Evaluation of the use of recycled construction and demolished waste in road construction in Sri Lanka

Abstract

The construction industry is developing rapidly in Sri Lanka with new building constructions and demolishing old buildings. These activities are accompanied by production of debris material which stockpiles annually in large quantities. On the other hand highways are constructed rapidly in Sri Lanka causing depletion of natural resources like gravel. This research attempts to evaluate the use of recycled construction and demolished waste in road construction in Sri Lanka which will provide a feasible solution to the said problem. The materials used were gravel, demolished concrete and crushed bricks. The gravel was selected from an excavation site at Galagedara which was within the specified limits of particle size distribution specified in ICTAD specifications. Recycled Concrete Aggregates (RCA) and Crushed Brick (CB) samples were prepared by mixing the sorted particles in different sizes to satisfy the ICTAD limits of gradation. The sieve analysis test was done for the control sample, for samples mixed with 35%, 40%, 45% and 50% of demolished concrete, for samples mixed with 35%, 40%, 45% and 50% of recycled brick and samples mixed with 35%, 40%, 45% and 50% of demolished concrete & recycled brick in 1:1 proportion. Gradations of all the samples were within the range specified in the standards for sub base material and shoulder material. Atterberg limit test results showed that the Liquid Limit and the Plasticity Index values decreases while Plasticity Limit increases when C&D waste content gets higher for all the samples. These Values did not meet the Atterberg limits specified for Upper Subbase in Rigid Pavements but show suitability to be used in embankments, sub base for flexible pavements, shoulder materials and gravel surfacing. Modified CBR tests performed on samples revealed that C&D waste addition increases the ability to stand on higher stresses with the increase of C&D waste percentage in the blend, confirming that these proportions are very much suitable for the construction of roads in Sri Lanka.