Flexural Strength Characteristics of Beams Reinforced with Fan Palm under Various Exposure Conditions

Abstract

The relative high cost of man-made imported fibres like, glass, steel and plastics used in cement based composites as reinforcement calls for investigation into the use of locally available natural fibre as a substitute. Fan palm is locally available and has been studied as a suitable alternative to steel reinforcement. The need for durability of the fan palm under varying exposure conditions is the concern of this study. The ultimate flexural strength of beams reinforced with fan palm under diverse exposure conditions was determined to evaluate its possible usage, both on short and long term basis. Fan palm specimens were cut, shaped to desired flexural reinforcements sizes and coated with water repellants (epoxy, sulphur and bitumen) and  blocking agents (hydroxylamine, sodium sulphate magnesium sulphate) for 24 hours. They were then used as reinforcements for concrete beams (75 x 100 x 500 mm) of 1:2:4 mix ratio and cured in alkaline media (0.1N sodium hydroxide solution). Two sets of uncoated fan palm reinforced beams (in alkaline solution and in water) were used as control experiments. Flexural strength test was carried out on the specimen beams at ages 7, 14, 28, 56, 90, 180, 270, and 365 days. The results were subjected to ANOVA analysis using STATA soft ware. The results at 365 days indicated that out of the beams reinforced with water repellant agents, those reinforced with bitumen retained the ultimate flexural stress of 36.98N/mm². For the beams reinforced with fan palm coated with blocking agents, those reinforced with hydroxylamine recorded the ultimate flexural stress of 25.59N/mm². The ultimate flexural stress of beams reinforced with uncoated fan palm is 4.69N/mm² and 18.07N/mm² in alkaline and water media respectively. It was concluded that coating fan palm reinforcements with bitumen (a water repellant agent) improved the durability of fan palm reinforced concrete beams in alkaline media.

Keywords: Fan palm, Flexural strength, Exposure conditions, Water repellant agents, Blocking agents.