Setting on demand for digital concrete – Principles, measurements, chemistry, validation

TLDR

Digital concrete fabrication, such as layered extrusion, demands precise yield‑stress evolution over time, with strength expected to grow linearly for self‑support and cubically to prevent self‑weight buckling. The study proposes integrating concrete yield‑stress chemistry with process‑imposed strength requirements to guide digital fabrication development. The Set‑on‑Demand approach employs tailored admixtures and novel rest‑state yield‑stress measurement methods to link chemistry to processing and mechanical stability. The authors argue that controlling cement hydration during fabrication can achieve the required yield‑stress evolution, as demonstrated by their Set‑on‑Demand strategy.

Abstract

Digital fabrication with concrete is a field of rapidly developing building processes – including layered extrusion - where specific yield stress evolution over time is needed, owing to concrete loading during fabrication. By combining physico-chemical principles of concrete yield stress evolution with strength requirements imposed by the building process an avenue is devised for an effective development of these processes. Most notably, strength should grow linearly with time to ensure strength-based self-support, while it should growth with its third power to avoid self-weight induced buckling. It is argued that the needed evolution can be achieved by adequately controlling cement hydration during fabrication. Specifically, we outline the Set on Demand approach, relying on a combination of admixtures adequate for the process under study. This strategy is implemented with newly developed methods capable of measuring concrete yield stress evolution at rest, thus providing the link from chemistry to processing and mechanical stability.