## 1 Introduction
#### Literature Review on Mortars with Natural Fibers: Coconut, Abaca and Toquilla
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Ref.** & **Fiber Addition** & **Fiber Length [mm]** & **Main Results** \\ \hline
[34] & 0.2, 0.3 and 0.4\% & & The best results were obtained in mortars made with treated fibers with a 3\% NaOH solution, with a length of 30 mm and incorporated at 0.2\% of the mortar weight. With this composition, it was possible to improve the mechanical resistance to bending and compression, with a good fiber integration in the matrix. \\ \hline
[35] & 0.2\% over the total solid weight & 30.0 & Flexural strength was improved by 20\%, compressive strength by 28\% and tensile strength by 26\% compared to the reference mortars. In addition, the abaca fiber mortars improved their dimensional stability by reducing shrinkage. \\ \hline
[36] & 0, 0.25, 0.5, 1 and 2\% & & The good hygroscopic properties of abaca fibers reduce the autogenous shrinkage of mortars, improving their mechanical performance and mitigating cracking risk. In addition, the presence of these fibers delays mortar setting time. \\ \hline
[37] & 1\% over the total solid weight & 10.0, 30.0, 80.0, 100.0 & Abaca fibers showed great potential for application in rehabilitation mortars for masonry houses. The optimum fiber length for improving flexural strength and wall ductility was found to be 80 mm. \\ \hline  & & & \\ \hline  & & & \\ \end{tabular} Note: Search in Web of Science with the keywords: ((“Abaca” OR “Abaca”) AND (“Fiber\"\") AND (“Mortar\"\")).  
\end{table} 
Table 2: Studies on abaca fiber-reinforced cement mortar. There are also some disadvantages of using these fibers in the matrix of mortars. As demonstrated in some research [44], the incorporation of these reinforcing materials can result in a loss of workability of the mix or wettability, as well as the difficulty to distribute the fiber homogeneously or the need for prior treatments that improve the behavior and durability of the fiber for application in matrices. In short, based on the current state of knowledge, the objective of this research is to analyze the physical and mechanical properties of masonry mortars made with recycled concrete sand and reinforced with natural fibers. For this purpose, a characterization of the developed cement materials, to which coconut, abaca, and toquilla straw fibers have been added, will be carried out. To date, no research work has been found that comparatively analyzes the effect of these three types of reinforcement on cement mortars made with RCA. This may be of particular interest for the development of sustainable mortars in South American countries where these three types of natural fibers are highly abundant. The aim is to contribute to the development of eco-friendly mortars and to promote their application in the building sector. The research thus falls within the framework of the Sustainable Development Goals (SDGs) included in the 2030 Agenda, and more specifically, SDG 9, \"Industry, Innovation and Infrastructure\" [50]. Moreover, this work is also essential in terms of the contemporary perception of the environmental impact of construction products, namely that using natural materials of plant origin is crucial [51], Any positive example of using recycled materials in construction is additionally significant because demolition/recycled materials are perceived as less valuable in construction for fear that they will not meet specific requirements in terms of mechanical strength [52]. Moreover, the innovative simultaneous use of RCA and natural fibers in masonry mortars is crucial for this research.