Fine Recycled Concrete Aggregates in 3D Printed Concrete

This study aims to develop a 3DPC containing fine recycled concrete aggregates (fRA) and recycled concrete fines. In the first part, methodology of fRA incorporation method was evaluated. Concurrently, the effect of recycled materials was evaluated in the scope of the hydration and hardening processes of the material using isothermal calorimetry and ultrasonic testing. Afterwards, the impact of recycled materials was assessed in terms of their performance on key fresh properties of 3DPC, including rheology, green strength, and early-age shrinkage. Study showed that the most efficient fRA incorporation method is addition of 100% water of absorption. Despite slightly delayed hydration pro-cess in presence of additional water the material exhibits sufficient performance during deposition phase. Overall, it was found that intermediate (50 vol.%) and full replacement levels (100 vol.%) of natural aggregate with fRA and cement with recycled fines (10 vol.%) in 3DPC can be effective with minor mixture modification and ensure satisfactory performance of the material.