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Creep, sulfate erosion resistance, fly ash content of concrete, and sustained compression load are important factors that will affect the long-term performance of concrete. It is of great interest to combine these effects together to make a comprehensive investigation of fly ash concrete. However, the concrete creep under both sustained compression load and sulfate attack conditions has rarely been reported. To obtain the creep characteristics of fly ash concrete in a sulfate environment, this paper first finishes the creep experiments of fly ash concrete under sustained compression load and sulfate attack. The test factors include the load stress level, the concentration of sulfate solution, and the content of fly ash. Based on the creep mechanism of fly ash concrete under sulfate erosion, the relationship between time-dependent section area variation and creep was carried out. After comparing different creep models, the creep calculation model of fly ash concrete under sulfate erosion was built via the B4 model combined with the cross-sectional area of the damaged layer and undamaged layer of concrete. Finally, comparing the calculated values with the test results, the calculated results were in good agreement with the test data, which is of practical significance to the practical engineering application and the improvement of structural reliability. [ABSTRACT FROM AUTHOR]

In order to clarify the deformation effect of fly ash concrete members after loading and unloading subsequently, experiments on creep and creep recovery of fly ash concrete were carried out on consideration of three fly ash contents and two concrete loading ages. After comparing the available prediction models for concrete creep, the B4 model was modified by multiplying the influence coefficient and creep terms, and the fly ash concrete creep prediction model was established correspondingly. The comparison shows that the modified B4 model is in good agreement with the experimental data. Furthermore, based on the experimental phenomena and the development law of creep recovery of fly ash concrete, the prediction model for creep recovery of fly ash concrete was proposed in combination with the factors affecting creep recovery which include loading age, fly ash content, etc. Finally, the calculated values of the proposed creep recovery model were compared with the experimental results and the applicability of the model was discussed. The creep and creep recovery model of fly ash concrete proposed is of great significance for revealing the time-varying law of fly ash concrete and improving the performance of concrete structures. • Creep and creep recovery of fly ash concrete. • Establishing a modified B4 model for fly ash concrete creep. • Proposing a creep recovery model for fly ash concrete considering load holding time, loading age and fly ash content. [ABSTRACT FROM AUTHOR]