1 Introduction

The disposal of waste tires has emerged as a pressing environmental concern globally, with an estimated 1000 million tires reaching the end of their useful life annually. By 2030, this figure is projected to escalate to 1200 million, resulting in the cumulative disposal of nearly 5000 million tires, including those stockpiled. This proliferation not only provides breeding grounds for various pests but also poses significant fire hazards when burned. Moreover, waste tires contribute to noise and air pollution and lead to the accumulation of tire stockpiles, a practice formerly mitigated by using these tires as fuel but is now prohibited due to environmental concerns [1,2,3]. In India alone, approximately 112 million waste tires are generated annually, exacerbating these environmental challenges [4]. Similarly, in the United States, the production of about 270 million waste tires yearly accounts for 1.2% of the total municipal solid waste by weight [5, 6]. Given these alarming statistics and the adverse impacts on public health and the environment, finding alternative methods for reusing or disposing of waste tire rubber is paramount. Therefore, this research is crucial for exploring innovative solutions to mitigate the environmental consequences of waste tire disposal and protect public health. With increasing environmental awareness, the aim for alternative applications for scrap tires has intensified. Beyond mechanical shredding, previous studies also examined alternative methods for obtaining rubber aggregates, such as chemical devulcanization and cryogenic processes, which offer different environmental and mechanical properties for the rubber particles [7, 8]. Currently, 21% of these tires are repurposed in civil engineering projects, such as asphalt and Portland cement concrete mixtures [9]. The primary applications of Portland cement concrete incorporating waste tires include non-critical structures like exterior walls [10], pedestrian blocks [11], and, as discussed in this paper, non-load-bearing elements, sound barriers, and shock-absorbent layers in structures. These applications align with the aim of the construction industry to produce more sustainable materials and structures [12]. Besides, these applications benefit from the material's reduced basic strength but enhanced flexibility and energy absorption, making them suitable for areas where such properties are advantageous [13, 14]. Recycling waste tire rubber significantly mitigates the environmental impact of tire disposal in landfills, which is undesirable due to the large space required by tires' 75% void space, the risk of catastrophic fires, and their potential to harbor insects in trapped rainwater [15, 16]. Tires in landfills can also trap methane gas, causing it to rise to the surface, potentially damaging the liners installed to prevent landfill contamination of groundwater [17]. Furthermore, this paper reviews the ecological benefits of incorporating recycled rubber in concrete, highlighting waste reduction, resource conservation, and reduced environmental impact compared to traditional concrete production [18]. Incorporating rubber in concrete has been shown to enhance its freeze–thaw durability, reducing the need for air-entraining admixtures for freeze–thaw protection [19]. Laboratory and field studies have indicated that leachate from crumb rubber does not adversely affect the environment [20]. Moreover, using recycled rubber in concrete not only reduces environmental pollution but also enhances concrete properties like sound and heat insulation, freeze–thaw resistance, and energy absorption [21,22,23]. Research suggests that rubberized Portland cement concrete can effectively prevent brittle failures and improve ductility [24, 25]. While adding crumb rubber may reduce concrete's strength and abrasion resistance, its impact on enhancing energy absorption is notably significant [26]. The potential applications of ductile rubberized Portland cement concrete include structural components subject to dynamic and impact loads, such as bridge approach slabs and airport runways. However, the significant reduction in strength due to the addition of rubber has hindered these applications. Concrete, being one of the most widely used materials worldwide, consumes a substantial number of natural resources annually. The sources of these resources are gradually diminishing, raising serious concerns within the concrete industry. The extraction of natural aggregates from lakes, riverbeds, and other water bodies over extended periods has led to significant environmental issues in certain regions [27, 28]. Given the extensive annual consumption of concrete, even a minor percentage replacement of natural aggregate with recycled materials can yield significant conservation of natural resources; hence, researchers have been exploring various recycled materials for concrete use in recent decades [29]. As natural construction materials become increasingly scarce, the imperative to recycle waste to mitigate environmental impacts has emerged as a global trend, promoting sustainable material use in the built environment. For example, using rubber from recycled tires to partially replace coarse and fine aggregate in concrete can produce rubberized concrete. Although rubberized concrete exhibits a lower compressive strength compared to traditional concrete, it offers superior characteristics such as enhanced toughness, increased ductility, improved dynamic properties, lighter weight, and better resistance to cracking, frost, and wear [30]. This study aims to review the most recent investigations on rubberized concrete and perform a brief bibliometric analysis of the existing literature.

2 Bibliometric analysis

The bibliometric analysis of 1131 published documents on rubberized concrete, sourced from the Web of Science and examined through VOSviewer, presents an insightful panorama of the field's evolution and current state. This comprehensive corpus comprises 1019 journal papers, 110 conference papers, and 2 book chapters, reflecting a multidimensional scholarly engagement with rubberized concrete. The temporal distribution of these documents reveals an exponential growth in research interest, culminating in 2022 with a remarkable peak of 199 published works. This uptrend, as depicted in Fig. 1, underscores the escalating academic and industrial focus on rubberized concrete, signifying its burgeoning relevance in contemporary material science and engineering domains. Exploring the content classification, as shown in Fig. 2 The majority of these documents are journal articles, which evidence a strong preference for disseminating research findings through this scholarly medium. This preference suggests an emphasis on peer-reviewed platforms for sharing advances in rubberized concrete research, ensuring the credibility and scientific rigor of the disseminated knowledge. The conference papers and book chapters, while fewer, indicate an ongoing dialogue within the academic community and an effort to consolidate and disseminate knowledge through various scholarly channels. The thematic exploration, facilitated by keyword co-occurrence analysis in Fig. 3, reveals 'crumb rubber', 'concrete', and 'rubberized concrete' as central nodes in the research network. These keywords, along with 'compressive strength', 'aggregate', and 'mechanical properties', form the conceptual backbone of the field, highlighting the core focus areas and research interests. This lexical landscape not only maps the thematic territories of rubberized concrete research but also signals the technical and material properties that dominate the discourse, reflecting the scientific community's quest to enhance the understanding and application of rubberized concrete in construction and engineering.

