein. Both systems provide readings at 10mm and 30 mm depth measured from the face exposed to the action of the degradation agents. The results obtained for chloride contamination show that the ionic resistivity of the concrete tends to decrease with the progression of the chlorides in depth, leading at a later stage to the corrosion of the reinforcement, which can be detected by the reduction of corrosion potential. Also, the polarization resistance of the reinforcement has been reduced when corrosion phenomena begin to develop in the reinforcement. The results related to the sulfate attack suggest a mechanism that leads to the formation of a barrier that prevents the progression of the attack in depth. The consequence of this phenomenon is a reduction of the ionic mobility of the concrete, leading to the increase of resistivity. This mechanism associated with the absence of mechanical actions that force the progression of sulfates in depth inhibits the development of corrosion processes of the reinforcement.
Pedro Romano; João Castro-Gomes; Paulo Brito. Monitoring of Reinforced Concrete for Decision Support in Maintenance Management Systems. KnE Engineering 2020, 256–264 -256–264.
AMA StylePedro Romano, João Castro-Gomes, Paulo Brito. Monitoring of Reinforced Concrete for Decision Support in Maintenance Management Systems. KnE Engineering. 2020; ():256–264-256–264.
Chicago/Turabian StylePedro Romano; João Castro-Gomes; Paulo Brito. 2020. "Monitoring of Reinforced Concrete for Decision Support in Maintenance Management Systems." KnE Engineering , no. : 256–264-256–264.
To determine the properties of paste, mortar or concrete, it is necessary to understand its rheological behaviour first. This study discusses the effect of the activator/precursor ratio on the rheological properties of the alkali-activated paste. The pastes consisted of a mix of 70 % of tungsten mining waste mud, 15% waste glass and 15% of metakaolin. This mix was activated by combining sodium hydroxide and sodium silicate. Five activator/precursor (a/p) ratios were studied: 0.37, 0.38, 0.39, 0.40 and 0.41. The result obtained shows that the rheology of the pastes is affected by the activator/precursor ratio. The rheological behaviour of the paste fits the Bingham model. The yield stress (τ0) and plastic viscosity (μ) increase inversely with the activator/precursor ratio (e.g. a/p=0.37 gives τ0=84.19 and μ=0.4185; a/p=0.41 gives τ0=30.389 and μ=0.2937). The workability increases proportionally with the activator/precursor ratio (e.g. a/p=0.37 gives a slump=133 mm; a/p=0.41 gives a slump=158 mm). The compressive strength decreases when the activator/precursor ratio increases (e.g. at 28 days for a/p=0.37, the compressive strength was 19.6 MPa; for a/p=0.41, the compressive strength was 13 MPa). Finally, the ideal ratios were 0.38 and 0.39.
Abdelhakim Benhamouda; João Castro-Gomes; Luiz Pereira-De-Oliveira. The Effect of the Activator/Precursor Ratio on the Rheological Properties of the Alkali-activated Mining Waste Mud Paste. KnE Engineering 2020, 1–13 -1–13.
AMA StyleAbdelhakim Benhamouda, João Castro-Gomes, Luiz Pereira-De-Oliveira. The Effect of the Activator/Precursor Ratio on the Rheological Properties of the Alkali-activated Mining Waste Mud Paste. KnE Engineering. 2020; ():1–13-1–13.
Chicago/Turabian StyleAbdelhakim Benhamouda; João Castro-Gomes; Luiz Pereira-De-Oliveira. 2020. "The Effect of the Activator/Precursor Ratio on the Rheological Properties of the Alkali-activated Mining Waste Mud Paste." KnE Engineering , no. : 1–13-1–13.
In this preliminary study, the effect of glass powder content at early age compressive strength and its effect at strength retention coefficient during water immersion period on magnesium silicate hydroxide cement pastes on carbonation curing was investigated. A magnesium oxide-rich powder with a maximum grain size of 150 μm was used, as well as, a waste glass powder with a maximum grain size of 250 μm, which was obtained from grinded flint glass bottles. Cement pastes were produced with 0, 10, 20, 30, 40, and 50 glass powder weight percentage. The specimens were compacted into cubic moulds (e = 20 mm) under 70 MPa and, subsequently, cured on accelerate carbonation chamber for 2h at >99% CO2 concentration. The compressive strength was determined 3 days after CO2, period which the specimens were preserved on room conditions (20∘C and 60%RH), and also at 3, 7 and 14 days of water immersion period. Comparison of the results obtained for different mixing compositions, as well as, different water immersion periods are discussed in this work.
