Valorization of Medical Waste in Cement-Based Construction Materials: A Systematic Review

Abstract

Worldwide, the healthcare industry produces massive quantities of medical waste (MW), most of which is incinerated, releasing large quantities of dioxins, mercury, and other pollutants. Despite this, only a limited number of studies have explored the incorporation of MW into construction materials, with a special focus on cement-based construction materials (CB-CMs). However, to the best of the authors’ knowledge, no existing review formally structures, summarizes, correlates, and discusses the findings of previous studies on MW in CB-CMs to encourage further research and applications of this promising alternative. Therefore, the added value of this study lies in providing an innovative and critical analysis of existing research on the use of MW in CB-CMs, consolidating and evaluating dispersed findings through a systematic literature review, enhancing understanding of the topic, and identifying knowledge gaps to guide future research. A robust systematic literature review was conducted, encompassing 40 peer-reviewed research articles, retrieved from the Web of Science Core Collection database. The methodology involved a three-stage process: a descriptive analysis of the included articles, the identification and synthesis of key thematic areas, and a critical evaluation of the data to ensure a rigorous and systematic report. The selection criteria prioritized peer-reviewed research articles in English with full text availability published in the last 7 years, explicitly excluding conference papers, book chapters, short reports, and articles not meeting the language or accessibility requirements. The results indicate that the influence of MW in CB-CM varies significantly. For example, while the incorporation of face masks as fiber reinforcement in concrete generally enhances its mechanical and durability properties, the use of gloves is less effective and not always recommended. Finally, it was found that further research is needed in this field due to its novelty.

1. Introduction

The cement and concrete industry represent a crucial role in economic development for both developed and developing countries, as reported by the Portland Cement Association [1]. Globally, concrete production reached about 14 billion m³ in 2020, as reported by the Global Cement and Concrete Association [2], equivalent to about 2 m³ of concrete per person in the world. However, this high production level has led to significant environmental challenges, including (i) massive CO₂ emissions, as cement production—the primary binder responsible for strength development in concrete—accounts for approximately 8% of global anthropogenic CO₂ emissions [3]; (ii) the depletion of natural resources, particularly coarse and fine aggregates [4,5,6]; and (iii) high volumes of waste disposal, with construction and demolition waste comprising 45% to 65% of total landfill waste [7]. Addressing these challenges necessitates reducing the environmental impact of cement production and aggregate consumption while promoting sustainable construction practices, among others.

In this context, several research efforts have been undertaken to reduce the environmental impacts of cement-based construction materials (CB-CMs) (i.e., cement paste, mortar, and concrete), by incorporating industrial wastes (IWs) as substitutes for cement, which are generally characterized by the presence of oxides such as SiO₂, Al₂O₃, Fe₂O₃, and CaO, and can contribute to improving the mechanical, physical, and durability properties (e.g., [8,9,10,11,12]) of filler (e.g., [13,14]), recycled aggregates (e.g., [15,16,17]), and fiber reinforcements (e.g., [18,19,20,21]), among others. The latter IWs originate from different industries such as (i) mining [8]; (ii) construction [22,23]; automotive [24]; and even livestock [21]. Additionally, the healthcare sector has recently gained attention for its potential contribution of IW in CB-CMs, although further research is still needed.

The World Health Organization (WHO) defines medical waste (MW) as waste generated by healthcare activities, ranging from used needles and syringes to soiled dressings, body parts, diagnostic samples, blood, chemicals, pharmaceuticals, medical devices, and radioactive materials [25]. This type of waste is produced by hospitals, dental clinics, nursing homes, veterinary practices, and community healthcare services providers [26]. Notably, MW constitutes 2–3% of the total global waste production, yet it is also among the most hazardous type of IW [27]. According to the Environmental Protection Agency [28], the United States generates approximately 5.9 million tons of MW annually. This figure is expected to increase globally, as high-income countries generate nearly 11 kg of hazardous MW per hospital bed each day, while low-income countries produce up to 6 kg, as reported by WHO [29]. On the other hand, up to 85% of MW is classified as non-hazardous, while the remaining 15% consists of infectious, toxic, or radioactive materials [25]. According to the U.S. Department of Commerce, the most commonly used medical supplies include (i) plastic syringes; (ii) needles; (iii) catheters; (iv) medical gowns; (v) disposable latex; (vi) nitrile gloves; (vii) vinyl gloves; and (viii) face masks, among others [30]. Consequently, these MW types will be analyzed for their potential incorporation in CB-CMs in this review. In addition to these items, many other medical supplies are common in the healthcare sector, such as stethoscopes, sponges, forceps, and cups. However, no studies have been found on their application in CB-CMs.

It is worth noting that, although MW has posed a significant waste management challenge for decades [31], since the COVID-19 pandemic was declared on 30 January 2020 [32], a significant increase in the generation of MW was reached due to the massive use of surgical masks, for the protection of both healthcare workers and the general population. The WHO estimated a monthly demand of approximately 89 million medical masks to combat the COVID-19 pandemic [32], leading to unprecedented consumption. Even today, these masks remain widely used and readily available. Consequently, the valorization of MW in the construction industry, particularly in the production of CB-CMs, presents a promising waste management solution. From both a technical and environmental perspective, it offers an effective strategy for managing and reutilizing MW.

In addition to this approach for managing MW, several other efforts have been undertaken to enhance waste management processes, though significant challenges remain. Mazzei and Specchia [33] identified some of these challenges, along with emerging technologies being applied to MW management. Among the primary challenges are the previously mentioned COVID-19 pandemic, the hazardous components of certain MW, and pollution concerns. As stated by Hossain et al., [30] improper clinical waste management severely threatens public health through disease spread and environmental contamination, disproportionately affecting healthcare workers and developing nations, so urgent improvements in waste handling practices are crucial to mitigate these risks and protect both human health and the environment; therefore, various strategies are currently being implemented for MW management, including plasma gasification, chemical disinfection, and hybrid systems that integrate multiple treatment processes, as stated by Mazzei et al. [33].

It is important to note that the valorization of MW has also been explored in industries beyond construction. For instance, Arcuri et al. [34] investigated energy production from MW containing blood and saliva, developing a bioanode capable of generating electricity to meet the energy needs of a consulting room. Similarly, Dharmaraj et al. [35] utilized MW—specifically COVID-19 plastic waste—to produce energy based on biohydrogen, subjecting these plastics to chemical processes that degrade them and eliminate potential hazards. On the other hand, Zhou et al. [36] implemented a co-valorization process integrating plasma gasification to convert MW and biomass waste into mixed eco-friendly fuels. Additionally, Li et al. [37] developed a hybrid design solution that combines MW with other waste materials to enhance electrical energy efficiency.

In general, the valorization of MWs beyond the construction industry remains limited, with only a few applications demonstrating a significant impact. However, notable efforts have been made to integrate MWs into CB-CMs. These include the use of MW incineration ash as a partial cement replacement in concrete [38], medical gloves as fiber reinforcement in mortar [39], surgical gowns of as fiber reinforcement in concrete [40], and face masks as fiber reinforcement in concrete [41,42,43], among other studies.

Although previous studies have offered valuable insights into the valorization of MW in CB-CMs, a comprehensive and critical synthesis of these findings remains lacking. This study addresses that gap by systematically compiling, evaluating, and contextualizing existing research to enhance the understanding of MW applications in cementitious matrices. Through a rigorous systematic literature review (SLR), this study consolidates fragmented information into a coherent framework, allowing future researchers to build upon a centralized body of knowledge without the need to examine each article in isolation. Ultimately, this work seeks to support scientific progress in sustainable construction by offering both clarity and direction for ongoing and future investigations in the field.

To achieve the above-mentioned objectives, this SLR is structured as follows: Section 2 outlines the methodology used to conduct the SLR. Section 3 provides details on each type of MW examined in this study, including its definition, material composition, consumption trends, and summary of material properties. The MW analyzed include: (i) face mask (FM); (ii) needles (NDs); (iii) plastic blisters (PBs); (iv) plastic syringes (PSGs); (v) medical glass (MG); (vi) gloves (GL); (vii) medical textiles (MT); and (viii) medical waste incineration ash (MWIA). Section 4 discusses the chemical and physical treatments used to disinfect these MWs before their incorporation into CB-CMs. Section 5 presents the applications of various MW types in CB-CMs, as well as their applications in other CMs. Finally, Section 6 provides conclusions and recommendations based on the findings of this review.

2. Search Strategy Methodology

This section outlines the search protocol used to conduct this SLR. The review follows the methodology proposed by Marying [44] and applied by Seuring et al. [45], which consists of the following four main steps: (i) material collection: clearly defining and limiting the scope of the materials to be gathered; (ii) descriptive analysis: assessing the collected material by specifying relevant aspects (e.g., the number of publications per year and the number of publications per country) to establish a background for further theoretical analysis; (iii) category selection: identifying and categorizing related topics within the collected data, also known as stream identification; and (iv) material evaluation: analyzing the collected material based on stream identification using the “Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram and check list.

