Review of gypsum reinforced composites as building materials

Abstract

The utilization of gypsum reinforced composites as building materials has garnered considerable attention owing to their exceptional amalgamation of mechanical strength, fire resistance, and versatile applications. This review initiates by introducing gypsum as a pivotal mineral in construction, subsequently exploring the concept of composite materials and elucidating the synergistic effects achieved through reinforcement. Various reinforcement types, such as fibers, polymers, and particles, are meticulously evaluated for their contributions in augmenting mechanical properties, acoustic and thermal insulation, as well as fire resistance in gypsum composites. The review extensively discusses the mechanical attributes of gypsum composites, focusing on compressive strength and flexural behavior enhancements attained through strategic reinforcement methods. Looking ahead, the review emphasizes ongoing research endeavors dedicated to refining material formulations, exploring cutting-edge technologies, and uncovering innovative applications. By addressing challenges and capitalizing on advantages, these composites stand poised to revolutionize conventional building practices, bolster sustainability, and enhance safety and efficiency in built environments.

1 Introduction

The construction industry constantly seeks innovative building materials that balance structural strength, environmental sustainability, and functional versatility. Gypsum-reinforced composites have emerged as a promising avenue in rethinking construction practices. These composites, stemming from the fusion of gypsum—a mineral known for its fire-resistant properties—and various reinforcing materials, present significant potential in tackling the multifaceted challenges faced by the construction sector [1, 2].

Gypsum, a pivotal building material, is formed by heating gypsum rock to eliminate its naturally occurring crystallization water, a technique utilized since ancient times. By subjecting calcium sulfate dehydrate (CaSO₄⋅2H₂O) from gypsum rock to varying temperatures, partial or complete dehydration occurs [3,4,5]. Heating beyond 190–200 °C results in the complete dehydration of gypsum rock, yielding CaSO₄, commonly referred to as gypsum anhydrite [6,7,8,9] due to the loss of crystallization water.

The hemihydrate phase (CaSO₄⋅2H₂O) can take two crystalline structures, alpha or beta, contingent upon the calcination method during manufacturing. The alpha form originates from a wet process from gypsum, while the beta form results from a dry process extracting water vapor as it forms. Paris plaster, known as the alpha-hemihydrate, finds applications in construction [7,8,9]. Extensive research has investigated the hydration of hemihydrate, exploring kinetics and setting characteristics [10,11,12,13,14,15].

Le Chatellier's hydration technique involves the dissolution of hemihydrate in water, releasing Ca²⁺ and SO₄²⁻. These ions combine to form a dihydrate, precipitating out of the solution and creating crystallization nuclei. These nuclei are enveloped by crystals, forming a network of long, interconnected crystals that bolster the substance's strength [12, 16, 17]. The resulting material, (CaSO₄⋅2H₂O), mirrors gypsum rock chemically [18, 19].

The microstructure of the hardened paste is shaped during the hydration process and is influenced by the water-to-gypsum ratio, initiating hydration processes and ensuring the workability of the gypsum slurry. Elevated water content weakens the bond between gypsum crystals, causing vacancy fractions and diminishing material strength [12, 20]. Particle size distribution, particle diameter (fineness), and homogeneity coefficient also impact the water requirement for maintaining slurry workability [21].

Compared to other inorganic cements, gypsum binders are considered more environmentally friendly due to their lower thermal treatment temperatures and closed-loop recycling capability [3, 22, 23]. Gypsum plasters are extensively used in ceiling designs, partition walls, and wall coverings. Gypsum-based materials, including mortar, composites, and boards, are increasingly favored in construction for their exceptional fire resistance, thermal properties, and sound insulation features [24,25,26,27,28,29,30,31,32,33].

Gypsum board, commonly recognized as drywall or plasterboard, is a prevalent interior building material in construction, widely utilized for finishing purposes. Created by bonding gypsum plaster to a sturdy paper liner, it offers a reliable and cost-effective solution for partitioning components in residential and commercial projects. The design and thickness of gypsum boards can be easily adjusted to meet specific structural and acoustic requirements. The usage of gypsum boards continues to rise, necessitating further research to comprehend their characteristics and behaviors. While gypsum boards boast excellent sound insulation, rapid manufacturing, and easy installation [34,35,36], they have drawbacks like flimsiness, low flexural strength, and inadequate sound absorption.

Scientists have explored various additive-based methods to enhance the physical and mechanical properties of gypsum products. These methods encompass the use of expanded polystyrene (EPS), foaming agents, silicate fillers (vermiculite, perlite, silica fume, fly ash, clay minerals), mineral wool, glass fibers, organic fibers, rice husk [37], and cork [38]. Previous research has also employed natural and fiberglass fibers to distribute stress load within the composite, addressing issues of low flexural strength [39, 40].

Despite the favorable attributes of gypsum products, challenges like waste generation due to rapid setting times persist. Research endeavors focus on improving sustainability and reducing waste production in gypsum-based materials [17, 41].

Developing gypsum composites with natural fiber that maintain acceptable mechanical properties while considering thermal and acoustic characteristics becomes crucial to address environmental concerns related to carbon dioxide emissions from synthetic fiber production [42]. According to Jiménez-Rivero et al. [43], the energy-related conservation and recycling life cycle of gypsum plasterboard highlight the health benefits of natural fiber gypsum composites by minimizing dangerous dust produced during the separation phase.

Various review studies on gypsum composites shed light on their distinct characteristics. Al-Rifaie [44] examined palm fiber-gypsum composites and found that, despite maintaining an advantage over fiberglass composites, the compressive strength declined with increasing palm fiber content. Iucolano et al. [45] suggested that employing bio-degummed hemp as reinforcement improved the mechanical properties and thermal resistance of gypsum composites. This body of research collectively concludes that fiber reinforcement significantly and efficiently modifies the mechanical properties of gypsum composites, tailoring them for specific applications.

Previous studies on the performance of natural fiber-gypsum composites scrutinized their mechanical, physical, and fiber characteristics [46,47,48,49,50,51,52], as well as thermal [53], and microstructure [41, 54, 55]. Overall, reinforced gypsum boards incorporating natural fibers are found to be a safer and more environmentally friendly alternative in construction applications.

The review on gypsum composites presents valuable insights but also highlights several areas for further investigation and refinement. Firstly, it indicates a need for deeper exploration into the synergistic effects achieved through reinforcement, particularly in elucidating the underlying mechanisms that optimize composite properties. Additionally, there's a call for a more comprehensive characterization of mechanical properties, including factors influencing compressive strength and flexural behavior under varying loading conditions. Moreover, the review underscores the importance of exploring novel reinforcement materials beyond the currently mentioned natural fibers. Investigating alternative reinforcement options and their impact on composite properties could lead to significant advancements in gypsum composite technology. Furthermore, the review suggests addressing practical implementation challenges associated with manufacturing, handling, and installation of gypsum composites in real-world construction scenarios. Understanding and mitigating these challenges could facilitate wider industry adoption of gypsum-based materials, ultimately enhancing their practical utility and sustainability.

The purpose of this article is to delve into the properties, applications, and benefits of gypsum composites in construction. It aims to educate readers on the significance of these materials in enhancing building performance and sustainability while providing insights into their various uses and advancements in the field. Additionally, the article explore emerging trends and innovations in gypsum composite technology to offer a comprehensive understanding of their role in contemporary construction practices.

2 Introduction to gypsum and its composites

In the construction realm, the convergence of age-old materials and groundbreaking innovations defines an intriguing landscape. Gypsum reinforced composites stand as a synthesis of tradition and modernity, blending time-honored attributes with contemporary engineering. This exploration aims to delve into the realm of gypsum reinforced composites, unraveling their characteristics, applications, and the transformative potential they offer within construction.