Fig. 1
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Number of published documents on rubberized concrete over the period between 1992 and 2023

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Fig. 2
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Classification of published documents on rubberized concrete over the period between 1992 and 2023

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Fig. 3
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Co-occurrence of keywords in rubberized concrete publications over the period between 1992 and 2023

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The citation analysis of influential journals, illustrated in Fig. 4, positions 'Construction and Building Materials', 'Journal of Cleaner Production', and 'Journal of Building Engineering' as pivotal platforms for rubberized concrete research dissemination. The prominence of these journals indicates their role in shaping the academic and practical conversations around rubberized concrete, serving as key repositories of knowledge and innovation in the field. Their influence underscores the interdisciplinary nature of rubberized concrete research, bridging environmental sustainability, material science, and construction engineering.

Fig. 4
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Citation analysis of influential journals on rubberized concrete publications over the period between 1992 and 2023

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Furthermore, the geographical distribution of contributions, as depicted in Fig. 5, shows a significant research output from countries like China, Australia, England, Egypt, Malaysia, India, and Iraq. This global spread underscores the universal relevance and applicability of rubberized concrete across diverse climatic, economic, and cultural contexts. It reflects a collective endeavor to address the challenges of sustainable construction materials and practices, highlighting the international research community's commitment to advancing rubberized concrete technology.

Fig. 5
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Citation analysis by country in the field of rubberized concrete over the period between 1992 and 2023

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3 Recent investigations on rubberized concrete

Recent scholarly investigations into rubberized concrete have directed attention toward various dimensions of its properties and applications, offering a comprehensive perspective on its potential within the construction and material science fields [31]. This section aims to discuss the latest studies that focused on the properties and characteristics of rubberized concrete. For instance, Assaggaf et al. [32] examined the effects of different crumb rubber treatments on the durability characteristics of rubberized concrete. The study endeavors to discern how these treatments may augment the durability and performance of rubberized concrete across diverse construction applications. In a similar vein, Romanazzi et al. [33] concentrated on scrutinizing the bond strength of rubberized concrete with deformed steel bars, probing the potential utility of rubberized concrete in reinforced concrete structures. Their investigation delves into elucidating the compatibility and efficacy of bonding between rubberized concrete and steel reinforcement. Alsaif & Alharbi [34], on the other hand, conducted a comprehensive examination of the strength, durability, and shrinkage behaviors of steel fiber-reinforced rubberized concrete. Their study seeks to unravel the influence of steel fibers on the mechanical properties and long-term durability of rubberized concrete. Moreover, Yasser et al. [35] work on experimental research into the durability properties of rubberized concrete, aiming to unravel the impact of rubber incorporation on the concrete's longevity and resilience against environmental stressors. Employing regression and GA-BPNN approaches, Zhang et al. [36] determined the compressive strength of rubberized concrete using ultrasonic pulse velocity with the intent of refining predictive accuracy for the structural performance of rubberized concrete. Agrawal et al. [37] explored the experimental effects of pre-treatment of rubber fibers on the mechanical properties of rubberized concrete, investigating how distinct pre-treatment methods of rubber fibers may influence the overall performance and mechanical strength of rubberized concrete. Grinys et al. [38] explored the mechanical properties and durability of rubberized concrete modified with glass powder for white topping structures, aiming to evaluate how these modifications may impact the mechanical performance and long-term durability of the concrete. Pham et al. [39] focused on the dynamic properties of ultra-high-performance rubberized concrete, analyzing how rubberized concrete behaves under dynamic and high-stress conditions, a crucial aspect for high-performance applications. Similarly, He et al. [40] discussed the properties of rubber concrete containing surface-modified rubber powders, with a focus on how surface modification may influence the concrete's performance, aiming to bolster its mechanical properties and durability. Youssf et al. [41] assessed the performance of crumb rubber concrete made with high contents of heat-pre-treated rubber and magnetized water. This study aims to understand the effects of these unique treatment methods on the physical and mechanical properties of rubberized concrete. Kang et al. [42] presented a numerical study on the effectiveness of surface treatment on rubber particles towards the compressive strength of rubber concrete, focusing on the rubber-cement interface. The study aims to enhance the understanding of how surface treatments affect the interfacial bonding and overall strength of rubberized concrete. Swilam et al. [43] explored the effect of rubber heat treatment on the mechanical performance of rubberized concrete. The research investigates how heat treatment processes alter the properties of rubber within the concrete, affecting its mechanical performance. Mhaya et al. [44] focused on the improved strength performance of rubberized concrete through the amalgamation of ground blast furnace slag and waste glass bottle nanoparticles. The study examines how these materials can enhance the strength and durability of rubberized concrete. Al-Fasih et al. [45] presented an experimental and numerical evaluation of rubberized alkali-activated concrete, exploring the synthesis and performance characteristics of this type of concrete and how rubberization affects its properties. Prasad et al. [46] investigated the mechanical properties of rubberized concrete using truck scrap rubber, aiming to understand how scrap rubber from trucks can be utilized to enhance the mechanical properties of concrete. Nocera et al. [47] developed probabilistic models of concrete compressive strength and elastic modulus with rubber aggregates, aiming to provide a statistical understanding of how rubber aggregates influence the compressive strength and elasticity of concrete. Jiang and Zhang [48] focused on an experimental and analytical study on the mechanical properties of rubberized self-compacting concrete. The research investigates how the incorporation of rubber affects the mechanical properties of self-compacting concrete, including flowability and strength. Ahmad et al. [49] explored the microstructure and durability performance of rubberized concrete with waste glass as a binding material. It aims to understand how the combination of rubber and waste glass affects the concrete's durability and structural integrity. Nisticò et al. [50] investigated improving rubber concrete strength and toughness by plasma-induced end-of-life tire rubber surface modification. The study assesses how plasma treatment of tire rubber affects the mechanical properties of the resulting rubberized concrete. Dong et al. [51] presented a study on the mechanical properties and constitutive model of steel fiber-reinforced rubberized concrete. It focuses on developing a model to predict the behavior of rubberized concrete reinforced with steel fibers, enhancing understanding of its structural performance. Liu et al. [52] evaluated the compressive strength-reducing behavior of concrete containing rubber aggregate. It aims to quantify how the addition of rubber aggregates affects the compressive strength of concrete, providing insights into the trade-offs involved in rubberization. Fadiel et al. [53] provided a comprehensive evaluation of the mechanical properties of rubberized concrete. The study seeks to detail the overall impact of rubberization on concrete's mechanical behavior, covering aspects like strength, elasticity, and durability. Jiang et al. [54] investigated the compressive behavior of rubberized concrete under high strain rates, focusing on how rubberized concrete responds to rapid loading and stress conditions, which is critical for understanding its behavior in dynamic environments. Sun et al. [55] conducted an experimental analysis and evaluation of the compressive strength of rubberized concrete during freeze–thaw cycles. The study aims to understand how rubberized concrete withstands cyclic freezing and thawing, which is vital for its application in cold climates. Zhang et al. [56] explored the uniaxial tensile properties of multi-scale fiber-reinforced rubberized concrete after exposure to elevated temperatures. Figure 6 illustrates that as the temperature increases from 21 °C to 600 °C, the residual compressive strength of concrete decreases across all mixtures. Concrete with added rubber (0% to 20%) shows a smaller decline in strength with rising temperatures compared to the control mix, indicating better thermal resistance. However, the inclusion of rubber reduces the overall strength of the concrete. Figure 7 shows a decreasing trend in the residual splitting tensile strength of concrete as temperature increases across all rubber replacement levels. The strength is highest at 21 °C and significantly drops at 600 °C for each concrete mix, from the control mix without rubber to the 20% rubberized concrete. The graph indicates that while rubber inclusion impacts the tensile strength, all mixes are susceptible to reduced strength at elevated temperatures.

