Waste Gypsum Research Articles

저비용 PBAT 복합체 제조를 위한 폐석고와 탄산칼슘 충전제 비교 연구

폐석고(CaSO₄) 및 탄산칼슘(CaCO₃)을 이용하여 poly(butylene adipate-co-terephthalate)(PBAT) 복합체를 용융혼합으로 제조한 뒤 비교하였다. 석고와 탄산칼슘은 Ca<SUP>2+</SUP> 양이온을 동일하게 포함하지만 다른 크기의 음이온 즉, 각각 SO₄<SUP>2-</SUP>, CO₃<SUP>2-</SUP>을 함유하고 있다. Fajans’ rule에 따르면 CaCO₃는 이온성이 더 큰 반면, CaSO₄는 편극성이 더 크다. 석고는 탄산칼슘에 비해 편극성이 크기 때문에 filler-matrix간 정전기적 상호작용에 의해 PBAT 내에 분산이 더 잘 되었다. 석고/PBAT 복합체는 충전제-고분자 함량 20:80의 비율에서 탄산칼슘/PBAT 복합체 대비 낮은 인장강도와 높은 연신율 값을 나타냈다. Polylactic acid(PLA)를 첨가함에 따라 석고/PLA/PBAT 복합체는 인장강도와 연신율이 향상했지만 탄산칼슘/PLA/PBAT 복합체의 경우에는 PLA의 첨가에 따른 효과가 관찰되지 않았다. 이는 탄산칼슘에 의한 PLA의 depolymerization에 기인하는 것으로 사료된다. 이러한 복합체의 기계적 거동은 열적, 형태학적, 결정학적 분석을 통해 잘 설명되었다.

Industrial Verification and Research Development of Lime–Gypsum Fertilizer Granulation Method

This work concerns non-pressure granulation of mineral materials used for the production of agricultural fertilizers for soil deacidification. In order to expand the product range of Nordkalk Poland sp. z o. o. located in Poland, the granulation conditions of the gypsum–lime mix were examined with the use of various granulation methods. The processed mixture was Jurassic lime flour mined in the Sławno mine (Poland) and waste gypsum (sulfogypsum) obtained from the largest coal-fired power plant in the EU, Bełchatów Power Plant (Poland). This paper presents the results of the optimization of the gypsum–lime fertilizer granulation process. The results of the study of granulation of gypsum–lime mixture realized in one-stage technology in a disc granulator were compared with the effects of two-stage agglomeration. During the research, a mixture (in a 1:1 ratio) of waste sulfogypsum and lime flour was used. Such a weight ratio provides maximum use of the sulfogypsum waste while maintaining good mechanical properties of the granulate. The granulated bed was moistened with a lignosulfonate solution. The process was carried out periodically. After the experiment, the grain composition of the granulate obtained was determined and tests were performed to determine the strength of the product. The test results were compared with analogous ones obtained during granulation with the use of molasses (waste from sugar production). The results obtained were verified during a trial carried out on an industrial scale.

Environmental Evaluation of Gypsum Plasterboard Recycling

Gypsum is widely used in the construction sector, and its worldwide consumption has been increasing for several decades. Depending on the lifetime of the used gypsum products, an increase of gypsum in construction and demolition waste follows. Especially against the background of a circular economy, the recycling of waste gypsum is of growing importance. However, the use of recycled gypsum only makes sense if it is environmentally friendly. Therefore, an evaluation of the environmental impacts of industrial-scale processing for the recycling of post-consumer gypsum waste was conducted. The evaluation was performed with an established life cycle assessment software. Original data provided by the industry and complementary data from a database for life cycle assessments were used for the calculations. Two scenarios for recycled gypsum with different transportation distances were calculated. These results were compared with the results of the environmental evaluation of gypsum derived from coal-fired power plants (FGD gypsum) and natural gypsum. The results showed that the utilization of recycled gypsum can be environmentally advantageous compared to the use of natural gypsum or FGD gypsum, especially in the impact categories of land transformation and resource consumption (abiotic depletion potential). For most environmental impact categories, the specific transportation distances have a strong influence.

Heat and mass transfer of waste gypsum powder in a closed rotating container by external heating

Heat and mass transfer of waste gypsum powder in a closed rotating container by external heating

Ideal quality control for waste gypsum board recycling and social implementation

Gypsum board is used all around the world as a key material for the construction industry. One of the challenges with this product is the resulting waste, the majority of which is simply thrown away. Dr Kazuto Endo, of the National Institute for Environmental Studies in Japan, has been investigating the issue of gypsum board waste recycling for the past 15 years and has been instrumental in the creation of quality guidelines for recycled gypsum powder and the implementation of these standards across the industry, resulting in higher levels of recycling and safer, more sustainable use of resources. Endo's work, both on recycling gypsum board waste and the development and implementation of quality control guidelines for this process, have the potential to play a significant role in increasing both safety and sustainability of the use of this resource.

