College of Engineering, Abu Dhabi University, PO Box 59911, Abu Dhabi, UAE.
Sci Rep. 2022 Apr 4;12(1):5634. doi: 10.1038/s41598-022-09682-z.
The effect of submerging geopolymer mortar samples in highly acidic solution for 7-, 28-, and 90-days on stability of mass and the development of compressive strength development was assessed experimentally. The mortar binder consisted of GGBS or blends of GGBS and fly ash activated using combinations of NaOH and NaSiO solutions, and samples were cured in room temperature. It was found that maintaining mortar samples continuously under sulfuric acid doesn't cause reduction compressive strength or mass from one age to the other, up to 90 days. While decalcification, delaumination, and formation of calcium salts due to sulfate attack may have affected mass and strength, submerging samples under water supported formation of geopolymerization products C-A-S-H and N-A-S-H, and consequently increased the mass and compressive strength of cubic mortar samples with fly ash + GGBS blended binder. The resistance of mortar to sulfuric acid remained consistent when mortars were prepared using GGBS:fly ash ratio of 3:1, equal amounts of GGBS and fly ash, and GGBS as sole binder. When geopolymer mortar samples made with each of the three binders was left exposed to air after casting, compressive strength increased from 7- to 28-days after casting, but at 90-days, all mortar samples experienced decrease in compressive strength relative to the 28-day values. The relatively high content of GGBS (≥ 50%) and absence of curing water in relatively dry conditions caused shrinkage cracking and decrease in compressive strength.
将地质聚合物砂浆样品在强酸溶液中浸泡 7、28 和 90 天，评估其质量稳定性和抗压强度发展的影响。砂浆结合剂由 GGBS 或 GGBS 和粉煤灰的混合物组成，使用 NaOH 和 NaSiO 溶液的组合进行激活，样品在室温下养护。结果发现，将砂浆样品连续浸泡在硫酸中，在 90 天内不会导致抗压强度或质量从一个龄期到另一个龄期降低。虽然脱钙、层状剥落和硫酸盐侵蚀形成钙盐可能会影响质量和强度，但将样品浸泡在水中会支持地质聚合产物 C-A-S-H 和 N-A-S-H 的形成，从而增加了粉煤灰+GGBS 混合结合剂立方砂浆样品的质量和抗压强度。当使用 GGBS:粉煤灰比例为 3:1、等量的 GGBS 和粉煤灰以及 GGBS 作为单一结合剂制备砂浆时，砂浆对硫酸的抵抗力保持一致。当三种结合剂中的每一种制备的地质聚合物砂浆样品在铸造后暴露在空气中时，抗压强度从铸造后 7 天到 28 天增加，但在 90 天时，所有砂浆样品的抗压强度相对于 28 天的值都有所下降。相对较高的 GGBS（≥50%）含量和相对干燥条件下缺乏养护水导致收缩开裂和抗压强度降低。