Fig. 6
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Impact of different temperature values on the compressive strength of various rubberized concrete at various rubber replacement percentages (Fadiel et al. [118])

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Fig. 7
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Impact of different temperature values on the tensile strength of various rubberized concrete at various rubber replacement percentages (Fadiel et al. [118])

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It assesses how heat affects the tensile properties of rubberized concrete, particularly when it is reinforced with fibers of various scales. Chaturvedy and Pandey [57] investigates the effect of graphene oxide on the physical and mechanical properties of high-strength rubberized concrete using RStudio. The research aims to determine how graphene oxide can enhance the performance of rubberized concrete in terms of strength and durability. Han et al. [58] provided an analytical evaluation of the stress–strain behavior of rubberized concrete incorporating waste tire crumb rubber. It focuses on understanding how crumb rubber from waste tires affects the stress–strain characteristics of concrete, influencing its mechanical performance under load.

4 Rubber aggregate classification

The recycling of tire rubber represents a prevalent practice, typically involving grinding processes to repurpose the material for various applications. Crumb rubber, commonly employed in asphalt paving and concrete mixtures, spans a size range from 0.0075 mm to 4.75 mm [7]. The production of crumb rubber entails a series of steps, including shredding, separation of steel and textile components, granulation, and classification. Initially, tires undergo cutting into larger pieces, followed by shredding into smaller fragments. Subsequently, the separation of textile and steel wires occurs post-shredding. Granulation through mechanical grinding can occur under different conditions, including ambient temperature, wet conditions, high temperature, or cryogenic temperature. In ambient temperature grinding, waste tire chips are processed in mills or granulators without the application of heat. Wet ambient grinding involves the addition of water to the crumb rubber to reduce temperature, followed by drying to remove moisture. High-temperature grinding, performed at around 130 °C, yields rubber granules ranging from 1 to 6 mm. However, the efficacy of high-temperature grinding is constrained by the viscoelastic nature and low heat conductivity of crumb rubber. Cryogenic grinding involves cooling tire rubber below its glass transition temperature, followed by shattering in an impact-type mill. Both ambient and cryogenic grinding methods are commonly utilized for tire rubber granulation [7]. Researchers in [8] have classified discarded tire rubber into several categories. Shredded or chipped rubber, capable of replacing coarse aggregates, undergoes a two-stage shredding process. Initially, rubber particles are shredded to lengths of 300–430 mm and widths of 100–230 mm. In a subsequent stage, dimensions are reduced to 100–150 mm and then further to 13–76 mm, termed as 'shredded particles', suitable for substituting coarse aggregates. Crumb rubber, produced in specialized mills, is ground into granules ranging from 0.425 to 4.75 mm, with particle size depending on the mill type and generated temperature. Ground rubber, which can partially substitute for cement, exhibits varying sizes determined by the reduction equipment employed. Through a micro-milling process, rubber particles can be refined to sizes of 0.075–0.475 mm. The production of ground rubber typically involves a two-stage method comprising magnetic separation and screening. Figure 8 illustrates three samples of rubber particles utilized in concrete mixes, showcasing variations in size [8].

