Analysis of C3A hydration using soft X-rays transmission microscopy: Effect of EVA copolymer

The hydration of pure C3A (Ca3Al2O6) in calcium hydroxide–gypsum saturated solution was analyzed using soft X-ray microscopy. The images show the presence of at least two different types of ettringite crystals during the first 4 h of hydration. They differ in morphology and growing rate. When poly(ethylene-co-vinyl acetate) (EVA) is present, there is a significant change in the hydration kinetics and morphology of the hydration products. EVA particles inhibited or even prevented the formation of ettringite crystals during the early stage of hydration. A cloud of small, bright particles are observed concentrated around the hydrating C3A grains. The particles are most likely to be a product of reaction between EVA and inorganic species in solution.