Developing a rational method to participation cementitious mortars containing Meta-Kaolin for application in additive manufacturing

There is a growing interest in adopting additive manufacturing processes using cement-based materials in the construction industry. However, the approach to developing a viable cementitious mixture for 3D printing has been empirical in nature and relies heavily on repeated trials, until suitable mixture proportions are determined for a given set of materials. Although the ultimate aim of the on-going study is to develop a rational approach for mixture proportioning cementitious mixtures for 3D printing, the focus of the present study is to examine the behavior of cementitious mixtures prepared with portland cement in combination with meta-kaolin and other admixtures such as super plasticizer (SP), viscosity modifying agent (VMA) and additives such as polypropylene (PP) fibers. In this parametric study, the influence of meta-kaolin addition at various dosage levels on the rheological and mechanical behavior of mortars was investigated Rheological properties of mortars (i.e. yield stress and plastic viscosity) were determined using ICAR PLUS rheometer to correlate the fundamental rheological properties with the performance measures such as extrudability, buildability, thixotropic open time and shape retention. Setting time of various mortar mixes were also determined using ASTM C403 method. The compressive strength and flexural strength of the material was evaluated. The bond behavior between the layers will be evaluated using pull-off testing (ASTM C 1583) in the future. The results from this investigation showed the relevance between the fundamental rheological properties and the performance measures for achieving a viable 3D printable mixture