2.1. Bibliometric Assessment

In this study, the Web of Science (WoS) Core Collection database was used to identify scientific research articles related to the valorization of clinical waste (CW) or medical waste (MW) as construction materials (CMs) within cement-based construction materials (CB-CMs). To characterize the evolution and geographic distribution of research on medical-waste valorization in cement-based materials, a bibliometric analysis was performed covering publications from January 2017 to October 2024.

The search process initially returned 131 documents. After applying the inclusion and exclusion criteria detailed in

Table 1. Inclusion and exclusion criteria.

Features	Inclusion Criteria	Exclusion Criteria
Type of research	Peer-reviewed research articles	Conference papers, book chapters, and short reports
Language	English	Other languages
Availability	Full: The complete research article is accessible, including all sections	Not available: Articles for which only abstracts or summaries are available but not the full text
Objective	Main objective is the valorization of CW/MW as a CM within CB-CMs (i.e., cement paste, mortar, and concrete) Valorization of CW/MW as CM to produce other CMs (e.g., pavements, asphalt, and geopolymers) will be considered in “Other CMs section”	Reason 1: Articles where the primary objective is the valorization of CW/MW as a raw feed material to produce materials other than CMs Reason 2: Articles where the primary objective is the use of materials other than CW/MW to enhance the performance of an already developed CB-CM with MW

, 40 documents were selected for analysis. All included documents corresponded to peer-reviewed research articles, while conference papers, book chapters, and short reports were excluded from the study to ensure the quality and relevance of the analysis.

Descriptive Analysis

After reading and selecting the articles, a data matrix was created containing information on titles, authors, keywords, journals, the year of publication, the country of publication (based on the affiliation of the first author/corresponding author), and other relevant characteristics.

Subsequently, as shown in Figure 1, the publication frequency per year was analyzed for the period January 2017–October 2024. The total body of literature consists of 40 articles, with a higher concentration of publications between 2020 and 2023. Although the number of articles collected is lower compared to other SLRs in different disciplines, the data indicate a growing trend in publications over time. This trend suggests an increasing interest among scientific groups in addressing MW-related issues and exploring its valorization as CM within CB-CMs.

Figure 2 presents a world map illustrating the global distribution of publications, highlighting the countries where researchers have contributed to the valorization of MW as CM within CB-CMs and other CMs. The color scale represents the publication frequency, with lighter colors indicating fewer publications and darker colors representing higher publication counts. China and India stand out as the leading contributors, which may be attributed to the substantial amounts of MWs generated in these regions, as reported by Hou et al. [46] and Goswami et al. [47]. This high MW generation has driven research and development in valorization processes.

2.2. Category Selection

A category selection framework was established to classify different MW types based on their role as CM (i.e., fiber reinforcement, filler, or supplementary cementitious material (SCM), fine aggregate, coarse aggregate, or other) and their application/valorization in various matrices (i.e., cement paste, mortar, concrete, or other). This classification accounts for the specific role each MW plays in enhancing the performance of CB-CMs or other CMs. The decision to focus on these matrices stems from their prevalence in existing literature and their relevance in CMs research.

For each category, the collected articles were grouped as follows: (i) the type of MW used; then, (ii) the type of CM in which MW is valorized; and finally, (iii) the type of CM matrix improved by the valorized MW. This structured categorization enables a focused comparison of MW behavior in different CB-CMs. Additionally, other CMs, such as asphalt and geopolymers, which exhibit distinct chemical, mechanical, and physical properties compared to traditional CB-CMs, will be discussed in a separate sub section to highlight their distinct characteristics and applications.

3. Medical Wastes

3.1. Face Masks (FMs)

3.1.1. FM Definition and Material Composition

FMs are primarily composed of polymers, with polypropylene (PP) being the most commonly used component. However, other materials such as polyurethane, polycarbonate, polystyrene, poly-acrylonitrile, and PE are also used in FM production, as reported by Asim et al. [48] and Akarsu et al. [49]. Most FMs are manufactured using a melt-blown process [49], which produces webs of fine filaments that bond together. Figure 3a presents a typical FM, while Figure 3b–d illustrate different microscopic images obtained through scanning electron microscopy (SEM). These images reveal the fine filament network that forms the microstructure of the FMs, with filaments of diameters ranging from approximately 18–20 µm (see Figure 3d).

3.1.2. FM Consumption Trends

The use of personal protective equipment, such as disposable FMs, has significantly increased in both the medical and public sectors since the onset of the COVID-19 pandemic. This surge has led to the disposal of approximately 3.4 billion single-use FMs globally per day [50,51], amounting to around 129 billion per month [48]. Currently, FM waste is primarily disposed of through incineration or landfill, both of which pose significant environmental risks [52], including the release of toxic contaminants (e.g., dioxin, oxides of sulfur, and hydrochloric acid) and leachates into the environment [53].

3.1.3. Summary of FM Material Properties

According to the collected studies [41,54,55], FMs have primarily been used as fiber reinforcement in mortars and concrete matrices. When used for this purpose, they are typically shredded, as shown in Figure 4. Although the fibers in the image measure 30 mm in length and 3 mm in width, these dimensions vary across different studies. Once shredded, their mechanical and physical properties have been characterized in various studies, and some of their main properties are summarized in

Table 2. Physical and mechanical properties of face masks as fiber reinforcement.

l 1,2 (mm)	Height 2 (mm)	Width 2 (mm)	A 2 (mm2)	¥ 2 (mm2)	${\mathit{d}}_{{\mathit{E}}_{\mathit{q}}}$ (mm)	AR 2	Density 1 (g/cm3)	Tensile Strength 1 (MPa)	Modulus of Elasticity 1 (GPa)	Melting Point 1 (°C)
5~30	0.045	0.25–0.30	0.011–0.013	0.59–0.69	0.074–0.075	65.56–400	0.91 [57]	4.25 [57]	0.26 ± 0.02 [58]	160 [57]

¹ Previous studies. ² Own study.

. It is important to note that these shredded FMs in their macrostructure present a rectangular shape. Thus, the aspect ratio presented in Table 2 was calculated based on the formulation proposed by Naaman et al. [56], which accounts for a non-circular cross-section, and is expressed in Equation (1).

$$\mathrm{AR}={\displaystyle \frac{l}{d_{E_q}}}={\displaystyle \frac{l}{4_{\yen }^A}}$$

(1)

where l is the fiber length, $d_{E_q}$ is the equivalent diameter, A is the cross-sectional area of the fiber, and ¥ is the perimeter of the cross-section of the fiber.

3.2. Needles (NDs)

3.2.1. ND Definition and Material Composition

Hypodermic NDs, which are part of syringes, are used to administer liquids, particularly substances that cannot be taken orally [59]. The hub is primarily made of PP, while the cannula is a hollow tube typically composed of stainless steel. The cap, also made of PP, serves to protect the canula from contamination [59].

3.2.2. ND Consumption Trends

The global use of NDs is estimated at approximately 16 million injections administered worldwide each year [60]. However, not all NDs are properly disposed. Additionally, according to a market report [61], the ND market size is projected to grow from 7.7 billion USD in 2022 to 10.6 billion USD by 2027, driven by the increasing cases of chronic diseases and population growth.

3.2.3. Summary of ND Material Properties

The gauge of an ND varies depending on the inner diameter of the stainless-steel hollow tube. Generally, ND length and gauge are inversely proportional; as length decreases, the gauge increases [59]. To the best of the authors’ knowledge, only one study, conducted by Hamada et al. [62], has reported the valorization of NDs as fine aggregate replacement. In this study, NDs were cut in small pieces (see Figure 5), and the reported dimensions, as along with other physical properties, are summarized in

Table 3. Physical properties of NDs reported in a technical sheet.

Gauge	Length (mm)	Weight (g)
16~30 [59]	40–48 [59]	25–30 [59]

and

Table 4. Physical properties of processed NDs reported in the study [62].

Gauge	Length (mm)	Volumetric Mass Density (kg/m3)
16~30 [59]	5–15 [62]	1455 [62]

.

3.3. Plastic Blisters (PBs)

3.3.1. PB Definition and Material Composition

PBs are low-cost packaging solutions for drugs and capsules, produced through thermoforming or cold-forming process. They consist of multiple layers composed of aluminum and plastics such as polyvinyl chloride (PVC), PP, and terephthalate, as reported by Yaren et al. [63]. The aluminum and plastics content has been reported to be approximately 15% and 85% by weight, respectively, as reported by Rimšaitė et al. [64]; however, this composition can vary depending on the type of PB. According to Yaren et al. [63], there are three main types of PBs, each with component proportions (see Figure 6). Type A is the most commonly used, while type 2 and 3 are designed for drugs sensitive to moisture and light. For the valorization of PBs, separating the plastic from the aluminum is necessary. However, this process requires complex separation techniques, including hydrometallurgical and thermal processes, making PB valorization particularly challenging.

