Cement paste
Cement paste is a material formed by mixing cement with water. It is a primary component of concrete and mortar, and its properties significantly influence the performance of both fresh and hardened cementitious materials. In its initial state, cement paste is a concentrated suspension of cement grains in water, undergoing a series of chemical and physical transformations during hydration.[1]
Composition
[edit]The primary constituents of cement paste consists of cement (most commonly Portland cement) and water, with optional admixtures included to modify its behavior.[1][2] Common chemical admixtures include water-reducing agents and superplasticizers, which enhance workability and flow properties.[2] The incorporation of mineral admixtures and fillers have also been studied to tailor the rheological and mechanical characteristics of the paste.[2]
Rheological properties
[edit]Fresh cement paste is a highly concentrated suspension of cement particles in water. Its rheological behavior is typically non-Newtonian, most often approximating a Bingham plastic model characterized by a yield stress and plastic viscosity. Depending on the formulation and additives, it may also exhibit pseudoplastic (shear-thinning), dilatant (shear-thickening), or time-dependent behavior such as thixotropy.[1]
Rheology determines key processing characteristics such as flowability, pumpability, and segregation resistance.[3] The flow behavior is strongly influenced by the water–cement ratio, particle size distribution, admixture dosage, mixing time, and temperature. Superplasticizers reduce yield stress and viscosity, enhancing workability without increasing the water content.[2] Conversely, ultrafine mineral admixtures tend to increase both parameters due to their high specific surface area and tendency to promote particle flocculation.[3]
References
[edit]- ^ a b c Kurdowski, Wieslaw (2014). "The Properties of Cement Paste". Cement and Concrete Chemistry. Dordrecht: Springer Netherlands. pp. 279–368. doi:10.1007/978-94-007-7945-7_5. ISBN 978-94-007-7944-0.
- ^ a b c d Chindaprasirt, P.; Hatanaka, S.; Chareerat, T.; Mishima, N.; Yuasa, Y. (2008-05-01). "Cement paste characteristics and porous concrete properties". Construction and Building Materials. 22 (5): 894–901. doi:10.1016/j.conbuildmat.2006.12.007. ISSN 0950-0618.
- ^ a b Nazar, Sohaib; Yang, Jian; Thomas, Blessen Skariah; Azim, Iftikhar; Ur Rehman, Sardar Kashif (2020). "Rheological properties of cementitious composites with and without nano-materials: A comprehensive review". Journal of Cleaner Production. 272: 122701. doi:10.1016/j.jclepro.2020.122701.