Evaluation of Mortar Strength Using Bamboo Leaf Ash as a Supplementary Cementitious Material in Cross River State

Bamboo is an abundant biomass resource in Cross River State, South South Nigeria, and the ash derived from bamboo leaf incineration has attracted interest as a pozzolanic supplementary cementitious material. This study evaluates the effect of bamboo leaf ash partial cement replacement on the compressive strength and workability of cement mortar. Bamboo leaves were collected from Oban Hills, incinerated in a controlled furnace at 600 degrees Celsius, and the resulting ash was characterised for chemical composition by X-ray fluorescence, particle size distribution, loss on ignition, and pozzolanic activity index. Mortar cubes were prepared at bamboo leaf ash substitution levels of 0%, 5%, 10%, 15%, and 20% by weight of binder, at a fixed water-to-binder ratio of 0.5 and sand-to-binder ratio of 3.0. Compressive strength was tested at 7, 28, and 56 curing days. The bamboo leaf ash exhibited a combined silica, alumina, and iron oxide content of 74.3%, satisfying the ASTM C618 Class N pozzolan requirement. Compressive strength at 10% substitution surpassed the control at 56 days by 4.2%, attributed to the pozzolanic reaction forming additional calcium silicate hydrate gel. Substitution above 15% caused progressive strength reduction. The findings support bamboo leaf ash as a viable supplementary cementitious material at up to 10% replacement in mortar applications, with relevance to green construction material development in South South Nigeria. Keywords: bamboo leaf ash, pozzolan, cement mortar, compressive strength, Cross River State