2.1 Gypsum's enduring presence in construction

Gypsum, a naturally occurring mineral comprising calcium sulfate dihydrate, boasts a storied legacy in construction. Its renowned fire resistance and mold inhibiting qualities have rendered it a cornerstone in interior finishes, partitions, and ceilings. Gypsum's historical application stems from the quest to harmonize functionality, safety, and aesthetics. Its widespread availability further cements its enduring appeal in construction.

2.1.1 Composite materials: innovating construction

Composite materials, at the intersection of materials science and construction, amalgamate distinct elements to create materials with heightened properties. Embraced across industries like aerospace and automotive, composites unlock new possibilities, addressing challenges and fostering creative potential within the construction sector.

2.1.2 Unveiling the potential of gypsum reinforced composites

Gypsum composites are materials composed primarily of gypsum, a soft sulfate mineral, combined with various additives to enhance its properties. These composites are widely used in construction due to their fire resistance, sound insulation, and mold resistance characteristics. They are commonly employed in interior walls, ceilings, and partitions.

The importance of gypsum composites in construction lies in their ability to improve building safety, comfort, and durability while also offering cost-effective solutions. These materials contribute to the overall structural integrity of buildings and provide thermal and acoustic insulation, making them essential components in modern construction practices.

Gypsum reinforced composites epitomize this fusion, amalgamating gypsum's advantages with diverse reinforcements to craft a versatile material. Leveraging gypsum's innate fire resistance, these composites elevate it with enhanced mechanical properties, thermal insulation, and design flexibility. By marrying these elements, gypsum composites surpass traditional gypsum limitations, paving the way for safer, more efficient, and visually captivating construction solutions [56].

To mitigate gypsum composites' brittleness, researchers integrate organic and inorganic fibers at low water and gypsum concentrations, enhancing their durability and reducing weight [57, 62]. Strategies involve concentrating fibers in stress zones to counter external pressures or creating a homogenous mix with evenly distributed fibers throughout the matrix [58]. Notably, natural gypsum composites with fiber reinforcement exhibit lower mechanical strength compared to synthetic gypsum composites [59]. To address synthetic fiber's environmental impact, a shift toward natural fiber usage is observed, despite the cost-effectiveness favoring synthetic options [57]. Synthetic fiber-reinforced gypsum composites, while pricier, lack biodegradability unlike their natural fiber counterparts, posing environmental concerns.

2.2 Types of gypsum reinforced composites

This section explores the diverse methodologies of combining gypsum with various materials to fabricate composite materials suitable for construction applications.

2.2.1 Gypsum-fiber composites

Gypsum-fiber composites amalgamate natural fibers like jute, flax, or hemp with gypsum, presenting a blend of sustainability and performance. These natural fibers introduce biodegradability, reduce embodied energy, and minimize environmental impact. When integrated with gypsum, they bolster fire resistance and insulation, enriching the repertoire of eco-friendly construction materials [60]. Incorporating natural or synthetic fibers into gypsum-based materials such as drywall, plaster, and composites is a standard practice in the construction industry [61, 62]. Glass, cellulose, and basalt fibers are commonly utilized to fortify tensile and flexural strength, thereby augmenting the overall toughness of these composites [63]. The process involves integrating fibers into the gypsum slurry before casting, molding, or application. The dispersed fibers play a crucial role in:

• 1. Stress Distribution: Fibers aid in evenly distributing mechanical stresses within the gypsum matrix, mitigating its inherent brittleness and low tensile strength. This redistribution of load between gypsum and fibers diminishes the likelihood of localized stress concentrations, thereby reducing cracks or fractures [64].

• 2. Crack Prevention: Fibers act as barriers impeding crack formation and propagation. Their presence within the composite disrupts crack advancement, diverting or stopping it along a convoluted pathway. This characteristic significantly elevates tensile and flexural strength [64].

• 3. Enhanced Toughness: Incorporating fibers significantly fortifies the composite's overall toughness. When subjected to stress, the fibers absorb and dissipate energy by deforming and breaking, thereby preventing abrupt failure and bolstering resilience and durability.

The choice of fiber type, length, concentration, as well as their distribution and bonding within the gypsum matrix, profoundly influences specific mechanical properties [65, 66].

2.2.2 Gypsum-polymer composites

The construction and materials industry commonly employs a blend of polymers such as acrylics, polyvinyl acetate (PVA), or styrene-butadiene (SBR) with gypsum. This combination effectively merges the flexibility inherent in polymers with the structural robustness of gypsum, resulting in composite materials that exhibit superior qualities. These composites offer heightened impact resistance, enhanced durability, and increased water resistance. By harnessing the hardness of gypsum and the resilience of polymers, this amalgamation finds widespread utility across various construction applications [67, 68]. Notably, it reinforces interior wall panels and ceilings, creating drywall with superior properties. Additionally, it bolsters the durability of underlayment and self-leveling compounds in flooring, enhances the weather resistance of exterior coatings, and unlocks new possibilities for durable sculptures and decorative elements. This seamless integration of polymers and gypsum significantly elevates the performance and longevity of products within the construction and manufacturing sectors [69].

2.2.3 Gypsum-particle composites

The properties of gypsum-based materials can be significantly transformed by incorporating various particles like sand, perlite, or lightweight aggregates. This addition alters aspects such as density, thermal conductivity, and acoustic insulation [70], customized to suit diverse applications, from construction to interior design. Crucial to these changes are the size and distribution of the particles, impacting both the structural integrity and thermal performance of the composite.

The introduction of these particles into gypsum reduces the overall density of the resulting composite [71]. Lightweight aggregates like perlite or expanded clay are often employed for this purpose as they are less dense than gypsum, displacing some of its material within the matrix. This yields a lighter composite, especially favored in applications prioritizing reduced weight, such as lightweight concrete or ceiling plasterboard.

Furthermore, the incorporation of particulate materials can influence the structural behavior of gypsum composites. For instance, adding sand enhances the strength and load-bearing capacity, crucial for applications demanding structural robustness [70]. The mechanical properties of the composite are affected by particle size and distribution: smaller particles bolster strength and cohesion, while larger, unevenly distributed ones might create vulnerabilities.

Utilizing particulate materials to modify gypsum-based composites offers versatility in tailoring their properties to specific needs. Considering particle size and distribution becomes paramount in designing gypsum composites for targeted applications ensuring desired structural and thermal characteristics are achieved [67, 70].

2.2.4 Gypsum-nanocomposites

Gypsum nanocomposites are at the forefront of materials science, integrating nanoscale additives such as nanoparticles or nanofibers into gypsum-based materials [72]. These additions offer several benefits:

• 1. Enhanced Strength and Toughness: Nanoscale materials significantly increase the strength and toughness of gypsum composites, crucial for applications requiring robust structural integrity.

• 2. Improved Durability: Nanomaterials create a barrier, reducing water absorption and enhancing the durability of gypsum nanocomposites, particularly in moisture-prone environments.

• 3. Enhanced Fire Resistance: The inclusion of nanoscale additives improves the fire resistance of gypsum materials, slowing down combustion and enhancing overall fire performance, especially in construction materials.

• 4. Superior Thermal Properties: Gypsum nanocomposites exhibit superior thermal insulation and conductivity due to the inclusion of nanoscale materials, making them more energy-efficient and suitable for applications requiring precise temperature control.