Erick Grünhäuser Soares; João Castro-Gomes. Early Age Compressive Strength of Waste-based-glass-powder Magnesium Silicate Binders on Initial Carbonation Curing. KnE Engineering 2020, 61–73 -61–73.
AMA StyleErick Grünhäuser Soares, João Castro-Gomes. Early Age Compressive Strength of Waste-based-glass-powder Magnesium Silicate Binders on Initial Carbonation Curing. KnE Engineering. 2020; ():61–73-61–73.
Chicago/Turabian StyleErick Grünhäuser Soares; João Castro-Gomes. 2020. "Early Age Compressive Strength of Waste-based-glass-powder Magnesium Silicate Binders on Initial Carbonation Curing." KnE Engineering , no. : 61–73-61–73.
This study investigates the effect of the increasingly compressing pressures on the properties of the low liquid-to-solid (L/S) ratio binary alkali-activated binder to use as a binder for the manufacturing of engineered stones. The binders were a combination of two types of wastes (aluminosilicate source) as precursors (TMWM 50 Vt.% + EAF-Slag 50 Vt.%), blended with (11.11 wt.%) alkaline activator solution (NaOH/Na2SiO3 with weight ratio 4/1). The mixtures were molded in cube and exposed to five different pressures (20, 40, 60, 80 and 100 MPa) in order to obtain a compressed alkali-activated binder. The main evaluation techniques in this study were compressive strength, and Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the maximum compressive strength (50.57 MPa) was obtained at a pressing pressure 100 MPa at twenty-eight days of testing.
Naim Sedira; João Castro-Gomes. Low Liquid-to-solid Ratio of Mining Waste and Slag Binary Alkali-activated Material. KnE Engineering 2020, 202–213 -202–213.
AMA StyleNaim Sedira, João Castro-Gomes. Low Liquid-to-solid Ratio of Mining Waste and Slag Binary Alkali-activated Material. KnE Engineering. 2020; ():202–213-202–213.
Chicago/Turabian StyleNaim Sedira; João Castro-Gomes. 2020. "Low Liquid-to-solid Ratio of Mining Waste and Slag Binary Alkali-activated Material." KnE Engineering , no. : 202–213-202–213.
The iron ore beneficiation process produces a large quantity of waste. Mining companies are looking for technologies that make it possible to dispose of their waste and transform it into raw material for the manufacture of products that can be applied in other areas, for example in the production of concrete, mortar, ceramics, blocks, and bricks. This study aimed at the feasibility of using a calcined iron ore overburden as a precursor of alkali-activated binders. For alkaline activation of the precursors, sodium hydroxide solution and sodium silicate were used in the atomic proportions Al / Na = 2 and Si / Al> 0,7. Mineralogical and microstructural characterization was carried out by X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX). Tests of compressive strength were performed for the binders with 7, 14, 21 and 28 of curing days. The results of the analyses demonstrated that the properties of the alkali-activated binders produced with the overburden were similar to the binders obtained by precursors used traditionally. It was found, therefore, that the calcined iron ore overburden, can be considered a precursor for obtaining alkaline activated binders
Marina Filizzola Oliveira; Naim Sedira; Ana Cláudia Guimarães; Fernando Lameiras; João Castro-Gomes. Use of Iron Ore Overburden As a Precursor for the Synthesis of an Alkali-activated Binder. KnE Engineering 2020, 177–186 -177–186.
AMA StyleMarina Filizzola Oliveira, Naim Sedira, Ana Cláudia Guimarães, Fernando Lameiras, João Castro-Gomes. Use of Iron Ore Overburden As a Precursor for the Synthesis of an Alkali-activated Binder. KnE Engineering. 2020; ():177–186-177–186.
