Sustainability Performance of Plantain Leaf Ash and The Compressive Strenght of Concrete

Abstract

Agricultural activities include planting, crop production, harvesting etc, after which the plants sheds off its leaves. This is as a result of change in season or expiration of the plant. The leaves at this point become wastes that make the farm unattractive and needs to be disposed. In disposing these wastes, most time is by open burning which causes environmental pollution and as well global warming. In reducing the release of gaseous substances from burning to the atmosphere, these wastes can be converted to supplementary materials (pozollans) that are eco-friendly and useful to man, example Plantain Leaf Ash (PLA). These are products of agricultural wastes gotten from burning plantain leaves. The use of PLA will reduce environmental pollution, global warming and high cost of cementitious materials and it is readily available. The increase in human population has consequently led to need for increase in provision of infrastructures like buildings, roads, etc which has technically impacted on the construction industry leading to increase in use of concrete. The overall cost of concrete production depends on the availability and cost of its constituent’s materials and cement remains the most expensive of them. Consequent upon this is the trend towards sourcing for locally available and eco-friendly materials (PLA) that can replace cement in concrete production either partially or total. Materials used in this research include; Ordinary Portland cement, River Sand, Crushed Coarse Aggregates, PLA and Water. This paper showcased the usability of PLA as partial replacement of cement in concrete production. The PLA used was gotten from burning plantain leaves in an incinerator. The ashes passing sieve size 600um were used for this work. There was no further processing of the PLA like grinding. This is to keep the manufacturing process simple. Tests like particle size distribution, specific gravity, etc were performed on the aggregates and concrete grade of 25N/mm2 was used. With data gotten from the aggregate tests, design mix of 1:2:3 with w/c of 0.59 was computed and used to cast the concrete samples. Four different sample mixes were made which include; 0% (control sample), 5%, 10%, 15% partial cement replacements with the PLA. They were casted for the 7 days, 14, 21, 28, 56 and 75 days compressive strength. A total of 72 concrete cubes were cast using cube mould of 150mm x 150mm x 150mm. Three samples each of the mixes were crushed at the required age and the average data value computed and properly recorded. The investigation showed that the four concrete mixes attained the required strength as it ages. The normal concrete (mix 1) gained strength faster initially but the PLA concrete samples gained appreciable strength from the 7 to the 28 days age. A Mathematical model was developed to predict the compressive strength of concrete at varying crushing age and PLA/cement percentage replacement. The model sufficiently predicted the experimental data with an average correlation coefficient of 0.98. The result gave a strength that is very much comparable and sustainable at these percentage replacements. Using these PLA replacements in concrete, there would be significant impact on the structures construction cost and the concrete strength comfortably attained. Though the fineness of the PLA does not match that of cement as result of the production process, yet it gave a strength that is very much commendable at these percentage replacements thus it is recommended for use in concrete production.