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Yubonmhat K, Gunhakoon P, Sopapan P, Prasertchiewchan N, Katekaew W. Ordinary-Portland-cement solidification of Cs-137 contaminated electric arc furnace dust from steel production industry in Thailand. Heliyon 2024; 10:e25792. [PMID: 38352783 PMCID: PMC10862672 DOI: 10.1016/j.heliyon.2024.e25792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 01/21/2024] [Accepted: 02/02/2024] [Indexed: 02/16/2024] Open
Abstract
The cementation was used to immobilize the Cs-137 contaminated electric arc furnace dust (EAFD). Various mixing recipes were used to prepare the EAFD-cement waste form specimens. The strength test, the ANSI/ANS-16.1 leaching test and the immersion test were performed to judge whether the cured specimens satisfy the Radwaste disposal requirements. The strengths of all specimens were higher than the acceptable limit (3.45 MPa). The specimen's strength depended on the EAFD content, the water-to-binders ratio, and the curing time. Moreover, it could be affected by the leaching of the cement and EAFD components. The leaching results showed that the Cs-137 could be totally leached after ending of the test. There is a positive correlation between the quantity of Cs-137 in the leachate and the leachate pH. The Cs-137 leachability index (LI) decreased as the EAFD content and the ratio increased. The LI values ranged from 5.9 to 6.4. The Cs-137 leaching from the specimens could be controlled by the diffusion or the surface wash-off, depending on the recipes used. Additionally, the Cs-137 leaching might be controlled by multiple mechanisms. The findings reasonably recommend that the recipe with the ratio of 0.40 and 40 % EAFD could be used for the EAFD immobilizing.
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Affiliation(s)
- Klitsadee Yubonmhat
- Radioactive Waste Management Center, Thailand Institute of Nuclear Technology, Nakhon Nayok, 26120, Thailand
| | - Pattaranipa Gunhakoon
- Radioactive Waste Management Center, Thailand Institute of Nuclear Technology, Nakhon Nayok, 26120, Thailand
| | - Poonnaphob Sopapan
- Radioactive Waste Management Center, Thailand Institute of Nuclear Technology, Nakhon Nayok, 26120, Thailand
| | - Nikom Prasertchiewchan
- Radioactive Waste Management Center, Thailand Institute of Nuclear Technology, Nakhon Nayok, 26120, Thailand
| | - Witsanu Katekaew
- Radioactive Waste Management Center, Thailand Institute of Nuclear Technology, Nakhon Nayok, 26120, Thailand
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Nukah PD, Abbey SJ, Booth CA, Nounu G. Optimisation of Embodied Carbon and Compressive Strength in Low Carbon Concrete. MATERIALS (BASEL, SWITZERLAND) 2022; 15:8673. [PMID: 36500168 PMCID: PMC9739600 DOI: 10.3390/ma15238673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
To improve the prediction of compressive strength and embodied carbon of low carbon concrete using a program algorithm developed in MATLAB, 84 datasets of concrete mix raw materials were used. The influence of water, silica fume and ground granular base slag was found to have a significant impact on the extent of low carbon concrete behaviour in terms of compressive strength and embodied carbon. While the concrete compressive strength for normal concrete increases with reducing water content, it is observed that the low carbon concrete using lightweight aggregate material increases in compressive strength with an increase in embodied carbon. From the result of the analysis, a function was developed that was able to predict the associated embodied carbon of a concrete mix for a given water-to-cement ratio. The use of an alkaline solution is observed to increase the compressive strength of low carbon concrete when used in combination with ground granular base slag and silica fume. It is further shown that ground granular base slag contributes significantly to an increase in the compressive strength of Low carbon concrete when compared with pulverised fly ash. The optimised mix design program resulted in a 26% reduction in embodied carbon and an R2 value of 0.9 between the measured compressive strength and the optimised compressive strength.
