Rheological Behavior of Cement Paste Adding a Chemical Admixture
Rheological properties of cement paste are being investigated using a dynamic rheology method. The composition of commercial Portland Cement Type I, produced by Cemex Inc., is systematically altered with varying doses of the dispersing chemical admixture: a calcium salt of sulfonated naphthalene formaldehyde condensate (SNF). The amount of gypsum added to the final mixture (3% by mass) is kept constant. Cement pastes are prepared by varying the amount of SNF up to 2 % by mass and maintaining a constant water to cement ratio of 0.35. Small strains and yield stresses are measured using a computer- controlled constant stress rheometer. Rheological measurements are made by applying a small amplitude oscillatory shear. This technique measures the dynamic moduli in which the storage modulus, G' (solid like or elastic response), and the loss modulus G'' (liquid-like or viscous response), are monitored. Preliminary data suggests that the previously recommended SNF concentration (~ 0.8% by mass) is insufficient for the adequate dispersion of the cement paste.
School:
University of Puerto Rico at Mayagüez
Department:
Civil Engineering
Research Advisor:
Charles F. Zukoski
Department of Research Advisor:
Chemical Engineering
Year of Publication:
2002