Evaluation of Particle Effects in Portland Cement Systems

Abstract

Various filler materials were evaluated to identify and differentiate chemical reactions from physical particle reactions during hydration within a portland cement system. Laboratory teasting included solubility within a calcium hydroxide environment, heat generation via isothermal calorimetry, and portlandite formation identification via X-ray diffraction. Results indicate that quartz, which is often accepted as inert filler material in portland cement systems, is chemically reactive in highly alkaline environments. The study introduces diamond, a novel, truly nonreactive filler material that allows quantitative determination of the extent of pure physical reactivity, otherwise known as the filler effect, in the absence of additional contributions to hydration due to chemical reactivity. A proposed zero-reaction plot is suggested to evaluate material reactivity with respect to portland cement. Consequences of the zero-reaction plot are further reaching than a filler test; this method can evaluate the exothermic reactivity of amendments to portland cement in a manner that makes comparative analyses uncomplicated.