Transformation Behaviour of Sulfur from Gypsum Waste (CaSO&lt;sub&gt;4&lt;/sub&gt;·2H&lt;sub&gt;2&lt;/sub&gt;O) while Roasting with Tin-bearing Iron Concentrate for Tin Removal and Iron Recovery

Transformation Behaviour of Sulfur from Gypsum Waste (CaSO&lt;sub&gt;4&lt;/sub&gt;·2H&lt;sub&gt;2&lt;/sub&gt;O) while Roasting with Tin-bearing Iron Concentrate for Tin Removal and Iron Recovery

Influence of Waste Gypsum on the Microstructural Characteristics and Strength Behavior of Unfired Mud Block

Construction technology in the twenty-first century is on the peak yet developing countries of the world still dream for shelter in bad weather conditions and apply old traditional techniques for construction of their houses. The reason is the increasing cost of construction materials due to energy crises, poor economic conditions, and sometimes the love of people toward earthen architecture culture. The world will prefer low energy alternatives to conventional construction. Some alternatives regarding conventional construction like mud block masonry are part of this research paper to avoid shrinking natural resources and take control of the energy crisis. This research work focuses on the compressive strength of the mud block by stabilizing it with additives like waste gypsum. The study also intended to investigate the rapid hardening of the masonry block. Finally, study the morphology of the stabilized blocks by using scanning electron microscopy and energy dispersive X-ray microanalysis (EDXMA). This research found that the compressive strength of waste gypsum-stabilized mud block at 7 days and 14 days increases with the increasing rate of waste gypsum from 0 to 20%. This research will help the poor community by reducing the economy and energy consumed in the construction of houses. Besides, this research will play a role by minimizing the consumption of natural resources, encourage people to reuse waste gypsum in construction without compromising on environmental pollution.

Recycled gypsum powder from waste drywalls combined with fly ash for partial cement replacement in concrete

Recent developments towards sustainable infrastructure have motivated more environmentally conscious construction practices. The concrete industry is known to have a large carbon footprint, which can be decreased by reducing the amount of cement required, thereby reducing the demand for virgin material production and its associated carbon emissions. Excessive waste accumulation is another notable environmental issue, and gypsum drywall is a major source of construction and demolition waste, typically disposed of unsustainably in landfills. To assess the recycling potential of gypsum waste in concrete, this research utilized gypsum in quantities above those typically considered to partially replace cement. This experimental study was conducted to investigate the mechanical performance of concrete with recycled gypsum powder (hereafter called gypsum) combined with fly ash as supplementary cementing materials. A total of 15 different concrete mixes were prepared containing 0, 5, 10, 15, and 20% gypsum and 0, 25 and 50% fly ash as partial replacement for cement. Superplasticizer was used to regulate the mixture consistency, as adding gypsum was found to dehydrate the mix. Nine identical specimens per mix were cast into 200 mm × 100 mm cylindrical molds, and three of each were tested for compressive strength after curing in a moist room for 7, 28 and 90 days. The study revealed that using only gypsum as a partial cement replacement was disadvantageous to strength, however combining fly ash and gypsum was beneficial at later ages. After 90 days, all mixes containing 50% fly ash revealed that additional gypsum did not have negative effects on the compressive strength. The presented research suggests that the novel application of recycled gypsum in concrete is achievable from a structural perspective, and including fly ash is essential. In order to be considered a practical alternative to traditional concrete, further investigation is recommended.

Use of Polycarbonate Waste as Aggregate in Recycled Gypsum Plasters.

