The Experts below are selected from a list of 885 Experts worldwide ranked by ideXlab platform
Aly Ahmed - One of the best experts on this subject based on the ideXlab platform.
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A Decision Support System for Ground Improvement Projects Using Gypsum Waste Case Study: Embankments Construction in Japan
2016Co-Authors: Usama Hamed Issa, Aly Ahmed, Keizo UgaiAbstract:This paper introduces a multi criteria decision making model to support the decision makers who work in the ground improvement projects such as embankments construction using stabilizer materials. The use of cement as a stabilizer material in embankments construction has a long history while the application of Recycled Gypsum in cooperation with cement as a stabilizer material is recently introduced in Japan. Four criteria and many factors are identified to compare the two stabilizer materials, cement only or Gypsum-cement mixture, for the purpose of choosing one of them. The four criteria include: saving in cost, project scope achievement, durability, and geo-environmental impacts. The proposed model, which depends on the Analytic Hierarchy Process as a multi-criteria analysis method, is developed based on cost calculations, expert knowledge for achieving scope, and laboratory test results for durability and geo-environmental properties for each stabilizer material. It is applied on a real case study for embankments construction project in Japan. Based on the results of model application on the investigated case study, a decision introduced to Japanese construction market is that using Gypsum-cement mixture as a stabilizer in ground improvement projects is better than using cement only by almost 50%. This result supports the application of Recycled Gypsum, produced from Gypsum wastes, as a stabilizer in ground improvement projects to achieve the stability of society by reducing the quantities of wastes, meet sound environment, and reduce the cost of construction. Besides, the paper discusses in details the factors and reason
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an assessment of geo environmental properties for utilization of Recycled Gypsum in earthwork projects
Soils and Foundations, 2015Co-Authors: Aly Ahmed, Ahmed M Soliman, Hesham El M Naggar, Takeshi KameiAbstract:Abstract This paper presents an assessment of geo-environmental properties for the incorporation of Recycled Gypsum, produced from Gypsum waste, as an additive material in earthwork projects. In this study, the solubility of Fluorine, Boron and hexavalent Chromium and the emission of hydrogen sulfide gas refer to geo-environmental properties. To achieve this objective, the tested soil was mixed with Recycled Gypsum in conjunction with lime and cement in different proportions to overcome the solubility of Gypsum and to reduce the solubility of harmful substances. The results of the study show that the utilization of Recycled Gypsum alone, as an additive material for earthwork projects, has a negative effect on the emission of hydrogen sulfide, while the addition of a solidification agent, such as cement or lime, to the Recycled Gypsum reduced the emission of hydrogen sulfide gas. The suggested contents and ratios for the Gypsum–cement and Gypsum–lime admixtures used in this study are safe against the emission of hydrogen sulfide because their measurements were found to be below the standard limits. Increasing the proportion of cement or lime in a Gypsum–soil mixture has a significant effect on the reduction in Fluorine solubility. The content of the admixture has a significant effect on the reduction in Fluorine solubility in the case of Gypsum–cement, while there is not much difference in the measured values of Fluorine in the Gypsum–lime admixture. The intensity of ettringite increases with the increase in admixture content and the decrease in the admixture ratio, while the intensity of calcite increases with increases in both the content and the ratio of the admixture. The formation of ettringite has a significant effect on the capture of Fluorine, namely, the solubility of Fluorine decreases with the increase in ettringite intensity. The measured values for the solubility of harmful substances, including Fluorine, Boron and hexavalent Chromium and the emission of hydrogen sulfide gas, were found to lie within the standards for the investigated limits of the Gypsum–soil mixture treated with cement or lime in the present study. This proves that the utilization of Recycled Gypsum in conjunction with cement or lime, as a stabilizer material and within the investigated limits, is safe and meets the environmental standards.
