A starch-based admixture for reduction of hydration heat in cement composites

In this paper, the effect of a new starch-based chemical admixture (SA) on cement hydration is investigated and its preliminary action mechanism is discussed. The results from isothermal calorimeter and semi-adiabatic calorimetry test show that SA could decrease the maximum heat flow from the 2.6 mW/g to 1.5 mW/g and the peak temperature from 35.9 °C to 24.9 °C when the SA dosage increased from 0% to 0.6% (weight ratio of SA/cement). The effect of SA with different dosage on cement hydration has also been investigated by electrical resistance test and X-ray diffraction analysis. Though the cement hydration rate is decreased at early stage, it has no influence on the final total heat release and no influence on concrete compress strength at 28 d. Such results show that it might have great sense to control thermal crack in mass concrete in practical application which is normal problem in mass concrete.