  • Shredded or chipped rubber, which can replace coarse aggregates: Tires are shredded in two stages. Initially, rubber particles are shredded to lengths of 300–430 mm and widths of 100–230 mm. In the second shredding stage, the dimensions are reduced to 100–150 mm and then further to 13–76 mm, termed as ‘shredded particles’, suitable for replacing coarse aggregates.

  • Crumb rubber, which can replace fine aggregates: Produced in specialized mills, this rubber is ground into granules ranging from 0.425 to 4.75 mm. The size of the rubber particles depends on the mill type and the temperature generated.

  • Ground rubber, which can partially substitute for cement: The size of ground rubber varies depending on the reduction equipment used. In a micro-milling process, the rubber particles can be refined to 0.075–0.475 mm. The process to produce ground rubber involves a two-stage method of magnetic separation and screening. Figure 8 displays three samples of rubber particles used in concrete mixes, varying in size.

Fig. 8
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Different rubber sizes: (a) rubber less than 1 mm; (b) rubber between 3 to 5 mm; (c) rubber between 7 and 10 mm (Abbas et al. [119])

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5 Mechanical properties

5.1 Compressive strength

The existing body of literature consistently highlights a consensus regarding the detrimental impact of rubber inclusion on the compressive strength of concrete, a phenomenon observed across various studies [1,2,3,4,5,6,7,8,9,10,11, 13, 15,16,17,18,19,20,21, 24,25,26,27,28,29,30, 59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89], as depicted in Fig. 6 and summarized in Table 1. This reduction in compressive strength is ascribed to several interrelated factors inherent in rubber-modified concrete compositions. Primarily, the presence of rubber particles within the cement paste significantly alters the microstructural characteristics of the composite material, rendering the paste softer compared to its non-rubberized counterparts. Consequently, the susceptibility to crack initiation and propagation around the embedded rubber particles under load is markedly heightened, ultimately leading to premature failure of concrete specimens. An intrinsic challenge associated with rubber incorporation lies in the suboptimal bonding between rubber particles and the surrounding cementitious matrix, particularly when juxtaposed against the robust interfacial bonding observed between cement paste and conventional natural aggregates. This disparity in bonding quality exacerbates the propensity for crack formation within the concrete matrix, exacerbated by the non-uniform distribution of applied stresses. Moreover, the compressive strength of concrete is inherently contingent upon the mechanical and physical properties of its constituent materials. The partial replacement of these materials with rubber invariably engenders a reduction in compressive strength, attributed to the lower relative density of rubber and its limited interfacial bonding with other concrete constituents. During concrete compaction, the low density and inadequate bonding of rubber particles with the surrounding matrix facilitate their upward migration, resulting in a higher concentration of rubber at the surface layer and concomitant weakening of the concrete matrix [8]. Furthermore, rubber, owing to its non-polarity and hydrophobic nature, functions as an air-entraining agent within the concrete matrix. The quantity of entrained air increases with escalating rubber content and diminishing particle size, with smaller rubber particles exhibiting a larger specific surface area conducive to enhanced gas adsorption capacity. In practice, the uneven distribution of rubber particles within the concrete matrix predisposes the material to internal stress concentration, thereby fostering the nucleation and propagation of internal cracks along defective interfaces. Notably, rubber particles of smaller dimensions exert a more pronounced influence on the compressive strength of concrete compared to their larger counterparts [13] Fig. 9.

Table 1 Compressive strength changes of rubberized concrete collected for different mixtures
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Fig. 9
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Compressive strength changes across various types of rubberized concrete

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Figure 10 shows two key trends: first, the compressive strength of both compressed and uncompressed rubber concrete decreases as the percentage of rubber replacement increases from 0 to 50%. Second, the percentage variation in strength shows that while uncompressed rubber concrete consistently weakens with more rubber, compressed rubber concrete initially strengthens, peaking at 20% rubber content before also declining.

Fig. 10
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(a) Effect of various rubber percentages on the compressive strength of concrete; (b) effect of various rubber percentages on the percentage of variation of compressive strength (Dhiman et al. [120])

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5.2 Tensile strength

Concrete, renowned for its high compressive strength, often exhibits comparably low tensile strength, typically estimated at about 10% of its compressive strength, and a limited strain capacity [18]. Nonetheless, tensile strength holds paramount significance in the design of critical infrastructure such as highways, airfield slabs, and structures where shear strength and crack resistance are imperative considerations. The introduction of crumb rubber into concrete exacerbates these inherent weaknesses, culminating in a general reduction in tensile strength, a phenomenon attributable to analogous factors influencing compressive strength. The intricate relationship between compressive and splitting tensile strength is subject to the influence of various parameters, including aggregate type, particle size distribution, air entrainment level, curing age [59], as well as the content and type of powder and admixtures [60, 61]. As illustrated in Fig. 11, the incorporation of rubber into concrete significantly influences its tensile strength characteristics. Notably, compressed rubber concrete tends to exhibit comparatively higher tensile strength levels than uncompressed counterparts when rubber is added, particularly up to a 50% replacement level. However, the tensile strength of both compressed and uncompressed rubber concrete manifests a decreasing trend with increasing rubber content. This trend is particularly pronounced in uncompressed rubber concrete, where a steady decline in strength is observed. Conversely, compressed rubber concrete initially demonstrates an increase in tensile strength with the addition of rubber up to a 20% replacement level, followed by a subsequent decline as the rubber content is further augmented.

Fig. 11
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(a) Effect of various rubber percentages on the tensile strength of concrete; (b) effect of various rubber percentages on the percentage of variation of tensile strength (Dhiman et al. [120])

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The observed fluctuations in tensile strength underscore the intricate interplay between rubber content and concrete mechanical properties, highlighting the need for meticulous consideration of these factors in concrete design and formulation. Such nuanced insights into the behavior of rubber-modified concrete under tensile loading conditions are instrumental in informing the development of robust infrastructure solutions that effectively mitigate the inherent vulnerabilities of conventional concrete formulations.

