Modification of Recycled Cement with Different Additives

Abstract

The unmodified recycled cement (RC) paste has unfavorable properties (like fast setting, high water demand and low strength) restricting application. This paper intends to rectify these shortcomings and improve RC with different additives. A comprehensive experimental program combining flowability, setting time, isothermal calorimetry and mechanical tests of modified recycled cement (M-RC) paste with different proportions were conducted. The results indicate that adding TEA and pectin could significantly improve the early flowability of RC and delay its setting, but it will have adverse effects on the mechanical properties of RC paste. Adding 0.5% TEA or 0.075% pectin can increase the fluidity by 240% and 293%. For the 0.5% TEA and 0.075% pectin groups, the 3-day compressive strengths were reduced by 44.3% and 49.5%, respectively.