Influence of formate-based accelerators on hydration process and mechanical properties of Portland cement dopped by zinc

abstract

English

The amount of zinc in Portland cement is increasing due to the greater use of alternative fuels and secondary raw materials. Zinc significantly slows down the hydration process of cement, which poses a serious problem for the construction industry; even 1% zinc can slow hydration by as much as ten times. One way to reduce this effect is by using accelerators. This study analyzes the impact of formates, commonly used as accelerators, on zinc-doped Portland cement. Isoperibolic calorimetry was used to monitor the hydration process, focusing mainly on the primary hydration peak in the hydration curve. Mechanical properties were measured, including compressive strength and flexural tensile strength. By using an appropriate accelerator, the hydration of zinc-doped cement can be reduced to a hydration time comparable to Portland cement without zinc. The mixture treated with a specific concentration of calcium formate showed a reduction in hydration time of the zinc-doped cement by half and exhibited a more gradual release of hydration heat, as well as lower total hydration heat compared to Portland cement without zinc. Additionally, the mechanical properties of some accelerated mixtures with zinc can reach at least a similar compressive strength as Portland cement without zinc. Although Portland cement with zinc is typically unusable due to hydration retardation and insufficient compressive strength, formate-based accelerators allow for the conversion of this waste material into a usable resource.

Keywords: Portland cement, zinc, isoperibolic calorimetry, calcium formate, compressive strength

9. 4. 2025

University of Split

Split, Croatia

https://zorh.ktf-split.hr/en/program-eng/