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stability of soft clay soil stabilised with Recycled Gypsum in a wet environment
Soils and Foundations, 2014Co-Authors: Aly Ahmed, Usama Hamed IssaAbstract:Abstract This study investigates the effect of the soaking condition in a wet environment on the stability and durability of soft clay soil treated with Recycled Gypsum. Cement and lime are the two types of solidification agents used to improve the durability of the clay–Gypsum mixture and to reduce the solubility of the Gypsum in a wet environment because Gypsum is soluble in water. The Recycled Gypsum was mixed with cement and lime in different ratios in the dry state, and different amounts of admixtures were mixed with the tested soil to explore the effect of the wet environment on the stability and durability of the stabilised Gypsum–clay soil. Cylindrical stabilised soil specimens were cured for 3, 7, and 28 days and then soaked in water for different intervals up to 60 days. The soaked samples were evaluated based on the compressive strength, durability index, deformation changes, soil deterioration, and water absorption. The results show that increasing the content of both types of admixtures had a positive effect on the improvement of stability and durability for the tested soil in a wet environment, while the increase in the admixture ratio had a slightly negative effect on both the stability and the durability of the samples subjected to soaking. Short soaking times, up to 15 days, had a negative effect on the stability, durability, and changes in volume, and brought about a deterioration in the soluble soil and the water absorption compared with longer soaking times. The short curing times of 3 and 7 days exhibited a positive effect on the improvement of the stability, strength, and durability for the stabilised specimens subjected to soaking compared with the longer curing time of 28 days. Increasing the admixture content and soaking time had a significant effect on the water absorption and the soil deterioration of the tested soil. The effect of the soaking condition on the volume changes for the soil stabilised with the two admixtures was found to be insignificant, because the maximum volume change was found to be less than 0.15%.
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performance assessment of clay soil stabilized with Recycled Gypsum based on sem and xrd
2nd International Conference on Transportation Geotechnics (ICTG)International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE), 2012Co-Authors: Aly Ahmed, M Kobayashi, Keizo UgaiAbstract:The use of Recycled Gypsum, produced from Gypsum waste plasterboard, as a stabilizer material for ground improvement projects is initiated in Japan recently. This application is considered one of the appropriate solutions that aims to eliminate the huge quantities of Gypsum waste plasterboards and to avoid the cost of their disposal in landfill sites while preserving the environment. Although the incorporation of Recycled Gypsum in ground improvement projects has many advantages, it poses many challenges since Gypsum is a soluble material. Therefore, it is essential to explore the microstructure and mineralogical compositions of clay soil stabilized with Recycled Gypsum in order to achieve successful results. To achieve this purpose, Recycled Gypsum was mixed with furnace cement type-B or lime, in dry state, in different ratios to prevent the solubility of Gypsum. Subsequently, different contents of these admixtures were mixed with clay soil to mold cylindrical stabilized soil specimens and then subjected to different curing times before testing. SEM and XRD were used to investigate microstructure and mineralogical composition respectively, while unconfined compression test was used to investigate the compressive strength. Test results showed that the addition of Recycled Gypsum improves the strength of clay soil compared to identical untreated samples. The improvement in strength based on compressive strength results in agreement with the results of SEM images and XRD. The formation of ettringite increases with the increase of Recycled Gypsum content in soil mixture. XRD results showed that the improvement in strength is not only due to the formation of ettringite but also due to the formation of calcium carbonate and hydrate calcium sulphate in soil mixture. Curing time has a significant effect on the formation of ettringite and the improvement of strength especially in the early curing times. The initial improvement in strength is related to the potential of Gypsum for water absorption while the permanent improvement is related to the formation of ettringite and calcium carbonate in soil mixture.
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laboratory and field evaluations of Recycled Gypsum as a stabilizer agent in embankment construction
Soils and Foundations, 2011Co-Authors: Aly Ahmed, Keizo Ugai, Takeshi KameiAbstract:ABSTRACT Approximately 1.6 million tons of Gypsum waste plasterboard are produced annually in Japan. As such, it is essential to find an alternative way to reduce the quantities of this waste material to avoid environmental problems and the high cost of disposal in landfill. This paper describes a case study focused on the use of Recycled Gypsum, which is derived from Gypsum waste plasterboard, to improve the strength of soft clay soil for embankment construction projects taken in consideration environmental impacts. Four different Recycled Gypsum contents ranging from 0 to 10% was investigated. Two different types of cements—Portland and Furnace slag type B—with a content ranging from 0 to 3% was used to develop solidification for Recycled Gypsum and improve environmental properties. For this purpose, a series of unconfined compression tests were conducted to evaluate strength performance of treated clay. While a series of environmental tests were conducted to explore the solubility concentration of fluorine, boron, and hexavalent chromium in the untreated and treated soil specimens. Furthermore, hydrogen sulfide and pH were investigated. Results showed that compressive strength and unit weight of treated clay soil increased with the increase of Recycled Gypsum content. The strength obtained in the field for treated soil with Recycled Gypsum was found to be greater than that obtained in the laboratory. The early curing days for soil-Gypsum mixture had a significant effect on strength performance compared to the later days. The additives of Recycled Gypsum for tested soil swiftly increased the strength. This is a vital property for improvement embankment trafficability that helps to reduce the construction time and cost. The use of Recycled Gypsum within the investigated limits had no adverse effect on pH value and hydrogen sulfide gas was found to be less than the standard permitted limits. As well, the solubility concentrations for fluorine, boron, and hexavalent chromium were found within the permitted standard limits in Japan. The curing time had a significant effect on the reduction the release of harmful substance elements investigated. Furnace cement type B had the potential to improve the mechanical and environmental functions for soil-Gypsum mixture. It is recommended that Furnace cement type B be used as a solidification agent for soil treated with Recycled Gypsum because it has low cost and it is more environmentally friendly than Portland cement.