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Affiliation(s)
- Promise D. Nukah
- School of Engineering, College of Arts, Technology and Environment, University of the West of England, Bristol BS16 1QY, UK
| | - Samuel J. Abbey
- School of Engineering, College of Arts, Technology and Environment, University of the West of England, Bristol BS16 1QY, UK
| | - Colin A. Booth
- Centre for Architecture and Built Environment Research (CABER), College of Arts, Technology and Environment, University of the West of England, Bristol BS16 1QY, UK
| | - Ghassan Nounu
- School of Engineering, College of Arts, Technology and Environment, University of the West of England, Bristol BS16 1QY, UK
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Fabian M, Tolnai I, Kis Z, Szilagyi V. Characterization of Simulated Liquid Radioactive Waste in a New Type of Cement Mixture. ACS OMEGA 2022; 7:36108-36116. [PMID: 36278063 PMCID: PMC9583344 DOI: 10.1021/acsomega.2c05507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 09/28/2022] [Indexed: 06/16/2023]
Abstract
There is still a safety challenge for the long-term stabilization of nuclear waste. Due to its affordable price and easy manufacturing, cement is one of the most promising materials to immobilize a large volume of low- and intermediate-level radioactive liquid waste. To investigate the effect of borate on the cementation of radioactive evaporator concentrates and to provide more data for solidification formula optimization, simulated liquid waste in various concentrations was prepared. Different borate concentrations were solidified in ordinary Portland cement (OPC) and in two new cement compositions with water resistance and boron-binding additives. The chemical and mechanical properties were investigated for nine cementitious samples, together with three compositions in three concentrations. The leaching rate of the boron is lower in the case of a high strength cement mixture. The compressive strengths of the solidified waste correlate with the leaching rates of the boron. The leaching rates of Ca were changed with the cement composition and even with the boron concentrations; first, they were lower in the initial OPC in the case of the same boron concentration (50 g/L); second, they were lower at a higher boron concentration (250 g/L) for the OXY-B composition. The simulated liquid waste with higher boron concentrations solidified with newly developed cement composition (OXY-B) shows a homogeneous boron distribution in the volume of the cement cylinder both before and after leaching. The formulas of OXY and OXY-B developed in this application were effective for cementation of the simulated borate evaporator concentrates.
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Carbstone Pavers: A Sustainable Solution for the Urban Environment. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11146418] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To reduce CO2 emissions from the building industry, one option is to replace cement in specific applications with alternative binders. The Carbstone technology is based on the reaction of calcium- and magnesium-containing minerals with CO2 to form carbonate binders. Mixes of carbon steel slag and stainless-steel slag, with tailored particle size distributions, were compacted with a vibro-press and subsequently carbonated in an autoclave to produce carbonated steel slag pavers. The carbonated materials sequester 100–150 g CO2/kg slag. Compressive and tensile splitting strength of the resulting pavers were determined, and the ratio was found to be comparable to that of concrete. The environmental performance of the Carbstone pavers, with an average tensile splitting strength of 3.6 MPa, was found to be in compliance with Belgian and Dutch leaching limit values for construction materials. In addition, leaching results for a concrete mix made with aggregates of crushed Carbstone pavers (simulating the so-called “second life” of pavers) demonstrate that the pavers can be recycled as aggregates in cement-bound products after their product lifetime.
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Citizen Science Tools Reveal Changes in Estuarine Water Quality Following Demolition of Buildings. REMOTE SENSING 2021. [DOI: 10.3390/rs13091683] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Turbidity and water colour are two easily measurable properties used to monitor pollution. Here, we highlight the utility of a low-cost device—3D printed, hand-held Mini Secchi disk (3DMSD) with Forel-Ule (FU) colour scale sticker on its outer casing—in combination with a mobile phone application (‘TurbAqua’) that was provided to laymen for assessing the water quality of a shallow lake region after demolition of four high-rise buildings on the shores of the lake. The demolition of the buildings in January 2020 on the banks of a tropical estuary—Vembanad Lake (a Ramsar site) in southern India—for violation of Indian Coastal Regulation Zone norms created public uproar, owing to the consequences of subsequent air and water pollution. Measurements of Secchi depth and water colour using the 3DMSD along with measurements of other important water quality variables such as temperature, salinity, pH, and dissolved oxygen (DO) using portable instruments were taken for a duration of five weeks after the demolition to assess the changes in water quality. Paired t-test analyses of variations in water quality variables between the second week of demolition and consecutive weeks up to the fifth week showed that there were significant increases in pH, dissolved oxygen, and Secchi depth over time, i.e., the impact of demolition waste on the Vembanad Lake water quality was found to be relatively short-lived, with water clarity, colour, and DO returning to levels typical of that period of year within 4–5 weeks. With increasing duration after demolition, there was a general decrease in the FU colour index to 17 at most stations, but it did not drop to 15 or below, i.e., towards green or blue colour indicating clearer waters, during the sampling period. There was no significant change in salinity from the second week to the fifth week after demolition, suggesting little influence of other factors (e.g., precipitation or changes in tidal currents) on the inferred impact of demolition waste. Comparison with pre-demolition conditions in the previous year (2019) showed that the relative changes in DO, Secchi depth, and pH were very high in 2020, clearly depicting the impact of demolition waste on the water quality of the lake. Match-ups of the turbidity of the water column immediately before and after the demolition using Sentinel 2 data were in good agreement with the in situ data collected. Our study highlights the power of citizen science tools in monitoring lakes and managing water resources and articulates how these activities provide support to Sustainable Development Goal (SDG) targets on Health (Goal 3), Water quality (Goal 6), and Life under the water (Goal 14).