Chicago/Turabian StyleMarina Filizzola Oliveira; Naim Sedira; Ana Cláudia Guimarães; Fernando Lameiras; João Castro-Gomes. 2020. "Use of Iron Ore Overburden As a Precursor for the Synthesis of an Alkali-activated Binder." KnE Engineering , no. : 177–186-177–186.
Aim of this study was to produce alkali-activated foams with low thermal conductivity. Different precursors’ maximum particles sizes of 150μm, 300μm, and 500μm using a blend of 70% tungsten mining waste mud (TWM), 20% grounded waste glass (WG) and 10 % metakaolin (MK) with sodium silicate (SS) and sodium hydroxide (SH) as original material. Aluminium powder (Al) was used as a blowing agent and added first to the dry mix by changing content from 0.1g to 0.5g. Precursors and activators were mixed together to produce a homogeneous mixture, which was placed into a mould (100x200x60 mm3), and cured in the oven at 60∘C for 24 hours. The effect on foaming properties of different precursors maximum particles sizes were studied. The AAFs exhibited 28 day compressive strengths ranging from 2.28 to 16.1 MPa with the different densities from 913 to 1647 kg/m3 achieved through alteration of the foaming content. The thermal conductivity of AAFs was in the range 0.21– 0.33 W/m*K. Open celled hardened of the AAFs with 0.5g Al shows a high porosity of 58% with the mix made with 500μm. Therefore, tungsten mining waste-based alkali-activated foams shows a promise as thermal insulation material in some situations.
Imed Beghoura; João Castro-Gomes. Development of Porous Tungsten Mud Waste-based Alkali-activated Foams with Low Thermal Conductivity. KnE Engineering 2020, 113–125 -113–125.
AMA StyleImed Beghoura, João Castro-Gomes. Development of Porous Tungsten Mud Waste-based Alkali-activated Foams with Low Thermal Conductivity. KnE Engineering. 2020; ():113–125-113–125.
Chicago/Turabian StyleImed Beghoura; João Castro-Gomes. 2020. "Development of Porous Tungsten Mud Waste-based Alkali-activated Foams with Low Thermal Conductivity." KnE Engineering , no. : 113–125-113–125.
The rheological properties of Portland cement (PC) concrete have been extensively studied and compared with those of alkali-activated concrete (AAC). This study discusses the effect of the liquid to solid ratio on the rheological and mechanical properties of AAM concrete, based on mining waste mud as the binder phase, and compares them with those of Portland cement concrete (PCC). The AAM concrete studied is a mix of coarse aggregate 6/15, two types of sand (finer and coarse sand), and a precursor. The precursor is a mix of 70% tungsten mining waste mud, 15% waste glass and 15% metakaolin. This mix was activated by a combination of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) and the PCC was a mix of the same aggregate but with cement as binder and water as a liquid. The activator/precursor ratio was studied 0.5, 0.52, 0.54, 0.56 and 0.58. The results obtained show a similar rheological behaviour between AAC and PCC, the workability affected by L/S increases with the increasing ratio L/S in AAC and for L/S=0.5 slump was 6 cm and was 16 cm for L/S =0.58. Regarding the mechanical properties, the results obtained in 7 days showed similar performance in AAC and PCC. The compressive strength also decreases with the increasing of L/S, in AAC with L/S=0.5 the compressive strength was 15.9 MPa and for L/S =0.58 was 10.5. Keywords: Tungsten mining waste, Rheology, Mechanical properties, Portland cement, alkali-activated concrete
Abdelhakim Benhamouda; João Castro-Gomes. Preliminary Study of the Rheological and Mechanical Properties of Alkali-activated Concrete Based on Tungsten Mining Waste Mud. KnE Engineering 2020, 101–110 -101–110.
AMA StyleAbdelhakim Benhamouda, João Castro-Gomes. Preliminary Study of the Rheological and Mechanical Properties of Alkali-activated Concrete Based on Tungsten Mining Waste Mud. KnE Engineering. 2020; ():101–110-101–110.
