Characterizing Sticky Concrete from Rheological Perspective

Increasing urbanization is driving the construction of tall buildings in congested areas. Tall buildings call for concrete with high compressive strength and modulus of elasticity, resulting in a low water-cementitious materials ratio (w/cm) and high cementitious content mixtures. At these lower w/cm, such mixtures are typically "sticky" and difficult to pump or finish. However, high-rise construction requires pumping such "sticky" concrete, potentially leading to high pumping pressures and clogged pumps. The word "sticky" does not have a clear technical defnition, nor is it currently associated with specific rheological mechanisms. This article explores the quantification of "stickiness" through small amplitude oscillatory rheometry. This work is a step toward connecting the human perception of stickiness and fundamental rheological properties. Keywords: high-range water reducer (HRWR); polycarboxylate; rheology; small-amplitude oscillatory rheometry (SAOS); stickiness.