The effect of carbon fiber additive on early hydration of calcium aluminate cement

Abstract

The effect produced by the short carbon fiber additive on the hydration of calcium aluminate cement under the ambient temperatures of 10, 20 and 30° C is investigated. The calorimetric analysis of the cement paste has shown that the carbon fiber additive increases heat release and decreases the induction period of hydration at the ambient temperatures of 10 and 30° C, while at the temperature of 20° C, this period is increased. X-ray diffraction and thermal analysis have shown that carbon fiber additive does not have any influence on the composition of the formed hydrates; however, their amount depends on it. It has been also found that a dense layer of cement hydrates is formed around the fibers. Due to the positive effect of carbon fiber additive on cement hydration and microstructure, as well as its reinforcing effect, the compressive strength and the bending strength of cement stone are increased by 3–23 and 13–70 %, respectively, depending on the ambient temperature.