Chicago/Turabian StyleAbdelhakim Benhamouda; João Castro-Gomes. 2020. "Preliminary Study of the Rheological and Mechanical Properties of Alkali-activated Concrete Based on Tungsten Mining Waste Mud." KnE Engineering , no. : 101–110-101–110.
In this preliminary study, the effect of the pre-drying stage, water immersion, carbonation curing cycles, and/or drying stage on carbonation curing of magnesium oxide-rich powder (MRP) was investigated. In addition, a blend of tungsten mining waste mud (TMWM) with MRP was also evaluated. The MRP and TMWM used have maximum grain sizes of 125 μm. The cement pastes were produced with 0 and 50 of TMWM weight percentage. The specimens were compacted into cylindric moulds (∅ = 20 mm; h = 40 mm) under 30 MPa and, subsequently, submitted to five different processes of curing involving a pre-drying stage before carbonation, rapid water immersion cycles, additional drying periods, and different carbonation curing periods. The atmosphere of the pressurized carbonation curing chamber was controlled to provide a CO2 concentration of > 99%, the partial pressure of 1 bar and temperature of 60°C. The influence of the curing processes on the compressive strength of each mix was determined 12 hours after the carbonation curing period. This study demonstrates that the water content during the curing process plays an important role in the increase of the hardening process and on the compressive strength. Keywords: Carbonation curing, magnesium oxide, mining waste, curing processes, magnesium-based cement
Erick Grünhäuser Soares; João Castro-Gomes. Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud. KnE Engineering 2020, 215–227 -215–227.
AMA StyleErick Grünhäuser Soares, João Castro-Gomes. Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud. KnE Engineering. 2020; ():215–227-215–227.
Chicago/Turabian StyleErick Grünhäuser Soares; João Castro-Gomes. 2020. "Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud." KnE Engineering , no. : 215–227-215–227.
This study determines the effect of ground granulated blast furnace slag (GGBFS) and metakaolin (MK) on the microstructural properties of the tungsten mining waste-based alkali-activated binder (TMWM). During this investigation, TMWM was partially replaced with 10 wt.% GGBFS and 10 wt.% MK to improve the microstructure of the binder. In order to understand the effect of the substitutions on the microstructure, two pastes were produced to make a comparative study between the sample contain 100% TMWM and the ternary precursors. Both precursors were activated using a combination of alkaline activator solutions (sodium silicate and sodium hydroxide) with the ratio of 1:3 (66.6 wt.% sodium silicate combined with 33.33 wt.% of NaOH 8M). The alkali-activated mixes were cured in oven at temperature of 60 °C in the first day and at room temperature for the next 27 days. The reaction products N-A-S-H gel and (N,M)-A-S-H gel resulted from the alkaline activation reaction process. In addition, a formation of natrite (Na2CO3) with needles shape occurred as a reaction product of the fluorescence phenomena. However, a dense matrix resulted from the alkline activation of the ternary precursors containg different gels such as N-A-S-H, C-A-S-H and (N,M)-C-A-S-H gel, these results were obtained through SEM-EDS analyses, as well FTIR tests. Keywords: Mining Waste, Alkali-activated, Microstructure, Slag, Metakaolin
Naim Sedira; João Castro-Gomes. Microstructure Features of Ternary Alkali-activated Binder Based on Tungsten Mining Waste, Slag and Metakaolin. KnE Engineering 2020, 195–206 -195–206.
AMA StyleNaim Sedira, João Castro-Gomes. Microstructure Features of Ternary Alkali-activated Binder Based on Tungsten Mining Waste, Slag and Metakaolin. KnE Engineering. 2020; ():195–206-195–206.
Chicago/Turabian StyleNaim Sedira; João Castro-Gomes. 2020. "Microstructure Features of Ternary Alkali-activated Binder Based on Tungsten Mining Waste, Slag and Metakaolin." KnE Engineering , no. : 195–206-195–206.