5.3 Flexural strength

An escalation in rubber content within concrete precipitates a discernible reduction in its flexural strength, a phenomenon attributed to the considerable discrepancy in modulus of elasticity between rubber and concrete. As elucidated in prior studies [61,62,63,64], the markedly lower modulus of elasticity exhibited by rubber vis-à-vis concrete engenders disparate stress distributions within the composite material under external loading conditions. Consequently, the tensile or compressive forces exerted on rubber particles are substantially alleviated relative to those experienced by the surrounding aggregate constituents, thereby fostering stress concentrations that culminate in a diminution of flexural strength. Notably, concrete formulations incorporating rubber fibers deviate from this general trend, demonstrating elevated flexural strength values compared to conventional control mixes. This deviation is often attributed to the reinforcing effects imparted by the presence of rubber fibers within the concrete matrix. However, as elucidated in studies [65], the incremental increase in rubber content beyond a certain threshold, typically observed in the transition from 20 to 30% rubber content, serves to progressively diminish the flexural strength of concrete mixtures. Nevertheless, the extent of this reduction tends to exhibit variation contingent upon factors such as the size of the tire rubber particles, with studies indicating a less pronounced decline in flexural strength as the particle size diminishes. Illustrative insights gleaned from Fig. 12 corroborate the observed trend, elucidating a direct correlation between increasing rubber content and the concomitant reduction in various types of strength within concrete, including compressive, splitting tensile, and bending strengths. Of particular note is the differential impact observed in concrete compositions characterized by distinct mineral aggregate compositions, with concretes featuring low mineral fines and a higher coarse to fine aggregate ratio exhibiting a more pronounced susceptibility to strength diminution with escalating rubber content. Furthermore, irrespective of mineral fine aggregate content, the overarching trend elucidates a proportional reduction in strength metrics with incremental rubber addition, albeit with a more pronounced effect observed in concretes characterized by lower mineral fines. Such nuanced observations underscore the multifaceted interplay between rubber content, mineral aggregate composition, and concrete mechanical properties, necessitating meticulous consideration in concrete formulation and structural design endeavors.

Fig. 12
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Impact of different rubber content on the strength reduction for: (a) high mineral fine aggregates (HF) and 0.7 coarse aggregate to fine aggregate ratio (G/S); (b) low mineral fine aggregates (LF) and 1.1 coarse aggregate to fine aggregate ratio (G/S) (Khaloo and Parvin Darabad [121])

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5.4 Elastic modulus

The correlation between the modulus of elasticity and compressive strength is similar to the observed trends. The addition of rubber to concrete significantly reduces the modulus of elasticity, correlating with the decrease in compressive strength. A higher percentage of rubber leads to a marked reduction in the static elastic moduli, attributed to the diminished paste quantity [61,62,63,64,65,66,67,68,69]. Therefore, the decrease in the modulus of elasticity is mainly due to the inherently low modulus of elasticity of rubber [64]. Figure 13 demonstrates that as rubber content in concrete increases, the static modulus of elasticity decreases for both GR-8 and CR-40 rubberized concrete types. The decrease is more significant in the CR-40 mix, which also has a higher correlation between rubber content and reduction in elasticity, as indicated by a higher R-squared value. The trend is linear and inversely related for both concrete types.

Fig. 13
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Effect of the rubber content on the static modulus of elasticity (Zheng et al. [122])

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Figure 14 indicates that the dynamic modulus of elasticity for both GR-8 and CR-40 types of concrete decreases as rubber content increases. The trend is stronger and more consistent in the CR-40 mix, as reflected by its higher R-squared value. This relationship suggests that rubber additions make the concrete less dynamically stiff.

Fig. 14
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Effect of the rubber content on the dynamic modulus of elasticity (Zheng et al. [122])

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5.5 Stress–strain relationship

The stress–strain curves for rubber concrete under axial compression reveal that rubber content significantly affects the concrete's properties. Rubber decreases the strength of concrete but enhances its deformation capabilities. The influence of rubber on the peak strain of concrete is dictated by the combined factors of concrete strength and deformation, which are constrained by the rubber content, particle size, and addition method. Enhancements in the peak strain of concrete are achievable through external addition methods, although the trend of peak strain in rubber concrete, relative to rubber content and particle sizes, remains unclear. With increasing rubber content and decreasing rubber particle size, the crack strain consistently rises [13]. Over time, the stress–strain curves tend to linearize, possibly because strength increases with age, leading to a more linear stress–strain response in higher strength concretes [61]. Figure 15 depicts stress–strain relationships for concrete with varying compositions. Normal concrete (NC) and steel fiber concrete (SFC) serve as the baselines. The inclusion of crumb rubber reduces peak stress across the board, with higher rubber contents leading to more significant reductions. Steel fiber concrete enhanced with crumb rubber shows a less pronounced reduction, suggesting improved performance due to steel fibers. High rubber aggregate concrete (R20 to R60) exhibits a marked decrease in strength, highlighting a negative correlation between rubber content and peak stress capacity. These results illustrate how modifying concrete with rubber impacts its mechanical properties, specifically its elasticity and strength under load.