2.2.5 Hybrid composites

Hybrid composites stand as sophisticated materials amalgamating various reinforcement elements like fibers, particles, and polymers, yielding a composite that embodies a harmonious spectrum of properties [73]. This approach facilitates the fine-tuning of material traits, catering to precise performance demands across a broad array of uses. The crux of hybrid composites lies in recognizing that individual reinforcement materials possess unique strengths and limitations [74, 75]. By artfully merging these materials, designers craft composites that leverage the strengths of each component while offsetting their weaknesses. The outcome is bespoke composites presenting an unparalleled amalgamation of properties tailored to meet specific application requisites. Hybrid composites furnish a flexible, customizable avenue for material innovation. They grant engineers the prowess to fashion materials tailored precisely to meet distinct performance criteria across diverse industries. By judiciously selecting and integrating different reinforcement types, hybrid composites furnish bespoke solutions for applications where conventional materials come up short.

2.2.6 Bio-based gypsum composites

The trend of using bio-based materials as reinforcement in gypsum composites is gaining momentum for several sustainability-related reasons. This innovative approach involves incorporating agricultural residues, natural fibers, or bio-based polymers into gypsum-based construction materials to reduce environmental impact and lower the carbon footprint [76]. Natural fibers, such as jute, hemp, and flax, are being incorporated into gypsum composites to enhance their mechanical properties. These fibers are biodegradable, have a low environmental impact, and can potentially replace synthetic reinforcements like glass fibers, which have a higher carbon footprint. Many green building certification programs, such as LEED (Leadership in Energy and Environmental Design), reward the use of sustainable and bio-based materials [77]. Using these materials in gypsum composites can help construction projects earn certification points and meet sustainability goals. The trend of incorporating bio-based materials into gypsum composites offers substantial environmental benefits by reducing the carbon footprint, promoting the use of renewable resources, and enhancing the sustainability of construction materials [78]. As sustainability becomes an increasingly important consideration in the construction industry, these innovations are likely to gain more prominence in the market.

Incorporating bio-based materials into gypsum composites presents several challenges, but with innovation and research, many of these obstacles can be overcome. Some of the significant challenges include:

• 1. Compatibility: Bio-based materials may have different properties compared to traditional additives used in gypsum composites. Ensuring compatibility between the bio-based materials and gypsum matrix is crucial to maintain the desired mechanical properties and durability.

• 2. Moisture Sensitivity: Many bio-based materials are susceptible to moisture absorption, which can lead to dimensional instability and degradation of the composite over time. Strategies such as surface modification or encapsulation can be employed to reduce moisture sensitivity and improve the durability of the composite.

• 3. Processing Conditions: The processing conditions required for incorporating bio-based materials into gypsum composites may differ from those used for traditional additives. Optimizing processing parameters such as temperature, pressure, and mixing time is essential to achieve homogeneous dispersion of bio-based materials within the gypsum matrix.

• 4. Cost: Bio-based materials may be more expensive than traditional additives, which can impact the overall cost of producing gypsum composites. However, advancements in manufacturing techniques and economies of scale can help reduce the cost of bio-based materials and make them more competitive in the market.

• 5. Performance: Bio-based materials may not always offer the same level of performance as traditional additives in terms of strength, fire resistance, and other mechanical properties. Research and development efforts focused on improving the properties of bio-based materials through chemical modifications or blending with other additives can help overcome this challenge.

• 6. Scale-up and Commercialization: Scaling up the production of gypsum composites incorporating bio-based materials from laboratory-scale to commercial-scale can be challenging due to differences in processing equipment and conditions. Collaborations between academia, industry, and government agencies can facilitate the scale-up process and accelerate the commercialization of bio-based gypsum composites.

2.2.7 Comparative analysis of types of gypsum-reinforced composites

Gypsum-reinforced composites are composite materials that incorporate gypsum as a key component to enhance their properties. These composites are used in various applications, and the choice of the specific type depends on factors like cost, availability of materials, manufacturing complexity, and long-term performance. Table 1 shows the comparison of some common types of gypsum-reinforced composites:

Table 1 Types of Gypsum-reinforced composites and their properties, weakness, applications [45, 67, 79]

The choice of gypsum-reinforced composite depends on the specific application's requirements, cost constraints, and availability of materials [29]. GFRG and GFRC are suitable for high-strength applications, while NFRG and recycled gypsum composites are more eco-friendly but have limitations in terms of strength. Synthetic fiber-reinforced gypsum composites offer versatility but can be costlier. Understanding the strengths and weaknesses of these composites is essential for selecting the right material for a given project.

2.3 Challenges faced by gypsum composites

Gypsum composites, commonly used in construction for various applications such as wallboards, panels, and moldings, face several challenges that can affect their performance, durability, and overall quality. These challenges range from issues during manufacturing to problems encountered during installation and use. Here are some specific examples along with potential solutions:

• 1. Moisture Sensitivity:

  • Challenge: Gypsum composites are highly sensitive to moisture, which can lead to warping, swelling, and mold growth, particularly in humid environments or areas prone to water exposure.

  • Potential Solution: Incorporating water-resistant additives or coatings can help mitigate moisture absorption. Additionally, improving the manufacturing process to ensure proper drying and sealing of the finished products can enhance their resistance to moisture.

• 2. Mechanical Strength:

  • Challenge: Gypsum composites may lack sufficient mechanical strength, especially when subjected to high loads or impact forces, leading to cracking, breakage, or deformation.

  • Potential Solution: Reinforcing the gypsum matrix with fibers (e.g., fiberglass, cellulose) or incorporating structural reinforcements (e.g., metal or fiberglass mesh) during manufacturing can enhance the mechanical properties of the composites, making them more durable and resistant to damage.

• 3. Fire Resistance:

  • Challenge: While gypsum composites inherently possess fire-resistant properties, they may not always meet the increasingly stringent fire safety regulations or performance requirements.

  • Potential Solution: Enhancing the fire-retardant additives or incorporating synergistic materials (e.g., intumescent additives, fire-resistant coatings) can improve the fire resistance of gypsum composites, ensuring compliance with safety standards and enhancing their suitability for various applications, such as in commercial buildings or residential structures.

• 4. Environmental Impact:

  • Challenge: Traditional gypsum composites may have a significant environmental footprint due to the energy-intensive manufacturing process and the use of non-renewable resources.

  • Potential Solution: Utilizing recycled gypsum or alternative eco-friendly binders (e.g., bio-based binders, recycled cellulose fibers) can reduce the environmental impact of gypsum composites. Additionally, optimizing the manufacturing process to minimize energy consumption and waste generation can further enhance the sustainability of these materials.

• 5. Dimensional Stability:

  • Challenge: Gypsum composites may exhibit dimensional instability over time, leading to shrinkage, expansion, or warping, which can compromise the integrity and aesthetics of the finished products.

  • Potential Solution: Implementing advanced manufacturing techniques, such as controlled curing processes and formulation optimization, can improve the dimensional stability of gypsum composites. Additionally, proper storage and handling practices during transportation and installation can help minimize dimensional changes and ensure the long-term performance of the materials.

2.4 Physical properties of gypsum composites

It is unquestionably crucial to be aware of how efficiently a product like gypsum absorbs moisture while examining its physical properties. However, the research so far indicates that a number of physical traits, including moisture content, water absorption, and microstructure features, are present in gypsum materials.

2.4.1 Setting time of gypsum composite

The setting time of gypsum composite refers to the time taken for the material to transition from a liquid or semi-liquid state to a solid state. This property is crucial in various applications, particularly in dentistry, construction, and art-related industries.

