Abstract
We proposed a method to reuse returned or residual waste fresh concretes, hereafter referred to as waste fresh concretes that are now being treated in ready-mixed concrete plants, as a preceding mortar for concrete pumping constructions taking into consideration of the resource saving and control of construction wastes emission. A super set-retarding agent to halt the cement hydration of the waste fresh concretes and a superplasticizer to improve the efficiency of the subsequent wet-screening and pumpability were added to the waste fresh concretes. Resulting Eco-mortar can be used as a preceding mortar for the next day or later. Effects of mixture proportions and the type of cement of waste fresh concretes on the fluidity, set-retardation and compressive strength of Eco-mortar were examined. As a results, availlable ranges of the original waste concrete quality satisfying the requirements of Eco-mortar and the Eco-mortar production system were determined.