Fig. 15
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Stress–strain of: (a) normal concrete (NC), 5% crumb rubber concrete (CRC-5), 10% crumb rubber concrete (CRC-10), 15% crumb rubber concrete (CRC-15); (b) steel fiber concrete (SFC), 5% steel fiber crumb rubber concrete (SFCRC-5), 10% steel fiber crumb rubber concrete (SFCRC-10), 15% steel fiber crumb rubber concrete (SFCRC-15); (c) traditional concrete (R00), 20% rubber aggregate (R20), 40% rubber aggregate (R40), 60% rubber aggregate (R60); (d) NC, 6% CRC, 12% CRC, 18% CRC

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5.6 Abrasion resistance

Concrete's abrasion resistance, or its ability to resist surface abrasion, is dependent on its compressive strength and the type of aggregate used. Harder aggregates provide better abrasion resistance compared to softer ones. Notably, the abrasion resistance index of concrete incorporating rubber shows a decreasing trend as the rubber content increases. Since cement paste exhibits limited abrasion resistance, the overall abrasion resistance relies on the stiffness of the aggregate. Consequently, replacing aggregate with rubber diminishes the volume of aggregate and thus the abrasion resistance [64]. Figure 16 illustrates the impact of rubber particle (RP) content on the abrasion resistance of two classes of concrete, C30 and C50, in Group A and Group B, respectively. Each graph shows two trends based on the size of the RP: 1–3 mm and 3–5 mm. In both groups, as the percentage of rubber content increases, the abrasion resistance also increases, with a more pronounced effect in the larger particle size (3–5 mm). The quadratic equations and high R-squared values indicate a strong correlation between RP content and abrasion resistance. The trend is consistent across both concrete classes, suggesting that rubber particles enhance abrasion resistance in concrete.

Fig. 16
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Effect of rubber content on the abrasion resistance of: (a) C30 concrete class (group A); (b) C50 concrete class (group B) (Feng et al. [123])

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5.7 Dry density of concrete

The substitution of natural coarse or fine aggregate with rubber particles results in a reduction in the unit weight of concrete, attributed to the lower specific gravity of rubber. Notably, the reduction in compressive and flexural strength is more significant when coarse aggregate is replaced with waste tire rubber particles than when fine aggregate is replaced [65,66,67,68,69,70,71]. Figure 17 shows the effect of crumb rubber replacement on the density of concrete. Both fresh and hardened densities decrease as the percentage of crumb rubber increases. Heat treatment of crumb rubber slightly mitigates this reduction, yielding higher densities compared to untreated crumb rubber at equivalent replacement levels. However, all replacements result in lower densities than the control mix, with the reduction more pronounced at higher rubber contents. Standard deviations indicate greater variability in density measurements with increased rubber replacement.

Fig. 17
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a Fresh density of concrete for control, 40%, 60%, and 80% of crumb rubber replacement (F40, F60, F80), and 40%, 60%, and 80% of heat-treated crumb rubber replacement (F40T, F60T, F80T); b hardened density of concrete for control, 40%, 60%, and 80% of crumb rubber replacement (F40, F60, F80), and 40%, 60%, and 80% of heat-treated crumb rubber replacement (F40T, F60T, F80T) (Swilam et al. [43])

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5.8 Impact resistance

An increase in rubber content enhances the concrete's capacity to withstand more blows, thus improving its energy absorption ability. Concrete with added rubber demonstrates promising behavior against impact loading, though the increase in rubber content tends to reduce the compressive strength of these mixes compared to those without rubber [11, 30, 71,72,73,74,75,76,77,78,79]. Figure 18 depicts that the inclusion of chipped tire rubber in concrete significantly increases impact energy, peaking at 40% replacement before stabilizing. Conversely, crumbed tire rubber shows an initial increase in impact energy with a peak at 20% replacement, followed by a decline as more rubber is added. This suggests chipped tire rubber may be more effective than crumbed rubber at enhancing the impact resistance of concrete.

Fig. 18
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Effect of rubber replacement on the impact energy (Reda Taha et al. [124])

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5.9 Toughness

The toughness of concrete consistently rises with the rubber content, reaching up to 25% of total aggregate substitution, beyond which it starts to decline due to reduced ultimate compressive strength [72]. It was noted that the fracture toughness of concrete significantly increases with rubber content, with the highest increase at 75% volume of rubber replacement, resulting in a 350% improvement compared to the base reference mix [73]. These observations generally align with other studies [60, 75,76,77,78,79]. Figure 19 indicates that increasing the rubber replacement ratio in concrete leads to a rise in fracture toughness. The experimental data points create an upward trend, which is captured by a curve-fitting equation. This trend highlights that the addition of rubber to concrete can significantly enhance its resistance to crack propagation and fracture, particularly after surpassing 20% replacement. The graph suggests that concrete's toughness improves with higher rubber content, although the rate of increase slows as the replacement ratio approaches 100%.

Fig. 19
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Effect of the rubber replacement on the fracture toughness (Reda Taha et al. [124])

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5.10 Brittleness index

For ductile materials, the brittleness index approaches zero as all energies become irreversible, while for brittle materials, the brittleness index approaches one. The brittleness index decreases with an increase in rubber aggregate content, indicating a more ductile nature of the concrete. Specifically, substituting 20% and 40% of sand with rubber aggregates reduces the brittleness index by 23% and 29%, respectively, demonstrating increased ductility with higher rubber content in concrete [78]. However, it is important to acknowledge that there is an optimal rubber aggregate content where the material's behavior transitions from brittle to ductile [77]. Figure 20 shows that the brittleness index of concrete decreases as the rubber content increases, for both GR-8 and CR-40 mixes. This trend suggests that adding rubber to concrete reduces its brittleness, making the material less likely to fracture under stress. The CR-40 mix demonstrates a more pronounced reduction in brittleness than GR-8, implying it becomes more ductile with higher rubber content.