There are two main types of gypsum materials used in construction: plaster of Paris and gypsum plaster. Plaster of Paris typically has a shorter setting time (around 5–15 min) and is commonly used for casting molds, crafting, and minor repairs. Gypsum plaster, used for wall plastering, has a longer setting time (around 20–30 min), allowing more time for application before it hardens [80]. Factors influencing setting time include the water-to-powder ratio, temperature, and additives used [81]. Adjusting these variables can modify the setting time to suit specific project requirements.

This time is crucial as it determines when the material can be molded while still malleable. Khalil et al. [37] conducted research on the impact of various additives on gypsum composites and observed that an increase in rice husk content prolonged the setting time. Conversely, Flores and Medina [82] found that higher volumes of graphite filler in graphite-gypsum composites led to reduced setting times, possibly due to a lower water content in the mixture with more graphite present. The contrasting effects of rice husk content and graphite filler content on the setting time of gypsum composites are influenced by their interactions with water, their effects on the hydration process of gypsum, and their influence on the microstructure of the composite material.

Alicia San-Antonio [83] studied gypsum with added extruded polystyrene waste and noted that the setting time is affected by the volume of this waste material, with an increase causing a decrease in setting time. The periodic changes in gypsum rheology during setting play a significant role in the utilization of gypsum-based materials. These materials are often applied with a high water-to-gypsum ratio initially, creating a consistency that extends the setting period and optimizes material usage. Following mixing, sometime is required for the consistency to reach an ideal level, allowing for further work to be carried out.

2.4.2 Workability of gypsum composite

The workability of gypsum, defined by ASTM C472-99, refers to the ease of handling freshly mixed gypsum with minimal loss of homogeneity. This quality, often linked with terms like strength, fluidity, and mobility, can be assessed through tests like the slump test, flow table test, and angle flow box test. Studies exploring gypsum mortar with added fiber have shown that while fiber doesn't affect the manipulation of the gypsum matrix, higher fiber content decreases workability [44, 84]. Additionally, the use of polypropylene fiber has been found to reduce gypsum matrix workability, likely due to uneven fiber dispersion hindering gypsum penetration [85].

Sophia et al. [86] examined the impact of mineral admixture and bio-carbonate filler on gypsum plaster's physico-mechanical characteristics. They used various water-gypsum ratios and tested the influence of natural zeolite and shell powder on gypsum paste workability. Their findings suggested that adding shell powder significantly enhanced gypsum manageability, while zeolite made it more challenging to work with. Studies by Krejsova [87] indicated that gypsum with smoother particles is more workable compared to gypsum with rough particles. Hernandez-Olivares [88] also observed that a water-to-gypsum ratio of 0.6 reduced gypsum composite workability compared to a higher ratio of 0.8.

2.4.3 Moisture/water absorption of gypsum composite

Exploring the impact of moisture on composites involves investigating their water absorption tendencies. Composites reinforced with natural fiber are less favored due to their susceptibility to moisture. The hydrophilic nature of the fibers leads to swelling when exposed to moisture, resulting in microcracks that compromise mechanical strength [89, 90]. Treating fibers chemically can significantly reduce this effect by altering their surface to minimize water absorption. Construction materials face long-term challenges from environmental conditions, requiring accelerated aging processes to anticipate their behavior [91]. Temperature and humidity variations can affect materials, emphasizing the importance of evaluating their endurance and compliance with safety standards.

In assessing water resistance, bio-composites made of gypsum often undergo drying-wetting cycles rather than prolonged water exposure. Studies indicate that these bio-composites can withstand approximately 40 cycles, although immersion has occasionally led to binder loss on the filler surface, impacting strength. Interestingly, hemp fiber composites subjected to chemical and biological treatments showed a 17% decrease in moisture absorption compared to untreated fibers [90]. Biologically treated hemp fibers displayed greater hydrophobicity compared to both chemically treated and untreated fibers.

Manipulating manufacturing processes can also influence water absorption. For instance, pressed curing resulted in a notable 40% reduction in water absorption for granulated cork and cellulose fiber samples [92]. Temperature variations during manufacturing affect water absorption in materials like gypsum particle boards; higher temperatures reduced water absorption percentages. Adding rice husk to bio-composites was found to decrease water absorption due to the hydroxyl group present in the husk [93]. Similarly, the addition of bagasse and wheat straw improved water resistance in gypsum composites. Wheat straw demonstrated notable water resistance due to its concentrated extractives and wax content [94].

Furthermore, adjusting the quantity of cotton fiber in gypsum reinforcement altered the composite's physical and mechanical properties, enhancing water absorption due to the fiber's presence [95]. Biopolymers tend to absorb more moisture compared to synthetic composites, and natural composite materials have demonstrated poor performance when exposed to water.

2.4.4 Density of gypsum composite

Variations in density significantly impact the quality of composite materials. For instance, incorporating expanded perlite into gypsum composites, alongside micro silica and calcium carbonate, resulted in a substantial decrease in bulk density, as evidenced by Vimmrova et al. [30]. Gypsum containing 20% perlite showed a drastic reduction from the initial 300 kg/m³ to 547 kg/m³, marking a decrease of over 50%.

Herrero et al. [96] explored plaster-rubber mortars and observed a density drop from 1222 kg/m³ to 650 kg/m³ when recycled tires with rubber particles were utilized. This reduction in density spanned between 16 to 47% for the smallest particles.

Khalil et al. [97] demonstrated a 9% decline in density (from 1150 kg/m³ to 1030 kg/m³) in regular gypsum by introducing a 10% silica composite, possibly influenced by extensive additive use.

Researchers, such as Borreguero et al. [98], investigated smart gypsum composites with thermoregulating microcapsules, noting a decrease in density with higher microcapsule compositions compared to standard gypsum.

Shiroma et al. [49] achieved a composite density of 1100 kg/m³ by incorporating up to 5% wood particles in the mass, while Morale-Conde [99] observed a reduction in the quantity and number of additives (wood shavings or sawdust) resulting in a decrease of 53.94% and 41.92% respectively, yet increasing the proportion of additives.

Carmen and Maria [100] found that composite wood waste-gypsum exhibited a lower density than normal gypsum, and only [82] reported an increase in composites made with gypsum. Notably, the density of isostatic graphite filler increased as filler amount increased, reaching 1280 kg/m³. Fiber-based composites generally display higher densities than regular gypsum. All these can be found in Fig. 1.

Fig. 1

Plain gypsum and composite samples

2.4.5 Porosity of gypsum composite

According to Khalil et al. [97], combining silica fumes with gypsum paste reduced porosity by 5% compared to using regular gypsum. In another study, Khalil et al. [37] observed that increasing slag or calcium carbonate content by 10% made rice husk and PVA polymer more porous. Gencel et al. [27] investigated novel lightweight gypsum composites involving diatomite and polypropylene fiber production. Diatomite significantly increased porosity to a desirable level, ranging from 35.9% to 47.8% in gypsum composites. Introducing diatomite at a 20% ratio elevated material porosity by 32.4%, unaffected by the fibers' presence. The porous nature of diatomite contributed to this increase in porosity. Ferreira et al. [101] discovered that in gypsum reinforced with natural caroa fibers, increasing fiber mass content to 3% raised porosity to 52%. Vimmrova et al. [30] found that incorporating expanded perlite increased the porosity of gypsum composites (micro silica/calcium carbonate) from 59.2% to 69.4%, as depicted in Fig. 2. Borreguero et al. [98] observed a minor increase in gypsum composite porosity from 0.47% to 0.48% upon adding thermoregulating microcapsules. This higher microcapsule content improved porosity compared to regular gypsum. However, conflictingly, Vimmrova et al. [30] and Borreguero et al. [98] contradicted the findings of Flores Medina and Barbero-Barrera [82]. They observed a decrease in composite porosity from 37.2% to 34.1% due to the use of isostatic graphite filler, contrary to the initial assumptions (Fig. 2).

