Use of Crushed Concrete Aggregate Waste in Stabilization of Clayey Soils for Sub Base Pavement Construction

Abstract

The research aimed at stabilizing lateritic soils, using crushed concrete aggregates from demolished buildings, foundations, roads and other structures, for use as sub-base for a paved road. Lateritic soils were sampled along the Mukono-Jinja Highway from a borrow pit owned by Stirling Company LTD. Crushed concrete aggregate wastes were fairly angular and strong as they showed comparative values to the fresh aggregates as earlier researched. The lateritic soils were blended with different percentages of waste aggregates 0%, 30%, 40% and 50%, chosen basing on previous studies. The study looked at properties such as grading and flakiness of the waste aggregates, grading, atterberg limits, Optimum Moisture Content, Maximum Dry Density and 4 day soaked California Bearing Ratio for the stabilized and un-stabilized material. Mix designs with 40 % and 50 % of the waste aggregates were considered suitable for use as sub base material. They had CBR of 46 and 59, respectively, at 95 % relative compaction and PI values of 13.64 and 11.40. These met the specified standards of a CBR equal or greater than 45 and PI equal or less than 14 according to the general specifications of Ministry of Works, Housing and Communications (2004).