Fig. 20
figure 20

Effect of the rubber content on the brittleness index (Zheng et al. [122])

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5.11 Crack resistance and energy absorption

Concretes with higher rubber contents exhibit improved deformation capacities and energy absorption abilities compared to those with lower rubber contents [63]. The replacement of crumb rubber aggregate decreases the flexural strength but significantly enhances the strain capacity, leading to reduced Crack Mouth Open Displacement compared to the reference mix. This improvement is crucial from a serviceability perspective [60]. The rubber content influences the crack length, width, and timing in rubberized concrete, with rubber acting to bridge the cracks and restrain them from widening [80]. Post-cracking behavior in concrete samples remains unaffected by the partial replacement of fine aggregate with similarly sized rubber particles, while a notable residual strength and significant energy absorption are observed in rubberized concrete mixes that include coarse rubber chips instead of coarse aggregate [69]. Figure 21 depicts the energy absorbed by concrete at different stages of cracking with varying levels of rubber content. The pre-crack energy peaks for concrete with 10% rubber content and decreases thereafter. During the crack phase, 10% rubber content again shows the highest energy absorption. Post-crack, energy absorption drops significantly with increased rubber content, reaching a minimum at 15% before a slight recovery at 20%. The trend suggests rubber content influences the toughness of concrete, with 10% rubber optimizing energy absorption before and during cracking, but higher levels decreasing post-crack toughness.

Fig. 21
figure 21

a Pre-crack absorbed energy; (b) during crack absorbed energy; (c) post-crack absorbed energy (Guo et al. [125])

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5.12 Fatigue resistance

Samples with a rubber content of 15% and a steel fiber volume fraction of 0.75% exhibited the highest fatigue resistance, regardless of the applied stress level. It was observed that specimens exposed to 90% of their flexural strength had a reduced fatigue life. However, as the stress level decreased, fatigue strength improved significantly. Fatigue life data, when subjected to a load range of 60% of the flexural strength, showed greater variability, suggesting that the endurance limit of the material was likely being approached. The inclusion of rubber in concrete enhanced the fatigue strength by approximately 15%. Moreover, an increase in rubber content consistently led to higher fatigue strength [81]. Figure 22 shows that adding rubber to concrete increases its fatigue life, with more significant improvements seen at a lower stress ratio (S = 0.75) compared to a higher one (S = 0.85). The graph indicates that as the percentage of rubber in the concrete increases, so does the material’s endurance against repeated loading, suggesting enhanced durability. The variability in fatigue life is represented by the shaded areas between the maximum and minimum values, which also increase with rubber content.

Fig. 22
figure 22

Effect of various rubber percentages (0%, 2.5%, 5%, 7.5%, and 10%) on the fatigue life (Pei et al. [126])

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5.13 Dry shrinkage

Shrinkage escalated with the increase in rubber content, as rubber particles augmented the concrete's porosity. The rise in total shrinkage, alongside water content, resulted from heightened open porosity, thereby amplifying shrinkage. The maximum shrinkage strains were recorded at the highest water-to-cement (w/c) ratios, while the minimum shrinkage occurred at the lowest w/c ratios. Evaporation of free water from macro pores contributed to this increase in shrinkage. Nevertheless, the growth in drying shrinkage of all specimens decelerated after 100 days. Introducing rubber, ranging from 10 to 50%, effectively reduced the drying shrinkage of concrete with w/c ratios of 0.40, 0.43, and 0.47 over 180 days. Conversely, the highest drying shrinkage was observed in concrete with high rubber content (40% and 50%) at the highest w/c ratios [82]. Concrete shrinkage increased with the substitution ratio of natural coarse and fine aggregate by rubber, although this variation was less pronounced for coarse aggregates. Water absorption through immersion also increased with the natural aggregate substitution by rubber, particularly as the particle size of the replaced aggregate grew [83]. Figure 23 demonstrates that the shrinkage strain in concrete increases with both the age of the concrete and the level of rubber particle replacement. Across all time points measured, from 1 to 360 days, higher percentages of rubber lead to higher shrinkage strains. This relationship indicates that rubber particles contribute to the long-term deformation of concrete, a factor that must be considered in its structural applications.

Fig. 23
figure 23

Effect of different rubber replacement on the shrinkage strain (Lv et al. [22])

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6 Influence of rubber pre-treatment and pre-coating

The utilization of recycled tire rubber as an aggregate constituent in concrete formulations has emerged as a promising avenue, yielding notable enhancements in mechanical properties and performance metrics. On the other hand, various effects have been observed with specific rubber pre-treatment through combinations and chemical treatments, showing substantial improvement in compressive strength and changes to the microstructure of the cement matrix, as shown in Fig. 24. For instance, incorporating 15% silica fume alongside chemical treatment with sodium hydroxide yielded a remarkable enhancement, elevating compressive strength to 50 MPa [84]. Similarly, the introduction of CaCl2 in a volume ratio of 5% alongside rubber particles evinced a notable strengthening effect, culminating in a 14% increase in the strength of rubberized concrete [85]. Notably, the magnitude of strength reduction in rubberized concrete exhibits variability, ranging from 24.7 to 17.5%, contingent upon the specific composition and treatment regimen employed [85]. Further advancements have been realized through targeted chemical treatments aimed at enhancing the interfacial adhesive behavior between rubber particles and cement hydrates. Treatments involving CSBR latex and KH-570 SCA have been particularly efficacious in refining the concrete's microstructure, thereby facilitating enhanced compressive strength. Notably, the incorporation of a low volume fraction of treated rubber in lieu of traditional aggregates has demonstrated the potential to surpass the compressive strength thresholds observed in conventional concrete formulations [86]. This augmentation in compressive strength at lower levels of rubber substitution can be attributed to rubber's inherent ability to mitigate cracking mechanisms, thereby fortifying the structural integrity of the composite material. However, it is noteworthy that at higher replacement levels, the porous microstructure engendered by increased rubber content imparts a deleterious effect on mechanical properties, precipitating a reduction in compressive strength [86]. Moreover, investigations have underscored the intricate interplay between rubber content and concrete porosity, elucidating a direct correlation between increased rubber content and heightened porosity levels, which, in turn, contribute to diminished mechanical properties [87]. Nevertheless, promising avenues for mitigating strength loss associated with rubber waste utilization have been delineated through novel material combinations. Mixtures incorporating coated crumb rubber alongside additives such as limestone powder and silica fume have exhibited notable improvements in both compressive and tensile strengths, outperforming reference mixtures at specified fine aggregate replacement levels [88]. Additionally, the synergistic effects between fly ash and meta-kaolin have been harnessed to mitigate strength reduction attributed to rubber waste incorporation, with optimized formulations demonstrating marked improvements in compressive strength compared to reference mixtures [88]. Such nuanced insights into the interplay between rubber waste utilization, material composition, and mechanical properties underscore the pivotal role of material engineering in enhancing the sustainability and performance of rubberized concrete formulations.