The use of gypsum as an indoor coating material for buildings is very extensive. This means that huge amounts of gypsum waste are generated daily worldwide. Therefore, many researchers in the last years have been working on the generation of new gypsum-related materials and products that incorporate recycled gypsum waste as a replacement for the commercial one. On the other hand, trying to reduce the large amounts of plastic generated globally each year, several studies have used different types of plastic waste as aggregates for the development of new construction and building materials. However, up to now, no previous studies have been found in which any type of plastic waste has been used as an aggregate in a recycled gypsum matrix. This paper presents a study in which two different types of waste were mixed for the development of new gypsum plasters: unheated gypsum waste from industrial plasterboard production (GPW) and polycarbonate (PC) waste from rejected compact discs (CDs) and digital versatile discs (DVDs). In this sense, the mechanical and thermal performance of plasters was evaluated. Finally, in order to evaluate the changes in the microstructure of the composites, a scanning electron microscopy (SEM) analysis was conducted. The results showed a good performance of the new composites when both types of waste were combined in the mixes. New lightweight eco-efficient plasters, completely recycled, with enhanced flexural strength (by 14.8%), compressive strength (by 26.8%), and thermal conductivity (42.8% less), compared to the reference material, were achieved.

Comparative study of embodied energy of affordable houses made using GFRG and conventional building technologies in India

The present situation vis-á-vis increased energy use and environmental emissions has urged the building sector to contribute more towards sustainable construction. This is possible only through appropriate choice of building materials and technologies that minimize the environmental impacts. Nevertheless, the adoption of the same need to necessarily satisfy the user in terms of aesthetics, utility and cost. This paper presents the comparison of embodied energy of a two-storey residential building, made using, i) GFRG (glass fibre reinforced gypsum), and, ii) load-bearing brick masonry, building technologies. GFRG technology uses load-bearing walls and slabs that are manufactured using gypsum waste, and consumes reduced quantity of reinforced concrete in comparison with conventional construction. It has been found in this study that the embodied energy related to building materials of the GFRG building is 16% less, and that associated with transport of resources is twice, compared to the conventional brick masonry building. The major advantages of the GFRG building construction are found to be about – reduction in structural weight and construction cost, – savings in construction time and – savings in total man power requirement for construction. Further, the use of cement, steel rebar and sand is reduced by 25%, 36% and 44% respectively.

Mechanochemically synthesized gypsum and gypsum drywall waste cocrystals with urea for enhanced environmental sustainability fertilizers

Abstract New, cost-effective and sustainable methods are needed to decrease the reactive N-losses into the environment from mineral fertilizers. For this purpose, we demonstrate a successful mechanochemical synthesis of urea cocrystals containing secondary nutrients calcium (Ca) and sulfur (S) using widely abundant drywall gypsum waste. Resulting CaSO4⋅4urea cocrystal possesses unique reactive properties. In particular, it possesses a higher urea decomposition temperature of 195 °C as it foregoes the melting of urea at 137 °C as inferred from thermogravimetric measurements. A combination of Dynamic Vapor Sorption (DVS) and in situ Raman spectroscopy measurements suggested a much lower CaSO4⋅4urea propensity to adsorb and react with water as relative humidity than urea alone. Ab initio thermodynamics framework was devised and showed a large apparent thermodynamic barrier of crystalline CaSO4⋅4urea to transform into urea and the resulting reactive gases, NH3 and CO2. Detailed N and S measurements suggested their enhanced availability when using cocrystals especially during the early stages of the experiments. The synthesis process described using waste drywall gypsum to form CaSO4·4urea cocrystal mechanochemically thus can provide a new value proposition for this abundant waste and contributing to sustainable use as it can decrease the use of various enzyme inhibiting synthetic organophosphorus compounds.

Study on the inorganic synthesis from recycled cement and solid waste gypsum system: Application in grouting materials

Grouting reinforcement technology plays an important role in the field of disaster prevention and control of deep underground engineering. Due to the insufficient workability and mechanical property of recycled cement (RC) under high water to solid ratio, there is still a blank about recycled cement used in grouting materials. In order to propose a new high-performance, low-cost environmental grouting materials and expand the application field of RC, this study examined the effect of phosphogypsum and flue gas desulfurization gypsum on the performance and microstructure of RC thermal activated with different temperatures, high purity natural gypsum and blank sample were designed as control group. Test results indicated that three kinds of gypsum all prolonged the initial setting times, and improved the fluidity and mechanical properties of RC grouts. Especially, 10% phosphogypsum added to the 750 °C thermal activated RC, optimal proportion of RC to gypsum system, can obtain a higher compressive strength (6.33 MPa for 3d and 11.26 MPa for 28d) than P.O.42.5 cement with 1.0 water to solid ratio, prolong the initial setting times from 5 min up to 27 min, which makes the RC capable of using as grouting materials. The microscopicanalysis results showed that the increase in the compressive strength was attributed to gypsums can promote the generation process of C-S-H and ettringite in RC, the impurity of phosphogypsum also participate in the hydration process and generated crystalline substances such as calcium phosphate silicate.

