AN EXPERIMENTAL INVESTIGATION ON THE USE OF RECYCLED CONCRETE SHINGLES AS PARTIAL REPLACEMENT OF COARSE AGGREGATE AND RECYCLED METAL SHINGLES AS FINE AGGREGATE IN FLEXIBLE PAVEMENT

Abstract

Construction materials are essential in every facet of civil engineering. Throughout history, societies have demanded vast quantities of construction materials, road pavement is a unique case where a large amount of aggregate are needed for the construction of asphalt roads leading to significant exploitation of natural resources. For purposes of cost effectiveness and sustainable use of natural resources, exploring alternative sources of construction materials that can substitute natural aggregates including residues of metal shingle scrap melting and concrete shingle waste is essential. The present research focuses on examining the potential use of recycled concrete shingle aggregates as partial replacement of coarse aggregate and recycled metal shingles as fine aggregates in flexible pavement. To meet the objective of the research, physical and mechanical tests of aggregates along with performance tests were conducted on a control mix and on the mixture containing recycled shingle aggregates in proportions of 10%, 20%, 30% and 40% replacement. Results indicated that both recycled concrete shingle aggregates (RCSA) and recycled metal shingle aggregates (RMSA) have a good physical and mechanical properties except the water absorption. Their physical and mechanical properties improved when combined with natural aggregates relative to their individual properties. The Marshall stability rises highest at 10% replacement of recycled metal shingle aggregates (RMSA) giving a stability of 13.97 kn. Similarly, the test result of mix containing recycled concrete shingle aggregates (RCSA) shows best performance at 40% replacement having a stability of 14.21kn. However, it was observed that recycled shingle aggregates mixes exhibit a substantial increase in bitumen consumption compared to that of the control mix. The indirect tensile strength results show that the control mix gives the highest value of tensile strength (903) Kpa in dry state better than the mixture containing recycled concrete shingle aggregates (RCSA) whereas for recycled metal shingle aggregate (RMSA) the highest indirect tensile strength value, were 915.2kpa in dry state at 30% replacement. The tensile strength ratio shows recommendable result of 77.96 at 30% replacement for recycled metal shingle aggregates (RMSA) and 83.02 at 40 % replacement for RCSA surpassing the minimum requirement value of 75% specified by ERA manual.