Gypsum Composites Research Articles

Upcycling Automobile End-of-Life Tires for Development and Characterization of Circular Plasterboards

The number of end-of-life tires (ELTs) has increased enormously in the world during the last decades, accumulating progressively in landfills and ecosystems. For this reason, the application of secondary raw materials derived from their recycling has become one of the great challenges for today’s society. In this work, different types of prefabricated plaster products were developed incorporating recycled rubber aggregates from ELTs in different granulometries, aiming to study their feasibility to develop construction systems. It was possible to replace up to 40% of the original raw material, obtaining plasterboards that exceed the 0.18 kN flexural breaking load established by regulations. Likewise, the addition of these rubber aggregates reduced the thermal conductivity of the gypsum composites, and the thermal resistance of the lightened partitions was improved by up to 21.8% when used in conjunction with thermal break layer. On the other hand, its greater durability against the action of water was also tested, and fire resistance class B-s1, d0, was obtained. With all these positive results, this study presents a possible application of recycled rubber aggregates for the development of prefabricated plates and panels, addressing one of the main gaps in the literature, the applicability of these building materials produced under circular economy criteria in sustainable construction.

Fiber-reinforced gypsum composites with ultra high ductility: Investigation of physical and mechanical properties

The brittleness of traditional gypsum hinders its widespread utilization, despite its positive attributes as an environmentally and economically sustainable material. To tackle this challenge, Ultra High Molecular Weight Polyethylene (UHMWPE) fibers were introduced into gypsum matrix to produce a novel kind of gypsum composites with superior ductility (named Ultra High Ductility Gypsum Composites, UHDGC). Fiber content and water-gypsum ratio were investigated as experimental variables. Test results indicated that the UHDGC exhibits strong pseudo strain hardening behavior, with tensile strains capacity up to 7.4 %, which is several orders of magnitude higher than that of the original gypsum. The addition of fibers dramatically enhanced the strength and deformability of the UHDGC. With an increase in water-gypsum ratio, the compressive, tensile, and flexural strengths of the specimens decreased linearly, while toughness plateaued. Microscopic morphology analysis revealed that fibers were tightly bound to hydrated gypsum, and high fiber dosage (i.e., 2 %) led to fiber agglomeration. Furthermore, proposed prediction models for porosity and mean tensile cracking strength aligned well with test results. That can be an invaluable guide for the design and strength prediction of UHDGC.

САМОУПРОЧНЕННЫЕ ГИПСОВЫЕ КОМПОЗИЦИИ НА ОСНОВЕ ЗОЛ-УНОСА

This work is devoted to the study of self-reinforced gypsum stone with increased strength properties and low creep due to the reinforcement of the gypsum matrix with filiform ettringite crystals. However, with this method of self-reinforcement, difficulties may arise in providing a sufficient volume of an alkaline medium when using a saturated solution of calcium hydroxide obtained by slaking air calcium lime. The method is simplified by replacing saturated lime solutions with powder mixtures of fly ash captured by electrostatic precipitator systems during combustion of coals from the Kansk-Achinsk brown coal basin at thermal power plants. Gypsum composite based on fly ash has increased strength, which confirms the possibility of effective use of fly ash from the combustion of brown coal in building gypsum composites used to create structural elements of buildings. According to the study of the results of microscopic imaging of the resulting self-reinforced structure, the forming gypsum matrix becomes denser with differently directed crystals and fly ash microspheres included in the work. Utilization of fly ash waste in the composition of reinforced composites allows not only to simplify the method of self-reinforcement, reduce costs, but also to solve the problem of recycling chemically active ash.

A Newly Bio-Based Material for the Construction Industry Using Gypsum Binder and Rice Straw Waste (Oryza sativa)

