**1. Introduction**

Glass is one of the world's most diverse substances because of its substantial properties, such as chemical inertness, optical clarity, low permeability, and high authentic strength [1–3]. The usage of glass items has greatly increased, leading to enormous quantities of WG. Globally, it is estimated that 209 million tons of glass are produced annually [4–6]. In the U.S., according to the Environmental Protection Agency (EPA) [7–9], 12.27 million tons of glass were created in 2018 in municipal solid waste (MSW), as shown in Figure 1, most of which were containers for drinking and food. Furthermore, in 2018, the EU generated 14.5 million tons of glass package wastes [10–12]. The quantity of generated WG will increase due to the increasing demand for glass components [13–16].

Recycling and reducing waste are key parts of a waste-management system since they contribute to conserving natural resources, reducing requests for waste landfill space, and reducing pollution of water and air [17,18]. According to Meyer [19], by 2030, the EU zero-waste initiative estimates that improvements in resource efficiency throughout the

**Citation:** Qaidi, S.; Najm, H.M.; Abed, S.M.; Özkılıç, Y.O.; Al Dughaishi, H.; Alosta, M.; Sabri, M.M.S.; Alkhatib, F.; Milad, A. Concrete Containing Waste Glass as an Environmentally Friendly Aggregate: A Review on Fresh and Mechanical Characteristics. *Materials* **2022**, *15*, 6222. https://doi.org/ 10.3390/ma15186222

Academic Editor: Krzysztof Schabowicz

Received: 1 August 2022 Accepted: 2 September 2022 Published: 7 September 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

chain could decrease material input requirements by 17% to 24%, satisfying the demand for raw materials between 10% to 40%, and could contribute to reducing emissions by 40% [20–22].

**Figure 1.** Distribution of MSW stream produced in the U.S in 2018. Adapted from [7].

In fact, innovative options for recycling WG must be developed. One significant option is to use WG for construction materials [23]. The recycling of WG not only decreases the demand for landfill sites in the building sector but also significantly helps in decreasing the carbon footprint and saving resources [24–26]. In 1963, Schmidt and Saia [27] performed the first research on the use of WG for building materials. The authors recycled WG into useful glass particles for wall-panel production. Subsequently, a significant study was conducted in order to use recycled glass for fine or coarse aggregate in mortar and concrete, because of the good hardness of the glass [14,28,29]. This study aims at reviewing the possibilities of utilizing WG in concrete as a partial or full replacement for fine or coarse aggregates in order to give practical and brief guidance on recycling and using WG [30–33].

#### **2. Research Significance**

Besides the above-mentioned dangers of WG and the need to recycle it economically and environmentally, this research explores the source of WG as well as its physical and chemical characteristics. In addition, this study aims to review the literature that discusses the use of recycled WG in concrete as a partial or complete alternative to aggregates by focusing on the effect of this waste on the fresh and mechanical properties of concrete in order to demonstrate the possibilities of using recycled WG in concrete and to provide practical and brief guidance. Furthermore, we are establishing a foundation for future study on this material and describing research insights, existing gaps, and future research goals.
