Study on Palmyrah as a material for construction

Abstract

For the pursuit of sustainable development, construction of cost effective houses, with fewer disturbances to nature is a major concern. A permanent rise in the price of building materials which involves heavy capital investments is the reason for the utilization of all kinds of innovative materials. Palmyrah is an important economic resource, which is widely spread all over North East region in Sri Lanka and has found use in many structural applications. This research explores the possibility of using Palmyrah as a material for construction; as an individual structural member as well as reinforcement member in lightly loaded concrete elements. Structure of this research consisted of literature survey, basic design, construction, testing, analysing of results and discussion. There are two main objectives in this study. First objective is identifying mechanical properties of Palmyrah strips for the efficient use of Palmyrah as a structural timber. Static bending test, tensile test and compression test were conducted to identify characteristic values of strength and stiffness properties along with density and moisture content. Ultimately, Palmyrah is graded into a strength class for the benefit of timber suppliers and designers. Second objective is to determine the technical feasibility of using Palmyrah strips as an alternative for reinforcing steel in short span, lightly loaded slabs and beams. Failure loads, crack loads, mode of failure and crack patterns of test slabs and beams were observed. Flexural capacity of concrete slabs and beams reinforced with Palmyrah strips was evaluated. Results of mechanical tests showed variation of properties with maturity, height, cross section and origin. Although heartwood of Palmyrah inherits high bending, tensile and compressive strength, it has to be graded into D40 owing to its low modulus of elasticity. Strength and density of sapwood part is relatively lower due to its high moisture and starch content. It was observed in the experiments conducted that Palmyrah reinforcement enhanced the failure load of the slab by 107% and failure load of beam by 370%. Experimental failure load of slab and beam averaged 140% and 164% of theoretically predicted value respectively. Thus it is concluded that Palmyrah strips have potential to be used as reinforcement in lightly loaded slabs and beams.