Study of the behaviour of bamboo reinforced concrete beams

Abstract

An experimental study has been made to explore the possibility of using bamboo and bamboo twig as a potential reinforcement in concrete beams. To achieve this objective, a series of tension tests were conducted to derive the stress-strain characteristics of bamboo along with a number of pullout tests to evaluate bond strength followed by bending test of beam to determine the ultimate load carrying capacity of concrete beams reinforced with bamboo and bamboo twig. Finally, the test results were compared with similar steel reinforced concrete beams. For tension test, two types of reinforcements were tested, bamboo and bamboo twig. First three samples of finished bamboo and bamboo twig were tested in natural condition (without treatment). Then five samples of finished bamboo and bamboo twig were tested with GI wire spiral at the ends for improved gripping. From these tests, the tensile strength, proof strength and modulus of elasticity were determined from stress-strain curve for both bamboo and bamboo twig. Nine pull out tests were performed for both bamboo and bamboo twig specimen. In these pullout tests, three samples were in natural condition, three samples were coated with tar for water proofing and three samples were coated with tar along with pierced nails at the ends. From this test, bond strength of bamboo and bamboo twig was determined. Four beams with same cross section were constructed and tested under two point loading. The main parameters considered are the reinforcement type and the reinforcement ratio. To improve the bond strength, pierced nails were used at both ends of bamboo and bamboo twig reinforcement. Two types of shear reinforcements (bamboo and bamboo twig) were used. The beams were tested after fifty days and concrete compressive strength was determined from cylinder test on the same day. During testing, two dial gages were installed to measure the deflection. From bending tests, cracking load, ultimate failure load and failure patterns were obtained. Finally, the ultimate failure loads were compared with the corresponding failure load of steel reinforced concrete beam.From these tests, satisfactory results are obtained in terms of tensile strength, bond strength, stress-strain characteristics of bamboo and bamboo twigs and flexural behaviour of bamboo reinforced concrete beams.