Construction is one of the economic sectors with the greatest influence on climate change. In addition to working procedures, the primary carbon footprint is attributed to the choice of materials and the energy required for their manufacturing. The underlying idea of this study is to minimize the effects and offer new solutions to emerging problems in the quest for materials that can be deemed as natural, such as gypsum (calcium sulphate dihydrate) and rice straw (Oryza sativa). The acquisition of these materials involves a lower carbon footprint compared to the conventional materials. It is well known since ancient times that gypsum and cereal straw can be used in construction, with numerous examples still available. Cereal straw is one of the oldest construction materials, traditionally combined with earth and occasionally with certain binders, with it continuing to be employed in construction in many countries to this day. This work showcases the feasibility of producing stable prefabricated elements from straw waste with construction gypsum, addressing a significant environmental concern posed by the alternative of having to burn such materials. In this study, for the proposed bio-based material, specific tests, such as thermal conductivity, flexural and compressive strength, and fire resistance, were carried out to evaluate the principal physical and mechanical characteristics for different compositions of water, gypsum, and straw fiber samples. The results highlighted the good performance of the proposed materials in order to spread their use in the green building industry. The addition of straw fibers improved, in different ways, some important physical characteristics of these components so as to diminish environmental pollution and to obtain better material performance. The tests highlighted the different behaviors of the proposed material with respect to the different cuts of the straw and as well as the water/gypsum ratio; this is not very well understood and probably depends on the micro structure of the straw fibers. The blocks with raw straw showed a significant improvement in the breaking mechanism (1775.42 N) compared to the blocks with cut straw (712.26 N) when subjected to bending tests, and their performance in compression tests was also acceptable. Additionally, a very interesting reduction in thermal conductivity was achieved by incorporating rice straw (0.233 W/mK), and high fire exposure times were obtained, with gypsum preventing the spread of ignition in any type of fiber.

Manufacturing and mechanical performance of lightened gypsum reinforced by hemp/epoxy composites

In recent years, the construction industry has increasingly focused on reducing its environmental impact, addressing research efforts towards innovative materials and technological solutions. In this context, gypsum-based materials and natural fibers represent some of the most promising alternatives in terms of sustainability. This paper aims to propose a new gypsum structure reinforced with a composite hemp fabric impregnated with epoxy resin, investigating its manufacturing process and the mechanical properties, specifically in terms of flexural, impact and bearing strength. To achieve lightweight structures, lightened gypsum was also considered in addition to conventional gypsum. Both the lightened gypsum matrix and the hemp/epoxy reinforcement were produced using specific techniques able to obtain lightweight gypsum composites. Beneficial effects in the use of lightened gypsum matrix were found indeed, the reinforced lightweight samples exhibited higher values of flexural strength coupled with a density reduction of about 18%. Additionally, a significant change in post-cracking behavior was observed, with a gradual failure rather than a brittle one. The same trend was observed for the impact, while for bearing strength, the presence of porosity affected negatively the resistance of the composites, prevailing over the benefits of density reduction. Experimental results demonstrated the presence of a good interaction between the hemp fabric and the gypsum matrix, which was further confirmed by the microstructure analysis. The interesting mechanical properties showed by these lightweight gypsum/hemp composites, suggested their possible use for different and unconventional applications of gypsum-based walls and components.

Water Resistance Analysis of New Lightweight Gypsum-Based Composites Incorporating Municipal Solid Waste

Incorporating waste to produce new environmentally friendly construction products has become one of the great challenges of the industry nowadays. The aim of this research is to analyse the behaviour of novel gypsum composites against water action, incorporating recycled rubber aggregates (up to 8.5% vol.) and dissolved expanded polystyrene (up to 10.0% vol.). To this end, a total of 10 dosages have been proposed with the progressive substitution of natural resources by these secondary raw materials. The results show how it is possible to reduce the total water absorption of the gypsum composites by up to 8.3% compared to traditional gypsum material. In addition, it is also possible to reduce water absorption by capillary by up to 52.7%, resulting in lighter composites with good performance against water action. In all composites analysed, the mechanical strengths exceeded the minimum values of 1 MPa in bending and 2 MPa in compression, making them an optimal solution for the development of lightweight prefabricated products for damp rooms.

