PSI - Issue 78

Sandoli Antonio et al. / Procedia Structural Integrity 78 (2026) 1342–1349

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By synthesizing the existing research, this study seeks to elucidate the advantages and disadvantages associated with the incorporation of natural fibers into mortar mixtures, from a mechanical behavior standpoint. The findings of this research are intended to serve as a valuable resource for academic, practitioners and industrial stakeholders. Understanding the performance characteristics of natural fiber-reinforced mortars can inform the development of more effective, robust and sustainable construction practices. Additionally, this review will aid in the design of experimental testing programs aimed at further exploring the potential of natural fibers in mortar applications. 2. Bibliometric and literature overview The analysis of the bibliometric data underscores the importance which are assuming the natural fiber-reinforced bio-mortars in the scientific context. To this purpose, indexed bibliometric data provided by the Scopus database (i.e., including also conference papers and books) were extrapolated analyzed and discussed in this Section. The analysis was performed by selecting papers using the (simple) search key word “natural fiber reinforced mortar” on Scopus. As first outcomes, the histogram of Fig. 2a shows the distribution of the number of papers of the last 25 years by countries. The interest of the researchers in this field is increasing worldwide. Europe, and particularly Italy, resulted as the country which have provided the greater number of scientific papers and then those in which the topic of sustainable natural-fiber reinforced mortars has mainly attracted the attention of the researchers. Fig. 2b instead collects the number of paper available on Scopus in the considered time interval 2020-2025. Starting from 2000’s the interest of the researchers in the field of fiber-reinforced mortar increased significantly, especially in the last ten years. Moreover, also in comparison with mortar reinforced through Fiber-Reinforced Polymers (FRP) - which is the material mostly used in such a field - natural fibers are assuming a prominent role in the last years. As far as the types of vegetal fibers is concerned, the Fig. 3a compares the number of papers subdivided by the main types of fibers used to reinforce the mortar. The most commons type of natural fibers are jute, hemp, broom, cotton, kenaf, flax, bamboo, sisal. As it can be noted, hemp fibers are those most attractive and for which resulted an appreciable number of scientific papers. At the same time, also jute and flax reinforced mortar are assuming importance. The same Figure shows that other types of fibers, such as broom or those coming from waste of wooden materials, are adopted as reinforcement material. Finally, the Fig. 3b reports the subdivision of the total number of the papers belonging to different scientific sectors. The most of papers come from the engineering and material science field. First studies about the investigation of the mechanical properties of natural fiber-reinforced mortar were conducted by Chakraborty et al. 2013 which tested jute fiber reinforced-cement mortar specimens under compression and flexure loads. Moses et al. 2015, instead, investigated the compression behavior of kenaf fiber reinforced composite mortar packaged using fiber contents variable among 1.0%, 2.0% and 3.0 % (by weight of cement) and with fiber lengths set equal to 10 mm, 20 mm and 30 mm. Research achievements showed that water absorption and density of the composite mortar increased as the volume of fiber and its length increases, and that compressive strength decreases with increasing fiber volume and length. Experimental flexural and uniaxial compression tests on lime mortar reinforced with hemp fibers have been carried out by Formisano et al. 2017; the study highlighted as the addition of hemp fibers change the failure modes of the specimens from brittle to ductile, leaving basically unaltered the strength capacity of reinforced specimens with respect to unreinforced ones. Instead, Meglio and Formisano 2024 tested two types of lime-based plasters reinforced with hemp braids, having different diameters. Two pre-mixed natural hydraulic lime mortars with strength M5 and M15 were added with three diameters of hemp braids (0.4 mm, 1.0 mm, 2.2 mm) in percentage by lime weight from 0.25% to 3.0 %. Variable results were obtained in terms of maximum strength of reinforced mixture, resulting in some cases greater and in other lower of those unreinforced, depending on fibers diameters. All the mix designs were tested on shaking table to assess the role of hemp fibers on the workability of the mixture, resulting that it decreases as the amount of hemp increases. Similarly, Comak et al. 2018 investigated the mechanical response of hemp fibers on cement-based mortar by assuming fiber percentage equal to 1%, 2% and 3% and fiber length equal to 6 mm, 12 mm and 18 mm. They conducted density, water absorption, compressive, flexural and