EFFECT OF THE PARTIAL REPLACEMENT OF CEMENT WITH WOOD ASH ON THE COMPRESSIVE STRENGTH OF CONCRETE

As sustainability becomes an essential focus in modern construction, the exploration of alternative materials and the reuse of industrial waste have gained increasing attention. This study examines the feasibility of using wood ash (WA) as a partial replacement for Ordinary Portland Cement (OPC) in the production of Grade 25 concrete, assessing its effects on workability and compressive strength. Concrete samples were produced using a 1:1:2 mix ratio with a 0.41 water–cement ratio, incorporating 0%, 5%, 10%, 15%, and 20% replacements of cement by wood ash. Tests conducted included particle size distribution, slump test, compressive strength test, and water absorption test, with evaluations carried out at 7, 14, and 28 days of curing. The results revealed a consistent reduction in workability as wood ash content increased, with slump values decreasing from 30 mm (control) to 0 mm at 20% replacement. Compressive strength results showed that 5% replacement yielded comparable performance to the control mix (32.49 N/mm² vs. 32.51 N/mm²), while higher replacement levels resulted in strength reduction. Water absorption tests indicated varied permeability levels. The 5% replacement demonstrated an absorption rate of 6.21%, conforming to BS 1881 122:2011, while 10%, 15%, and 20% replacements recorded progressively lower values, with 20% achieving 1.25%, indicating excellent quality and durability. Based on these findings, the study concludes that wood ash can effectively replace up to 5% of cement in structural concrete applications without significant compromise in strength or durability. Beyond this level, the decrease in strength suggests that higher replacements are more suitable for non-structural uses, such as blocks or pavements, where lower strength requirements apply