Fig. 24
figure 24

SEM image rubberized cement-based material before and after treatment: (a) As-received rubber (5000 ×); (b) treated rubber (5000 ×) from Chen and Lee [127]

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7 Estimation of rubberized concrete mechanical properties

The exploration of mechanical properties in rubberized concrete has emerged as a focal point in contemporary research endeavors, marking a notable transition towards the integration of sophisticated computational methodologies within the realm of material science. This integration endeavors to enhance the predictive precision and elucidate the nuanced behavior of rubberized concrete under diverse operational scenarios, leveraging the capabilities of machine learning and artificial intelligence techniques. Noteworthy contributions in this domain include the work by Gao et al. [90], who applied machine learning methodologies to estimate the frost resistance of rubberized concrete. Similarly, Pal et al. [91] expanded the purview of machine learning applications by developing predictive models for the compressive strength of fiber-reinforced concrete incorporating waste rubber and recycled aggregates. Further, Habib and Yildirim [92] conducted an exhaustive investigation into the mechanical and dynamic properties of rubberized concrete utilizing machine learning techniques, emphasizing the holistic capabilities of such methodologies in capturing the intricate effects of rubber incorporation on concrete properties. Their study underscores the pivotal role of machine learning in facilitating material selection and structural design processes through comprehensive analysis. Ly and Nguyen [93] explored machine learning-driven innovations in the design of environmentally sustainable rubberized concrete, underscoring its potential to foster sustainability without compromising performance metrics. Moreover, Ofuyatan et al. [94] evaluated the properties of self-compacting rubberized concrete through a combined experimental and machine learning approach, demonstrating the efficacy of machine learning in elucidating the material's behavior and enhancing its quality for construction applications. Subsequent efforts by Sobuz et al. [95] optimized recycled rubber self-compacting concrete through a synergy of experimental findings and machine learning-based evaluations, further accentuating the efficacy of such integrated approaches. Expanding the purview of machine learning applications, Hasanipanah et al. [96] focused on predicting the compressive strength of rubberized concrete using feature importance and partial dependence analysis techniques. Pal et al. [97] ventured into predicting the slump of fiber-reinforced concrete containing waste rubber and recycled aggregate through data-driven machine learning approaches, exemplifying the versatility of such methodologies in diverse material contexts. In simplifying the modeling of rubberized concrete properties, Habib and Yildirim [98] employed multivariable regression analysis, highlighting the potential of simpler statistical methods in furnishing expedient insights into material behavior. Additionally, Cakiroglu et al. [99] utilized explainable ensemble learning for data-driven modeling of mechanical properties in fiber-reinforced rubberized recycled aggregate concrete, while İpek et al. [100] investigated the thermal conductivity of rubberized concrete using artificial intelligence techniques, emphasizing its potential as an energy-efficient building material. Further advances in predictive modeling were realized by Adamu et al. [101], who predicted the mechanical properties of rubberized concrete incorporating fly ash and nano silica employing artificial neural network techniques. Similarly, Habib et al. [102] applied kernel principal component analysis to enhance multivariable regression modeling of rubberized concrete properties, exemplifying the utility of advanced statistical techniques in elucidating the factors governing material behavior. In summary, recent investigations into the mechanical properties of rubberized concrete underscore a notable trend towards the adoption of machine learning and artificial intelligence techniques. These endeavors collectively contribute to a deeper comprehension of material behavior, thus optimizing performance and sustainability in construction applications. The integration of computational modeling with empirical research has proven instrumental in advancing the field, facilitating the development of more efficient, durable, and environmentally friendly concrete solutions.

8 Conclusion

In summary, this comprehensive review on the effects of recycled rubber content on the mechanical properties of concrete has focused on recent advances of rubberized concrete mixtures as a structural material. Generally, the inclusion of crumb rubber in concrete formulations has been shown to enhance ductility and energy absorption, contributing to the mitigation of brittle failures in concrete structures. Despite the reduction in compressive strength and abrasion resistance, the environmental and mechanical benefits of incorporating waste rubber into concrete are significant, offering a sustainable alternative to traditional concrete materials. The optimal rubber content for concrete, found to be between 2 and 5%, suggests a balanced approach to enhancing mechanical properties while contributing to environmental sustainability by repurposing waste tires. However, the study also highlights gaps in current research, particularly concerning the creep behavior of rubberized concrete and the mechanical properties of treated rubber, necessitating further investigation. This underscores the need for continued research and development in the field, aiming to refine the use of recycled rubber in concrete to maximize both its environmental and structural benefits. Ultimately, this study provides an understanding of rubberized concrete and encourages the construction industry to adopt sustainable practices that also meet the requisite mechanical performance standards.