Effects of freeze-thaw damage on fracture properties and microstructure of hybrid fibers reinforced cementitious composites containing calcium carbonate whisker

• Published in: Construction & building materials Vol. 300; p. 123872
• Main Authors: Xie, Chaopeng, Cao, Mingli, Yin, Hong, Guan, Junfeng, Wang, Lijiu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20.09.2021
• Subjects: Calcium carbonate whisker (CW); Fracture energy; Fracture toughness; Freeze-thaw (F-T) cycle; Hybrid fibers; Microstructure; Calcium carbonate whisker (CW); Microstructure; Freeze-thaw (F-T) cycle; Fracture energy; Hybrid fibers; Fracture toughness
• ISSN: 0950-0618
• DOI: 10.1016/j.conbuildmat.2021.123872

•CW addition alleviated the deterioration of fracture properties for SPFRCC.•Microstructural analysis revealed the microaggregate filling and microfiber cracking inhibition effects of CW.•CW was conducive to delay the damage at the initial F-T damage development stage.•CW3-SPFRCC had the most extended service life under F-T cycle conditions. The effects of freeze–thaw (F-T) damage on fracture properties and microstructure of steel-PVA hybrid fibers reinforced cementitious composites containing calcium carbonate whisker (CW-SPFRCC) were investigated in this paper. Three-point bending tests were carried out to study the fracture properties of CW-SPFRCC after different F-T cycles based on Double K fracture criterion. Compared with SPFRCC, the relative fracture parameters in CW-SPFRCC dropped less within 0 to 50F-T cycles, while rapid deterioration was observed in 50 to 100F-T cycles, indicating that the presence of CW could effectively delay F-T damage in SPFRCC. Moreover, fracture parameters were estimated to quickly predict the fracture behavior of CW-SPFRCC subject to F-T cycles. The microstructures of CW-SPFRCC was analyzed using scanning electron microscope (SEM), vacuum epoxy impregnation (VEI), mercury intrusion porosimetry (MIP) and optical microscope observation (OM), respectively. SEM results showed that PVA fiber and CW maintained intact morphologies subject to F-T cycles, but the surface of steel fibers was severely corroded by F-T actions. The results of VEI and MIP demonstrated that better frost resistance of SPFRCC was related to the improved pore structure because of the presence of CW. Furthermore, F-T damage was more likely to occur on the interfacial transition zone (ITZ) of steel fibers or aggregates. Finally, a parabolic model of F-T damage was developed to predict the service life on-site of CW-SPFRCC.