Upcycling EPS waste and mineral wool to produce new lightweight gypsum composites with improved thermal performance

Energy efficiency and waste management are crucial for sustainability of construction sector. In this research, a new gypsum composite material is presented in which traditional raw materials have been partially replaced by thermal insulation waste from facades energy retrofitting projects, using an innovative process to recover this waste. Consequently, a novel lightweight gypsum composite has been developed with a replacement of up to 14.7 % by weight of the original material with EPS waste, adding mineral wool as reinforcement fibres (0.375 %wt.). Thus, thermal behaviour analysis of these new composites has been conducted, both material itself and of its performance as part of a real construction system, including finite element analysis of the construction system. In addition, the physicochemical, physical and mechanical characterisation of the new composites has been carried out. Results show that the developed new material has a density 20.3 % lower than the traditional gypsum composite, resulting in a 30.4 % reduction in thermal conductivity. Furthermore, the use of these new lightened gypsum composites as finishing boards in lightweight steel frame (LSF) wall systems reduces the overall thermal resistance of the wall by up to 10.6 % with just 25 mm thickness. On the other hand, the mechanical resistance of this new material exceeds the reference values established by current standards, ranging between 4.18 and 1.87 MPa for flexural strength and between 7.87 and 4.27 MPa for compressive stresses. Additionally, the developed composites have shown a reduction in both total and capillary water absorption compared to traditional gypsum by 19.6 % and 40.0 % respectively, enhancing the material’s durability and its excellent thermal properties throughout its lifespan.

The Influence of Hemp Fibers (Cannabis sativa L.) on the Mechanical Properties of Fiber-Gypsum Boards Reinforcing the Gypsum Matrix.

The modern construction industry is looking for new ecological materials (available, cheap, recyclable) that can successfully replace materials that are not environmentally friendly. Fibers of natural origin are materials that can improve the properties of gypsum composites. This is an important issue because synthetic fibers (hardly biodegradable-glass or polypropylene fibers) are commonly used to reinforce gypsum boards. Increasing the state of knowledge regarding the possibility of replacing synthetic fibers with natural fibers is another step towards creating more environmentally friendly building materials and determining their characteristics. This paper investigates the possibility of manufacturing fiber-gypsum composites based on natural gypsum (building gypsum) and hemp (Cannabis sativa L.) fibers grown in Poland. The effect of introducing hemp fibers of different lengths and with varying proportions of mass (mass of gypsum to mass of fibers) into the gypsum matrix was investigated. The experimental data obtained indicate that adding hemp fibers to the gypsum matrix increases the static bending strength of the composites manufactured. The highest mechanical strength, at 4.19 N/mm2, was observed in fiber-gypsum composites with 4% hemp fiber content at 50 mm in length. A similar trend of increased strength was observed in longitudinal tension. Again, the composite variant with 4% fiber content within the gypsum matrix had the highest mechanical strength. Manufacturing fibers-gypsum composites with more than 4% hemp fiber content negatively affected the composites' strength. Mixing long (50 mm) hemp fibers with the gypsum matrix is technologically problematic, but tests have shown a positive effect on the mechanical properties of the refined composites. The article indicates the length and quantity limitations of hemp fibers on the basis of which fiber-gypsum composites were produced.

Evaluation of environmental geochemical signatures due to RO rejects on arid agricultural farms and tangible solutions

The impact of reverse osmosis (RO) rejects in the groundwater presents a significant challenge in arid regions. This study collected groundwater samples, product water, and reverse osmosis brine (ROB) from evaporation ponds and analyzed them for major ions and trace elements. Test boreholes were drilled near the ROB site along the flow direction, and borehole sediment samples were collected. The samples were predominantly gravelly sand, and the depth to water level fluctuated around 30 m below ground level (bgl), with minerals mainly consisting of calcite, gypsum, and quartz. Data loggers reflected a rise in water level (<22 m bgl) corresponding to higher electrical conductivity (>16 mS/cm) during the cropping period in many locations, confirming the impact of ROB in groundwater. The results were further supported by enriched signatures of δ18O (∼ +1.5‰) and δ2H (∼ +15‰). The saturation index of the minerals reflected that carbonate minerals (Calcite > Dolomite) were saturated in the ROB relative to the groundwater. The vertical variation of mineral assemblages in the boreholes indicated gypsum precipitation in the capillary zone along with calcite and dolomite. The assemblage varies as the groundwater moves from the disposal site. The speciation of different compounds along the groundwater path indicated higher carbonate and sulfate species (CaCO3 > CaHCO3> CaSO4 > NaSO4 > MgSO4) near the disposal site, with variations along the flow direction. Considering the significant variation in temperature in the region (5 to 50 ℃), the water sample composition was modeled using PHREEQC, suggesting that the increase in temperature led to supersaturation of epsomite and gypsum compositions. The ROB was theoretically mixed with groundwater and product water in different proportions, and an optimum composition (10:90) for safe disposal was derived and tested fit for reuse in agriculture.

