Strain hardening behaviour of PE fibre reinforced calcium aluminate cement (CAC) – Ground granulated blast furnace (GGBFS) blended mortar

[Display omitted] •A novel strain hardening CAC-GGBFS mortar was developed for sewerage pipe repair.•CAC-GGBFS mixture shows no conversion issue and good potential for acid resistance.•CAC-GGBFS mixture exhibited superior tensile strain of 4.7% with 1% PE fibre.•XRD analysis revealed the sable crystalline phase in the CAC- bearing mixtures.•Acid-soluble products were observed in OPC-containing mortar mixture. Calcium aluminate cement (CAC) is regarded as an effective protective coating material for concrete sewerage pipes to prevent bacterial induced acid corrosion. However, the conversion process occurred in pure CAC mortar limited its application for structural purpose. Ground granulated blast furnace slag (GGBFS) blended with CAC can change the hydration mechanism and stop the conversion process. To better utilise CAC-GGBFS blended mortar for retrofitting concrete sewerage pipes, the inherent brittleness needs to be addressed. Introduction of polyethylene (PE) fibres into CAC-GGBFS blended mortar can help to form multiple tiny cracks under tensile loading for better crack control, give it high potential for the use in concrete structure retrofitting. In this paper, the authors took a first attempt on developing a new type of PE fibre reinforced CAC-GGBFS mortar with strain hardening behaviour. The new composite reached a compressive and flexural strength of 59.76 MPa and 22.12 MPa, respectively. The tensile strength was 5.46 MPa with the corresponding strain of 4.78%. Multiple cracks behaviour was observed under tensile and flexural loads. Classic pseudo strain hardening (PSH) criterion was validated on the new composite.