3.3.2. PB Consumption Trends

The PB market is projected to reach approximately US$149.3 billion by 2026, with a compound annual growth rate of 6% from 2019 to 2029 [63]. Additionally, the use of PBs has increased to the extent that they now account for approximately 4% of the total daily packaging waste by weight [65]. Furthermore, another study [66] estimated that the demand for PBs is expected to surpass 2.18 million tons by 2026.

3.3.3. Summary of PB Material Properties

According to the collected studies on PBs [67,68], they are primarily valorized as fine aggregate replacement in concrete matrices. For this purpose, PBs are crushed and mechanically ground into a powdered form to achieve a particle size distribution (PSD) similar to sand. The primary physical property reported in these studies is the PSD, which ranged from 0.15 mm to 10 mm [67,68].

3.4. Plastic Syringes (PSGs)

3.4.1. PSG Definition and Material Composition

PSGs are primarily manufactured through injection molding using PP and are commonly used to administer various fluids into the body [69]. Since they contain a high percentage of PP (approximately 90%), as reported by Rashidi et al. [70], they represent a promising material for valorization in the construction sector. Figure 7 presents a schematic of the main components of the PSGs, where “L” denotes length and “W” denotes width.

3.4.2. PSG Consumption Trends

According to reported studies [71], the global disposable PSG market size is expected to grow at a compound annual growth rate of 5.3%. Currently, the most common disposal method in hospitals for expired PSGs is to send them to collection agencies, which then dispose of them in landfills [70]. Additionally, many PSGs are discarded before being used due to quality issues [69], such as leaks, breakage, and other defects, contributing to an increase in expired PSG waste.

3.4.3. Summary of PSG Material Properties

To the best of the authors’ knowledge, only one study, conducted by Rashidi et al. [70], has investigated the valorization of PSGs as fine aggregate replacement in concrete matrices. For this purpose, PSGs were shredded using a 1.5 kW jaw crusher to achieve a PSD similar to sand. Consequently, the steel needle parts were removed using a 2-ton Beaver Permanent Magnet Lifter, as reported by Rashidi et al. [70]. The resulting PSG particles (see Figure 8) were physically characterized, and their main properties are summarized in

Table 5. Physical properties of processed PSGs reported in the study [70].

Specific Gravity	Water Absorption (%)	Maximum Size (mm)
0.97	0.1	4.75

.

3.5. Medical Glass (MG)

3.5.1. MG Definition and Material Composition

A significant fraction of hospital waste consists of MG, which accounts for more than 11% of MW [72]. MG exhibits high impermeability, high hardness, low water absorption, and a low fusion temperature [72,73]. Its chemical composition varies, but generally contains a high percentage of SiO₂ (greater than 69% by weight), along with lower concentrations of oxides such as CaO, Al₂O₃, Na₂O, K₂O, and BaO [72]. Due to its high SiO₂ content, GM can be used as SCM in concrete production or as a precursor for geopolymers synthesis [74,75,76,77].

3.5.2. MG Consumption Trends

The volume of waste glass has been constantly increasing over the past few decades [78]. According to Guo et al. [79], only 21% of the total 130 million tons of MG waste generated in 2018 was valorized. Among the different waste glass streams, the MG stream has grown significantly in recent years, particularly due to the COVID-19 pandemic. Asia alone generates approximately 16,659 tons of medical solid waste per day, which includes MG [78].

3.5.3. Summary of MG Material Properties

According to Ho et al. [78], MG can be valorized as a fine aggregate in concrete matrices. Additionally, other studies [73,80] have reported its use as a raw material for geopolymer matrix production. For both applications, MG must undergo crushing, milling, and sieving processes to achieve the required fineness. When used as a fine aggregate, its particle size should be comparable to sand, whereas for geopolymer applications, an even finer powder is required. The main physical properties of the MG powder, as reported in different studies, are summarized in

Table 6. Physical properties reported in the collected studies for MG powder as a fine aggregate.

Density (kg/m3)	Fineness Modulus
2486 [78]	3.37 [78]

and

Table 7. Physical properties reported in the collected studies for MG powder for its use in geopolymers.

Density (kg/dm3)	Specific Gravity	D50-PSD (µm)	Blaine Specific Surface Area (m2/kg)
2.48 [78]–2.50 [80]	2.03–2.23 [73]	30 [80]	402 [80]

.

3.6. Gloves (GLs)

3.6.1. GLs Definition and Material Composition

Several types of GLs are used in the medical field, each made of different materials based on their intended application and specific requirements. Among them, latex GLs are widely used due to their elasticity and close fit. Latex rubber is a naturally occurring substance that appears as a thick, milky-white colloidal suspension containing a hydrocarbon polymer. In general, its composition consists of approximately 50% water and 40% rubber-based materials [39]. Additionally, the demand for single-use nitrile GLs has increased significantly since the onset of the COVID-19 pandemic in late 2019 [81].

3.6.2. GLs Consumption Trends

In 2023, the global GL market was valued at USD 4.3 billion, with a projected compound annual growth rate of 12% from 2024 to 2032 [82]. The isoprene rubber latex market was valued at USD 268.8 million in 2023 and it is expected to have a CAGR of 4.4% from 2024 to 2032. Moreover, technological advancements and the expansion of applications across industries are expected to drive this growth [83]. Additionally, the nitrile butadiene rubber latex market was valued at over USD 2.9 billion in 2023, with a projected compound annual growth rate of 10.4% from 2024 to 2032 [84].

3.6.3. Summary of GLs Material Properties

In general, GLs can be utilized as fiber reinforcement [39,85,86], filler [75,87], or coarse aggregate [88] when mixed with either concrete or mortar. Some of the key properties of gloves reported in these studies include specific gravity, tensile strength density, and porosity, among others. These properties are shown in

Table 8. Mechanical properties reported in the collected studies for GLs as fiber reinforcement [81,85].

Tensile Strength (MPa)	Tensile Strength at Break (MPa)	Rupture Force (N)	Elongation at Break (%)
2.73	2.71	4.15	103.55

,

Table 9. Physical properties reported in the collected studies for GLs as fiber reinforcement [81,85].

Specific Gravity	l 1 (mm)	Height 2 (mm)	Width 1 (mm)	A 1 (mm2)	¥ 1 (mm2)	${\mathit{d}}_{{\mathit{E}}_{\mathit{q}}}$ (mm)	AR 2
1.26	15	0.08–0.13	5	0.4–0.65	10.16–10.26	0.15–0.25	100–160

¹ Previous studies. ² Own study.

and

Table 10. Physical properties reported in the collected studies for GLs as coarse aggregate [88].

Water Absorption (%)	Maximum Size (mm)
8%	5

.

3.7. Medical Textiles (MTs)

3.7.1. MTs Definition and Material Composition

MTs are fiber-based products and structures used in medical environments for injury treatment or to support clinical conditions during wound or illness management [89]. They are typically composed of 55% PP and 45% PE [85]. Single-use disposable personal protective equipment (PPE) gowns constitute the greatest percentage of landfilled PPE by weight and are primarily made from non-degradable synthetic materials [90]. MTs are structured as woven and predominantly nonwoven materials, derived from either natural fiber (e.g., wood pulp and cotton) or synthetic fibers (e.g., polyester) [91].

3.7.2. MTs Consumption Trends

In 2022, the global MTs market was valued at approximately USD 32.30 billion, with a projected CAGR of 4.3% from 2023 to 2030 [92]. For comparison, the general medical clothing market was valued at approximately USD 96.3 billion in 2023 and expected to grow at a CAGR of 6.6% between 2024 and 2032 [93]. Regarding SGs, their global market was valued at USD 3.6 billion in 2023 and is expected to exhibit a 2.1% CAGR [94]. This growth is attributed to their increasing popularity due to their convenience and durability.

3.7.3. Summary of MT Material Properties

Some studies have examined MTs, particularly surgical gowns (SGs) [95]. According to Troynikov et al. [96], SGs exhibit high heat and water vapor resistance. Another study [95] investigated the incorporation of shredded SGs into concrete aggregates in various percentages of the volume of concrete, where they generally helped to enhance the quality of the mixture; they also exposed some of the properties of SGs which are shown below in

Table 11. Physical properties reported in the collected studies for medical textiles as fiber reinforcement [95].

Breaking Force 1 (N)	Elongation at Break 1 (%)	Specific Gravity 1	Water Absorption 1 (%)	AR 1	l 1 (mm)	Height 2 (mm)	Width 1 (mm)	A 1 (mm2)	¥ 1 (mm2)	${\mathit{d}}_{{\mathit{E}}_{\mathit{q}}}$ (mm)	AR 2
183	42	0.93	7.6	5	20	0.1–0.5	4	0.4–2	8.2–9	0.19–0.8	105.2–125

¹ Previous study. ² Calculated in this study based on Equation (1).