Takeshi Kamei - One of the best experts on this subject based on the ideXlab platform.
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an assessment of geo environmental properties for utilization of Recycled Gypsum in earthwork projects
Soils and Foundations, 2015Co-Authors: Aly Ahmed, Ahmed M Soliman, Hesham El M Naggar, Takeshi KameiAbstract:Abstract This paper presents an assessment of geo-environmental properties for the incorporation of Recycled Gypsum, produced from Gypsum waste, as an additive material in earthwork projects. In this study, the solubility of Fluorine, Boron and hexavalent Chromium and the emission of hydrogen sulfide gas refer to geo-environmental properties. To achieve this objective, the tested soil was mixed with Recycled Gypsum in conjunction with lime and cement in different proportions to overcome the solubility of Gypsum and to reduce the solubility of harmful substances. The results of the study show that the utilization of Recycled Gypsum alone, as an additive material for earthwork projects, has a negative effect on the emission of hydrogen sulfide, while the addition of a solidification agent, such as cement or lime, to the Recycled Gypsum reduced the emission of hydrogen sulfide gas. The suggested contents and ratios for the Gypsum–cement and Gypsum–lime admixtures used in this study are safe against the emission of hydrogen sulfide because their measurements were found to be below the standard limits. Increasing the proportion of cement or lime in a Gypsum–soil mixture has a significant effect on the reduction in Fluorine solubility. The content of the admixture has a significant effect on the reduction in Fluorine solubility in the case of Gypsum–cement, while there is not much difference in the measured values of Fluorine in the Gypsum–lime admixture. The intensity of ettringite increases with the increase in admixture content and the decrease in the admixture ratio, while the intensity of calcite increases with increases in both the content and the ratio of the admixture. The formation of ettringite has a significant effect on the capture of Fluorine, namely, the solubility of Fluorine decreases with the increase in ettringite intensity. The measured values for the solubility of harmful substances, including Fluorine, Boron and hexavalent Chromium and the emission of hydrogen sulfide gas, were found to lie within the standards for the investigated limits of the Gypsum–soil mixture treated with cement or lime in the present study. This proves that the utilization of Recycled Gypsum in conjunction with cement or lime, as a stabilizer material and within the investigated limits, is safe and meets the environmental standards.
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laboratory and field evaluations of Recycled Gypsum as a stabilizer agent in embankment construction
Soils and Foundations, 2011Co-Authors: Aly Ahmed, Keizo Ugai, Takeshi KameiAbstract:ABSTRACT Approximately 1.6 million tons of Gypsum waste plasterboard are produced annually in Japan. As such, it is essential to find an alternative way to reduce the quantities of this waste material to avoid environmental problems and the high cost of disposal in landfill. This paper describes a case study focused on the use of Recycled Gypsum, which is derived from Gypsum waste plasterboard, to improve the strength of soft clay soil for embankment construction projects taken in consideration environmental impacts. Four different Recycled Gypsum contents ranging from 0 to 10% was investigated. Two different types of cements—Portland and Furnace slag type B—with a content ranging from 0 to 3% was used to develop solidification for Recycled Gypsum and improve environmental properties. For this purpose, a series of unconfined compression tests were conducted to evaluate strength performance of treated clay. While a series of environmental tests were conducted to explore the solubility concentration of fluorine, boron, and hexavalent chromium in the untreated and treated soil specimens. Furthermore, hydrogen sulfide and pH were investigated. Results showed that compressive strength and unit weight of treated clay soil increased with the increase of Recycled Gypsum content. The strength obtained in the field for treated soil with Recycled Gypsum was found to be greater than that obtained in the laboratory. The early curing days for soil-Gypsum mixture had a significant effect on strength performance compared to the later days. The additives of Recycled Gypsum for tested soil swiftly increased the strength. This is a vital property for improvement embankment trafficability that helps to reduce the construction time and cost. The use of Recycled Gypsum within the investigated limits had no adverse effect on pH value and hydrogen sulfide gas was found to be less than the standard permitted limits. As well, the solubility concentrations for fluorine, boron, and hexavalent chromium were found within the permitted standard limits in Japan. The curing time had a significant effect on the reduction the release of harmful substance elements investigated. Furnace cement type B had the potential to improve the mechanical and environmental functions for soil-Gypsum mixture. It is recommended that Furnace cement type B be used as a solidification agent for soil treated with Recycled Gypsum because it has low cost and it is more environmentally friendly than Portland cement.
