# Sustainable Development of Concrete through Aggregates and Innovative Materials: A Review
## 1 Introduction  
Concrete is the material most used in the construction industry and its mechanical strength depends on the quality and properties of the aggregates, the water-cement ratio and the uniformity of the mixture [1, 2]. This material is an essential component in the modern infrastructure due to its high structural resistance and durability. Concrete is widely employed in the construction of bridges, dams, tunnels and numerous physical infrastructures [3, 4]. It is a key material in the recent and future infrastructure with estimation of yearly consumption of 25 billion tons [5]. The high production of cement generates environmental contamination through carbon dioxide (CO\({}_{2}\)) emissions. For this, the use of new sustainable materials in the construction sector can contribute to decreasing the CO\({}_{2}\) emissions and costs as well as the reuse waste materials [6]. In order to reduce greenhouse gases emissions, it is necessary to recycle waste materials and conserve the natural resources. The increment in the use of recycled materials with aggregates and cement-based materials can improve the concretecompatibility with the environment [7; 8]. The partial substitution of cement for other sustainable materials may increase the durability of the concrete, reducing the maintenance of structural components [9]. The population growth and urban development demand a great amount of natural resources in the construction industry [10]. This industry has increased the cement production due the increment in the concrete consumption [11; 12]. This high cement fabrication can cause close 7% of the global CO2 emissions [13]. The consumption of industrial products cause waste that may be harmful for the environment. However, several of these waste materials could be mixed with cement to obtain sustainable concrete and improve its mechanical strength and durability [14]. Thus, the sustainable concrete can be an important alternative to reuse some waste materials and reduce the problem of waste disposal [15; 16]. Figure 1 depicts different recycled materials, organic aggregates and synthetic fibers used in sustainable concrete. The recycled materials include rubber, plastic, glass and industrial waste. The organic aggregates consider the bamboo, coconut fiber and nanocellulose. On the other hand, the synthetic and mineral fibers use steel, glass, carbon and textile fiber and epoxy resins. The mechanical strength, durability and workability of concrete can be enhanced by replacing the cement or aggregates with recycled materials [17]. The incorporation of waste materials in the concrete production may contribute to the conservation of natural resources [18]. For instance, polymers added to cement may enhance the concrete strength and durability [19; 20]. These polymers are used as matrix materials, modifiers and concrete adhesives. [PERSON] and [PERSON] [19] used polyester resin as binder in polymer concrete production [19]. This polyester resin has the following characteristics: a concentration of 60% of unsaturated polyester resin and 40% of styrene; a physical state of liquid; flash point of 34 \({}^{\circ}\)C; ignition point (solvent) of 490 \({}^{\circ}\)C; specific weight of 1.13; viscosity of 475 \(\pm\) 75 cp; gelling time (25 \({}^{\circ}\)C) of 4 \(\pm\) 1 min; bending strength of 100 MPa and tensile strength of 55 MPa [19]. In this review, we present recent investigations about different recycled materials, organic aggregates and synthetic and mineral fibers used in the concrete industry. The effects of these materials on the mechanical (compressive, tensile and flexural strength) and physical (porosity, density and water absorption) properties of concrete samples are discussed. Numerous researchers have reported methodologies for the use of these materials in sustainable concrete. Optimal dosages of these materials can enhance the  
Figure 1: Diagram of different material types used in sustainable concrete. compressive, tensile and flexural strength of the concrete.