. No properties were found in the paper regarding medical textiles used as fine aggregate.

3.8. Medical Waste Incineration Ash (MWIA)

3.8.1. Definition and Material Composition

MWIA is classified as a hazardous solid waste, as reported by Fang et al. [97], and, according to Jang et al. [98], incineration is the most prevalent method for MW reduction [93], making MWIA readily accessible. MWIA contains significant concentrations of heavy metals (e.g., As, Pb, Cd, and Ag), dioxins, and chlorine [99]. Additionally, its primary chemical constituents include CaO (10–60%), SiO₂(5–58%), and Al₂O₃ (5–28%) [100,101].

These components indicate that medical waste ash could serve as a viable pozzolanic material in cementitious mixtures [100,101]. However, it is important to note that the chemical composition of MWIA can vary depending on several factors, including the nature of the input medical waste, the type of incinerator used, the combustion temperature, and the internal temperature profile of the incineration process [102]. The physical properties of municipal waste incineration ash (MWIA) largely depend on the conditions of the incineration process. It is generally gray in color, with a specific gravity ranging from 1.82 to 2.75 [103]. Particle size can range from 6.3 µm to 225 µm, although there may be small fractions (<15% wt.) with sizes up to 9.5 mm [102]. The percentage of water absorption varies according to the particle size, being lower when the particles are smaller. Absorption values range from 2.38% to 4.89%.

3.8.2. MWIA Consumption Trends

MWIA is obtained from MW, and its production continues to rise due to an aging population, increasing health awareness, and advancements in medical technology [104,105]. According to Global Market Insights, the MW management market was valued at USD 14 billion in 2022, and is projected to grow at a CAGR of 7.2% from 2023 to 2032 [106]. Furthermore, the incineration segment led the market in 2023, accounting for the largest revenue share (39.73%) [103,107].

3.8.3. Summary of MWIA Material Properties

Several studies have explored the use of MWIA in CM [103,108]. In the literature, MWIA has been employed as fine aggregate [108,109]. For instance, Chakravarthy et al. [109] used MWIA as a partial replacement of fine aggregate at levels ranging from 0% to 30% by weight in self-compacting concrete. They observed a decrease in flowability as the MWIA content increased. A similar behavior was reported in compressive strength, with the mixture containing 20% MWIA exhibiting the lowest loss in mechanical performance. Additionally, MWIA has been studied as SCM [33,103,110], and as a precursor for geopolymer production [111,112,113]. The key physical and chemical properties of MWIA reported in these studies are summarized in

Table 12. Physicochemical properties of MWIA as fine aggregate.

Specific Gravity	Fineness Modulus	Water Absorption by Mass (%)	Water Absorption (%)	Specific Gravity	Bulk Density (kg/m3)
2.48 [108]	3.17 [108]	4.89 [108]	3.9 [109]	2.54 [109]	1415 [109]

and

Table 13. Physicochemical properties of MWIA as SCM.

Density (kg/m3)	Pore Volume (cm3/g)	Specific Surface Area (m2/g)	Electrical Conductivity (dS/m)	pH	TOC * (mg/kg)	Bulk Density (g/cm3)	Water Absorption (%)	Nitrate (mg/L)	Fineness Modulus
3390.4 [38]	0.003 [38]	3.991 [38]	8.55 [38]	10.88 [38] –11.63 [103]	7097 [38]	0.68 [103]	3.01 [103]	27.80 [103]	3.14 [103]

* Total organic carbon (TOC) analysis.

.

4. Chemical and Physical Treatments

In MW management, chemical and physical treatments play crucial roles in ensuring safe and effective waste handling, particularly for its incorporation in CB-CMs. According to Oke et al. [114], chemical treatment involves the addition of specific chemical agents to remove pollutants or hazardous components present in MW. These treatments typically include disinfection and sterilization processes. In contrast, physical treatments utilize methods such as incineration or microwave radiation. Through an exhaustive literature review, various MW treatment methods have been identified to enhance its safe application in CB-CMs. These treatments are summarized below [114].

4.1. Protein Crosslinking Technique

The protein crosslinking technique is applied to natural rubber GLs to reduce their toxicity while maintaining their mechanical properties. Crosslinking is a process in which two or more molecules are chemically joined by covalent bonds [115]. A study by Suwandittakul et al. [116] demonstrated that this treatment effectively reduces the toxicity of rubber GLs without compromising their mechanical properties. Additionally, this technique helps mitigate allergic reactions associated with these types of GLs.

4.2. Heat Treatment

Heat treatment is one of the most common methods used to eliminate hazardous agents in MW. However, it is it is crucial to apply heat cautiously to materials such as face masks, as excessive temperatures (above 160 °C) can render them unusable due to fiber fusion [117]. Additionally, heat exposure can degrade the mechanical properties of face masks, particularly their mechanical strength [118].

MWIA is generated through the incineration of biomedical waste at temperatures ranging from 850 to 1100 °C [102]. The ash resulting from this process typically presents high specific surface areas (e.g., 8.012 m²/g to 9.10 m²/g), which may contribute positively to its reactivity. However, further grinding and particle size reduction have been shown to enhance the pozzolanic activity of SCMs, including MWIA. As noted by Juenger and Siddique [119] and Riyanto et al. [120], decreasing particle size increases the reactive surface area, thereby improving the potential for pozzolanic reactions and improving the mechanical performance of mixtures [119,121].

4.3. Chemical Treatment

A chemical treatment applied specifically to MWIA consists of the use of a chemical solution of Na₂CO₃ at a concentration of 0.25 M. This treatment allows dissolving aluminum compounds and sulfated minerals present in the ashes, which not only contributes to the reduction of toxic elements, but also improves the compressive strength of the mortar when MWIA is used as a partial replacement of the fine aggregate [122]. Other chemical treatments used for the removal of heavy metals from MWIA include the application of chelating agents such as ethylene diaminetetra acetic acid disodium (EDTA) and sodium sulfide. Among these, EDTA has proven to be more effective, achieving significant reductions in the concentrations of heavy metals such as cadmium (from 7 to 0 mg/kg), lead (from 38 to 10 mg/kg), and zinc (from 44 to 6 mg/kg), when compared to sodium sulfide treatment. On the other hand, when MWIA is used with the treatments as a partial replacement for cement, a monotonic decrease in compressive strength is observed as its proportion in the mixture increases [122].

4.4. Gas Phase-Advanced Oxidation Process

The gas phase-advanced oxidation process is used to reduce the risks associated with viruses and pathogens present in FMs before their incorporation into CB-CMs. This process does not alter the mechanical or physical properties of FMs [123]. It is important to note that this treatment has only been evaluated on N95 FMs, which are specifically ¡ designed for environments with a high risk of fluid exposure and capable of filtering at least 95% of airborne particles, including very small ones. Consequently, further research is needed to assess the applicability of this treatment to other FM types.

4.5. Boiling

Boiling is one of the simplest and most accessible decontamination methods [124]. However, when applied to FMs, boiling causes a thinning of microfibers, leading to the formation of large pores and voids. This deterioration negatively impacts the mechanical properties of MWs. Therefore, boiling is not recommended as a decontamination method for FMs [125].

4.6. Graphene Oxide

The use of graphene oxide as a disinfection treatment for FMs has been found to improve the interface between mask microfibers and the cementitious paste matrix [54]. This is attributed to graphene oxide’s ability to alter cement hydration while increasing the degree of polymerization [54]. Although this treatment appears promising for FMs, further research is needed to evaluate its applicability to other types of MWs.

4.7. Other Treatments

According to the literature, several other treatments and disinfection methods can be applied to MW, such as (i) ethanol and bleaching; (ii) wet heat treatments (e.g., steaming and autoclaving); (iii) dry heat treatments (e.g., ironing and oven exposure); (iv) irradiation (e.g., microwave treatment); (v) deep burial; (vi) plasma pyrolysis technology; and finally, (vii) bio-oxidation [102,125]. In studies investigating these methods, different temperatures and exposure times have been applied to MWs. However, these protocols cannot yet be fully considered in this review, as the available results do not indicate significant changes in the mechanical or physical properties of MWs.

Consequently, it remains unclear whether these treatments allow MWs to be safely incorporated into composite materials without affecting their performance.

5. Bibliometric Analysis

5.1. Delimitations

It is important to note that this study has certain limitations. First, only publications available in the WoS Core Collection database were considered, potentially excluding relevant studies indexed elsewhere. Second, the analysis was limited to English-language articles with full-text availability, which may introduce language or accessibility bias. Third, the review focused specifically on the valorization of CW and MW as CMs within cementitious systems, and therefore, studies valorizing these wastes into non-cementitious construction materials (such as asphalt or geopolymers) were considered separately under an “Other CMs” section. Finally, a flowchart summarizing the protocol is presented in Figure 9.