Influence of sulfur trioxide in clinker on the hydration heat and physical properties of Portland cement

The cement industry has achieved stable usage of waste gypsum board in clinker production. However, few studies have focused on the heat of hydration and physical properties of cements with high-SO3 clinker with different C3A and gypsum contents. Clinker with different amounts of SO3 and coexisting C3A was prepared in an electric furnace. Cement samples were then prepared by adding gypsum. Increasing the clinker SO3 content accelerated the alite reaction and caused aluminate hydrate reaction to occur later. Compressive strength at 3 days increased with SO3 content whereas that after 28 days decreased. The drying shrinkage strain of mortar decreased with increasing SO3 content of the clinker and gypsum at each C3A content. The decrease of drying shrinkage attributed to SO3 in the clinker was smaller than that caused by gypsum SO3. As the clinker SO3 content increases, cement physical properties can be maintained by adjusting the gypsum content.

Consequential Life Cycle Assessment of energy generation from waste wood and forest residues: The effect of resource-efficient additives

Combustion of waste wood can cause slagging, fouling and corrosion which lead to boiler failure, affecting the energy efficiency and the lifetime of the power plant. Additivation with mineral and sulfur containing additives during waste wood combustion could potentially reduce these problems. This study aims at understanding the environmental impacts of using additives to improve the operational performance of waste wood combustion. The environmental profiles of four energy plants (producing heat and/or power), located in different European countries (Poland, Austria, Sweden and Germany), were investigated through a consequential life cycle assessment (LCA). The four energy plants are all fueled by waste wood and/or residues. This analysis explored the influences of applying different additives strategies in the four power plants, different wood fuel mixes and resulting direct emissions, to the total life cycle environmental impacts of heat and power generated. The impacts on climate change, acidification, particulate matter, freshwater eutrophication, human toxicity and cumulative energy demand were calculated, considering 1 GJ of exergy as functional unit. Primary data for the operation without additives were collected from the power plant operators, and emission data for the additives scenarios were collected from onsite measurements. A sensitivity analysis was conducted on the expected increase of energy efficiency. The analysis indicated that the use of gypsum waste, halloysite and coal fly ash decreases the environmental impacts of heat and electricity produced (average of 12% decrease in all impacts studied, and a maximum decrease of 121%). The decrease of impacts is mainly a consequence of the increase of energy generation that avoids the use of more polluting marginal technologies. However, impacts on acidification may increase (up to 120% increase) under the absence of appropriate flue gas cleaning systems. Halloysite was the additive presenting the highest benefits.

Preparation of Sintered Glass-Ceramic from CRT Glass and Red Gypsum Wastes for Tiling Application

This study aims to prepare sintered glass-ceramic (SGC) from a combination of cathode ray tube glass and red gypsum wastes specifically for tiling application. Bentonite clay which acted as a binder was also added to the prepared formulation. The starting materials were milled individually, mixed and compacted into button shape by using a uniaxial hydraulic press machine. The effects of sintering temperature and red gypsum content on the physical- mechanical properties and crystallization behaviour were investigated. The test results revealed that the glass-ceramic sintered at 850°C with 20 wt.% of red gypsum gave the best combination of physical-mechanical properties. Modulus of rupture and linear shrinkage were measured at 33.75 MPa and 6.47 %, respectively. Water absorption was low enough and recorded at 0.4759 % while the density was measured at 2.6638 g/cm3. The results also discovered that increasing red gypsum content by 10 wt.% and sintered at similar temperature deteriorated the quality of the glass-ceramic. Therefore, this particular sintered glass-ceramic has the potential to be used as outdoor walkway tile or brick owing to the high physical-mechanical properties, colour suitability as well as low production cost.

Search for Novel Use of Waste Gypsum: Part 1. Detailed Investigation on Waste Gypsum Phosphatization

Search for Novel Use of Waste Gypsum: Part 1. Detailed Investigation on Waste Gypsum Phosphatization

Influence of gypsum wastes on the workability of plasters: Heating process and microstructural analysis