Effect of fiber content on flexural properties of jute fiber reinforced perlite/gypsum composite core-based sandwich structures

In this work, two types of sandwich structures were fabricated to develop sustainable building materials using renewable and waste resources. The chopped jute fiber reinforced perlite-filled gypsum composite was used as the core and the brown paper and the woven jute fiber reinforced epoxy composite (JFRC) were used as skins to manufacture the sandwiches. The effect of jute fiber content (10 g - 20 g) in the core on the flexural properties was studied. The flexural test was conducted to determine the flexural strength, modulus, energy absorption, and the load-bearing capacity of brown paper skin-based sandwiches (BPSS) and JFRC skin-based sandwiches (JFSS). The results of this study show that the flexural properties of both BPSSs and JFSSs are improved significantly with increasing jute fiber content up to 17.5 g indicating the optimum fiber content. The flexural strength and modulus of BPSS at 17.5 g jute fiber content are respectively 8.44 % and 30.16 % greater than those at 10 g jute fiber content. On the other hand, the JFSSs show 30.24 % and 60.36 % increase in flexural strength and modulus respectively at 17.5 g jute fiber content compared to those at 10 g fiber content. The flexural energy absorptions of BPSS and JFSS are also increased by 45.40 % and 22.90 % respectively when jute fiber content in the core is increased from 10 g to 17.5 g. The specific load-bearing capacity of JFSSs is 130.38 % - 216.56 % greater than BPSSs depending on the fiber content in the core.

Advancing reinforcement of sustainable gypsum composites: High-performance design by reusing waste materials

This study tends to optimize and develop an innovative gypsum material by incorporating hybrid waste compounds. Using a Doehlert design, this work explores the effects of introducing paper (X1), polystyrene (X2), and polyester fibers (X3), as well as their interactions, on gypsum's thermophysical and mechanical behavior. Bulk density, thermal conductivity, flexural strength, compressive strength, and the fire resistance test were performed on the developed formulations. Statistical analysis emphasizes the significant influence of all process variables on gypsum properties. Polyester fibers notably enhance flexural strength when combined with the cooperative effect of paper and polystyrene wastes, which strike a balance between physical and mechanical characteristics. The optimum formulation parameters lead to a significant 33% decrease in bulk density, a 43% reduction in thermal conductivity, a notable 42% increase in flexural strength, and a significant reduction in compressive strength of around 50%, but still meet the 2 MPa standard. The new samples show ductile behavior, highlighting gypsum's potential as a load-bearing material with excellent thermal insulation properties and impressive fire resistance. This research significantly improves our understanding of the effectiveness of a gypsum compound incorporating waste in a hybrid manner, bringing this approach into line with sustainable development objectives.

Eco-friendly construction materials: new gypsum-based composite with dregs waste from the cellulose industry

The production of materials for civil construction is a process that imposes a significant environmental impact, due to factors, such as the extraction of raw materials and the high energy consumption required to obtain the final product. Consequently, the search for new materials has grown seeking more environmentally sustainable materials. An approach to address this issue is to incorporate industrial residues as fillers to replace traditional construction materials. In this study, dregs, a waste product generated by the cellulose-paper industry, were used as a filler in gypsum composites. Gypsum plasters were replaced with dregs in proportions of 5, 15, 30, and 45%, in nature (GD x ) and Na2SO4-treated (GTD x ). The compressive strength of the resulting composites was evaluated after 21 days. Compared to gypsum plaster (17.01 MPa), the incorporation of GD5 led to a reduction of 18.6% in compressive strength (13.84 MPa), while GTD5 demonstrated mechanical properties similar to those of gypsum plaster (17.02 MPa). Composites with incorporation of up to 30% of treated dregs presented mechanical resistance above the standard international recommendations. Thus, the gypsum/dregs composite has the potential alternative to the partial replacement of plaster in civil construction, providing a more sustainable solution to the current environmental challenges.

