Investigation of the Effect of Bamboo Leaf Ash Blended Cement on Engineering Properties of Lateritic Blocks

Abstract: Laterite is the commonly used building materials in rural Nigeria. It has been observed that it became the traditional building construction material due to its availability, low processing cost and ease of handling with little or no equipment and skill requirements. However, studies have shown that lateritic soils are generally weak in compression and tend to absorb moisture and become soften. Consequently, walling materials such as lateritic blocks has been the subject of investigation for decades; partly, to serve as an alternative to the conventional sand Crete blocks. Such effort is especially desirable as it is well known that the production processes of cement; which is the main binder employed in the production of sand Crete blocks is associated with huge energy consumption and emission of harmful gases such as CO₂. This study investigated the effect of bamboo leaf ash blended with cement on some engineering properties of lateritic blocks. The bamboo leaves used for this study were collected in the campus of the University of Uyo and the laterite was obtained from a borrow pit in Itu L.G.A. of Akwa Ibom State, Nigeria. The leaves were sun-dried, burnt in an open atmosphere and then heated in a muffle furnace at 600^oC for 2hours to obtain the bamboo leaf ash (BLA). Tests on the physical and chemical properties of bamboo leaf ash blended with cement were conducted in accordance with BS 4550: 1978 and BS 12: 1996. The chemical analysis of the BLA showed that the combined Silica Oxide (SiOâ‚‚), Aluminum oxide (Alâ‚‚O₃) and Ferrous oxide (Feâ‚‚O₃) content was above the 70% minimum standard requirement specified by ASTM (ASTM C 618, 2008) for pozzolanic materials. Varying levels of percentage replacement of cement with bamboo leaf ash was obtained at 0%, 5%, 10%, 15%, 20% and 25%. A total of 72 blocks comprising of 12 blocks for each percentage replacement of the lateritic block size of 225mm x 113mm x 75mm of mix ratio 1:20 and water-cement ratio of 0.8 were cast, cured and crushed at 7, 14, 28, and 56 days curing respectively. Analysis of the compressive strength, moisture absorption resistance and the abrasion resistance of the lateritic blocks produced from cement blended with bamboo leaf ash (BLA) showed that the 5% and 10% cement replacements is suitable for load bearing outer walls whereas the 20% and 25% substitution was found more suitable for non-load bearing indoor walls. The 15% substitution was however found to be suitable for non-load bearing outer walls.