Lacante Maïté, Delsaute Brice, Staquet Stéphanie
BATir Department (LGC), Université libre de Bruxelles (ULB), 1050 Brussels, Belgium.
CRIC-OCCN, 1050 Brussels, Belgium.
Materials (Basel). 2025 Jun 5;18(11):2644. doi: 10.3390/ma18112644.
This research investigates whether metakaolin can be used as a partial substitution for slag to mitigate significant volume changes in alkali-activated slags. Its effect on compressive strength and workability (as well as on isothermal calorimetry, autogenous strain, and coefficient of thermal expansion (CTE)) were found to depend on both the type and concentration of the alkaline activator. When using 8 M and 10 M sodium hydroxide (NaOH), increasing the substitution rate increased the compressive strength. With sodium silicate (NaSiO), compressive strength decreased as the substitution increased. Isothermal calorimetry revealed metakaolin's dilution effect at 10% substitution. With 8 M NaOH, a third reaction peak appeared, whose magnitude increased with the substitution rate, while the second peak decreased. The swelling was increased at 10% substitution, followed by constant shrinkage in case of NaOH-activation. Shrinkage was mitigated with NaSiO-activation. Higher substitutions with 8 M NaOH resulted in a significant increase in the shrinkage rate and CTE, occurring when the third reaction peak appeared. A 10% substitution delayed the CTE increase but resulted in higher later-age values (dilution effect). The 20% substitution led to a similar final CTE value at 300 h, while 30% substitution resulted in a decrease in CTE after the initial increase.
本研究调查偏高岭土是否可用作矿渣的部分替代物，以减轻碱激发矿渣中显著的体积变化。发现其对抗压强度和工作性（以及对等温量热法、自生应变和热膨胀系数（CTE））的影响取决于碱性激发剂的类型和浓度。使用8M和10M氢氧化钠（NaOH）时，提高替代率会增加抗压强度。使用硅酸钠（NaSiO）时，随着替代量增加抗压强度降低。等温量热法显示在10%替代率下偏高岭土的稀释效应。使用8M NaOH时，出现了第三个反应峰，其幅度随替代率增加而增大，而第二个峰减小。在10%替代率下膨胀增加，随后在NaOH激发的情况下持续收缩。用NaSiO激发可减轻收缩。用8M NaOH进行更高比例的替代会导致收缩率和CTE显著增加，这发生在第三个反应峰出现时。10%的替代率延迟了CTE的增加，但导致后期值更高（稀释效应）。20%的替代率在300小时时导致最终CTE值相似，而30%的替代率导致初始增加后CTE降低。
