Samenvatting

This paper is aimed at understanding the role Miscanthus x giganteus has in the strength development of concrete. The use of natural fibres to reinforce brittle materials is not a novel idea, but its use has been limited. This paper is designed to provide more knowledge on the topic of natural fibre cementitious composites. Two fibre sizes (2-10mm & 0.5-2mm) were used to develop concrete, the fibres were subjected to two pre-treatments before being used; a separate batch of untreated 2-10mm fibres were used to create concrete with the same cementitious properties.

This was done to improve the fibre-matrix interaction. The fibres in the matrix were at 27% of the overall volume of the concrete. The concrete developed utilized sand 0-4mm and gravel 4-20mm; the type of cement used was CEM I 52.5 R with a specific density of 3100Kg/m3 and the water cement ratio was kept at 0.5. The fibres were treated with an alkali treatment using 5% wt NaOH and a separate treatment referred to in this paper as cement pre-treatment; a 1:1 ratio of cement and water was used to coat the fibres to improve the fibres hydrophobicity. The mechanical properties of the concrete were tested; the compressive strength and split tensile tests for all samples were conducted. The results from this test showed the concrete made using cement treated fibres of size 0.5-2mm had the highest compressive strength, while for tensile strength, concrete made using alkali treated 0.5-2mm fibres performed best. The next step in the process was to evaluate the alternatives using a Multiple Criteria Analysis (MCA), for this the method adopted was the Analytical Hierarchy Process (AHP). Using this method, the concrete mixtures were given a score based of five criteria, which are: Cost, Sustainability, Workability, Compressive Strength and Tensile Strength. At the end of the evaluation, the concrete mixture consisting of 0.5-2mm cement treated fibres was found to have better qualities which satisfied all criteria.