Fig. 2

Porosity of plain gypsum and composite samples

2.5 Microstructures properties of gypsum composite

In the production of fiber-gypsum composites, analyzing the microstructure is pivotal for understanding fracture types, assessing the impact of treatments on fiber surfaces, determining crystallinity indices, and evaluating other critical factors. This analysis reveals the degree of fiber compatibility within the gypsum matrix and the adhesion between fiber and matrix, shedding light on inherent defects [102,103,104,105].

Various microscopic techniques, including scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), and optical microscopy, have been employed extensively to examine gypsum composite materials [106,107,108]. SEM, in particular, has been instrumental in exploring interactions between fibers and the matrix, detecting voids, and studying fiber surface morphology.

Microstructure refers to the composition, quantity, shape, size, and distribution of phases within a solid material. Gypsum, comprising calcium sulfate dihydrate crystals, forms a network of interconnected needle-like crystals characterized by high porosity (up to 70%) and consistent size [109]. Precisely modeling their microstructures remains challenging, but understanding these characteristics is crucial for quality control purposes.

Microscopic imaging aids in understanding how natural fiber composites weaken or fracture at the micro-level. Studies using SEM have shown enhanced surface adhesion between cellulose fibers and the gypsum matrix, consequently improving the mechanical properties of composites. Investigations on gypsum composites treated with hemp fibers, whether chemically or biologically, exhibited stronger bending behavior and reduced damage, highlighting the impact of treatments on composite toughness [110].

Furthermore, surface modifications, such as alkaline treatments, were found to enhance fiber-matrix adhesion, reducing the likelihood of fractures at the interface. Figure 3 illustrates how biologically treated fiber-reinforced composites shown improved toughness and less damage. Additionally, alkaline treatment increased the composites' toughness by lowering the likelihood of fracture at the fiber-gypsum matrix interface, according to Fatma et al. [53] Varying NaOH concentrations in treatments exhibited differing effects, with higher concentrations contributing to improved fiber performance. Other studies explored the influence of additional components, like matcher powder or polyamide fibers, on gypsum composites, revealing alterations in hydration rates and the development of distinct microstructures [111].

Fig. 3

SEM images of hemp fiber at two different magnifications, showing the fiber both untreated (RF) and processed (BTF and CTF) [90]

Alajmi [112] looked into the morphological alterations brought on by various NaOH concentrations. The outcomes demonstrated that in solutions containing 6% NaOH, treated fibers outperformed untreated fibers. The micrograph also demonstrates the high fiber effect, which is likely to have contributed to the failure, by displaying a sisal fiber with a 20% volume shattered fracture plane.

Li [113] looked into the viability of employing matcher powder as an addition in gypsum composites and found that the composite took longer to hydrate the more matcher it contained. In comparison to reference samples, gypsum with a higher matcher powder concentration took longer to set and hydrate. Eve [114] published the results of a study in which gypsum and polyamide fiber were combined. The mechanical and microstructural characteristics of the gypsum composite were thoroughly examined. It was discovered that the gypsum matrix and the polyamide fiber had different microstructures from regular gypsum. As the fiber concentration grew, piquets with big confined holes and areas rich in matrix developed more often. Foti [55] also used SEM to study composites consisting of wastepaper and gypsum. Better fiber-matrix adhesion was produced by gypsite crystal formations around the fibers, which enhanced mechanical characteristics. SEM photos of a broken sample of the composites demonstrate that the porosity of the gypsum-cellulose composites was decreased by filling the pores produced by the interlocking of the two components. This demonstrates that the mechanical properties of the composites are improving and that samples containing 1% cellulose adhere to one another more tightly than samples made entirely of gypsum [115].

Observations from SEM images showcased gypsite crystal formations around fibers, which improved fiber-matrix adhesion, resulting in enhanced mechanical properties. Notably, the reduction in porosity in gypsum-cellulose composites indicated improved mechanical strength, emphasizing the significance of composite structures in enhancing material properties [116].

2.5.1 X-ray diffraction of gypsum composite

X-ray diffraction (XRD) is a powerful technique used to analyze the structure of materials, including gypsum composites. Gypsum composites typically consist of gypsum (calcium sulfate dihydrate) combined with other materials like additives, fillers, or reinforcing agents to enhance specific properties. Recent studies delved into cellulose fiber [115], bio-degummed hemp fiber [45], and hemp fiber [90]. Kondratieva [54] suggested that incorporating Taurit additives alters mineral unit morphology, refining gypsum's structure and enhancing its strength. Analysis via XRD of chemical additives demonstrated that higher additive volumes expedited hydration, yielding thicker, denser crystals.

Enhancing cellulose crystallinity through chemical treatments can heighten the composite's strength [115]. The diffraction pattern of the composite displays a hemihydrate peak at 14.7 and 29.4. Assessing chemical additive samples using XRD revealed that increased concentrations expedited hydration and led to a denser crystal structure. Hernandez-Olivares [88] unveiled the optimal bond between cork cells and hydrated gypsum crystals, yet the composite's mechanical properties remain insufficient. Table 2 depicts the phases identified through XRD analysis.

Table 2 XRD phases

According to Table 2, the X-ray diffraction (XRD) analysis conducted on calcium sulfate (CaSO₄) samples reveals the presence of different phases, each characterized by distinct crystal structures. Anhydrous calcium sulfate, devoid of water molecules, is indicated by the absence of peaks around 11.6° and the presence of a characteristic peak at 29.2°. This phase is crucial for various applications but is not explicitly detailed in the provided data.

Hemihydrate, known as gypsum powder (CaSO_4.0.5H₂O), exhibits peaks at 14.6°, 25.6°, 29.7°, 31.7°, 32.9°, and 49.1°, representing specific crystallographic planes. These peaks confirm the presence of gypsum powder, which contains half a water molecule per calcium sulfate unit.

In contrast, the hydrated hemihydrate phase (CaSO_4.2H₂O) displays additional peaks at 11.6°, 20.7°, 23.4°, 29.1°, 31.1°, 33.3°, and 43.3°. These peaks signify the incorporation of two water molecules per calcium sulfate unit, indicating a higher degree of hydration compared to gypsum powder.

The composite material observed in the analysis likely combines anhydrous calcium sulfate with hemihydrate. The presence of peaks at 14.7° and 29.4° suggests the presence of hemihydrate, while the absence of the 11.6° peak indicates the exclusion of hydrated calcium sulfate. Such composite materials can be tailored to possess specific properties by adjusting the relative proportions of the constituent phases.

Overall, the XRD results offer valuable insights into the crystalline phases present in the samples. Understanding these phases is essential for various applications, ranging from construction materials to pharmaceutical formulations. By identifying and characterizing the phases accurately, researchers can optimize the composition and properties of calcium sulfate-based materials to meet specific requirements in different fields.

2.6 Mechanical properties of gypsum composites

There have been several developments in building materials that make use of recyclable or natural resources. Natural and synthetic fibers are used to strengthen plasterboards. These constructions must undergo a rigorous evaluation for compressive and flexural strength before being made available for commercial use. Gypsum composites, often used in construction and manufacturing, exhibit various mechanical properties that make them valuable in different applications. Gypsum composites typically consist of gypsum (calcium sulfate dihydrate) combined with additives or reinforcements to enhance their mechanical characteristics.