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investigation of Recycled Gypsum in conjunction with waste plastic trays for ground improvement
Construction and Building Materials, 2011Co-Authors: Keizo Ugai, Aly Ahmed, Takeshi KameiAbstract:Abstract During the three stages of production, construction and demolition, approximately 15 million tons of Gypsum waste plasterboard is generated annually in the world. It is considered a serious problem due to scarcity of land-filling space, increasing the cost of disposal and increasing environmental regulations. Investigations of using Recycled Gypsum “bassanite” which is derived from Gypsum waste plasterboard and waste plastic trays for ground improvement were studied. Recycled Gypsum was used as a stabilizing agent to improve the compressive strength while the waste plastic trays were used to improve the tensile strength. Recycled Gypsum content, curing time and frost heave property throughout capillary rise test were investigated to determine the behavior of treated soil with Recycled Gypsum. In addition, size, content and aspect ratio of strips of waste plastic trays were investigated. Test results showed that increasing Recycled Gypsum content has a more significant effect on compressive strength compared to the tensile strength. The effect of curing time on the strength of treated soil samples with Recycled Gypsum is much pronounced in the early curing days compared to later ages. Adding strips of waste plastic trays to samples treated with Recycled Gypsum enhanced both splitting tensile and compressive strengths as well increased the value of secant modulus. Capillary rise rate was reduced with the increase of Recycled Gypsum content, which helps to reduce the formation of ice lenses; hence the susceptibility of treated soil against frost heave is increased. The size and content of strips of waste plastic trays have significant effect on the potential of capillary rise and the enhancement of strength and stiffness of tested soil.
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Application of Gypsum Waste Plasterboard and Waste Plastic Trays to Enhance the Performance of Sandy Soil
Ground Improvement and Geosynthetics, 2010Co-Authors: Aly Ahmed, Keizo Ugai, Takeshi KameiAbstract:This paper presents the results of a research project that evaluated the use of Recycled Gypsum obtained from waste plasterboard along with strips of waste plastic trays to enhance the performance of tested soil. Recycled Gypsum was used as a stabilizing agent for stabilized soil to improve the compressive strength, whereas the waste plastic trays were used to improve the tensile strength. The effects of waste Gypsum content, size, aspect ratio and waste plastic trays content were investigated to determine the mechanical behavior of soil treated with such waste materials. Experimental test results showed that unconfined compressive and splitting tensile strengths increased with increasing waste Gypsum content. The increase in waste Gypsum has a more significant effect on the unconfined compressive strength than on the tensile strength. Adding strips of waste plastic trays to samples treated with waste Gypsum enhanced the splitting tensile strength. The size, aspect ratio and content of waste plastic trays have significant effect on the enhancement of soil strength.
Gladis Camarini - One of the best experts on this subject based on the ideXlab platform.
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Pressured Recycled Gypsum plaster and wastes: Characteristics of eco-friendly building components
Construction and Building Materials, 2018Co-Authors: Rodrigo Henrique Geraldo, Janaina Domingos De Souza, Sofia Cristina De Campos, Luiz Flávio Fernandes, Gladis CamariniAbstract:Abstract The objective of this paper is to study some characteristics of a component to buildings made with Gypsum plaster (commercial – CGP and Recycled – RGP), and wastes (red ceramic – RC and porcelain – PW) by loading-pressure. Bricks were prepared with a solid mass composition containing 50% (by weight) of binder, 50% (by weight) of waste, and very small water/dried powder ratio (0.22). Specimens were molded with uniaxial loading-pressure (10 kN) before setting times. Compressive and flexural strengths, porosity, and microstructure were evaluated. The compressive results were in the range of 12.3 and 33.9 MPa, higher than the minimum required by Brazilian Standards to building components (≥2.5 MPa). The low water/solid mass ratio and the uniaxial loading-pressure before setting times contribute to decreasing the porosity, which was shown in the dense microstructure. The obtained results show that these components present a good quality building component.
