Natural Cellulosic Alfa fiber improved with environment-friendly treatment cementitious composites with a stable flexural strength

Abstract

Using natural fibers in structural applications is the subject of much research in the scientific world. Natural fibers are bio-sourced, biodegradable, have a low carbon footprint, and have interesting mechanical properties. The lightness, tensile strength, and elongation before break make natural fibers suitable candidates to replace synthetic fibers. Sometimes, natural fibers must undergo heavy chemical treatment for the extraction of microfiber. This is not the case in this paper, which presents a first attempt to use esparto fiber in its raw state without heavy treatment without soda and bleach. In this paper, the raw esparto stem cut into short fibers is treated, then prepared and used as reinforcement in mortar. The mechanical properties of the esparto stems were identified, analyzed, and improved. The mechanical tests showed a weak adhesion between the mortar and Alfa. Also, excessive absorption of water by the stem induced a delay in the mortar's setting. Even with unsaturated stems, this phenomenon is observable. An improvement was applied to the natural Alfa stem to improve its adhesion and reduce the absorption of spillage water. For the first time, as a major innovation in natural fibers used for cementitious composites, a method is presented in this paper allowing the use of Alfa (esparto) fiber in a mortar while keeping the mechanical strength properties of the mortar. Test specimens 4x4x16 cm were made and reinforced with short fibers of 2 and 3 cm with different volume concentrations: 1%, 2%, and 5%. The flexural strength and compressive strength were determined experimentally. The results show that for the 1% concentration of short fibers of 3cm, the compressive strength is 26 MPa, which is almost identical to the strength of the control specimen equal to 26.03 MPa. Flexural strength of the improved fibers concentrated at 1%, 2%, and 5% reach nearly 4.75 MPa very close to the flexural strength of the control specimen, which is 5.57 MPa. The flexural strength doesn't decrease with treated Alfa fiber concentration increase: this is a unique case in which flexural strength doesn't decrease compared to other natural fibers results in the literature. In a conclusion, Alfa-treated short fibers can be used in secondary structural applications subject to compressive and light bending forces, for example, paving applications.

The Viscoelastic Comportment of Composite Plates Reinforced with Synthetic and Natural Alfa (Stipa tenacissima L.) Fibers for Structural Applications

“…Composite materials, which are composed of a combination of different types of fibers, have a wide range of applications in various fields, such as crash and safety [1], [2], civil engineering [3]- [5], and biomechanics [6]- [8]. Researchers in Tunisia have been investigating using natural fibers [9]- [14], including palm [15] and cellulosic fibers [16]- [18], in composite materials to utilize local resources and promote sustainability. The current study examines the static, vibratory [19], and relaxation behavior of Alfa/PMMA45% composite materials made of Alfa natural fibers and PMMA resin.…”

Road guardrail beam made of natural stem (Stipa tenacissima L.) eco-composite: Impact energy absorption improvement by stems and pre-tensioning

“…Composite structures are widely used in automotive engineering, 1,2 biomechanics, [3][4][5] renewable energies, 6 and aerospace engineering, 7,8 and it has become commonly used in the field of civil engineering. [9][10][11][12] One of the challenges in road safety is the design of road safety beam barriers. 13,14 Collisions resulting from impact into barriers present a major challenge for public health, trauma medicine, and traffic safety professionals.…”