5.2. Bibliometric Results

A preliminary scan was conducted to determine the main types of CW or MW valorized in CB-CMs, leading to the identification of key waste categories (i.e., FM, NDs, PBs, PSGs, MG, GL, MT, and MWIA). Subsequently, specific sets of keywords and Boolean operators were developed and applied for each MW type (

Table 14. Set of keywords and Boolean operators used in this SLR.

MW	Set of Keywords and Boolean Operators	Data Results–WoS (No.)
General search	(“Medical waste” OR “clinical waste”) AND (“construction material” OR cement paste OR mortar OR concrete)	40
FM	(“facemask” OR “surgical mask” OR “medical mask”) AND (“construction material” OR cement paste OR mortar OR concrete)	19
NDs	(“needles”) AND (“medical waste” OR “clinical waste”) AND (“construction material” OR cement paste OR mortar OR concrete)	1
PBs	(“pharmaceutical blisters”) AND (“medical waste” OR “clinical waste”) AND (“construction material” OR cement paste OR mortar OR concrete)	1
PSGs	(“plastic syringes”) AND (“medical waste” OR “clinical waste”) AND (“construction material” OR cement paste OR mortar OR concrete)	2
MG	(“medical glass” OR “pharmaceutical glass”) AND (“construction material” OR cement paste OR mortar OR concrete)	4
GLs	(“surgical gloves” OR “latex gloves” OR “gloves”) AND (“construction material” OR cement paste OR mortar OR concrete)	42
MT	(“medical textile” OR “surgical gowns” OR “protective suit” OR “surgical caps”) AND (“construction material” OR cement paste OR mortar OR concrete)	3
MWIA	(“medical waste incineration ash” OR “biomedical waste ash” OR “medical waste ash”) AND (“construction material” OR cement paste OR mortar OR concrete)	19
Total results		131

).

The selection process was systematically summarized using the PRISMA flow diagram, as recommended by the Macquarie University Library’s Systematic Reviews guide (i.e., [126,127,128]). Figure 10 presents the PRISMA flow diagram illustrating this process.

6. Applications of Medical Waste as CMs Within CB-CMs

CB-CMs face multiple challenges, including the need to enhance mechanical performance, durability, and cost-effectiveness while reducing environmental impact. Among these factors, environmental sustainability has gained significant attention in the construction sector [3]. MWs are increasingly being explored as a sustainable alternative, as they can be valued as CMs in CB-CMs. Given their large-scale generation, MWs offer a readily available resource that can help address both MW mismanagement and the environmental footprint of CB-CM production.

The applicability of MWs as CMs depends on their properties after treatment. The most common applications include their incorporation as fiber reinforcement, fine or coarse aggregates, fillers, or SCMs in CB-CMs, as summarized below.

6.1. Applications of Face Masks in CB-CMs

The incorporation of FMs as fiber reinforcement in CB-CMs, has shown varied effects on mechanical, physical, and durability properties, as summarized in

Table 15. Effects of face masks as fiber reinforcement within CB-CMs.

Type of Matrix	% of Fiber	Physical Properties	Mechanical Properties (MPa) (28d)	Durability Properties	Citation Article
Cement paste	0.1% (vol.)	-	Compressive strength 67~/−6%/0.1% Splitting tensile strength 8~/+47%/0.1%	-	[54]
Mortar	0.5% (wt.)	-	Compressive strength 30~/−21%/0.5% Flexural strength 4~/−38.4%/0.5%	-	[55]
Mortar	0.5% 1% 1.5% 2% (vol.)	-	Compressive strength 41~/+17%/1% Tensile strength 3~/+22%/1.5% Flexural strength 3~/+30%/1%	Sorptivity (mm/√sec) 0.0225/+28%/2%	[130]
Mortar	0.10% 0.15% 0.20% 0.25% (vol.)	Bulk density (kg/m3) 2090~/−0.3%/0.15% (28d)	Compressive strength 47~/−14.5%/0.15% Tensile strength 2.7~/+44.8%/0.15% Flexural strength 7.24/+34.8%/0.15%	Water absorption (%) 3.8/+25.2%/0.25% (28d)	[129]
Concrete	0.1% (vol.)	-	Compressive strength 81~/−8%/0.1% Splitting tensile strength 4.3~/+35%/0.1%	Freeze–thaw resistance NR/+15%/0.1%	[131]
Mortar	0.3% 0.5% 0.8% 1% (wt.)	Dry bulk density (kg/m3) 2392/+0.4~/0.3% (28d)	Compressive strength 74.4/+0.5%~/0.3% Flexural strength 14.9/+26%~/0.3%	Water absorption (%) 1.79/−4.5%/0.3% (28d) Porosity (%) 3.16/+3%~/0.3% (28d)	[132]
Concrete	0. 5% 1% 1.5% 2% (vol.)	Workability (mm) 125~/+0%/0.5% 125~/−40%/1% Density (kg/m3) 2360~/−19%/2%	Compressive strength 35~/−20%/0.5% Split tensile strength 2.4~/−11%/0.5%	Water absorption (%) 3.5~/+22% to +70%/0.5% to 2%	[43]
Concrete	1% (wt.)	-	Compressive strength 67.25/+5%/1% Tensile strength 8.07/+3%~/1%	Frost resistance (measured with compressive strength in MPa) 72.48/+4.7%~/1% (100 freezing–thawing cycles)	[41]
Concrete	As fibers (F) 1% 1.5% 2% (vol.)	-	(F) Compressive strength 27.3/+11.7/2% Tensile strength 3.5~/+14.57/2%	(F) Chlorine permeability (RCPT charge in C) 3800~/−23.2/1.5%	[42]
	As 1–2mm shredded FM (S) 0.75% 1% 1.5% (vol.)		(S) Compressive strength 27.3/+18.28%/1% Tensile strength 3.5~/+1.14%/1% 3.5~/−14.57%/1.5%	(S) Chlorine permeability (RCPT charge in C) 3800/−41.3%/1%
Concrete	0.2% (fiber only) 0.1% 0.2% 0.3% (mixed w/recycled coarse aggregate)	Elastic modulus (GPa) 16.2~/+4.73%/0.2% Workability (mm) 690~/−3%~/0.2%	Compressive strength 41~/+12%~/0.2% Splitting tensile strength 3.2~/+3%~/0.2% Flexural strength 4~/+35%~/0.2%	-	[133]
Concrete	0.3% 0.5% (vol.)	-	Compressive strength 96.4/−1.4%~/0.5% Tensile strength7.1/+11.3%/0.5% Tensile strain 2.03/+28.1%/0.5% First cracking strength 5.17/+0.4%~/0.3%	Average crack width (μm) 123.8/−53%~/0.5% (28d)	[134]
Concrete	0.1% 0.15% 0.2% 0.25% (vol.)	Young modulus (GPa) 29.24/+3.3%/0.1% (28d) 29.24/−2.05%/0.15% (28d) * No significant influence was found regarding the Young modulus	Compressive strength 50.34/+17%~/0.2% Tensile strength 3.27/+12.23%/0.2%	UPV (m/s) 4590/+4%~/0.2% (28d)	[57]
Concrete	1% 2% (vol.)	Permeable voids (%) 9.4/−4.4%~/1% 9.4/+12,7%~/2%	Compressive strength 33.5/+41%/1% Flexural strength 10.5/+21.9%/1% 10.5/+38%/2% Interlayer bond strength 1.4/+21.4%/1%	-	[58]
Concrete	0.2% (vol.)	-	Compressive strength 67.25/+5.3%/0.2% Splitting tensile strength 8.13/−6.3%/0.2%	-	[135]

. The dosage of fibers ranges from 0.1% to 4% by volume or weight, influencing materials’ properties depending on the specific cementitious matrix. In cement pastes, lower fiber dosages (e.g., 0.1% by volume) resulted in reduced compressive strength, while tensile properties increased significantly (up to +47% compared to reference mixtures) [54]. In a mortar matrix, most studies indicate that the incorporation of FMs as a fiber reinforcement enhances tensile and flexural properties, with tensile strength increments up to +44.8% at optimal dosages (0.15% by volume) compared to a fiber-less sample [129]. However, compressive strength was often reduced, particularly at higher fiber dosages, such as. a 21% reduction with 0.5% fiber by weight [55].

