Effect of a novel hybrid TiO2-graphene composite on enhancing mechanical and durability characteristics of alkali-activated slag mortar. (15th March 2021)

• Record Type: Journal Article
• Authors: Zhang, Su-Lei; Qi, Xiao-Qiang; Guo, Si-Yao; Ren, Jie; Chen, Ji-Zhou; Chi, Bo; Wang, Xu-Chun
• Is Part Of: Construction & building materials. Volume 275(2021)
• Publication Date: 2021-03-15
• Subjects: TiO2-graphene composite -- Alkali-activated slag -- Durability performance -- Mechanical properties -- Chloride diffusion; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2020.122154
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Irrespective of different dosages, TiO2 -graphene composite improved the mechanical and durability properties of AAS mortars. The optimal dosage of TiO2 -graphene was 0.03% compared to a lower (0.01%) or higher one (0.05%). TiO2 -graphene is able to facilitate the hydration process of AAS and refine its porous microstructure. Abstract: A highly dispersed hybrid TiO2 -graphene composite was synthesized in-situ and for the first time utilized in alkali-activated slag (AAS) mortars. The effects of the TiO2 -graphene composite in different dosages of 0.0, 0.1%, 0.3% and 0.5% on the mechanical and durability properties of AAS mortars were investigated. The results showed that an optimal dosage of the TiO2 -graphene composite exists which was 0.03 wt% in this study, leading to about 26.6%, 11.3% and 13.6% increase in compressive strength, flexural strength and flexural-to-compressive strength ratio, respectively. In addition, the capillary sorptivity, chloride penetration depth and diffusion coefficients were significantly reduced via TiO2 -graphene additions. Similarly, 0.03 wt% dosage led to the best performance by decreasing these values by upto 32.0%, 66.5%, 68.7% respectively. All these experimental results were due to a densified microstructure of AAS incorporated TiO2 -graphene composite, verified by lower porosity, especially at meso-capillary pore levels and also probably due to wrinkled surface of TiO2 -graphene nanosheets. It was also noticed that an overdosage of the TiO2 -graphene composite would compromise these beneficial effects due in large part to agglomerations. The well-dispersed hybrid TiO2 -graphene composite assisted by the in-situ intercalating method improves the AAS binder in terms of mechanical and durability performances, thus making it more promising in partial replacement of ordinary Portland cement counterparts.