Stiffening control of cement-based materials using accelerators in inline mixing processes: Possibilities and challenges

Abstract

In many applications such as grouting, shotcrete, and 3D concrete printing, conflicting material requirements exist between the transportation and fabrication process, as fresh materials should be pumped easily with a low stiffening rate and a high fluidity while a rapid strength gain must occur after placement. In such applications, it is therefore imperative to achieve a stiffening control of the concrete. In this paper, we discuss how the inline mixing process of an accelerator post-pumping can be used to achieve this stiffening control. We begin with a review of the mechanisms of various commonly used accelerators. This is followed by a detailed discussion on the inline mixing process of accelerators. Finally, we also point out the problems and challenges of using accelerators in these applications.