In order to reduce the dependency on conventional materials and negative environmental impacts, one of the main responsibilities of the construction field is to find new eco-friendly resources to replace the traditional materials partially. Natural fibers were known as potential candidates for the reinforcement of structures in civil engineering by virtue of their advantages. Among the different kinds of vegetable fibers, coconut fiber has been exploited in a limited way over the past few years. This paper aims at evaluating the different properties of local coconut fibers (Vietnam). Several laboratory tests provide geometrical, physical, mechanical properties and durability properties that are compared with literature results obtained from similar natural fibers. The local coconut fibers tested demonstrated properties suitable for reinforced mortars. With adequate control of their preparation, they could be reused in the manufacture of mortars in the construction.
The carbonation action in concrete, in which carbonation reactions transform calcium hydroxide into calcium carbonate, is considered as a multi-phase physico-chemical process. Generally, carbonation in the cementitious composites has negative effects on the protection of reinforced bars due to the accelerated corrosion problem. The investigation of the carbonation degree is, therefore, necessary to evaluate the carbonation influence on the reinforced cementitious composites. In the present paper, experimental techniques to measure the carbonation degree in concrete are reviewed, including both qualitative and quantitative methods. It should be noted that, while qualitative technique focuses on the alterations in the concrete pore solution alkalinity which reflects the carbonation depth through the pH indicator, most quantitative methods could provide accurate determination of the CO2 penetration capacity during the carbonation process. The method used, for the practical phase, depends on the purpose of the carbonation degree measurement.
Natural fibre-reinforced cementitious composites are commonly used as outer construction materials. They usually suffer weather as a result of being expose to various types of climates. In this study, a series of experimental tests were carried out to investigate the deterioration mechanism and mechanical properties of mortars incorporating coconut fibres due to repeated wetting and drying. The results indicated that although the compressive strength was found to increase after the first cycle, both compressive and flexural strengths underwent a significant decrease in the fifth cycle. In addition, at high temperatures, mortar matrixes retain their stable structure, according to the results of TGA analysis. When wetting and drying curing was applied, there was a significant degradation of fibres in the mortar.
This chapter deals with the reuse and recycling of tropical natural fibers and their potential valorization in construction materials in a context of circular economy and sustainable development. These fibers constitute large volumes of fibrous waste resulting from various agro-food industries worldwide. Depending on their intrinsic qualities and properties (physical and mechanical), they can be reused as reinforcing material in cementitious mixes (hardened mixes) or mixes with soils (raw mixes) and molded into a prismatic brick-like shape. These bricks constitute construction materials that have mechanical and other characteristics. A whole methodology specific to the development of such materials and their optimization is presented. It includes the preparation, characterization, cutting of the fibers to the desired length and the making of the mixtures. This is followed by optimization (fibers distribution), control and quality of the fiber-reinforced material. Two examples illustrate the application of this methodology: a reinforced mortar based on coconut fibers (hardened cementitious mix) and a green brick based on sediment and oil palm fibers.
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