Experimental investigation of triaxial strength of ultra-high performance concrete after exposure to elevated temperature. (9th August 2021)

• Record Type: Journal Article
• Authors: Xu, Zhenhuan; Li, Jun; Wu, Pengtao; Wu, Chengqing
• Is Part Of: Construction & building materials. Volume 295(2021)
• Publication Date: 2021-08-09
• Subjects: Ultra-high performance concrete -- Triaxial compression test -- Elevated temperature -- Stress–strain relationship -- Failure criteria; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.123689
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Hybrid steel and polypropylene (PP) fibre reinforced UHPC showed reduced thermal spalling. Ratio of cylinder strength to cube strength is independent of temperature. UHPC strength increases after exposure to up to 400 °C. Stress–strain relationship of UHPC under triaxial compression after thermal effects are established. Abstract: Equipped with excellent strength and energy absorption capacity, ultra-high performance concrete (UHPC) is a promising material to improve structural resistance against extreme loads. Material and structural tests at ambient temperature have been conducted extensively on UHPC specimens in recent years, and its mechanical properties have been well-documented. In this study, a hybrid steel and polypropylene (PP) fibre reinforced UHPC is investigated under uniaxial and triaxial compression states after exposure to elevated temperatures. Cubic (50 mm) and cylindrical specimens (50 mm diameter × 100 mm height) were first heated in electric furnace to target temperatures, i.e. 200 °C, 400 °C, 600 °C, 800 °C and 1000 °C. After naturally cooled down to ambient temperature, the specimens were tested under uniaxial compression and triaxial compression with confining pressure ranging from 5 to 40 MPa. The triaxial stress–strain relationships and failure modes after exposure to elevated temperatures were then compared and discussed. Several common failure criteria for concrete material were adopted to describe the high temperature effect on UHPC's strength. An empirical model for reproducing the triaxial compression stress–strain curves of UHPC after elevated temperature was proposed.