Performance improvement of recycled aggregate concrete using fly ash and Portland blast-furnace slag cement

Several countermeasures are implemented in the manufacture of construction materials to avoid negative impacts on the environment. Using concrete debris in construction demolition waste as a recycled aggregate to make recycled aggregate concrete (RAC) is one of the countermeasures. Further, the use of recycled construction waste and industrial by-products, such as fly ash and ground granulated blast-furnace slag, in concrete not only promotes resource circulation and reduces CO2 emissions in the cement manufacturing process but also improves concrete performance. In this study, low-quality recycled aggregate was mixed with normal aggregate at various replacement ratios to produce RAC. Additionally, ground granulated blast-furnace slag in Portland blast-furnace slag cement and fly ash were introduced in concrete to improve concrete performance. Applying the relative quality index method for performance evaluation, it was possible to design a mix proportion of RAC that achieved the requisite performance through the application of Portland blast-furnace slag cement and fly ash as a cement substitute or as a fine aggregate substitute.