Effect of bamboo leaf ash on cement stabilization of Makurdi shale for use as flexible pavement construction material

Abstract

A study was carried out on the cement stabilization of Makurdi shale treated with bamboo leaf ash (BLA), for use as flexible pavement construction material. Classification, Compaction, Consistency, California Bearing Ratio (CBR) and unconfined compressive strength (UCS) tests, were conducted on Makurdi shale specimen treated with Cement and BLA in combined incremental order of 2 % up to 14 % cement, and 4 % up to 20 % BLA of dry weight of soil sample respectively. Results of tests showed that Makurdi shale can be classified as an A-7-6, CH and high swell potential soil by the AASHTO, USCS and NBRRI classification systems respectively. The plasticity index (PI) reduced from 39.4 % for untreated Makurdi shale to 4.7 % at 14 % cement + 20 % BLA. Maximum dry density (MDD) of untreated shale increased from 1.49 Mg/m 3 to a peak value of 1.80 Mg/m 3 at 0 % BLA + 14 % cement. While, the optimum moisture content (OMC) of shale increased from 14.5 % to 33.1 % at 14 % Cement + 20 % BLA. Maximum soaked CBR and 7 day UCS values of 80 % and 1783.9 kN/m2 was obtained at 14 % Cement + 20 % BLA. Based on the results of the different tests, the use of Makurdi shale treated with 14 % cement + 20 % BLA are recommended for use as sub-base materials in flexible pavement.