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Gypsum plaster waste recycling a potential environmental and industrial solution
Journal of Cleaner Production, 2017Co-Authors: Rodrigo Henrique Geraldo, Sayonara M M Pinheiro, Jefferson Santos Da Silva, Heloysa Martins Carvalho Andrade, Jo Dweck, Jardel Pereira Goncalves, Gladis CamariniAbstract:Abstract Gypsum plaster waste (GPW) represents a large fraction of the total construction and demolition wastes generated by society, which may contaminate the soil and water resources. Although previous studies have indicated the possibility of recycling GPW, it is not known so far, if the recycling process affects the rehydrated products and how many times the GPW can be Recycled without changing its characteristics. The present paper evaluated the properties of Recycled Gypsum plasters produced from a GPW after 1, 3, and 5 recycling cycles, RGP-1, RGP-2, and RGP-3, respectively. The unhydrated and hydrated Recycled products were characterized by EDX, XRD, DTA, TG, DTG, as well as by measuring the Recycled plaster setting times and the mechanical properties of respective rehydrated products. The recycling process does not change the Gypsum plaster chemical composition which is similar to the commercial Gypsum plaster. Physical properties are changed: bulk density diminished, setting times were shorter due to the change in the grain size with the recycling process. The mechanical performance was good with similar results at longer ages. GPW recyclability has a great potential to be a successful industrial solution and it allows the production of new reusable products, with less negative environmental impacts.
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effect of citric acid on properties of Recycled Gypsum plaster to building components
Construction and Building Materials, 2016Co-Authors: Gladis Camarini, Maria Clara Cavalini Pinto, Aline Goulart De Moura, Natalia Reggiani ManzoAbstract:Abstract Gypsum plaster recycling shortens the setting times, changing the workability and becomes difficult to work with it. The works found in literature studied the α-hemi-hydrate. Few works studied the Gypsum plaster recycling with β-hemihydrate. This experimental work evaluates the performance of Recycled Gypsum plaster with citric acid to improve the setting times and workability to building components. Recycled Gypsum plaster with five admixture contents was used: 0%; 0.025%; 0.05%; 0.1% and 0.25%. The water/plaster ratio was kept constant (1.0) for all the mixtures. The results showed that the citric acid decreases the Recycled Gypsum plaster consistency, increasing the fluidity. The setting times were increased, but the compressive strength and hardness were diminished. The microstructure also changed with the admixture addition. Even with these changes in Gypsum plaster properties, the Recycled material can be used to make components because it reaches the minimum values required by the component standards.
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Gypsum Plaster Waste Recycling: Analysis of Calcination Time
Key Engineering Materials, 2015Co-Authors: Jaqueline Rosalí De Moraes Rossetto, Lucas Santos Correia, Rodrigo Henrique Geraldo, Gladis CamariniAbstract:The Gypsum plaster is a material widely used in constructions around the world. It is a material with high versatility that can be applied from wall coverings to decorative ornaments. However, during its application in buildings, large amounts of waste materials are generated. The average values of waste during its application are higher than 45% of the Gypsum amount used. A series of tests were conducted to develop a feasible methodology to reuse this waste material. The results collected at this stage indicated that it is possible to obtain a Recycled product with low energy consumption. It was noted that after a certain number of procedures in which Gypsum was subjected to recycling, there was a loss of workability; however, it did not present relevant changes in mechanical properties. This lack of workability avoids the Recycled material maintain its properties in the fresh state as it is subjected to recycling. This work evaluates the calcination time of Gypsum plaster waste for the production of a Gypsum plaster with binder properties for using as components. The temperature of calcination was kept constant (150 °C), but the residence time in the stationary kiln was modified. The properties in the powder state (bulk density, fineness modulus, specific mass and sieve analysis), fresh state (mini-slump, setting times and kinetics of temperature) and in the hardened state (compressive strength and hardness) were analysed in order to have some answers about the performance of the Recycled Gypsum. In the fresh state, the Recycled material showed good results for precast components. The initial setting times were good for all residence times and the final setting times for the material calcined in periods of 5 and 6 hours. In the hardened state, the best compressive strength results were obtained for all residence times, and hardness for calcination for 3, 4, 5 and 6 hours. All these results were satisfactory when compared to the commercial plaster took as reference. On the other hand, there was a lack of workability in those pastes indicating that an admixture is needed to adjust this property of the Recycled material.
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evaluation of dehydration temperature on properties of Recycled Gypsum plaster
Key Engineering Materials, 2015Co-Authors: Valdir Moraes Pereira, Gladis CamariniAbstract:Gypsum plaster is a material used as internal covering of walls in Brazilian constructions. However, this material has short setting times and generates a great quantity of material loss. The low energy necessary to dehydrate the waste material for utilization becomes recycling methods viable, since the Recycled products have the same properties of the commercial material. This paper aims to evaluate the behavior of Recycled Gypsum plaster calcined at 100 °C, 150 °C and 200 °C. It was also studied the use an admixture (superplasticizer). Physical and mechanical properties were evaluated. The results showed that the dehydration temperature influences in both fresh and hardened Gypsum properties. The temperature of 200 °C reported better values of initial and final setting times and compressive strength. Calcination at 150 °C showed higher values of hardness. The admixture utilization modified the initial and final setting times.
