_applied sciences_  
_Article_  
Experimental Study with Cement Mortars Made with Recycled Concrete Aggregate and Reinforced with Aramid Fibers  
[PERSON] 1, [PERSON] 1, [PERSON] 2 and [PERSON] 1,*(c)  
**Featured Application: This work aims to emphasize the possible applications of construction and demolition waste, performing an experimental analysis on cement mortars made with recycled concrete aggregate and reinforced with aramid fibers. This is especially relevant and innovative, since it focuses on the recovery and reuse of the fraction of fine aggregate smaller than 4 mm for use in building construction through the manufacture of masonry mortars, in addition to improving its mechanical performance by using aramid fiber as one of the synthetic reinforcements with the greatest future projection in the construction sector. In this way, it seeks to contribute to the Sustainable Development Goals and more specifically to the targets included in Goal 12, that is, to achieve sustainable management and efficient use of natural resources. **  
The reuse of construction and demolition waste is a necessary way to achieve greater sustainability in building, introducing the criteria of the so-called circular economy in the design of the production process of new construction materials. This research focuses on analyzing the properties of mortars made with recycled aggregates from concrete waste and reinforced with aramid fibers. For this purpose, an experimental campaign was carried out, including chemical, physical, mechanical and durability tests, performing a statistical analysis to discuss the different properties analyzed. The results show how the incorporation of aramid fibers in the matrix of cement mortars made with recycled concrete aggregate improves their technical performance and mechanical resistance, thus increasing their application possibilities and achieving similar results in some properties to those obtained with traditional mortars made with natural aggregate. **Keywords:** cement mortars; recycled concrete aggregate; aramid fiber; construction  
**1. Introduction**  
The progressive aging of the building stock in Spain, together with the large number of existing buildings and the high industrial activity of the construction sector, mean that year after year a large amount of Construction and Demolition Waste (CDW) is generated, which must be treated to avoid its accumulation in landfills [1, 2]. In Spain alone, more than 21 million tons of CDW are generated per year [3], which means a great environmental impact derived from the waste of these resources that can be recycled and reused as raw materials in the manufacture of mortars and concretes [4, 5]. More specifically, the CDW from the demolition of concrete structures can be recycled by mechanical processes to obtain recoverable products suitable for use as raw materials [6]. This is the case of the production plants in charge of manufacturing recycled aggregates, which are an asset of interest for the construction sector due to the large amount of sand demanded in this industrial activity [7], and to the fact that aggregates are the second most consumed natural resource on the planet after water [8]. Recycled concrete aggregates are characterized by being essentially composed of two materials: natural aggregate and bonded mortar [9; 10], however, these types of aggregates can present impurities such as remains of ceramic materials, metal chips or gypsum and plaster [1]. In general terms, it can be said that recycled concrete aggregates have in comparison with natural aggregates a lower density [11], a higher fines content [12], a higher water absorption [13] and a higher friability coefficient [14]. These characteristics of recycled concrete aggregates have a significant impact on the final properties of masonry mortars made with these materials [15].