The concrete matrix exhibited varied results, with fiber reinforcement generally improving tensile strength, impact resistance, and flexural strength. Particularly, flexural strength showed significant increases repeatedly, reaching up to +38% at a fiber content of 2% by weight [58]. Durability enhancements were demonstrated with substantial improvements in resistance to chloride migration and freeze–thaw cycles. These findings highlight the potential of face masks as fiber reinforcement to enhance CB-CM durability performance. These findings suggest that optimized fiber dosages can serve as a sustainable and effective reinforcement for CB-CMs while also mitigating the environmental impacts associated with MW mismanagement. It is worth noting that the information on physical, mechanical, and durability properties exhibited in Table 15,

Table 16. Effects of NDs as fine aggregate within CB-CMs.

Type of Matrix	% of Replacement	Physical Properties	Mechanical Properties (MPa) (28d)	Durability Properties (%)	Citation Article
Concrete	2% 4% 6% 8% 10% (wt.)	Dry density (kg/m3) 2400/−1.5%/10% Slump (cm) 7.8~/−10.2%/10%	Compressive strength 45~/−1.4%/10% Flexural strength 6~/+18.3%/10%	Water absorption 2.09~/−9.6%/10%	[62]

,

Table 17. Effects of PBs as fine aggregate within CB-CMs.

Type of Matrix	% of Replacement	Physical Properties	Mechanical Properties (MPa) (28d)	Durability Properties (%)	Citation Article
Concrete	5% 10% 15% 20% (wt.)	-	Compressive strength 34~/+14.87%/10% Splitting tensile strength 3.14/+11.78%/10% Flexural strength 3.97/+10.33%/10%	-	[68]
Concrete	5% 10% 15% 20% 25% 30% (wt.)	-	Compressive strength 33~/−10.8%/30% Flexural strength 7.6~/−23.36%/30% Tensile Strength 5.4~/−15.38%/30%	Water absorption 1.23/+5.6%/30%	[67]

,

Table 18. Effects of PSGs as fine aggregate within CB-CMs.

Type of Matrix	% of Replacement	Physical Properties	Mechanical Properties (MPa) (28d)	Durability Properties	Citation Article
Concrete	10% 20% 30% 40% 50% (wt.)	Slump flow (mm) 650/+1.5%/10% (28d) L-box test (H2/H1) 0.95~/+5%~/10% (28d)	Compressive strength 47~/+1.5%~/20% Splitting tensile strength 4.2~/−2%~/20% Flexural strength 3.3~/+9%~/20%	-	[70]

,

Table 19. Effects of MG as fine aggregate within CB-CMs.

Type of Matrix	% of Replacement	Physical Properties	Mechanical Properties (MPa) (120d)	Durability Properties (120d)	Citation Article
Concrete	20% 40% 60% 80% 100% (wt.)	-	Compressive strength 39.2/+12.3%/60%	Water absorption (%) 4.36/−10.84%/60% UPV (m/s) 4775/+2.6%/60% RCPT (coulombs) 709/−20.6%/60% Sulfate resistance (µm/m) 80/−20%/60%	[78]

,

Table 20. Effects of GLs as fiber reinforcement within CB-CMs.

Type of Matrix	% of Fiber	Physical Properties (28d)	Mechanical Properties (28d)	Durability Properties	Citation Article
Mortar	0.1% 0.2% (vol.)	Workability (average spread diameter in mm) 204.1/+6.6%/0.2% Buildability index 17325/+331%/0.2%	Compressive strength (MPa) 68.8/−23%~/0.2% Maximum flexural force (N) 2128.8/+17%/0.1% Direct tensile force (N) 1173.3/+37.5%/0.1%		[39]
Concrete	0.5% 1% 1.5% 2% (vol.)	-	Compressive strength (MPa) 26.1/−21.9%/1% Total strain NR/+13.5%/0.5% (50 cycles) Plastic strain 0.59~/+43.8%/0.5% (50 cycles)	-	[85]
Concrete	0.1% 0.2% (vol.)	Workability (mm) 204.1/+6.6%/0.2% Buildability index 17325/+361%~/0.2% Density (kg/m3) 2300~/+5%~/0.1%	Compressive strength (MPa) 68.8/−18%/0.2% Direct tensile force (N) 1173.3/+37.5/0.1% Ultimate bending force (flexural) 2099.3/+17%/0.1%		[86]

,

Table 21. Effects of GLs as filler within CB-CMs.

Type of Matrix	% of Replacement	Physical Properties	Mechanical Properties (MPa) (28d)	Durability Properties (28d)	Citation Article
Mortar	2.5% 5% 7.5% 10% (wt.)	Density (kg/m3) 2355.15/−3.4%/2.5% (28d)	Compressive strength 36.72/−27.5%/2.5%	Water absorption (%) 4.08/+79%~/10% UPV (km/s) 4.61/−16.5%/10%	[87]
Concrete	0.1% 0.2% 0.3% (vol.)		Compressive strength 50.34/+22%~/0.2% Concrete’s Young mod-ulus (GPa) 29.24/+3.5%/0.2%	UPV (m/s) 4590/+1.15%/0.2%	[81]

,

Table 22. Effects of GLs as coarse aggregate within CB-CMs.

Type of Matrix	% of Replacement	Physical Properties	Mechanical Properties (MPa) (28d)	Durability Properties (28d)	Citation Article
Concrete	2.5% 5% 7.5% 10% (wt.)		Compressive strength 37~/−86%/10%	Workability (mm) 110/−16%~/2.5% UPV (m/s) 3800/−17.3%/10%	[88]

,

Table 23. Effects of MTs as fiber reinforcement within CB-CMs.

Type of Matrix	% of Fiber	Physical Properties (28d)	Mechanical Properties (MPa) (28d)	Durability Properties (km/s) (28d)	Citation Article
Concrete	0.2% 0.4% 0.6% 0.8% 1% (vol.)	Density (kg/m3) 2364/−1.5%/1%	Compressive strength 37/−7.3%/1% Splitting tensile strength (MPa) 3.12/+43.6%/1%	UPV 5400~/−12.5%~/1%	[95]

,

Table 24. Effects of MTs as fine aggregate within CB-CMs.

Type of Matrix	% of Replacement	Physical Properties	Mechanical Properties (MPa) (28d)	Durability Properties	Citation Article
Mortar	14.3% 20% 33.33% (wt.)	-	Compressive strength 37/−16%~/33.33% Flexural strength 1/−19%~/20%	-	[136]

,

Table 25. Effects of MWIA as an alternative supplementary cementitious material within CB-CMs.

Type of Matrix	% of Replacement	Physical Properties	Mechanical Properties (MPa) (28d)	Durability Properties	Citation Article
Mortar	40% (wt.)	-	Compressive strength NR/+60%/40% *		[110]
Concrete	40% (wt.)	-		Acid resistance NR/+47%/40% (28d)	[110]
Concrete	5% 10% 15% 20% 25% 30% 40% 50% (wt.)	-	Compressive strength 38~/+2.6%~/5%	-	[38]
Concrete	2.5% 5% 7.5% 10% 12.5% (wt.)	-	Compressive strength 22.32/+20%/7.5% Split tensile strength 2.2/+17%/7.5% Flexural strength NR/+14%/7.5%	Workability (mm) 97/−13.3%/2.5%	[103]

Note: * The reported results were obtained when the MWIA was subjected to a calcination process prior to incorporation.

and

Table 26. Effects of MWIA as fine aggregate within CB-CMs.

Type of Matrix	% of Replacement	Physical Properties	Mechanical Properties (MPa) (28d)	Durability Properties (28d)	Citation Article
Concrete	5% 10% 15% 20% (vol.)	-	Compressive strength 27~/+33.28%/5% Splitting tensile strength 2.4~/+15%/5%	Water absorption (%) 4.26/+4.2%/5%	[108]
Concrete	10% 20% 30% (wt.)	Slump flow test (mm) 740/−1.3%/10% V-funnel test (sec) 8/−46%/10%	Compressive strength 30/−14.3%/10%	-	[109]

indicates the value of the property for the CB-CM associated with the incorporation of the particular MW indicated in each line, followed by the percentage variation in the property with respect to a reference mixture (without the incorporation of the MW), and, finally, the days of curing at which the properties were evaluated. For example, Table 15 (line 1) presents the study by [54], which investigated cement pastes incorporating FMs as fiber reinforcement. The compressive strength of the mixture with 0.1% (vol.) of FMs reached 67 MPa, representing a 6% reduction with respect to the reference mixture, evaluated at 28 days of curing.

In a micrograph from the study by Paul et al. [43], the interfacial bonding between the FM fibers and the surrounding mortar matrix, as well as the natural aggregate inclusions, is evident (Figure 11).

6.2. Applications of Needles in CB-CMs

Incorporating NDs as fine aggregate at 10% by weight in concrete has shown a slight reduction in dry density (1.5%) and compressive strength (1.4%), but a notable increase in flexural performance by 18.3% [62], as observed in Table 16. This improvement may be attributed to the rough surface of the NDs, which enhances bonding with the concrete matrix, thereby improving flexural performance. Additionally, durability improvements were observed, with a 9.6% reduction in water absorption [62]. These findings suggest that using NDs as fine aggregate in concrete can enhance flexural strength and durability while causing only a minimal reduction in compressive strength. This makes NDs a potential sustainable application for MW valorization in CB-CMs.