In this study, an Alkali-activation of tungsten mining waste mud (TMWM) was combined with aluminium powder (Al) as a blowing agent (gas foaming method). The synthesis of inorganic alkali-activated foamed mortar (AA-FM) and alkali-activated lightweight foamed mortar (AALW-FM) was achieved by incorporating expanded granulated cork (EGC) and one type of river sand < 2 mm. Al powder was added first to the dry mix with the mass used varying from 0.1 g to 0.5 g. Precursors and activators were included to produce a homogeneous mixture, which was placed into a mould (100x100x60 mm3), and cured in the oven at 60° C for 24 hours. The influence of two main parameters (Al powder contents and cork particles) on the AA-FM and AALW-FM properties (compressive strength, density, expansion volume and pore size distribution) were investigated. The compressive strength of the foams in the case of highly porous structures of the AALW-FM and AA-FM achieved 4.1MPa and 13.2MPa respectively, for samples with a larger amount of Al powder (0.5g). Open celled hardened of the AALW-FM and AA-FM with 0.5g Al shows a high porosity of 40% and 81% respectively. Therefore, tungsten mining waste-based alkali-activated foams shows potential as a thermal insulation material in certain situations. Keywords: Tungsten mining waste, Alkali-activated, Foamed Materials
Imed Beghoura; João Castro-Gomes. Development of Alkali-activated Foamed Lightweight Mortar Tungsten Mining Waste Mud-based Incorporating Expanded Cork. KnE Engineering 2020, 134–146 -134–146.
AMA StyleImed Beghoura, João Castro-Gomes. Development of Alkali-activated Foamed Lightweight Mortar Tungsten Mining Waste Mud-based Incorporating Expanded Cork. KnE Engineering. 2020; ():134–146-134–146.
Chicago/Turabian StyleImed Beghoura; João Castro-Gomes. 2020. "Development of Alkali-activated Foamed Lightweight Mortar Tungsten Mining Waste Mud-based Incorporating Expanded Cork." KnE Engineering , no. : 134–146-134–146.
The mineralogical properties of tungsten mining waste mud (TMWM) make its valorisation and re-usage as an alumino-silicate source material to produce an alkali-activated binder without calcination is a challenge. Moreover, the dissolution of silicate and alumina species from TMWM is very slow. Despite the crystallinity of TMWM, this study demonstrates that its combination with other sources of the alumino-silicate source was the materials–such as red clay brick waste(RCBW),ground granulated blast furnace slag (GGBFS) and electric arc furnace slag (EAFS) – improved the compressive strength and the pore structure of the alkali-activated matrix.Thecombinedprecursors (90 vt.%TMWM+10 vt.%RCBW, 90 vt.%TMWM+10 vt.%GGBFS, and 90 vt.%TMWM+10 vt.%EAFS) were activated using a combination of alkaline activator solutions (sodium silicate and sodium hydroxide) with the ratio of 1:3(66.6wt.%sodiumsilicatecombined with 33.33 wt.% of NaOH 10M). The results show that the compressive strength increased from11.23MPa at 28 days to reach 24.98MPawhentheTMWMwaspartially replacedby10vt.%RCBW. In addition,this study shows that the interconnected porosity decreased where the critical pore size was reduced from 21.28 µm to 0.55 µm for the tungsten mining waste-based alkali-activated binder and the binary alkali-activated binder based on TMWM and RCBW. Keywords: Mining Waste, Alkali-activated, Microstructure, MIP, Metakaolin
Naim Sedira; João Castro-Gomes. Strength Development and Pore Structure Characterisation of Binary Alkali-activated Binder Based on Tungsten Mining Waste. KnE Engineering 2020, 73–85 -73–85.
AMA StyleNaim Sedira, João Castro-Gomes. Strength Development and Pore Structure Characterisation of Binary Alkali-activated Binder Based on Tungsten Mining Waste. KnE Engineering. 2020; ():73–85-73–85.
Chicago/Turabian StyleNaim Sedira; João Castro-Gomes. 2020. "Strength Development and Pore Structure Characterisation of Binary Alkali-activated Binder Based on Tungsten Mining Waste." KnE Engineering , no. : 73–85-73–85.
Imed Beghoura; João Castro-Gomes. Design of alkali-activated aluminium powder foamed materials for precursors with different particle sizes. Construction and Building Materials 2019, 224, 682 -690.