INCREASING THE WATER RESISTANCE OF THE PLASTER MIXTURE BASED ON GYPSUM-CONTAINING BINDER

The article considers the prospects of using gypsum-based composite materials for repairing damaged walls of limestone-shell rock buildings. Repairing damaged shell rock structures with cement compositions intensifies destructive processes; the use of lime-sand mixtures for repair work on building facades is problematic due to their prolonged hardening. The article substantiates the use of gypsum as the basis of the repair composition. The use of gypsum composites for exterior works requires a significant increase in their water resistance. A plaster mixture based on an ash-cement binder with an addition of lime is proposed; a series of samples with different component contents were made in the planned experiment. Their water resistance was studied using two criteria: the conventional softening coefficient (Кр) and the new one - the water resistance index (Iw); a comparison of these criteria was performed. The significant dependence of these criteria on the measurement conditions, which are not currently standardized, is established. Mathematical models of water resistance characteristics have been built, with the help of which the influence of the content of components on the resistance of the plaster composition to water has been analyzed. To further improve the water resistance of the mixture, a hydrophobizing additive was selected in terms of surface wetting and water absorption. Further research is aimed at optimizing the repair composition using plasticizing, hydrophobizing, and adhesive additives.

Evaluating Sisal Fiber-Reinforced Gypsum Composites for Water Absorption and Mechanical Performance

There has been a great research interest for investigation of new construction materials which can reduce environmental impact and cost, with improved structural performance. Recently, sisal fiber is being used as a reinforcement material in the development of reinforced composites. Here, sisal fiber-gypsum reinforced composites were prepared using the hand lay-up method followed by the compression technique. The effects of weight percentage (Wt. %) of the sisal fiber reinforcement on the mechanical properties of the developed sisal fiber-gypsum composites were investigated experimentally by varying the Wt. % as 5, 10, and 15%. The mechanical properties were tested as per the ASTM standards. The results revealed that the long unidirectional sisal fiber-gypsum composites exhibited higher impact and hardness strengths with lower water absorption behaviour than the short-chopped sisal fiber-gypsum composites. In addition, the impact strength increased with increase in Wt. % for both short-chopped and long unidirectional sisal fiber reinforcement. While the hardness strength decreased with increase in Wt. % for both short-chopped and long unidirectional sisal fiber. The experimental investigation has established sisal fiber as an important reinforcement material for improving the performance of the neat gypsum in a wide range of architectural applications such as ceilings, decorative partitions, and light covers.

Physico-mechanical characterization of eco-friendly gypsum composites incorporating shredded surgical face masks

Physico-mechanical characterization of eco-friendly gypsum composites incorporating shredded surgical face masks

Assessment of the Thermal Properties of Gypsum Plaster with Plastic Waste Aggregates.

Building material manufacturers must support new production models that encourage the manufacture of more efficient and sustainable products. This includes thinking about savings in the use of raw materials, a contribution to the energy efficiency of buildings during their useful life, and a reduction in the generation and deposit of waste in landfills. In this research, an analysis of the thermal properties of gypsum composites added with plastic waste is carried out using the most common methods, the steady state method and the transient plane source method, and the effect of water saturation on these composites is tested. The results show an improvement in the thermal performance of the composites (values reduced with respect to the reference by 4-7%), despite their heterogeneity, as well as a variation in the measurements carried out, depending on the method used for the measurements (variation up to 10%). It is also found that the degree of humidity negatively affects the thermal conductivity coefficient but, on the contrary, this coefficient is not altered in the composites with plastic waste, due to their lower hygroscopicity. Therefore, it is considered that the proposed eco-plasters are a good alternative to traditional plasters, with which to contribute to the achievement of the objectives of the current European directives on waste and circular economy.

Integration of Phase Change Materials in Service Areas of Building Envelopes for Improved Thermal Performance: An Experimental Study in Saudi Arabia

