Spiraling Slipforms

Jeffrey Richmond + Lucas Rigney




Tsz Yan Ng


Concrete slip forming is an efficient construction process typically used for simple extrusions and monolithic construction. From highway barriers and elevator cores to nuclear reactor cooling towers, slip forming expresses a direct relationship between process and geometry. This thesis looks to engage this relationship, expanding the fabrication potentials by utilizing multi-axis robotic processes to slipform customized geometric profiles of building components.

Critical to developing the means and methods for controlling the robotic slip forming process is calibrating the concrete mix. The required parameters for the process are diametrically opposing in terms of the mix design; where it had to be low viscosity for casting, but rapid setting for the pour to be self-supporting. Precise measures of Portland Cement, silica fume, ground silica, fine sand, accelerant, superplasticizer, water, and glass fiber reinforcement were devised. Numerous tests were done using 6” tall molds that were robotically lifted, synced with a mechanized rotary base. The pour rate in relation to the robotic process thus largely depends on interdependent variables between the viscosity level of the mix, profile geometries of the slipform, and desired cast forms. Once these variables were fine-tuned, further iterations were developed as part of the research to push the potentials of the casting process.

Key aspects of the process refined include the extent of rotation possible given a specific height, as well as the slipform’s profile in terms of aspect ratio to provide self-supporting capabilities. Based on findings from the prototypes, the design proposal speculates on full-scale panel construction, with aggregated components to investigate part-to-whole design, façade porosity, as well as jointing details, These panels, interlocking in their twists, bends, scallops, and ribs, create a beautiful array basked in waves of light and shadow, an irreducible expression of construction efficiency and geometric complexity, not possible with conventional forming methods.