Response of concrete-filled polyethylene tubes under in-service thermal cycles in marine environments

Abstract

Concrete-filled polyethylene (PE) tubes (CFPT) are composite systems using the polyethylene tubes as confinement for the marine structures in the splash zone to extend the service life of structures subjected to harsh environments. However, thermal cycles in marine environments can affect the behavior of such composite systems. This paper evaluates the effect of concrete infill strength (30 MPa and 60 MPa), the number of thermal cycles (50, 100, and 150 cycles) ranging from 25 °C to 60 °C, and thermal cycle type (type A and B) on the compressive and bond response of CFPTs. Characteristics of control and conditioned concrete infill, PE tubes, and CFPTs were obtained by means of compression and disk-split tests. Furthermore, the push-out test was employed to obtain bond response of CFPTs. The results showed concrete infill strength increasing can lead to increment in the maximum compressive capacity of CFPTs, while exposing the specimens to thermal cycles reduced both the maximum compressive capacity and ductility. Regarding the bond test, it was concluded more thermal cycles led to increase in kinetic friction coefficient and bond strength. Finally, four linear models were introduced to predict load-bearing capacity, confined concrete strength, ductility factor, and bond strength after exposure.