Yankwa Djobo Jean Noël, Nkwaju Rachel Yanou
Local Materials Promotion Authority (MIPROMALO), MINRESI Nkolbikok Yaoundé 2396 Cameroon
Building Materials and Construction Chemistry, Technische Universität Berlin Gustav-Meyer-Allee 25 Berlin 13355 Germany
RSC Adv. 2021 Sep 30;11(51):32258-32268. doi: 10.1039/d1ra05433c. eCollection 2021 Sep 27.
This work assessed the potential of synthetic acid aluminum phosphate solutions for the enhancement of the characteristics of metakaolin phosphate geopolymer binders obtained at room temperature. The main parameters dealt with are the concentration of the initial phosphoric acid solution (40 wt%, 50 wt%, and 60 wt%) and the molar ratio Al/P (1/3 and 1.4/3) of the synthesized acid aluminum phosphate solutions. The prepared solutions have different contents and types of mono aluminum phosphate compounds (MAP) and their reactivity is pH-dependent. This is because of the continuous neutralization of the protons due to the dissolution of aluminum hydroxide, which raises the pH and decreases the conductivity. Thus the acid aluminum phosphate solutions with molar ratio Al/P of 1/3 are the most reactive. They have significantly enhanced the compressive strength of the resulting phosphate geopolymer binders. But, when compared to phosphate geopolymer obtained with pure phosphoric acid of the same concentration, the highest rate of compressive strength improvement is recorded for acid aluminum phosphate solutions having an initial concentration of phosphoric acid of 40 wt%. Thus, the modification of the composition of the phosphoric acid with the addition of the appropriate amount of aluminum is beneficial for enhancing the characteristics of phosphate geopolymer binder at any age.
本研究评估了合成酸性磷酸铝溶液对室温下制备的偏高岭土磷酸地质聚合物粘结剂性能的增强潜力。主要研究参数包括初始磷酸溶液的浓度（40 wt%、50 wt%和60 wt%）以及合成酸性磷酸铝溶液的铝/磷摩尔比（1/3和1.4/3）。所制备的溶液含有不同含量和类型的磷酸一铝化合物（MAP），其反应活性取决于pH值。这是由于氢氧化铝溶解导致质子不断中和，从而使pH值升高，电导率降低。因此，铝/磷摩尔比为1/3的酸性磷酸铝溶液反应活性最高。它们显著提高了所得磷酸盐地质聚合物粘结剂的抗压强度。但是，与用相同浓度纯磷酸制备的磷酸盐地质聚合物相比，初始磷酸浓度为40 wt%的酸性磷酸铝溶液的抗压强度提高率最高。因此，添加适量铝对磷酸组成进行改性有利于提高磷酸盐地质聚合物粘结剂在任何龄期的性能。