2.6.1 Compressive properties

The utilization of natural fibers to reinforce gypsum has seen notable advancements, promoting sustainability in the construction industry. Before these structures are commercially available, they undergo rigorous testing to assess their compressive strength. Several academic studies have delved into the influence of natural fibers like palm, sawdust, hemp, abaca, and coroa fibers on gypsum's compressive strength [44, 101, 110, 119].

Research consistently demonstrates that incorporating fibers enhances gypsum's compressive strength properties. For instance, Iucolano et al. [110] observed improved mechanical properties in hemp-reinforced gypsum samples compared to brittle, unreinforced ones. Dai and Fan's exploration of wood sawdust [120] revealed a significant enhancement in compressive strength with antifoam agent treatment, resulting in a 35% reduction in water content and a strength increase from 2.21 MPa to 13.25 MPa (Fig. 4).

Fig. 4

Shows fiber-reinforced gypsum for compressive strength characteristics

Similarly, Aghaee et al. [121] strengthened the gypsum matrix using textile waste materials, elevating compressive strength from 8 to 13 MPa. Al-Rifaie and Al-Niami [44] found that palm fiber addition increased compressive strength from 6.8 MPa to 13 MPa, altering the gypsum's brittleness to a more flexible nature.

Different studies showcased varied impacts. Shiroma et al. [49] highlighted that reinforcing with wood particles between 5 and 10% improved compressive strength, while Hostalkova et al. [47] noted a decrease in strength with increased wood fiber content, possibly challenging gypsum matrix control. Moreover, investigations by Regulska and Repelewicz [122] indicated good compressive strength for gypsum reinforced with sawdust at lower concentrations, albeit decreasing with higher filler content.

Ferreira et al. [101] reported enhanced compressive strength using caroa natural fibers with added PVA, while Aliewi et al. [123] found that PVC additions, even at 3%, increased strength to 8.19 MPa compared to pure gypsum.

Studies, such as Fatma et al. [53], revealed that surface treatments like NaOH on doum palm fibers improved compressive strength. Fatma's SEM measurements suggested that treated fibers linked more strongly on the break's surface than untreated ones.

Foti et al. [55] investigated Tetra packs, recycled papers, and paper boards in gypsum, determining the maximum filler content without significant mechanical property reduction. Gypsum-Tetra-pack composites exhibited high compressive strength at 6.46 MPa.

Lastly, Villoria Saez [51] found that gypsum reinforced with ceramic waste exhibited greater compressive strength compared to plain gypsum (Fig. 4), demonstrating potential for use as a building insulation material.

2.6.2 Flexural properties

The flexural strength of composite materials, crucial for structural use, depends on the interaction between their fibers and matrix. Various fiber types and matrix materials impact manufacturing costs and composite quality. Research suggests a potential correlation between fiber quantity and flexural strength. For instance, studies by [121] on natural fiber composites found increases in flexural strength, like textile waste fibers increasing from 3.63 MPa to 3.78 MPa (Fig. 5).

Fig. 5

Shows fiber-gypsum composites for a test of flexural strength

Other investigations have explored enhancing materials through additives or different fiber types. For example, treating sawdust-gypsum composites with an antifoam agent increased flexural strength from 4.43 to 4.59 MPa Dai and Fan [120]. Similarly, cellulose pulp fibers in gypsum showed a 13 MPa improvement in flexural properties compared to pure gypsum.

Iucolano et al. [124] conducted another test on the flexural characteristics of abaca fibers. With the addition of 2 percent abaca fibers and treatment with distilled water, the composite's flexural strength rose, reaching 2.95 MPa as seen in Fig. 5. When the number of fibers is increased and a water to 40 percent gypsum ratio is utilized, date palm fiber gypsum composites exhibit higher flexural strength qualities ranging from 7 to 11 MPa and ductile material at maximum stress [44].Tests on different fibers, like abaca or date palm fibers, showcased varying flexural strength changes when incorporated into gypsum, ranging from 2.95 MPa to 11 MPa. However, the inclusion of wood particles or natural wood fibers sometimes reduced flexural strength, contrary to expectations.

Further studies explored innovative additions like recycled PET fibers or caroa fibers in gypsum composites. While some increased strength by 40%, others showed that excessive fiber content weakened gypsum's flexural properties.

Moreover, the inclusion of ceramic and concrete debris, according to Villoria Saez [51], increases the composites' flexural strength from 2.65 MPa to 3.45 MPa (Fig. 5). Incorporating ceramic or concrete debris was found to elevate flexural strength, while the addition of industrial waste like PVC by Aliewi et al. [123] enhanced it from 4.77 MPa to 5.11 MPa.

Each study adds to our understanding of how different fibers, treatments, or additives impact composite materials' flexural strength, highlighting the complexity of optimizing these properties for various applications.

To provide practical guidance, researchers and manufacturers may need to conduct systematic experiments to identify the optimal fiber content range for specific composite formulations. This process would involve testing a range of fiber content levels and evaluating the resulting flexural properties to identify the point at which the maximum strength or other desired performance criteria are achieved.

Furthermore, it's essential to consider other factors such as cost-effectiveness, ease of manufacturing, and the overall performance requirements of the intended application. Balancing these factors alongside flexural strength optimization can lead to the development of composite materials with superior mechanical properties and commercial viability.

In summary, while excessive fiber content can indeed weaken flexural properties, determining the optimal fiber content range requires careful experimentation and consideration of various factors. Researchers and manufacturers should aim to strike a balance between reinforcing effects and practical considerations to achieve the desired performance characteristics in composite materials.

2.7 Thermal properties of gypsum reinforced composites

Gypsum itself possesses decent thermal insulating properties. When combined with reinforcing materials like glass fibers, cellulose fibers, or other additives, it further improves its thermal conductivity [53, 125, 126]. These reinforcements reduce heat transfer by impeding the movement of thermal energy through the material, making the composite more effective in insulation applications.

Gypsum-based composites often exhibit relatively low coefficients of thermal expansion. This means they are less prone to significant expansion or contraction due to temperature changes compared to some other construction materials [127, 128]. This attribute is particularly valuable in applications where dimensional stability is crucial, as it minimizes the risk of structural damage or deformation caused by temperature variations.

Determining the thermal conductivity of gypsum can be complex due to factors like radiation and moisture affecting its pores. Different methods yield varied results, particularly at higher temperatures, leading to discrepancies among studies. Andersson and Jansson [129] introduced the Transient Hot Strip method to gauge thermal conductivity by assessing a metal strip's resistance in gypsum. Harmathy [130] employed a technique using a TC-31 thermal conductivity meter, aligning closely with Mehaffey's [131] findings. These small-scale methods shed light on gypsum's thermal conductivity variations. Yet, pinpointing precise statistics for a specific product remains challenging due to water flow, radiation in voids, and gypsum cracks. However, despite differing results, both studies agree that thermal conductivity remains relatively stable until the initial dehydration phase commences.

As temperature rises, gypsum's thermal conductivity increases marginally until the onset of dehydration, as observed by Wang [132]. The presence of moisture decreases with temperature, affecting thermal conductivity. Notably, gypsum undergoes a significant decrease in thermal conductivity when water vaporizes, a key shift seen in Zhang et al. [133].

Scientists have calibrated thermal property values to fit experimental results, highlighting alterations after water evaporation and at higher temperatures as crucial factors influencing gypsum's thermal conductivity. Computational analyses by Wullschleger and Ghazi Wakili [134] showcased the minimal impact of changes in the enthalpy needed for gypsum dehydration on its temperature production.