However, further research is needed, as the available literature remains insufficient to fully assess the potential benefits and drawbacks of needle incorporation in concrete.

6.3. Applications of Plastic Blisters in CB-CMs

The valorization of PBs as fine aggregate in concrete has shown varying effects on mechanical properties, depending on the dosage level, as summarized in Table 17. At 10% by weight, concrete exhibited improvements in compressive strength (14.87%), splitting tensile strength (11.78%), and flexural strength (10.33%) [68]. However, at a higher dosage of 30%, mechanical performance declined, with compressive, flexural, and tensile strengths decreasing by 10.8%, 23.36%, and 15.38%, respectively, along with a 5.6% increase in water absorption [67]. These findings suggest that lower dosages of PBs (up to 10% by weight) can enhance mechanical performance, whereas higher dosages may significantly reduce both mechanical and durability performance.

Notably, the two studies presented contrasting results: in one, all properties improved, while in the other, they declined. Given that these differences are linked to varying PB dosages (10% and 30%, respectively), further studies are needed. Future research should investigate intermediate dosage levels or explore values beyond this range to provide a clearer understanding of the overall trend in concrete performance when incorporating plastic blisters.

6.4. Applications of Plastic Syringes in CB-CMs

The incorporation of PSGs as fine aggregate at 20% by weight in concrete resulted in a slight increase in compressive strength (+1.5%) and flexural strength (+9%) after 28 days of curing, while splitting tensile strength showed a small reduction of 2% [70], as shown in Table 18. These results suggest that PSGs can enhance flexural strength performance without significantly affecting compressive strength, making them a viable and sustainable strategy to mitigate the depletion of natural aggregates depletion.

6.5. Applications of Medical Glass in CB-CMs

The incorporation of MG as a fine aggregate replacement in concrete has shown promising results, particularly at a 60% replacement level by weight, identified as the optimum dosage. The resulting properties are summarized in Table 19. At this level, compressive strength increased by 12.3% after 120 days of curing [79]. Durability performance was also significantly enhanced, with water absorption decreasing by 10.84%, UPV increasing by 2.6%, and RCPT reduced by 20.6%, indicating improved resistance to chloride ion penetration [78]. Additionally, sulfate resistance improved with a 20% reduction in expansion. These findings suggest that MG at a 60% replacement level could effectively enhance both mechanical and durability properties, providing a sustainable alternative to natural aggregate depletion.

6.6. Applications of Gloves in CB-CMs

GLs as fiber reinforcement, filler, and aggregate in CB-CMS, along with their resulting properties, are detailed in Table 20, Table 21, and Table 22, respectively.

As fiber reinforcement in mortar and concrete at lower dosages (0.1–0.2% by volume), GLs improved the tensile and flexural performance, increasing direct tensile strength by 37.5% and flexural strength by 17%, along with a moderate gain in workability. However, compressive strength decreased by up to 18% [39]. The increase in tensile and flexural performance with GL incorporation as fiber reinforcement can be attributed to enhanced crack propagation control and improved load distribution, mechanisms similar to those observed with PP fibers, as reported by Ahmad et al. [137] and Nehvi et al. [138]. Conversely, the reduction in compressive strength is likely due to inadequate bonding between the GLs and the concrete matrix, attributed to the smooth surface of GLs. This smoothness hinders effective load transfer from the concrete matrix, leading to weak points under compressive loads and ultimately reducing the overall compressive capacity of the reinforced concrete.

As a filler in mortar, GLs at lower dosages (0.2%, 0.3% by volume) increased compressive strength by up to 22% and increased the UPV up to 1.15% after 28 days of curing compared to the reference mixture [81]. This improvement enhances the load-bearing capacity in compression, distributes stress within the concrete matrix, and limits microcrack propagation under load. The increase in UPV suggests that lower GL dosages contribute to a denser, more cohesive concrete matrix with fewer voids and microcracks. In contrast, at higher dosages (2.5% and 10% by weight), GLs significantly reduced compressive strength (by 27.5%) and increased water absorption (by 79%) in mortar mixtures [87]. Similarly, when used as a coarse aggregate up to 10% by weight in concrete mixtures, GLs reduced compressive strength by 86% [88]. These findings indicate that the physical and morphological properties of GLs are unsuitable as an effective filler or coarse aggregate in CB-CMs, especially at higher replacement levels (above 0.3% by volume).

The impact of GLs as filler on concrete’s Young modulus was also analyzed at 0.2% by volume, but the results did not provide a clear trend to determine whether this CW has a significant influence on this property [81].

Overall, GLs as fiber reinforcement can enhance tensile and flexural performance at lower dosages (0.1%, 0.2% by volume). However, their use as a filler or coarse replacement aggregate is not recommended, unless kept at lower dosages (0.2%, 0.3% by volume).

Observing the combined results of FMs and GLs, a study could propose to analyze the effects of both waste materials integrated into concrete or mortar mixtures. This proposal is based on the observation that face masks generally improve compressive strength, whereas gloves tend to weaken it. It would be valuable to experimentally assess whether these two clinical waste materials can function synergistically or if their effects counteract each other.

6.7. Applications of Medical Textiles in CB-CMs

The incorporation of MTs as fiber reinforcement and fine aggregate replacement in CB-CMs, along with their effects on mechanical and durability properties, is detailed in Table 23 and Table 24, respectively.

When used as fiber reinforcement in concrete at dosages between 0.2% and 1% by volume, MTs demonstrated notable improvements in tensile performance, with splitting tensile strength increasing by 43.6% at a 1% dosage. However, at this dosage, a reduction in compressive strength by 7.3% and a decrease in UPV by 12.5% were also observed [95]. These findings suggest that lower volume dosages may offer a favorable balance between tensile performance improvements and reductions in compressive strength and UPV.

Conversely, when used as a fine aggregate in mortar at 20% by weight, MTs led to reductions in both compressive and flexural strength, decreasing by 16% and 19%, respectively, after 28 days of curing [136]. These reductions may be attributed to limited bonding between MT particles and the mortar matrix, which affects the interfacial transition zone and consequently reduces load-bearing capacity.

Figure 12 shows the bonds created with the application of MT into concrete.

6.8. Applications of Medical Waste Incineration Ash in CB-CMs

The applications of MWIA in CB-CMs as SCM and fine aggregate, along with their respective effects on material properties, are shown in Table 25 and Table 26.

Incorporating MWIA as alternative SCM leads to a significant 60% increase in compressive strength when used in mortar. In concrete, the mechanical properties show positive improvements, especially when 5% to 7.5% of MWIA is added by weight. The most notable enhancements include a 20% increase in compressive strength and a 17% increase in tensile strength when 7.5% MWIA is used after 28 days of curing [103]. Regarding acid resistance and workability, preliminary findings indicate that acid resistance improves while workability decreases. However, due to limited data in the literature, these observations require further validation. A study by Manjunath et al. [102] also found that replacing up to 5% of cement and 15% of sand with MWIA produces high-strength concrete with enhanced durability, aligning with previous findings on MWIA as a sustainable alternative in construction.

Regarding its use as fine aggregate, Nahushananda Chakravarthy et al. [109] used MWIA as a partial replacement of fine aggregate at levels ranging from 0% to 30% by weight in self-compacting concrete (Figure 13). They observed a decrease in flowability as the MWIA content increased. A similar behavior was reported in compressive strength, with the mixture containing 20% MWIA exhibiting the lowest loss in mechanical performance. Additionally, MWIA has been studied as SCM [33,102,105], and as a precursor for geopolymer production [103,108]. The key physical and chemical properties of MWIA reported in these studies are summarized in Table 12 and Table 13.

Overall, additional research is needed to address remaining knowledge gaps, as many properties remain unexamined, and no clear pattern has been established in the available data.

Furthermore, beyond its applications in cement-based materials, MWIA presents potential for use in other fields such as soil stabilization, road-based materials, and the manufacturing of bricks and ceramics [120,121,139], owing to its pozzolanic and filler properties. However, the broader utilization of MWIA requires a profound investigation into its long-term environmental behavior, particularly concerning the possible leaching of hazardous elements under various exposure conditions [140,141]. Moreover, the durability performance of MWIA-based materials outside cementitious matrices, including their resistance to chemical attack, moisture variation, and mechanical stresses, should be thoroughly assessed. Future research should undertake a comprehensive evaluation of the environmental and technical risks associated with alternative applications to ensure the safe and sustainable use of MWIA.