AMA StyleImed Beghoura, João Castro-Gomes. Design of alkali-activated aluminium powder foamed materials for precursors with different particle sizes. Construction and Building Materials. 2019; 224 ():682-690.
Chicago/Turabian StyleImed Beghoura; João Castro-Gomes. 2019. "Design of alkali-activated aluminium powder foamed materials for precursors with different particle sizes." Construction and Building Materials 224, no. : 682-690.
This article illustrates the effects of different combinations of alkaline activator solutions (sodium silicate “SS”, sodium hydroxide, potassium hydroxide and dissolved waste glass powder in sodium hydroxide) as well as their concentrations and the Solid/Liquid ratios on the compressive strength development, and the microstructure of hybrid alkaline binder. The current study used a combination of tungsten mining waste mud (TMWM) (90 vt.%) and ground granulated blast furnace slag (GGBFS) (10 vt.%) as precursors. The obtained hybrid alkaline binder specimens were submitted by compressive strength tests. It was found out that the alkaline activator (KOH when mixed with SS) improves the compressive strength of the hybrid alkaline binders compared to the alkaline activator (NaOH mixed with SS), which depends on the presence of alkali metal K+ and Na+ cations. Moreover, the samples prepared by the alkaline activator (dissolved waste glass powder in NaOH mixed with SS) giving the highest compressive strength of about 32.8 MPa at 28 days. From the results of XRD, TGA-DTGA, FTIR analyses, and the obtained microstructures of the hybrid alkaline binders it indicates the existence of a different reaction product formed during the alkaline activation such as C-S-H, N-A-S-H, C-A-S-H, and K-A-S-H type cementitious gels. In addition to these conventional gels, there was a formation of a complex mixture of (C, M)-A-S-H cementitious gels were (M = K, Na). The pore structure of hybrid alkaline binder was evaluated through mercury intrusion porosimetry (MIP). The pore structure of specimens was characterised by the total porosity, average pore diameter, pore size distribution as well as characteristic pore sizes. The MIP results indicate that the type of alkaline activators, solid/liquid ratios and the alkaline activators’ concentration have a specific impact on all characteristics of the pore structure of all the hybrid alkaline binders. Finally, the cost impact on the compressive strength for different activators was also analysed.
Naim Sedira; João Castro-Gomes. Effect of activators on hybrid alkaline binder based on tungsten mining waste and ground granulated blast furnace slag. Construction and Building Materials 2019, 232, 117176 .
AMA StyleNaim Sedira, João Castro-Gomes. Effect of activators on hybrid alkaline binder based on tungsten mining waste and ground granulated blast furnace slag. Construction and Building Materials. 2019; 232 ():117176.
Chicago/Turabian StyleNaim Sedira; João Castro-Gomes. 2019. "Effect of activators on hybrid alkaline binder based on tungsten mining waste and ground granulated blast furnace slag." Construction and Building Materials 232, no. : 117176.
By using silicate inorganic binders and glass waste (colourless or coloured) it is possible to mould technical and artistic elements, which later can be hardened by means of high temperature processing. This procedure is controlled by both the glass transition temperature of binder and of glass waste used as aggregate. "water glass", catalysed with sodium hydroxide was used as a binder of glass shards from common industrial bottles, classified to a grain size distribution below 2 mm. Chemical analysis shows similarity of silica content between binder and aggregates of recycled glass, establishing as main differences in the percentages of chromophore oxides. In addition dilatometry curves of the two materials show close glass transition temperature values (575 and 598 °C, respectively), fact that facilitates sintering between binder and aggregates. The non-heat-treated samples present good compactness and mechanical resistance values, improved with heat-treatment at 700 °C. The high compactness of heated samples, showing rounded aggregate grains and softening of binder could let a good way for obtaining well-consolidated technical elements, made of recycled glass. From this test, it would be possible to use thermal ranges between 550 and 600 °C, as well as shorter exposure times for a proper hardening.
Jorge Duran-Suarez; Maria-Angeles Villegas; Rafael Peralbo-Cano; João Castro-Gomes. New casting glass technique through the use of geopolymers. MATEC Web of Conferences 2019, 274, 03004 .
