Impact of Palm Fruit Bunch Ash on Unconfined Compressive Strength of Cement-Stabilized Soils for Road Construction

Abstract

This study assesses the impact of Palm Fruit Bunch Ash (PFBA) on unconfined compressive strength (UCS) of cement-stabilized soils for road construction in south-western Nigeria. Three soil samples were collected from a federal road in each of the eighteen senatorial districts making a total of fifty-four samples. Classification tests were conducted on the soil samples. Thereafter, cement stabilization was carried out on the selected soil samples to determine the optimum cement content. This was followed by adding Palm Fruit Bunch Ash (PFBA) at varying percentages of 2, 4, 6, 8 and 10% to the optimum cement content. Results of classification tests showed that the soil samples fell within the range A-3 to A-7, that is excellent to good and fair to poor soils according to AASHTO classification system. Values of plasticity indices varied from 7.60% to 35.10%. Results of UCS of cement stabilization showed that optimum cement content was obtained at 6%. The results also revealed that addition of ashes of PFBA to 6% optimum cement content increased the values of UCS to an optimum content of 4% PFBA. and decreased thereafter. Range of values of UCS at 4% optimum content of PFBA ranged from 1621.22 kN/m2 to 2017.09 kN/m2 which met the requirement for sub-base and base materials. Summary of optimum UCS test results by statistical analysis showed that PFBA significantly contributed to the increase in UCS values of the soils. Therefore, optimum content of 4% PFBA further increased the UCS of cement-stabilized soils for road construction in southwestern Nigeria. Keywords: Palm fruit bunch ash, unconfined compressive strength, cement-stabilized soil, road construction