High industrial solid waste road base course binder: Performance regulation, hydration characteristics and practical application

The recycling ratio of industrial solid waste, e.g., steel slag (SS), phosphogypsum (PG) is still comparatively low in developing countries. This work aims to utilize industrial solid waste in a sustainable slow-setting slight-expansive road base course binder (RBCB) production involving the performance regulation, hydration characteristics and practical application. The results indicates that RBCB obtained the ideal retarding effect without additional retarder and avoided the strength loss which caused by the fast hardening during the rolling compaction process. The relatively high content of PG preferably stimulated the pozzolanic activity of fly ash (FA), and more effectively compensated the shrinkage through inhibiting the conversion of AFt to AFm in the later hydration stage. In addition, SS adjusted the setting time, improved the strength and regulated the expansion ratio of RBCB. Each kilometer of road base course absorbed 688.8 t solid wastes and saved 6.53% cost of materials compared with P·S 32.5 (Portland slag cement, strength grade is 32.5) in practical application. Excellent pavement performance, obvious environmental and economic benefits were achieved in the field experiment of RBCB containing high solid wastes. This investigation provides a promising and value-added way for the utilization of various original solid waste.