Justo García Navarro - One of the best experts on this subject based on the ideXlab platform.
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Characterization of quality Recycled Gypsum and plasterboard with maximized Recycled content
Materiales de Construcción, 2017Co-Authors: Ana Jiménez Rivero, Justo García NavarroAbstract:The quality of secondary materials is imperative to promote a circular economy. In order to improve the way in which the quality of Recycled Gypsum is assessed, European guidelines on Recycled Gypsum (RG) quality criteria have been outlined in the framework of the Life+ Gypsum to Gypsum (GtoG) project. Such GtoG guidelines, along with the European Standard on Gypsum plasterboard EN 520, provided the basis for this study. During the GtoG project, Gypsum recycling and plasterboard manufacturing processes were monitored by testing the Gypsum feedstock and the plasterboard produced. The aim of this paper is to discuss the results obtained on relevant parameters that characterize Gypsum as a secondary raw material, as well as the resulting product. The minimum requirements were fulfilled by 56% of the RG samples and 86% of the plasterboard with increased RG.
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Indicators to Measure the Management Performance of End-of-Life Gypsum: From Deconstruction to Production of Recycled Gypsum
Waste and Biomass Valorization, 2016Co-Authors: Ana Jiménez Rivero, Justo García NavarroAbstract:The management of the end-of-life (EoL) stage of a product directly affect the destination of EoL products. In the construction sector, EoL processes such as building deconstruction or conventional demolition commonly determine whether the material flows cycle is closed. In this context, increased knowledge on the EoL processes is considered vital for enabling stakeholders to make better informed decisions on each process. Pertinent parameters and key performance indicators may assist in this task, through the acquisition of relevant data that measure progress against targets. This paper focuses on EoL Gypsum, a non-inert material appropriate for closed-loop recycling. In particular, a set of performance indicators are developed with the aim to increase the amount of Gypsum waste capable of being Recycled. At the same time, the production of quality Recycled Gypsum (RG) is prioritized. To this end, monitoring parameters were first defined and combined in the form of monitoring indicators. Such indicators were subsequently used in five pilot projects (from building deconstruction to production of Recycled Gypsum) set in four national contexts: Belgium, France, Germany and the United Kingdom. After data collection and analysis, 17 best practice indicators are identified out of the initial indicators, which recognize and encourage best practices associated to the recycling route, from a technical, environmental, social and economic perspective. The ideal conditions to produce RG from EoL Gypsum are then formulated.
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Life cycle energy and material flow implications of Gypsum plasterboard recycling in the European Union
Resources Conservation and Recycling, 2016Co-Authors: Ana Jiménez Rivero, Roger Sathre, Justo García NavarroAbstract:Turning waste into a resource is a way to increase resource use efficiency and close the material loop of a circular economy. Gypsum plasterboard is well suited for this, because the raw material calcium sulphate dihydrate (CaSO4·2H2O) can repeatedly change its properties through a reversible hydration reaction. The waste hierarchy is applied when plasterboard is Recycled instead of landfilled, which contributes to the European 2020 target of 70% recovery of construction and demolition (C&D) waste, as defined in the Directive 2008/98/EC on Waste. This paper evaluates the energy and climate impacts of different levels of plasterboard recycling. First, we formulate a life cycle model of Gypsum mass flows in the European Union (EU-27) in the reference year 2013. This model constitutes the basis of the quantitative scenario analysis. Secondly, we assess the material flows, energy use and greenhouse gas (GHG) emissions in different recycling scenarios. We compare the current situation ("2013 base case") to two scenarios: a worst case scenario of 0% Recycled Gypsum ("Zero recycling case"), and a best case scenario of zero Gypsum waste sent to landfill, corresponding to 18.7% Recycled Gypsum in new plasterboard ("High recycling case"). We find no significant variation between scenarios in terms of life cycle energy use, as lower impacts from Gypsum mining, transport of natural Gypsum and final disposal in the best case scenario are balanced by the energy for the transport of plasterboard waste and Recycled Gypsum and for material pre-processing during manufacturing. In contrast, life cycle GHG emissions are lower as recycling increases, largely driven by the degradation of plasterboard lining paper in landfills.
Keizo Ugai - One of the best experts on this subject based on the ideXlab platform.
