For emerging casting approaches, e.g., 3D concrete printing, understanding and controlling the structural build-up behavior (or fresh-state stiffening) of fresh cements has become critically important. In the case of 3D concrete printing, due to the absence of formwork the freshly deposited material must exhibit rapid structural build-up to achieve shape stability.
Due to the complex nature of cementitious materials, structural build-up is a function of both reversible structural changes due to non-contact colloidal interactions and irreversible structural changes due to hydration mechanisms. We perform fundamental rheological studies to experimentally measure, control and model the structural build-up behavior of fresh cement pastes, where recent efforts have been on investigating the effects of additives such as nanoclays and viscosity modifying admixtures (VMAs) and the presence of internal stress at rest.
Relevant publications:
- Kawashima, S., Wang, K., Ferron, R. D., Kim, J. H., Tregger, N., & Shah, S. (2021). A review of the effect of nanoclays on the fresh and hardened properties of cement-based materials. Cement and Concrete Research, 147, 106502. doi:10.1016/j.cemconres.2021.106502
- Ma, S., & Kawashima, S. (2020). Role of shear stress at rest on the viscoelastic response of fresh cement pastes. Journal of Rheology, 64(2), 433-444. doi:10.1122/1.5129676
- Roussel, N., Bessaies-Bey, H., Kawashima, S., Marchon, D., Vasilic, K., & Wolfs, R. (2019). Recent advances on yield stress and elasticity of fresh cement-based materials. Cement and Concrete Research, 124, 105798. doi:10.1016/j.cemconres.2019.105798
- Ma, S., & Kawashima, S. (2019). A rheological approach to study the early-age hydration of oil well cement: Effect of temperature, pressure and nanoclay. Construction and Building Materials, 215, 119-127. doi:10.1016/j.conbuildmat.2019.04.177
- Ma, S., Qian, Y., & Kawashima, S. (2018). Experimental and modeling study on the non-linear structural build-up of fresh cement pastes incorporating viscosity modifying admixtures. Cement and Concrete Research, 108, 1-9. doi:10.1016/j.cemconres.2018.02.022