Strain model for traditional and self-compacting concrete during fire

摘要

In this paper, a complete strain model is derived that describes the strains developed during fire (up to 400 ℃) and is based on the model of Anderberg et al, published in 1976. This model describes the total measured deformation as a superposition of four strain types: free thermal strain, instantaneous stress-related strain, creep strain and transient strain. The strains are derived from loading tests on cylinders with dimensions Φ106 × 320 mm, submitted to load ratios of 0%, 20% and 30% of the initial strength before heating. For damage to the oven to be avoided, the instantaneous stress-related strain is found from Young's modulus tests immediately after cooling. All tests occurred at a heating rate of 5 ℃/min, and the specimens were pre-dried to avoid explosive spalling. The investigated concretes are a traditional and a self-compacting concrete with a testing age of about 30 months. Only small differences between both concrete types are found for the transient strain despite the different fracture of cement matrix. For the studied test conditions, the modern siliceous concretes such as self-compacting concrete yielded similar results as the traditional siliceous concretes tested in the 1970s.