Comparative Evaluation of the Applicability of 3D Printing Mortar with Different Waste-Powders (2024-08)¶

Compared to traditional concrete, 3D printing concrete requires a larger amount of cement, which has a negative impact on environment. Therefore, it is necessary to expand the types of supplementary cementitious materials (SCM) available for 3D printing concrete and to compare the effects of different SCMs on the same type of concrete. The aim of this study is to gain a better insight into the effects of recycled powder (RP) and dolomite powder (DP) on 3D printing mortar (3DPM). In order to assess the feasibility of incorporating waste powders into 3DPM, DP and RP were used to replace cement by mass at 0 wt%, 2.5 wt%, 5 wt%, 7.5 wt% and 10 wt%, respectively, to investigate printability (fluidity, open time, buildability), mechanical properties (compressive & flexural strength, interlayer bond strength) and environmental performance (CO2 emissions, energy consumption). The results showed that both DP and RP improved fluidity and prolonged open time, albeit with reduced mechanical strength. In particular, DP at dosages (0–5 wt%) can improve buildability and interlayer bond strength, while its dedolomitisation reaction increases later-stage strengths. Both powders reduce energy consumption and CO2 emissions, but RP's contribution dosages not fully compensate for the loss in compressive strength. In addition, the study recommends 5 wt% DP as the optimum dosage, while RP should be limited to ≤ 5 wt% to balance mechanical performance and environmental benefits.