AMA StyleJorge Duran-Suarez, Maria-Angeles Villegas, Rafael Peralbo-Cano, João Castro-Gomes. New casting glass technique through the use of geopolymers. MATEC Web of Conferences. 2019; 274 ():03004.
Chicago/Turabian StyleJorge Duran-Suarez; Maria-Angeles Villegas; Rafael Peralbo-Cano; João Castro-Gomes. 2019. "New casting glass technique through the use of geopolymers." MATEC Web of Conferences 274, no. : 03004.
This study presents the work developed with alkali activated mixtures to be used as component of a new modular green wall and green roof system (GEOGREEN). The aim is to find the most appropriate composition of alkali-activated mixture to maximize water absorption and porosity and also find a good mechanical strength with reduced density. Alkali-activated mixtures were produced using two precursors, mine waste mud from Panasqueira mine (W) and ground waste glass (G) and two alkaline activators, sodium silicate (SS) and sodium hydroxide (SH). A ventilated oven was used to speed up the curing process. Variables as percentage substitution of W per G, molar concentration of SH, cure length and temperature, were tested to identify the reference mixture. After these tests different percentages of aggregates as sand (S), expanded cork granules (C) and expanded clay (A) were added to reference mixture (REF). Results indicate that S25 obtained the maximum compressive strength of 35 MPa after 7 curing days. However, about 30% compressive strength loss is observed after immersion of this mixture in water for 24h. Capillary absorption coefficient can reach to 4,77 kg/m2.h0,5 with C25 and to 4,11 kg/m2.h0,5 with S25. Also C50 enables a 20% density reduction compared to REF.
Maria Manso; João Castro-Gomes. Design of alkali-activated materials for a modular green wall and green roof system. MATEC Web of Conferences 2019, 274, 04001 .
AMA StyleMaria Manso, João Castro-Gomes. Design of alkali-activated materials for a modular green wall and green roof system. MATEC Web of Conferences. 2019; 274 ():04001.
Chicago/Turabian StyleMaria Manso; João Castro-Gomes. 2019. "Design of alkali-activated materials for a modular green wall and green roof system." MATEC Web of Conferences 274, no. : 04001.
Generally, alkali-activated materials (aka geopolymers) present good behaviour at high temperatures, but previous studies of geopolymers under elevated temperatures are, in most cases, focused on metakaolin or fly ash based geopolymers, making the information on geopolymers with mining waste mud almost inexistent. In this paper, were analysed geopolymers with different combinations of mining waste mud, waste glass powder, metakaolin and expanded cork in a total of 15 different mixtures using sodium hydroxide and sodium silicate as alkaline activators. Materials particle size used is under 500 μm for mining waste mud, waste glass powder. Some mixtures also included expanded granulated cork with particle size between 2 to 4 mm. Ten samples with 40 × 40 × 40 mm dimensions were used for the compression test, one sample for the TGA test, and one cube (100 × 100 × 60 mm) with a frustoconical hole (50 mm deep) and a 100 × 100 × 25 mm cover, for the cup test. All the mixtures were cured for 24h at a temperature of 60 °C before being demoulded, and left at room temperature until they reach 7 days to be tested. On the 7th day, of each mixture, samples were placed in a static furnace before the compression test submitted to a temperature of 800 °C during 2h. Then, the compression test was performed and the values before and after exposure to high temperatures were compared. Were recorded maximum gains of 724% and maximum losses of 100% in the compressive strength. This preliminary result shows the potentials of mining waste alkali-activated materials for elevated temperatures applications.
Rafael Silva-Figueiredo; João Castro-Gomes. Effect of elevated temperatures on alkali-activated tungsten mining waste based materials. MATEC Web of Conferences 2019, 274, 03001 .
AMA StyleRafael Silva-Figueiredo, João Castro-Gomes. Effect of elevated temperatures on alkali-activated tungsten mining waste based materials. MATEC Web of Conferences. 2019; 274 ():03001.
Chicago/Turabian StyleRafael Silva-Figueiredo; João Castro-Gomes. 2019. "Effect of elevated temperatures on alkali-activated tungsten mining waste based materials." MATEC Web of Conferences 274, no. : 03001.