Flexural Performance of Concrete with Modified Eucalyptus Bark Waste as Partial Replacement of Fine Aggregate Indonesia

Abstract

The utilization of eucalyptus bark waste as an alternative material in concrete represents an effort to reduce by-products from the forestry industry. However, the organic nature of this material may influence the mechanical performance of concrete. This study investigates the effect of alkali-treated eucalyptus bark waste used as a partial replacement for fine aggregate on the flexural strength of concrete. Prior to mixing, the bark waste was modified through alkaline treatment using a 1% NaOH solution for approximately 24 hours to improve its compatibility with the cement matrix. Replacement levels of 0%, 1%, 2.5%, and 5% by weight of fine aggregate were examined. Concrete beam specimens were tested for flexural strength at 28 days. The results indicate that increasing the proportion of eucalyptus bark waste leads to a reduction in flexural strength. The control mixture (0%) satisfies the flexural strength requirement of K250 concrete based on SNI T-15-1991-03, whereas mixtures containing eucalyptus bark waste fail to meet the minimum criterion. These findings suggest that alkali-treated eucalyptus bark waste is not suitable as a fine aggregate substitute in structural concrete.