Feasibility of Using Recycled Combined Construction and Demolition Waste for Road Base and Subbase in Fooladshahr, Isfahan Province, Iran: A Case Study

The use of construction and demolition (C&D) waste in road construction has been an important and challenging issue in recent years. In this research, geotechnical characteristics of recycled combined construction and demolition waste (RCCDW) at Fooladshahr (located in the Isfahan province, Iran) are studied to determine whether they are an appropriate candidate in road base and subbase. Laboratory tests including sieving, soundness, Los-Angeles (LA) abrasion test, compaction, and California bearing ratio (CBR) are among the tests performed on these materials. The tests were carried out on two types of samples, namely, RCCDW and natural standard aggregates for road base and subbase layers. In Iran, often, no separation is made on C&D wastes such as concrete crumbs and brick lumps. To the best of the authors’ knowledge, the majority of the previous studies have been conducted on different percentages of concrete crumb and brick crumb or a combination of both. In comparison, the present study examines almost all types of construction and demolition wastes in place. The obtained results show that after initial recycling and resizing, residues have several remarkable characteristics for use in the base and subbase layers. Although their compressive properties and CBR number were less than the standard limits, they were improved by cement stabilization and became suitable for these road layers. The results show that the maximum dry density of without-cement wastes after stabilization with 12 percent cement (by weight), increased from 1.83 to $2.10\mathrm{g}/{\mathrm{cm}}^3$ , and their CBR value increased from 65.8% to 88.6%.