Predicting the strength development of 3D printed concrete considering the synergistic effect of curing temperature and humidity: From perspective of modified maturity model

This study aims to establish a development model for the compressive strength of 3D printed concrete (3DPC) under the coupling influence of temperature and humidity, utilizing the maturity method. Initially, diverse curing conditions were applied to 3D printed specimens, incorporating varying temperatures (10 degrees C, 20 degrees C, 40 degrees C) and relative humidity levels (100% RH, 80% RH, 60% RH, 40% RH), with strength value assessed at different ages. Subsequently, a maturity model for humidity modification was proposed, and the model was calibrated through experimental results. The results show that the strength of the specimens increases over time, irrespective of the variations in curing temperatures and humidity levels. Moreover, with a decrease in humidity level, a more pronounced decline in strength is observed. Furthermore, the anisotropy index values of the rate constant in the Y-direction specimen, when cured at temperatures of 10 degrees C and higher humidity conditions, such as 100% RH and 80% RH, exhibit significant variations across different temperatures and moisture levels, leading to increased anisotropies. The modified maturity model can be used to predict and evaluate the strength development of 3D PC under different environmental conditions with high accuracy.