Furthermore, studies on gypsum boards exposed to fire consistently advocated for an increased real heat value compared to conventional estimations, as proposed by Wang. Ang and Wang [135] supported this by examining moisture migration's impact on gypsum boards under high temperatures, emphasizing the influence of fire speed and airflow within gypsum boards.

Roy-Poirier and Sultan [136] discovered that the temperature background of the gypsum layer rises significantly by approximately 300 °C just as the fall-off occurs. They noted that fall-off isn't solely temperature-dependent, occurring more due to the temperature profile across the board thickness than a specific temperature.

In floor assemblies, wider screw spacing lowers fall-off temperatures due to increased tension close to wider-spaced screws. However, for walls, screw spacing isn't as critical. The failure of gypsum is influenced by temperature distribution and stress within the material, emphasizing the need for comprehensive investigations beyond temperature-based judgments.

Gypsum, on its own, possesses decent thermal insulating properties. However, when combined with reinforcing materials like glass fibers, cellulose fibers, or other additives, its thermal conductivity can be further improved. These reinforcements play a crucial role in reducing heat transfer by impeding the movement of thermal energy through the material, thus making the composite more effective in insulation applications. By incorporating these reinforcements, the composite's thermal performance is enhanced beyond what gypsum can achieve alone.

Moreover, the addition of reinforcing materials also contributes to the dimensional stability of gypsum-based composites. By reducing the coefficients of thermal expansion, these reinforcements help minimize the risk of structural damage or deformation caused by temperature variations. This is particularly valuable in applications where dimensional stability is crucial, as it ensures the integrity of the structure over time.

In studies exploring the thermal conductivity of gypsum, the impact of reinforcements is essential to consider. While different methods may yield varied results, particularly at higher temperatures, the presence of reinforcements can influence these findings. The combination of gypsum with reinforcing materials may exhibit different thermal conductivity behaviors compared to pure gypsum, especially during phases such as dehydration where moisture content plays a significant role. Understanding how reinforcements interact with gypsum in terms of thermal properties is thus essential for accurately assessing its performance in real-world applications.

Furthermore, investigations into the behavior of gypsum boards under fire conditions also underscore the importance of reinforcements. Studies have shown that the presence of reinforcements can affect the real heat value and thermal response of gypsum boards when exposed to high temperatures. Factors such as moisture migration and airflow within the boards, influenced by the composition of reinforcements, can significantly impact the fire resistance and thermal stability of gypsum-based materials.

In summary, the role of reinforcements in enhancing the thermal performance of gypsum-based composites is crucial and should be explicitly addressed in discussions concerning their thermal properties, dimensional stability, and behavior under fire conditions. Integrating this aspect provides a comprehensive understanding of how additives and reinforcements contribute to the overall performance of gypsum-based materials in various applications.

2.8 Acoustic properties of gypsum reinforced composites

Achieving effective sound absorption and insulation is crucial for maintaining favorable acoustic environments, especially in building construction. Research into the acoustic properties of building materials is essential to comprehend their sound absorption and insulating capabilities. Natural fiber composite materials have emerged as promising options due to their cost-effectiveness, reduced health risks, and use of renewable resources contributing to sustainability in construction [137,138,139,140,141,142].

In a study by Gunal et al. [143], gypsum ceiling tiles were enhanced by incorporating wool's thermal insulation qualities and coir's durability. Increasing coir content raised the composite's sound absorption coefficient, reaching 0.35 at 5500 Hz. Coir fibers exhibited superior acoustic performance compared to wool, potentially due to their rougher surface morphology.

Pedreno-Rojas [144] investigated the use of demolition wood debris in gypsum bio-composites, evaluating their physical, mechanical, and acoustic attributes. The composite, containing 10% sawdust and 20% wood shavings, showed a 20% improvement in sound absorption (0.531) at 2000 Hz compared to reference gypsum board.

Hernandez-Olivares [88] studied cork-gypsum composites, finding moderate sound absorption coefficients ranging from 0.2 to 0.3 in high-frequency fields. Though not strong sound absorbers, these composites exhibited sound insulating properties.

Gypsum-reinforced wood and rubber leftovers were examined for their ability to absorb sound by Adamopoulos [145], who discovered no discernible variations in the sound absorption coefficient between various quantities of wood and rubber. This solid block made of gypsum had an optimal absorption coefficient of 0.72 at 1 kHz, which fell to 0.43 as the frequency grew from 2 to 4 kHz. Elkhessaimi [146] looked at the results of adding glass fiber and citric acid to gypsum. The study concentrated on the materials' microstructural impacts on the transmission loss of gypsum board. The findings demonstrated that the acoustic insulation properties of the composites increased with increasing thickness and density. The group found that a 50-mm thick glass wool cored gypsum board containing citric acid has very promising insulating qualities. Ramezani [46] studied the acoustic properties of wood fiber-based mortars with partial gypsum substitution (10:90, 15:85, 20:80, 25:75, and 30:70 by ratio). With an STL of 18 dB as opposed to 15 dB for plain gypsum samples, the results showed that employing wood fiber in place of gypsum in a 30:70 ratio enhanced transmission loss characteristics over plain mortar. The outcomes also showed that the transmission loss decreased as the thickness rose from 1 cm to 1.5 cm. For each and every tested frequency, this was true.

More recent study was done on the impact of gypsum composites of expanded polystyrene and leftover cellulosic pulp on sound absorption by Oliveira [147]. The researchers found that the varied concentrations of each chemical did not significantly differ, and the best outcomes were achieved at a low frequency (250 Hz). However, the acoustic insulation requirements were met by the composites that were planned for usage. The recipe with the highest cellulose pulp content had the highest absorption coefficient, with values of 0.33 and 0.16 for the measured frequencies of 250 Hz and 500 Hz, respectively, and the second-highest absorption coefficient for the frequency of 1000 Hz (0.12). Additionally, Arroyo et al. [148] discovered that 5% micro silica added to gypsum foam enhanced the sound absorption coefficients of gypsum composites, especially at low frequencies. The sound absorption coefficient measured at 200 Hz was 0.64 (Table 3).

Table 3 Comparison of the coefficients of different composites

These studies demonstrate the diverse ways in which different materials and compositions affect the acoustic properties of gypsum-based composites, showcasing their potential for sound absorption and insulation in construction applications.

3 Comparison with traditional building materials

One of the most significant ways gypsum composites promote sustainability is through their low embodied energy. Embodied energy refers to the energy consumed throughout a material's entire life cycle, encompassing extraction, processing, transportation, and installation [149]. Gypsum composites, by requiring less energy-intensive manufacturing processes compared to some traditional building materials, contribute to a reduced carbon footprint [67]. This not only conserves precious resources but also lessens the environmental impact associated with construction.

Recyclability stands as another cornerstone of their sustainability profile. Gypsum composites can be reclaimed and recycled at the end of their lifecycle, preventing materials from ending up in landfills and reducing the demand for virgin resources [150,151,152]. This closed-loop approach aligns with circular economy principles, which prioritize resource efficiency and waste reduction. By embracing recycling, these composites minimize waste and extend their utility, thereby reducing the strain on finite resources.

Furthermore, the potential use of bio-based materials in gypsum composites amplifies their sustainability quotient. Incorporating natural fibers, binders, or additives derived from renewable sources infuses these composites with an eco-friendly edge [110, 153]. This not only reduces the reliance on fossil-based materials but also harnesses the regenerative capacity of nature. Such a shift towards bio-based components fosters a harmonious relationship between construction and the environment, fostering a greener and more sustainable future.

