Graduate Assistant: Prasanth Tanikella Faculty Advisor: Jan Olek

1. Incorporation of physical and chemical properties of fly ash in modeling hydration of ternary cementitious binders Graduate Assistant: Prasanth Tanikella Faculty Advisor: Jan Olek Technical support: Janet Lovell Research Objectives • There is a significant variation in the specific surface area measured by either techniques • The relation between the two is unknown and can be found out statistically • The primary focus of the project is to model the effect of properties of fly ash on the hydration process of ternary binders containing Type I Portland cement and two different fly ashes. • To quantify the synergistic effects due to the addition of fly ashes to predict the type and proportions of fly ashes to be added to cement Orthogonal Array Technique • This method is used to reduce the extremely large number of experiments into a small set • This also takes care of the pair wise interactions between different factors • Factors are identified and are tested at different levels • A test matrix is developed for different combinations of factors at various levels • ANOVA is used to find, statistically, the influence of each factor on the hydration properties and also pair wise interactions • Table 1. Factors affecting hydration process and their levels of testing • Fig 1. Example of the differences in the PSD for fly ashes obtained from two laboratories • Resolution of the differences • An attempt was made to resolve the differences in the observed PSD using the Andreasen Pipette Available characteristics of the fly ashes • Fly ashes (both class C and class F) selected from 19 sources commercially available in Indiana • Properties evaluated • -Total Chemical Analysis -Particle Size Distribution • -Magnetic particle content -X-Ray diffraction analysis • -Scanning electron -Strength activity index • microscopy • -Specific surface area and mean particle size Extent of hydration of various ternary binders • Fig 2. Comparative results with pipette analysis • Conclusions • The pipette analysis seems to work well for particles larger than 5 micron particle size and is coincident with Lab 1’s results. The results below 5 microns seem to diverge from either of the curves • Specific surface area • Fig. 3 Comparison of • surface area measured • using LPSA and • Blaine’s apparatus • Setting time • Heat of hydration • Strength of the paste • Porosity • Amount of calcium hydroxide produced in the reaction Discrepancies in the data • Particle size distribution (PSD) • PSD analyzed in two laboratories using laser particle size analyzer (LPSA) • Significant differences observed in the PSD obtained for most of the fly ashes, while a few agree up till a specific particle size Summary • The synergistic effects of using two fly ashes with required properties as components of a ternary binder system can be modeled using statistical methods