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Influence of Micro-Pore Connectivity and Micro-Fractures on Calcium Leaching of Cement Pastes-A Coupled Simulation Approach. MATERIALS 2020; 13:ma13122697. [PMID: 32545720 PMCID: PMC7345021 DOI: 10.3390/ma13122697] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/10/2020] [Accepted: 06/11/2020] [Indexed: 12/01/2022]
Abstract
A coupled numerical approach is used to evaluate the influence of pore connectivity and microcracks on leaching kinetics in fully saturated cement paste. The unique advantage of the numerical model is the ability to construct and evaluate a material with controlled properties, which is very difficult under experimental conditions. Our analysis is based on two virtual microstructures, which are different in terms of pore connectivity but the same in terms of porosity and the amount of solid phases. Numerical fracturing was performed on these microstructures. The non-fractured and fractured microstructures were both subjected to chemical leaching. Results show that despite very different material physical properties, for example, pore connectivity and effective diffusivity, the leaching kinetics remain the same as long as the amount of soluble phases, i.e., buffering capacity, is the same. The leaching kinetics also remains the same in the presence of microcracks.
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Nagpal M, Kakkar R. Adsorptive Degradation of Phosmet Using Hierarchically Porous Calcium Oxide : An Experimental and Theoretical Study. ChemistrySelect 2020. [DOI: 10.1002/slct.201904740] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Mudita Nagpal
- Department of ChemistryUniversity of Delhi Delhi- 110 007 India
| | - Rita Kakkar
- Department of ChemistryUniversity of Delhi Delhi- 110 007 India
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Calcium leaching behavior of cementitious materials in hydrochloric acid solution. Sci Rep 2018; 8:8806. [PMID: 29891897 PMCID: PMC5995840 DOI: 10.1038/s41598-018-27255-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 05/30/2018] [Indexed: 11/17/2022] Open
Abstract
The calcium leaching behavior of cement paste and silica fume modified calcium hydroxide paste, exposed to hydrochloric acid solution, is reported in this paper. The kinetic of degradation was assessed by the changes of pH of hydrochloric acid solution with time. The changes of compressive strength of specimens in hydrochloric acid with time were tested. Hydration products of leached specimens were also analyzed by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric (TG), and atomic force microscope (AFM). Tests results show that there is a dynamic equilibrium in the supply and consumption of calcium hydroxide in hydrochloric acid solution, which govern the stability of hydration products such as calcium silicate hydrate (C-S-H). The decrease of compressive strength indicates that C-S-H are decomposed due to the lower concentration of calcium hydroxide in the pore solution than the equilibrium concentration of the hydration products. Furthermore, the hydration of unhydrated clinker delayed the decomposition of C-S-H in hydrochloric acid solution due to the increase of calcium hydroxide in pore solution of cementitious materials.
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Testing Silica Fume-Based Concrete Composites under Chemical and Microbiological Sulfate Attacks. MATERIALS 2016; 9:ma9050324. [PMID: 28773452 PMCID: PMC5503062 DOI: 10.3390/ma9050324] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/06/2016] [Accepted: 04/21/2016] [Indexed: 11/25/2022]
Abstract
Current design practices based on descriptive approaches to concrete specification may not be appropriate for the management of aggressive environments. In this study, the durability of cement-based materials with and without the addition of silica fume, subjected to conditions that leach calcium and silicon, were investigated. Chemical corrosion was simulated by employing various H2SO4 and MgSO4 solutions, and biological corrosion was simulated using Acidithiobacillus sp. bacterial inoculation, leading to disrupted and damaged surfaces; the samples’ mass changes were studied following both chemical and biological attacks. Different leaching trends were observed via X-ray fluorescence when comparing chemical with biological leaching. Lower leaching rates were found for concrete samples fortified with silica fume than those without silica fume. X-ray diffraction and scanning electron microscopy confirmed a massive sulfate precipitate formation on the concrete surface due to bacterial exposure.
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