It is worth mentioning that the cost analysis and engineering feasibility of incorporating MWIA in CB-CMs is not a generalized evaluation, but rather a case-specific assessment. These factors are highly sensitive to variables such as the type, origin, and processing method of the MWIA, as well as the intended use, production process, and material composition of the CB-CM in question. Still, there have been previous specific studies addressing these issues. For instance, Memon et al. [142] found that replacing up to 2% (by weight) of cement with MWIA slightly increased early compressive strength (at 3 days) compared to the control mixture, although higher replacement levels (6–8%) reduced strength at 28 days. They also reported reduced workability and water absorption, indicating a denser microstructure at low dosages. Another study by Rachmawati et al. [143] conducted a life cycle assessment and environmental cost–benefit analysis of using MWIA in cement-based paving blocks, showing promising results both economically and environmentally. This study demonstrated that this approach not only immobilized heavy metals within the cement-matrix of paving blocks, but also resulted in an eco-cost savings of IDR 600,180.9 (approximately USD 38) per production cycle. The produced blocks achieved a compressive strength of 13.28 MPa, meeting durability standards for non-structural paving applications (e.g., parks and walking paths), and offered a sustainable alternative to conventional raw materials. Moreover, Chowdhury et al. [144] demonstrated that MWIA can be used as a mineral filler in dense bituminous courses, achieving optimal performance at a 5.5% filler ratio with Marshall stability exceeding 13.8 kN. This performance surpassed that of conventional stone dust mixtures, which required 9% filler to reach comparable strength. Environmental assessments confirmed that leaching levels of heavy metals, including Pb, Cd, Ni, Cu, and Zn, remained well below Dutch regulatory limits (U1), indicating that the MWIA–asphalt matrix posed no significant ecological risk and could be considered environmentally safe for pavement applications.

6.9. Other Applications of MWs in CMs (Asphalt and Geopolymers)

During the course of this review, several relevant studies were identified of CMs that are not CB-CMs, which is the primary focus of this paper. However, research related to the incorporation of FMs [145,146,147], MWIA [111,112,113], and MG [67,72] in asphalt and geopolymers is briefly summarized in this section.

Zhao et al. [145] found that the addition of FMs to asphalt increased rotational viscosity and tensile elongation, while reducing the phase angle of base asphalt, leading to enhanced performance at both high and low temperatures.

Regarding geopolymers, two notable studies were identified. Thoudam et al. [146] reported that incorporating 4% of FMs by volume resulted in optimal compressive and flexural strength, while having minimal impact on water absorption and efflorescence properties. Similarly, Zhang et al. [147] found that the addition of 0.4 wt.% of FMs enhanced geopolymers’ quality, with compressive and flexural strength increases of 5.8% and 22.68%, respectively.

Regarding the applications of MWIA in geopolymers, Kumar et al. [112] found that MWIA increased fracture energy. Similarly, Arunachalam et al. [113] reported that MWIA increased the setting time and flowability, while reducing density. Their study also demonstrated that 30% MWIA replacement by weight yielded the highest values of compressive strength, tensile strength, flexural strength, load-carrying capacity, ultimate strength, stiffness, and ductility.

The incorporation of MG in geopolymers was also studied in some papers [73,80]. Missoum et al. [80] reported that MG enhanced mechanical performance, particularly in terms of compressive, tensile, and flexural strength. Abdellatief et al. [73] found that medical glass increased compressive strength, tensile strength, and water absorption in geopolymers.

7. Conclusions

This study conducted an exhaustive systematic literature review (SLR) to assess the use and impact of various types of medical wastes (MWs)—including face masks (FMs), plastic syringes (PSGs), gloves (GLs), medical textiles (MTs), pharmaceutical blisters (PBs), and medical waste incineration ash (MWIA), among others—in different types of cement-based construction materials (CB-CMs), such as cement paste, mortar, and concrete. The findings confirm several advantages of incorporating these MWs into CB-CMs, demonstrated improvements in physical, mechanical, and durability performance, while also contributing to the mitigation of environmental impacts associated with the disposal of MW in landfills. Additionally, their inclusion helps conserve natural resources by partially replacing conventional materials in CB-CMs. Based on this literature review, the following conclusions can be drawn:

• The inclusion of FMs in concrete generally has a positive impact on compressive strength, with improvements ranging from 5% up to 40%. Although some studies report decreases in compressive strength, these reductions are generally minor, rarely exceeding −8%. Overall, the evidence suggests that FMs have promising potential to enhance mechanical performance when appropriately processed and integrated.
• Regarding GLs, the results showed that, in general, GLs negatively affect compressive strength when incorporated into concrete and mortar, with reductions averaging 20%. However, other properties, such as tensile and flexural strength, exhibit positive effects, with increases up to 20% or more. These contrasting effects suggest that while GLs may compromise compressive performance, they can enhance other structural characteristics.
• Further investigation is required to assess the long-term performance of mortar incorporating GLs as fiber reinforcement. Durability concerns must be comprehensively analyzed to ensure that these MWs do not induce significant long-term performance reductions.
• It was demonstrated that MTs have significant potential as fiber reinforcement. However, for their widespread acceptance within the construction sector, more comprehensive long-term studies on mechanical and durability performance are essential, as only surgical gowns (SGs) have been investigated so far. Future studies should aim to assess the long-term integrity and functional stability of these materials under diverse environmental conditions to validate their reliability and ensure their suitability for structural applications.
• Further research on the implementation of MWIA as alternative supplementary cementitious material is strongly recommended. The current literature primarily focuses on compressive strength, while other essential properties remain largely unexplored, with limited or no supporting studies. Although the inclusion of MWIA has demonstrated a positive impact, the existing evidence is insufficient to establish definitive conclusions.
• While overall statistical heterogeneity was limited, mainly due to the small number of studies found in the literature, some variability emerged in most explored MWs. These differences point to gaps in the current literature and highlight the need for more focused, high-quality research to improve the consistency and comparability of future findings.
• Based on the currently available information, it remains challenging to determine whether CW can be definitively considered a sustainable alternative for CB-CM production. This uncertainty arises primarily from the lack of comprehensive studies establishing clear trends for each waste type. However, this emerging research area not only has the potential to significantly mitigate the environmental impact of CW pollution worldwide but also represents a promising step toward the development of more sustainable construction materials. Given its substantial environmental and industrial relevance, continued investigation into this topic is strongly encouraged.
• Regarding the potential use of MWIA, it can be incorporated into mortar and concrete mixtures; however, its effectiveness depends on the role it plays within the mixture. When used as a partial replacement for cement, MWIA generally does not improve mechanical performance. In contrast, when applied as a partial replacement for fine aggregate, particularly at low substitution levels, it can lead to improved or comparable mechanical properties.
• The use of MWIA in cementitious matrix blends leads to materials with slightly lower densities as their content increases. In addition, its reactivity, associated with quantities of reactive silica and alumina, plays a key role in improving mechanical performance. This incorporation not only contributes to the development of more sustainable materials but also offers a viable alternative for medical waste management, helping to reduce environmental pollution and conserve natural resources.

8. Future Recommendations

As the main recommendation, further research into the implementation of MWIA as an alternative supplementary cementitious material is strongly recommended. Current literature primarily focuses on compressive strength, while other essential properties remain largely unexplored, with limited or no supporting studies.

Given the significant research gaps identified in this SLR, which highlight valuable opportunities for future studies, the following key areas for further investigation are suggested:

• MWIA in mortar;
• Nitrile GLs in mortar;
• Vinyl GLs in concrete;
• NDs in mortar;
• Other MTs in mortar and concrete;
• PSGs in mortar;
• MG in mortar;
• PBs in mortar.

Additionally, throughout this study, variability in the results of the different tests (compressive strength, flexural strength, etc.) carried out on the CB-CMs was observed when incorporating various types of CW. Notably, even when using similar addition percentages, the outcomes varied considerably depending on the specific type of waste used. This raises the possibility of conducting experiments with combinations of multiple waste types, with the expectation that their physical characteristics could complement each other to enhance CB-CM properties. Conversely, it remains uncertain whether such combinations might lead to negative effects due to material incompatibilities. This uncertainty presents an opportunity for the community to investigate the feasibility of combining different medical waste materials. Future research should explore the combined use of different types of medical waste—for example, utilizing MWIA as an SCM to enhance compressive strength, alongside incorporating fibers from discarded FMs to improve flexural performance—in both cementitious and non-cementitious construction composites. Such combinations may offer synergistic benefits in mechanical behavior and sustainability, and should be systematically evaluated for structural viability and environmental safety. With this in mind, the following waste combinations are proposed as potentially valuable for further research:

•    MG mixed with FMs;
•    MG mixed with GLs;
•    MWIA mixed with MTs;
•    MWIA mixed with PBs;
•    MWIA mixed with FMs.

Finally, a need to standardize the defibrillation process of FMs for their future application as reinforcement in both mortar and concrete has been identified. This is particularly important given the variability in fiber size and the aspect ratio can lead to inconsistencies in the mechanical performance of CB-CMs.