Fractional-order model of the compressive strength of hydraulic concrete in a real temperature and humidity environment
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Fractional-order model of the compressive strength of hydraulic concrete in a real temperature and humidity environment Yaoying Huang1
· Yong Zhou1 · Yu Liu1 · Lei Xiao1
Received: 11 February 2019 / Accepted: 21 June 2019 © Springer Nature B.V. 2019
Abstract Concrete is a kind of composite material that is in a plastic flow state in its initial stage, gradually hardening with the cement hydration reaction and then finally reaching a relatively stable condition. In addition, the compressive strength of concrete is related to not only the curing age but also the curing temperature and humidity. The Kelvin model with a software element is used to describe the growth rule of the compressive strength of concrete. The equivalent age theory is used to consider the coupling effect of the temperature and humidity, and then a fractional-order model of the compressive strength of hydraulic concrete considering this coupling effect is proposed. Next, tests of the compressive strength of concrete under three different curing conditions for different concrete ages are performed, and a fractional-order model of the compressive strength is implemented using the test data. The analysis results show that the fitting effect of the fractional-order model can reach a high level of accuracy with only a few model parameters, and with a better fit than the combinatorial exponential model or combinatorial modified logarithmic model. Keywords Coupling effect of temperature and humidity · Compressive strength of concrete · Fractional-order model
1 Introduction Concrete is a brittle material with a low tensile strength but a high compressive strength. Fully understanding the mechanical properties of concrete materials is necessary for preventing and controlling concrete cracks in dams. The compressive strength is one of the basic mechanical properties of concrete and develops via the cement hydration reaction. This property is a macroscopic reflection of the microstructure of the concrete. The test code for hydraulic concrete in China stipulates that a cubic concrete specimen (150 mm × 150 mm × 150 mm) is held in a standard curing room with the temperature controlled at
B Y. Huang
[email protected]
1
College of Hydraulic & Environmental Engineering, China Three Gorges University, Yichang 443002, China
Mech Time-Depend Mater
20.0 ± 5.0 ◦ C and the humidity controlled at over 95%. The American Society of Testing and Materials (ASTM) Concrete Testing Regulations stipulate that a compressive strength cylindrical specimen of concrete (Φ150 mm × 300 mm) should be cured at 23.0 ± 2.0 ◦ C (ASTM C 192) with a humidity greater than 50% (ASTM C 511). At present, mechanical performance models of the compressive strength of concrete are generally obtained based on the results of standard curing tests without considering the influence of the curing temperature and humidity conditions. However, the ambient temperature and humidity of a hydraulic concrete structure change dynamically during actual engineering. Understanding the influence of di
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