| Abstrakt: |
Soils which undergo large volume changes with change in water content like black cotton may be troublesome if used for highway or railroad fills or if structural foundations are placed on them. The soil volume changes result in bumps in roads and cracks in structures since the volume changes may not, and usually will not, be equal. The liquid and plastic limits may be used to predict potential problems in soils due to volume changes. However, to obtain quantitative indication of how much change in moisture can occur before any appreciable volume change occurs and to obtain, if volume change does occur, an indication of the amount of change, a shrinkage-limit test should be performed. The black cotton (expansive) soil used in this study was obtained from a borrow pit on the basement complex at Idogo in Yewa South Local Government, Ogun State, South-Western Nigeria. The borrow site lies within the coordinates 6⁰ 50' 6" N and 2⁰ 58' 42" N. The black cotton soils used in the study were collected from depths between 0.3-1.0m below ground level. The eggshell wastes were taken from Obasanjo Farms, Ota, Ogun State, Nigeria. The eggshells were milled into powder and then substituted for black cotton soil from 0% to 30% at 10% intervals while 0% eggshell powder substitution served as control experiment. In line with BS 1377 (1990) and other relevant codes, consistency tests were conducted on the composite materials of black cotton (on sedimentary formation) mixed varying degrees of eggshell powder for the determination of liquid limit, plastic limit, etc. It is evidently clear from the results that the percentage shrinkage limit became constant at 30% eggshell powder substitution in black cotton soil on sedimentary formation which is an indication of constancy of volume. [ABSTRACT FROM AUTHOR] |
