Drying Shrinkage Properties and Initial Bonding Strength of 3D Printing Mortar

Abstract

3D printing has emerged in the construction industry provide an effective and productive alternative construction methods. Cement-based material is the main choice in 3D printing construction due to its low cost and easy availability. This paper presents the drying shrinkage properties of hardened 3D printing mortar and the bonding strength of fresh mortar under the delayed phenomenon. Eight types of mortar mixtures in two series with varying percentages of sandy clay replacement ranging from 0% to 75% for both 1:1 and 1:2 cement sand ratios were used in the trial mix. Basic physical properties of 3D printing mortar such as workability, extrudability and buildability were conducted on the trial mix. Four mortar mixtures that complies with the basic 3D printing properties were used to conduct the drying shrinkage properties and the initial bonding strength test. The initial bonding strength test was conducted under delayed phenomenon for 0 minutes, 10 minutes, 20 minutes and 30 minutes. The experimental results showed a significant increase in drying shrinkage for mortars containing 75% sandy clay. However, the highest initial bonding strength is also achieved by mortars containing 75% sandy clay. The initial bonding strength of 3D printing mortar was decreased over the delaying time.