The construction sector consumes 95% of the total production of gypsum due to its multiple applications. Gypsum plaster is one of the most common indoor coating material (pastes and mortars), but it can also be used in prefabricated products like plasterboards, blocks and decorative elements. Gypsum waste recycling provides a solution to an important environmental problem from the use of gypsum plaster, which is the generation of large amounts of wastes at different phases (production, construction, rehabilitation and demolition).This paper studies two different replacement alternatives of natural gypsum: Flue Gas Desulphurization (FGD) gypsum and gypsum waste obtained from industrial plasterboard production. The influence of the previous types, amounts of waste (25, 50, 75 and 100 wt%) and different heating temperatures (100 °C, 150 °C and 180 °C) and processes on the workability of gypsum plasters is evaluated and discussed, based on a microstructure analysis using XRD and SEM techniques.This research highlights the feasibility, in terms of workability, of using Gypsum Plasterboard Waste (GPW), without any heating process, as a replacement gypsum in plasters. Despite the fact that a higher amount of water was necessary in the production of the mixes, a good workability was achieved. On the other hand, the unfeasibility of using unheated FGD as a constituent of plasters was demonstrated. However, a good performance, in terms of workability, of the FGD was obtained when the powder was subjected to a heating process at 180 °C during 6 h.

Possible use of gypsum waste from ceramics industry as semi-reinforcing filler in epoxidized natural rubber composites

In recent years, the incorrect disposal of industrial solid wastes is one of the main reasons for serious environmental pollution. The appropriate recycle of these waste materials in commercial purpose is the key way to protect the environment. In the present study, the suitability of gypsum waste (GW) from ceramics factory as a filler in epoxidized natural rubber (ENR) was explored. Most importantly, the properties of ENR/GW composites were compared with those of ENR composites filled with most widely used non-reinforcing filler calcium carbonate (CaCO3). In both ENR/GW and ENR/CaCO3 composites, the values of torque difference, hardness and tensile modulus increased steadily with increasing filler content. However, at same filler loading level, the mechanical and dynamic mechanical properties of ENR/GW composites were better as compared to those of ENR/CaCO3 composites. ENR/GW composite also exhibited considerably higher thermal stability as compared to either unfilled ENR or ENR/CaCO3 composite. As a whole, GW could be used as a cost-effective semi-reinforcing filler in ENR composites.

Effect of different gypsums on the workability and mechanical properties of red mud-slag based grouting materials

Abstract Grouting technology is widely used in the field of disaster prevention and in the control of underground engineering. Ordinary Portland cement based grouts are the most widely used grouting material at present. But it has the shortcomings of high energy consumption and high engineering cost. The development of a solid waste grouting material has become a current research effort in the field. This study examined the effect of incorporating gypsum dihydrate (NG), flue gas desulfurization (FGD) gypsum, and phosphogypsum (PG) on the workability and mechanical properties of red mud-slag grouting materials with different gypsum contents. Test results indicate that the incorporation of gypsums can decrease the fluidity and shorten the setting time of red mud-slag grouting materials. All of the specimens tested have rheological characteristics which follow the Herschel-Buckley model. All of the different gypsums significantly increased the compressive strength of the grout samples. Analysis of the hydration process, X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), infrared spectroscopy (IR), and scanning electron microscopy - energy dispersive spectrometry (SEM-EDS) showed that the increase in the compressive strength was due to the increase in the concentration of Al3+ and Si4+ leached from red mud and slag in the presence of SO42− and the generation of additional C–S–H. Fe3+ was shown to participate in the hydration process of the grout in the presence of SO42−. These results could lead to high-performance, low-cost grouting materials for grouting engineering, and promote the synergistic utilization of slag, red mud, and solid waste gypsum, to protect the ecological environment.

Use of Gypsum Waste and Tin Tailings as Stabilization Materials for Clay to Improve Quality of Subgrade

Clay is a soil with low stability, so an effort is needed to improve soil stability in order to improve the quality of subgrade. In this study, an effort was made to improve soil stability by adding gypsum waste and tin tailings as a mixture in clay. Gypsum waste and tin tailings have not been utilized optimally in Bangka Belitung Province, so the research needs to be done to determine the effect of using gypsum waste and tin tailings as a material for stability of clay. The tests of soil characteristics carried out in this study were sieve analysis, soil specific gravity, compaction and direct shear test. In this study, the addition of gypsum waste and tin tailings in soft soil with 4 variations, namely clay with additional 8% gypsum waste and 20% tin tailings, clay with additional 8% gypsum waste and 30% tin tailings, and clay with addition 8% gypsum waste and 40% tin tailing, besides that, testing of the original soil was also carried out. The results of sieve analysis test showed that the addition of gypsum waste and tin tailings to clay soils could change the gradation of clay. Addition of gypsum waste and tin tailings on clay soil increases cohesion (c) dan shear angel value so that increases soil shear strength. From the results of the study, the addition of gypsum waste and tin tailings can improve the stability of clay so Improve Quality of Subgrade.