Effect research of cement block on paste flow for 3D cement printing based on an improved lattice Boltzmann method

Abstract

3D cement printing can realize the rapid prototyping of the building materials effectively. Similar to other additive manufacturing (AM) methods, the extruding velocity is an important factor on the printing performance. Cement paste is easy to set when it flows through the extruding device (extruder screw), which will result in the formation of cement block(s) on the wall. It is essential to investigate the effect of the block on the flow. In order to facilitate the analysis, three simplified common geometries (rectangle, circle, trapezium) in a section of the expanded channel are taken as blocks for fluid analysis. Firstly, an improved lattice Boltzmann method (LBM) is put forward for the non-Newtonian cement paste and validated by Poisuille flow, which is beneficial for the stability and accuracy of numerical simulation. Then, a series of numerical cases on the factors of geometry, size, position and number are conducted. The results show that all of the mentioned factors have important influences on the flow trace, the high/low velocity-region distribution and the outlet velocity.