Utilization of glass cullet to enhance the performance of recycled aggregate unbound sub-base

This paper presents the findings of a laboratory investigation on the utilization of recycled glass cullet as fine aggregates to replace the fine-sized demolition aggregates for producing full-depth unbound aggregate sub-bases of pavement. The experimental results indicated that glass cullet was suitable for use as fine aggregates in unbound sub-base. The inclusion of glass cullet in recycled demolition aggregates in the sub-base materials provided higher bearing and crushing resistance under the penetration loads during the Californian Bearing Ratio test. Mixes of glass cullet and coarse demolition aggregates from a commercial source at a ratio of 3:7 by mass could achieve bearing capacities comparable with that of natural aggregates sub-base. Besides, blending the glass cullet with lower grade demolition aggregates collected from public dumping points could also produce recycled sub-base which satisfied requirements of the construction specifications. Glass cullet facilitated compaction of the mixes in the soaked condition leading to higher sub-base densities. The optimum moisture content of the recycled sub-base mixes decreased with increasing contents of glass cullet in the mixes. Some breakages of the aggregates occurred during the compaction process but the grading requirement was still met after compaction.