Unravelling the impact of ZIF-8, ZIF-67, and ZIF 8-67 on cement composites: insights into microstructure, mechanical strength and rheology

Abstract

Zeolitic imidazolate frameworks (ZIFs) are a novel material, a sub-group of metal-organic frameworks (MOFs) with a sodalite-type structure similar to zeolites and are formed by the bridging of imidazole with metallic nodes or clusters which find applications such gas storage, energy storage, drug delivery, catalysis, and membrane technology. ZIF-8 denotes a MOF containing zinc metal ions; ZIF-67 comprises of cobalt metal linkers; and ZIF-8-67 signifies a MOF containing both zinc and cobalt linkers. In the present study, aforementioned nanomaterials are lab-synthesized and added to cement in concentration of 0.4%, 0.5%, 0.6%, and 0.7% by weight of cement and characterized using XRD, FTIR, and SEM analysis. Various fresh and hardened tests were conducted to evaluate rheology, flexural, and compressive strength. The flexural strength test resulted in an increase of up to 21.72% in ZIF-8-67 cement specimens. ZIFs tend to offer extra nucleation sites for the production of hydration products and result in strength increment and densification of microstructure. The optimum concentration among the selected trials was 0.5% for ZIF-8, 0.6% for ZIF-67, and 0.5% for ZIF-8-67 in cement based on the strength increment criteria. The flow test results indicated the hydrophobicity of the added nanomaterials, thereby increasing the workability.