STRENGTH ASSESSMENT OF CALCIUM CARBIDE RESIDUE STABILIZED CLAY ADMIXED WITH ZEOLITE

Abstract

Clay soil collected at Niger State Polytechnic, Zungeru, was characterized and classified as A-7-6 (GI- 12) CH soil according to American Association of State Highway and Transportation Officials (AASHTO) soil classification system. The clay was treated with 5% Calcium Carbide Residue (CCR) and was admixed with 2% zeolite. Unconfined compressive strength (UCS) test using 40 samples each was used as evaluation criteria to measure the effect of zeolite on CCR stabilized clay soil. Results showed significant increase in UCS with increase in zeolite and CCR. In the absence of zeolite, the mean UCS was 337.15 kN/m2 all at 28 days curing strength, at the addition of zeolite into the CCR stabilized soil a sharp increase in the mean UCS was noticed it increased to 704.23 kN/m2 at 28 days curing. Standard deviation was calculated for both CCR stabilized soil samples and CCR admixed zeolite soil samples as 12.5 and 12.27 which shows a deviation towards accuracy for the zeolite stabilized soil samples. A confidence limit analysis was also carried out to establish a performance range of soil strength using the mean and standard deviation calculation. 95% Confidence limit for the mean value of strength of soil stabilized with 5% CCR and 0% zeolite was 381.02kN/m2 upper bound and 373.28 kN/m2 lower bound while the 99% confidence limit was 382.25 kN/m2 upper bound and 372.05kN/m2 lower bound. When the confidence limit for the 2% zeolite admixed CCR stabilized soil was calculated, for 95% confidence limit 708.03 kN/m2 upper bound and 700.42 kN/m2 lower bound and for 99% confidence limit 709.23 kN/m2 upper bound and 699.22 kN/m2 lower bound. This values show a certainty of obtaining similar results for the range of the strength UCS values tested of any given soil samples of the same nature as described in the index properties of the clay studied. Confidence limits tests for the standard deviation of the set of samples was computed and as presented in the result shows the allowable range for both 95% and 99% values for both of the sample mixes.