Creep behaviour of ultra-high-performance concrete (UHPC): A review

Although ultra-high-performance concrete (UHPC) has attracted great attention from researchers owing to its outstanding mechanical and durability performance, it has only a restricted range of applications compared to conventional concrete. UHPC possesses a high volume of cement, fibres and fine aggregates, hence, exhibits distinctive creep characteristics as opposed to conventional concrete. Therefore, the creep mechanisms and creep prediction models developed for conven-tional concrete cannot be directly utilised for UHPC. In order to promote the application of UHPC, numerous studies have been carried out to investigate its creep behaviour. Based on the available studies over the past few decades, this study gives a comprehensive review on the creep response of UHPC in order to highlight the current research achievements and research gaps. In this paper, present studies regarding the creep of UHPC in the literature are basically classified into two categories: studies on compressive creep and studies on tensile creep. The influencing factors, such as the fibre type, fibre content, curing condition, water-to-binder ratio (W/B), load-ing level, age at loading, etc., are reviewed and their effects on the creep behaviour are discussed. In addition, the theoretical models developed for predicting the compressive and tensile creeps of UHPC are summarised in this paper, of which the advantages and limitations are discussed. Lastly, several essential areas that require further research efforts are suggested based on the cur-rent research results.