Effects of temperature rise-inhibiting polycarboxylate superplasticizers on hydration process and mechanical properties of cement-based materials

A multifunctional temperature rise-inhibiting polycarboxylate superplasticizer (TR-PCE) was developed based on functionalized poly(vinyl alcohol), aiming to enhance the dispersion of cement slurry and mitigate thermal cracking by regulating heat release during hydration. Measurements of fluidity, setting time, semi-adiabatic temperature rise, and compressive strength demonstrated that the novel admixture improved the dispersion (with a fluidity increase of approximately 241.7%), inhibited the increase in temperature (decreased by 29.01%), and significantly enhanced the mechanical properties (a compressive strength increase of about 12.9%). Evaluations of the heat of hydration and ionic concentration of the pore solution, X-ray diffraction analysis, thermogravimetry/differential scanning calorimetry analyses, and scanning electron microscopy observations were conducted to study the exothermic process and phase evolution of slurries mixed with different TR-PCEs. The results show that TR-PCE significantly altered the reaction rate of cement hydration, inhibited the reaction of hydration products, especially calcium silicate hydrate, and reduced the maximum heat flow in the hydration acceleration period by up to 89.50%. These findings advance the understanding of how multifunctional superplasticizers influence cement hydration and help control thermal cracking in concrete, providing fundamental insights for the use of admixtures in managing concrete thermal stress.