Evaluation of the effect of wet grinding on limestone and slag for enhancing the mechanical performance of ternary binders

초록

This study investigates the effect of wet-grinding on limestone and slag for improving compressive strength of ternary Portland limestone cement (PLC) binder. To evaluate the effect of wet-ground slag, two laboratory-prepared ternary PLC mixture systems consisting of cement clinker, gypsum, and either limestone or wet-ground limestone were investigated. The first group contained 15 wt% of limestone, while the second contained 15 wt% wet-ground limestone. The wet-ground slag accelerated silicate and aluminate reaction and significantly increased cumulative heat and compressive strength of the PLC binder added with limestone. The wet-ground slag enhanced the carboaluminate phases at early ages and formed more polymerized C-(A-)S-H, resulting in densified microstructure for its filler effect and increased reactivity. Although wet-ground slag decreased early strength of the ternary PLC binder added with wet-ground limestone, comparable strength could be achieved after 7 days which would offset the dilution effect. Likewise, wet-ground slag induced more hydrate growths (i.e., carboaluminate phases and C-(A-)S-H) and reduced porosity and average pore size. The improvement in mechanical performance and the generation of hydrates was attributed to the respective roles of wet-ground limestone and wet-ground slag during hydration, increasing effective water availability and accelerating hydration, respectively.

키워드