Optimal water-cement ratio and volume of superplasticizers for blended cement-bamboo leaf ash high-performance concrete

Attention on the use of High-Performance Concrete (HPC) for construction works has soared considerably due to the need for large volume of concrete with high level of strength for such works. The mechanical properties of HPC with Bamboo Leaf Ash (BLA) as partial replacement of cement with varying proportions of superplasticizer and water-cement ratio was investigated in this paper. The percentage of BLA was fixed at 5%, while the proportion of superplasticizer ranged from 0 to 1.5% by weight of cement. The concrete mix was designed to attain a characteristic strength of 41 N/mm² after 28 days of curing. X-ray Fluorescence (XRF) and X-ray Diffraction (XRD) were employed in determining the chemical constituents and crystallinity of the BLA respectively. The slump of the fresh HPC was also established. Concrete cubes (for water absorption and compressive strength) were cast and immersed fully in water for 56 days. Water absorption and compressive strength were established on the fully cured HPC. The optimal combination of materials at the end of the curing period is 0.360 water-cement ratio at 0.128 % superplasticizer. This resulted in a slump height of 49 mm, compressive strength of 53.61 N/mm2 and 4.77% water absorption capacity.