Physical, mechanical and durability characteristics of date palm frond stalks as reinforcement in structural concrete

Abstract

This paper deals with an experimental investigation of the physical and mechanical properties of Date Palm Frond (DPF) stalks and their durability in concrete.

The study of the physical properties of DPF stalks reported here includes the anatomic structure of the stalk and the effect of water absorption on its volume. Tension tests were used to determine the mechanical properties of the stalks. Test results show that the tensile strength of the stalk walls ranges between 116 to 208 N/mm² while that of the core is almost one half of these values. The modulus of elasticity of the stalks is found to range between 10 to 30 kN/mm². Flexural tests carried out on concrete beam specimens reinforced with a single DPF stalk showed that the stalk provided no reinforcing effect due to lack of bond resulting from the tapered nature of the stalk. Chemical tests were designed to examine the durability of DPF stalks in fresh concrete while accelerated tests were designed to investigate the long-term durability of stalks encased in hardened concrete. Results presented in this paper show that the alkaline medium of fresh concrete has no effect on the tensile strength of DPF stalks. They also show that coating DPF stalks with varnish greatly improves their long-term durability in concrete.