This experimental study explores the integration of Phase Change Materials (PCMs) within building envelopes. The research specifically centers on the utilization of two microencapsulated paraffin-based PCMs with melting points of 37 °C and 43 °C. The study assesses their performance within cement and gypsum-based PCM composites, concentrating on service areas often overlooked in thermal analysis, including underground garages, staircases, and utility rooms. The experimental setup included constructing three chambers inside an underground garage during the hot months of June and July in Saudi Arabia. Two chambers were assigned to integrate the PCM, while the third chamber served as a control without PCM. The experiment unfolds in two phases. In the initial phase, the objective was to determine which PCM is more effective in reducing the heat load inside the chambers. This led to the adoption of the 43 °C PCM for the subsequent stage. The adoption of the 43 °C PCM resulted in a fourfold decrease in heat compared to the 37 °C PCM. The second phase investigates the integration of the selected PCM with cement and gypsum composites. The percentage of PCM incorporated into the concrete and gypsum composites was determined experimentally. For cement-based composites, the identified percentage that maintains material integrity is 20%, and for gypsum-based composites, it is 22%. The findings demonstrate a significant reduction in cooling load with PCM incorporation, with cement-based composites exhibiting superior thermal performance compared to gypsum-based alternatives and reducing the heat load by approximately 63%. Additionally, it was observed that concrete reduced the highest temperature during the day by 5.2 °C, which equates to about a 10% reduction, further enhancing comfort. Conducted over the course of two summer seasons, this study contributes valuable insights toward improving the quality of life for building occupants, considering various factors such as their living environment.

Enhancement of strength and water resistance of macro-defect free （MDF） gypsum modified by pregelatinized starch and hydrogen silicone oil

Gypsum, as a building material with renewable and environmentally friendly characteristics, is severely limited due to its poor mechanical properties and water resistance. Here, this paper investigates pregelatinized starch and hydrogen silicon oil modified macro-defect free (MDF) gypsum composite prepared by pressing. The compressive strength, water absorption, and softening coefficients of foamed MDF gypsum composite were subjected to strict testing. The hydration products, microtopography and pore structure was characterized using XRD, FTIR, SEM and LF-NMR. The result shows that the compressive strength of MDF gypsum composite with 5 % pregelatinized starch was 82.4 MPa, a 44.5% increase compared to the dry blank group, whilst water absorption also rose by 7.8%. Additionally, the compressive strength of MDF gypsum composite with 5 % pregelatinized starch and 1% hydrogen silicon oil was 123.9 MPa, 225.2% higher than that of the dry blank group. The water absorption rate decreases to less than 1.2%. Pregelatinized starch and hydrogen silicone oil assist in the accumulation and arrangement of crystals, while also reducing the space between them. The enhancement mechanism of compressive strength and water resistance of MDF gypsum involves pore filling by pregelatinized starch, as well as crystal contact point modification including stronger adhesion by the pregelatinized starch and hydrophobic properties of hydrogen silicon oil.

Development and Characterization of Innovative Hemp–Gypsum Composites for Application in the Building Industry

At present, the development of new eco-friendly building materials for the production of lightweight partitions has become a challenge in order to advance towards the industrialization of the building sector. This work aims to design, characterize, and analyze the possibilities of applying innovative ecological gypsum composites lightened with hemp. To achieve this, samples have been prepared with partial replacement of 15% and 30% in volume of the original gypsum material by adding hemp both in the form of powder and fiber. The results show how the replacement of 15% of gypsum by hemp fiber with a length between 8 and 12 mm improves the flexural strength of the composites. Likewise, all the dosages prepared for this study have met the minimum requirements for mechanical strength required by current regulations, while also improving the water resistance behavior of gypsum composites. However, the main advantage derived from the use of these hemp-lightened gypsum-based materials lies in their reduced thermal conductivity, being up to 50% lower than that obtained for traditional materials. These results suggest the possible application of these materials to produce prefabricated boards and panels for a more sustainable construction.

Gypsum reinforced using hemp fibers: Enhanced interfacial compatibility by dual-modification strategy

Natural fibers are promising as enhancements for gypsum. Herein, the effect of using untreated, NaOH-modified, and dual-modified hemp fibers on enhancing performances of gypsum composites is examined. The dual-modification strategy applies secondary treatment on NaOH-treated fibers with NaClO, polyoxyethylene, or Tween-80. The fibers and composites are characterized by SEM, ATR-FTIR, XRD, mechanical strength, etc. The secondary modification enhances interfacial compatibility between gypsum and fibers. Compared with pure gypsum, the elastic modulus and bending strength of the composites with dual-modified fibers increase by 56% and 42%, respectively. Hydration process reveals that dual-modification using polyoxyethylene contributes to form dense, compact composite structures.