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A Decision Support System for Ground Improvement Projects Using Gypsum Waste Case Study: Embankments Construction in Japan
2016Co-Authors: Usama Hamed Issa, Aly Ahmed, Keizo UgaiAbstract:This paper introduces a multi criteria decision making model to support the decision makers who work in the ground improvement projects such as embankments construction using stabilizer materials. The use of cement as a stabilizer material in embankments construction has a long history while the application of Recycled Gypsum in cooperation with cement as a stabilizer material is recently introduced in Japan. Four criteria and many factors are identified to compare the two stabilizer materials, cement only or Gypsum-cement mixture, for the purpose of choosing one of them. The four criteria include: saving in cost, project scope achievement, durability, and geo-environmental impacts. The proposed model, which depends on the Analytic Hierarchy Process as a multi-criteria analysis method, is developed based on cost calculations, expert knowledge for achieving scope, and laboratory test results for durability and geo-environmental properties for each stabilizer material. It is applied on a real case study for embankments construction project in Japan. Based on the results of model application on the investigated case study, a decision introduced to Japanese construction market is that using Gypsum-cement mixture as a stabilizer in ground improvement projects is better than using cement only by almost 50%. This result supports the application of Recycled Gypsum, produced from Gypsum wastes, as a stabilizer in ground improvement projects to achieve the stability of society by reducing the quantities of wastes, meet sound environment, and reduce the cost of construction. Besides, the paper discusses in details the factors and reason
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performance assessment of clay soil stabilized with Recycled Gypsum based on sem and xrd
2nd International Conference on Transportation Geotechnics (ICTG)International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE), 2012Co-Authors: Aly Ahmed, M Kobayashi, Keizo UgaiAbstract:The use of Recycled Gypsum, produced from Gypsum waste plasterboard, as a stabilizer material for ground improvement projects is initiated in Japan recently. This application is considered one of the appropriate solutions that aims to eliminate the huge quantities of Gypsum waste plasterboards and to avoid the cost of their disposal in landfill sites while preserving the environment. Although the incorporation of Recycled Gypsum in ground improvement projects has many advantages, it poses many challenges since Gypsum is a soluble material. Therefore, it is essential to explore the microstructure and mineralogical compositions of clay soil stabilized with Recycled Gypsum in order to achieve successful results. To achieve this purpose, Recycled Gypsum was mixed with furnace cement type-B or lime, in dry state, in different ratios to prevent the solubility of Gypsum. Subsequently, different contents of these admixtures were mixed with clay soil to mold cylindrical stabilized soil specimens and then subjected to different curing times before testing. SEM and XRD were used to investigate microstructure and mineralogical composition respectively, while unconfined compression test was used to investigate the compressive strength. Test results showed that the addition of Recycled Gypsum improves the strength of clay soil compared to identical untreated samples. The improvement in strength based on compressive strength results in agreement with the results of SEM images and XRD. The formation of ettringite increases with the increase of Recycled Gypsum content in soil mixture. XRD results showed that the improvement in strength is not only due to the formation of ettringite but also due to the formation of calcium carbonate and hydrate calcium sulphate in soil mixture. Curing time has a significant effect on the formation of ettringite and the improvement of strength especially in the early curing times. The initial improvement in strength is related to the potential of Gypsum for water absorption while the permanent improvement is related to the formation of ettringite and calcium carbonate in soil mixture.
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laboratory and field evaluations of Recycled Gypsum as a stabilizer agent in embankment construction
Soils and Foundations, 2011Co-Authors: Aly Ahmed, Keizo Ugai, Takeshi KameiAbstract:ABSTRACT Approximately 1.6 million tons of Gypsum waste plasterboard are produced annually in Japan. As such, it is essential to find an alternative way to reduce the quantities of this waste material to avoid environmental problems and the high cost of disposal in landfill. This paper describes a case study focused on the use of Recycled Gypsum, which is derived from Gypsum waste plasterboard, to improve the strength of soft clay soil for embankment construction projects taken in consideration environmental impacts. Four different Recycled Gypsum contents ranging from 0 to 10% was investigated. Two different types of cements—Portland and Furnace slag type B—with a content ranging from 0 to 3% was used to develop solidification for Recycled Gypsum and improve environmental properties. For this purpose, a series of unconfined compression tests were conducted to evaluate strength performance of treated clay. While a series of environmental tests were conducted to explore the solubility concentration of fluorine, boron, and hexavalent chromium in the untreated and treated soil specimens. Furthermore, hydrogen sulfide and pH were investigated. Results showed that compressive strength and unit weight of treated clay soil increased with the increase of Recycled Gypsum content. The strength obtained in the field for treated soil with Recycled Gypsum was found to be greater than that obtained in the laboratory. The early curing days for soil-Gypsum mixture had a significant effect on strength performance compared to the later days. The additives of Recycled Gypsum for tested soil swiftly increased the strength. This is a vital property for improvement embankment trafficability that helps to reduce the construction time and cost. The use of Recycled Gypsum within the investigated limits had no adverse effect on pH value and hydrogen sulfide gas was found to be less than the standard permitted limits. As well, the solubility concentrations for fluorine, boron, and hexavalent chromium were found within the permitted standard limits in Japan. The curing time had a significant effect on the reduction the release of harmful substance elements investigated. Furnace cement type B had the potential to improve the mechanical and environmental functions for soil-Gypsum mixture. It is recommended that Furnace cement type B be used as a solidification agent for soil treated with Recycled Gypsum because it has low cost and it is more environmentally friendly than Portland cement.
