The effectiveness of different superplasticizers in ambient cured one-part alkali activated pastes

This paper investigates the effect of using different admixtures on the one-part ambient-cured alkali activated pastes. Na2SiO3-Anhydrous powder was used as solid activator along with three superplasticizers including naphthalene, melamine and polycarboxylate with different water/precursor ratios. The flowability, setting time and compressive strength development were evaluated for all AAMs mixes. ATR-FTIR test was used to check the admixtures stability in high alkali media. All types of admixtures significantly improved the flowability of the Na2SiO3-anhydrous one-part AAMs and marginally affected the compressive strength. The results showed that polycarboxylate was effective for high water/precursor (>= 0.36) while naphthalene performed better in case of low water/precursor (<= 0.36) for Na2SiO3-anhydrous one-part AAMs. However, lowering the water/precursor ratio in the Na2SiO3-anhydrous one-part AAMs using superplasticizers showed no improvement or modest improvement in the compressive strength. The ATR-FTIR results revealed the relatively high stability of admixtures in Na2SiO3 alkali medium of one-part AAMs (for w/b = 0.4).