Effects of the Utilization of Alternative Accelerator Admixtures in the hydration of Portland Cement with Phosphogypsum
DOI:
https://doi.org/10.46421/enarc.v8i00.2939Keywords:
Phosphogypsum, Alternative accelerators, Hydration, Compressive strength, CalorimetryAbstract
Phosphogypsum, a by-product of phosphoric acid, is an alternative source of calcium sulfate to natural gypsum in cements. However, due to the presence of fluorides (F-) and phosphates (P2O5) in phosphogypsum, there is an extension of the setting times and a reduction in the initial mechanical strength in Portland cement. To mitigate this damaging effect, one option is the use of hydration and strength accelerators. Thus, this study aims to evaluate the effect of using alternative accelerators in the hydration of cements with phosphogypsum. These are: sodium chloride (NaCl), calcium chloride (CaCl2), sodium hydroxide (NaOH), sodium silicate (Na2SiO3). Isothermal calorimetry and compressive strength tests at 24h were performed on the fresh and hardened cement pastes. NaOH showed the highest strengths while Na2SiO3 exhibited lower values than the reference sample (REF). CaCl2 showed hydration compatible with REF while NaCl revealed higher strengths and cumulative heat.
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