Improving Mechanical Properties of 3D Printed Mortar by Exploiting Synergistic Effects of Fly-Ash-Microsphere and Nano-Silica (2024-11)¶

Fly ash microsphere (FAM), being a superfine fly ash, and nano-silica (N-S), being an ultrafine amorphous silica, have been proven to be useful for enhancing the performance of traditional cement-based materials. To explore the possibility of improving the performance of 3D printed mortar by the combined addition of FAM and N-S, a series of 3D printed mortars with varying water/cementitious materials (W/CM) ratios, FAM contents and N-S contents were made to evaluate their performance attributes. The results showed that optimizing the water reducer dosage could make the 3D printed mortars achieve great extrudability, buildability and dimensional stability. The W/CM ratio, FAM content and N-S content were the main factors determining the mechanical properties of the 3D printed mortar. The co-addition of FAM and N-S could enhance the flexural, compressive and bond strengths at a percentage increase larger than the sum of the percentage increase due to individual addition of FAM and N-S. Hence, the FAM and N-S should better be used together to release their synergistic effects for the design of 3D printed mortar.