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environmental effects on durability of soil stabilized with Recycled Gypsum
Cold Regions Science and Technology, 2011Co-Authors: Aly Ahmed, Keizo UgaiAbstract:Abstract The use of Recycled Gypsum, which is derived from Gypsum waste plasterboard, for ground improvement has recently been initiated in Japan and is not widespread around the world. As such, it is essential to explore the effect of environmental conditions on the performance and durability of soil stabilized with Recycled Gypsum. This is especially important in cold and rainfall regions such as in Japan, due to the solubility of Gypsum. This paper presents an integrated experimental study to investigate the effect of environmental factors, in terms of freeze–thaw and wet–dry cycles, on the durability of soil stabilized with Recycled Gypsum. For this purpose, four different contents of Recycled Gypsum ranging from 0 to 20% were used. Four different cement contents ranging from 0 to 5% were used as solidification agent to optimize the cement content which is adequate to prevent the solubility and improve the durability. To study the effect of environmental factors on the durability, cylindrical specimens of stabilized soil were compacted at maximum dry unit weight and cured for 7 days under constant temperature and humidity. Subsequently, specimens were subjected to different numbers of freeze–thaw and wet–dry cycles. They were then tested for compressive strength, loss soil weight, and volume change. Results showed that compressive strength of stabilized specimens decreased while accumulated soil losses weight increased with the increase of both numbers of freeze–thaw and wet–dry cycles. Freeze–thaw cycles have a significant effect on the durability reduction of stabilized soil compared with the effect of wet–dry cycles. The durability of stabilized soil improved with the increase of both contents of Recycled Gypsum and cement. The 2.5% cement content is adequate to improve the durability of soil stabilized with Recycled Gypsum based on ground mechanical and economic functions. Both freeze–thaw and wet–dry cycles have insignificant effect on the volume change of soil stabilized with Recycled Gypsum. After using 2.5% of cement content, the strength of stabilized soil specimens increased slightly with the increase of wet–dry cycles; subsequent to that, the strength declined with increasing wet–dry cycles. Soil stabilized with only Recycled Gypsum and without any solidification agents, such as cement, is not durable against environmental conditions.
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investigation of Recycled Gypsum in conjunction with waste plastic trays for ground improvement
Construction and Building Materials, 2011Co-Authors: Keizo Ugai, Aly Ahmed, Takeshi KameiAbstract:Abstract During the three stages of production, construction and demolition, approximately 15 million tons of Gypsum waste plasterboard is generated annually in the world. It is considered a serious problem due to scarcity of land-filling space, increasing the cost of disposal and increasing environmental regulations. Investigations of using Recycled Gypsum “bassanite” which is derived from Gypsum waste plasterboard and waste plastic trays for ground improvement were studied. Recycled Gypsum was used as a stabilizing agent to improve the compressive strength while the waste plastic trays were used to improve the tensile strength. Recycled Gypsum content, curing time and frost heave property throughout capillary rise test were investigated to determine the behavior of treated soil with Recycled Gypsum. In addition, size, content and aspect ratio of strips of waste plastic trays were investigated. Test results showed that increasing Recycled Gypsum content has a more significant effect on compressive strength compared to the tensile strength. The effect of curing time on the strength of treated soil samples with Recycled Gypsum is much pronounced in the early curing days compared to later ages. Adding strips of waste plastic trays to samples treated with Recycled Gypsum enhanced both splitting tensile and compressive strengths as well increased the value of secant modulus. Capillary rise rate was reduced with the increase of Recycled Gypsum content, which helps to reduce the formation of ice lenses; hence the susceptibility of treated soil against frost heave is increased. The size and content of strips of waste plastic trays have significant effect on the potential of capillary rise and the enhancement of strength and stiffness of tested soil.