In essence, gypsum composites present a holistic approach to sustainability. Their low embodied energy conserves energy resources, their recyclability minimizes waste, and their compatibility with bio-based materials reduces the ecological impact of construction [154, 155]. By embracing these composites, the construction industry takes a progressive step towards creating buildings that are not only structurally sound but also environmentally responsible. As society seeks to balance the needs of the present with the well-being of future generations, gypsum composites emerge as a catalyst for sustainable building practices.

The primary drivers of cost-effectiveness in gypsum composite production typically include raw material costs, energy consumption, labor costs, production efficiency, waste management, and transportation costs. To balance cost considerations with performance and sustainability goals, manufacturers can employ several strategies:

• 1. Raw Material Selection: Opt for cost-effective yet high-quality raw materials. Conducting thorough research and sourcing materials from reliable suppliers can help achieve this balance.

• 2. Energy Efficiency: Implement energy-efficient technologies and processes in manufacturing. This might involve investing in equipment upgrades, optimizing production schedules to minimize energy consumption during off-peak hours, and utilizing renewable energy sources where feasible.

• 3. Process Optimization: Continuously analyze and refine production processes to enhance efficiency and reduce waste. Lean manufacturing principles can be applied to streamline operations and minimize costs without sacrificing quality.

• 4. Labor Management: Invest in workforce training and development to improve productivity and reduce labor costs. Additionally, automation and robotics can be integrated into production lines to increase efficiency and reduce reliance on manual labor.

• 5. Waste Reduction and Recycling: Implement practices to minimize waste generation and maximize material recycling. This can include reusing production by-products, optimizing material usage to reduce scrap, and implementing recycling programs for waste materials.

• 6. Transportation Optimization: Strategically plan transportation routes and logistics to minimize costs and environmental impact. Consolidating shipments, utilizing efficient transportation modes, and optimizing inventory management can help reduce transportation costs while lowering carbon emissions.

• 7. Product Innovation: Invest in research and development to create gypsum composites that offer superior performance characteristics while maintaining cost-effectiveness and sustainability. This might involve exploring alternative materials, improving product design, or enhancing manufacturing processes.

• 8. Life Cycle Assessment (LCA): Conduct comprehensive LCAs to evaluate the environmental impacts of different production methods and materials throughout their life cycles. This holistic approach helps identify opportunities for improvement and informs decision-making to achieve sustainability goals while balancing costs and performance.

4 Summary of the findings

The literature review section provides a comprehensive overview of the physical, mechanical, thermal, and acoustic properties of gypsum composites, along with comparisons to traditional building materials. Here are the key findings and their implications for the construction industry:

• 1. The setting time and workability of gypsum composites are highly adjustable through manipulation of variables such as water-to-powder ratio and temperature. This adaptability facilitates tailored solutions for specific project needs, particularly in dentistry, construction, and art-related fields. Additionally, comprehending gypsum's workability is crucial for maintaining homogeneity and ease of application during construction processes.

• 2. Moisture absorption varies among gypsum composites due to factors like fiber content, additives, and manufacturing techniques. Effective management of moisture absorption is vital for preserving the structural integrity and longevity of gypsum-based materials, particularly in environments prone to humidity or moisture exposure.

• 3. The density and porosity of gypsum composites significantly influence their mechanical and thermal characteristics. Modifications with additives or reinforcements offer opportunities to enhance material performance, reduce weight, and improve insulation properties, thereby expanding their potential applications.

• 4. Analysis of gypsum composite microstructure provides valuable insights into mechanical properties, fracture behavior, and compatibility between fibers and the matrix. Understanding these microstructural features is essential for quality assurance and optimizing material performance across various applications.

• 5. Gypsum composites reinforced with natural fibers or additives demonstrate improved compressive and flexural strength compared to pure gypsum. These enhancements contribute to their suitability for structural applications, promoting sustainability through the use of recyclable or renewable materials.

• 6. Gypsum composites possess moderate thermal insulation properties, which can be further enhanced by incorporating reinforcing materials. Understanding thermal conductivity and expansion characteristics is crucial for designing energy-efficient buildings and ensuring dimensional stability under varying temperature conditions.

• 7. Gypsum composites exhibit potential for sound absorption and insulation, offering opportunities for creating favorable acoustic environments in buildings. Incorporating natural fibers or additives can further enhance acoustic performance, aligning with sustainable construction practices.

• 8. Compared to traditional building materials, gypsum composites offer several sustainability advantages, including low embodied energy, recyclability, and compatibility with bio-based materials. Embracing gypsum composites can mitigate environmental impact and promote resource efficiency in the construction industry.

5 Challenges and future directions

Although gypsum composites offer significant advantages, they face notable challenges related to moisture sensitivity and durability. Excessive moisture can lead to dimensional changes, loss of mechanical properties, and degradation over time, making the material susceptible to warping, cracking, and mold growth. To address these issues, ongoing research focuses on developing moisture-resistant additives, improving curing processes, and understanding material behavior under different humidity conditions. Durability concerns arise from exposure to weather, chemicals, and mechanical stress, necessitating the formulation of composites with enhanced resistance. Studies explore various surface treatments and coatings to mitigate these challenges. For instance, applying nano-silica and acrylic emulsion coatings creates a barrier against moisture ingress, improving dimensional stability and resistance to degradation. Hydrophobic treatments using silane coupling agents reduce water absorption and enhance moisture resistance. Nanostructured coatings, incorporating nanoparticles like nano-silica or nano-clay, reinforce the gypsum matrix and provide a dense barrier against moisture penetration, improving mechanical properties and durability. Polymer-modified coatings, containing polymers such as styrene-butadiene latex or acrylic polymers, form flexible barriers against cracking, warping, and degradation. These research efforts highlight the potential of surface treatments and coatings to enhance the performance and longevity of gypsum composites in diverse applications and environments.

6 Conclusion

In summary, this review underscores the transformative potential of gypsum-reinforced composites in revolutionizing the construction industry. By amalgamating gypsum's advantageous properties with various reinforcing elements, these materials offer versatile, long-lasting, and eco-friendly solutions for a broad spectrum of building applications. Our study contributes significantly to the existing literature by shedding light on key aspects of gypsum composites, with a particular focus on their mechanical properties and potential applications in underdeveloped regions.

The findings highlight the rapid adoption of gypsum composite materials in constructing building components, driven by their cost-effectiveness, efficient thermal and acoustic insulation capabilities, and lightweight yet robust construction elements. Moreover, the incorporation of natural fibers such as hemp, cotton, sisal, jute, and wood into the gypsum matrix is shown to enhance flexibility and mechanical strength, thereby expanding the scope of their applications.

Furthermore, our investigation reveals a consistent improvement in mechanical strength with increased fiber content, accompanied by a decrease in the density of gypsum composites. However, we recognize the need for further research to explore dimensional stability, thermal conductivity, and acoustic properties of these materials. Additionally, comprehensive studies on gypsum board applications in residential and commercial construction are warranted to unlock their full potential.

Looking ahead, the implications of our findings extend beyond academia, with practical implications for construction professionals, policymakers, and stakeholders. By fostering close collaboration between research and practical application, we can accelerate the widespread adoption of gypsum-reinforced composites, thereby advancing sustainability, efficiency, and resilience in the built environment.

In conclusion, our review underscores the critical role of gypsum composites in shaping the future of construction, emphasizing the need for continued research and innovation to unlock their full potential. Through concerted efforts, we can harness the transformative power of these materials to address pressing challenges and build a more sustainable and resilient built environment for generations to come.