Experimental observations on factors influencing shear-thickening characteristics of cement-based materials

Shear-thickening phenomena often arise in fresh high-performance concrete (HPC), presenting challenges in applications characterized by high shear rates, such as mixing and pumping. To enhance rheological control in HPC, a comprehensive series of experiments were conducted to systematically examine the influence of chemical admixtures, granular aggregates, and external factors such as temperature and shear rate on the shear-thickening behavior of concrete materials. The results suggest that the utilization of polycarboxylate superplasticizers with shorter side chains, reducing the total aggregate volume, the addition of air-entraining admixture, employing sand with a lower fineness module, and subjecting the material to lower pre-shear rates collectively mitigate the shear-thickening behavior. In contrast, the influence of viscosity-modifying agents, sand-to-total aggregate ratio, and temperature on shear-thickening was observed to be non-monotonic and relatively less pronounced. The study concludes by proposing strategies to reduce the intensity of shear thickening in HPC, aiming to enhance the efficiency and ease of pumping and casting processes in the construction. © 2024 Elsevier Ltd. All rights reserved.