Abstract
In order to explore the creep characteristics of thermal insulation shotcrete under the action of temperature and humidity circulation, a series of uniaxial compression creep tests were carried out with different cycles of temperature and humidity and hierarchical loading conditions. The test results show that the axial creep deformation and creep strain of the thermal insulation shotcrete specimens increase with the increase of the number of drying and wetting cycles under normal temperature water bath condition. After 28 cycles, the deformation value becomes larger obviously, and the creep strain increases greatly in the precycle period. The thermal insulation shotcrete axial steady‐state creep rate increases nonlinearly with the increase of the number of drying and wetting cycles under different stress levels. When the number of adjacent cycles is 0–3, the average increase is larger, and the axial steady‐state creep rate of thermal insulation shotcrete for 28 cycles increases with the increase of water bath temperature. The instantaneous deformation modulus of thermal insulation shotcrete decreases logarithmically with the increase of the number of drying and wetting cycles, and the total deterioration degree of the average instantaneous deformation modulus increases gradually, but the deterioration degree between adjacent cycles decreases successively. The thermal insulation shotcrete specimens with 3 cycles of fracture were mainly stretched, and with the increase of the water bath temperature, the specimen was damaged by shear failure. When the water bath temperature is 40°C, the fracture degree of the specimen increases first and then decreases with the increase of the number of cycles.
Highlights
Nowadays, some practical projects often face high-temperature damage problems [1, 2], such as the environment in which certain roadways are located in the process of coal mining
Creep Curve Analysis of Samples with Different Dry-Wet Cycles. e results show that the axial strain of thermal insulation shotcrete specimen increases with the increase of loading stages. e instantaneous deformation occurs at the moment of stress loading, and creep occurs when the stress is constant. e slope of early creep curve gradually decreases with time, showing deceleration creep, and the slope of curve basically tends to be a constant value, showing steady-state creep
It can be seen from the figure that the axial creep strain changing rule of thermal insulation shotcrete is basically the same under different stress levels, and the axial creep strain increases with the increasing times of the drying and wetting cycles. e results show that the axial creep strain is larger under the first-order stress and high stress level. e reason is that the compactness of the concrete itself is poor for manufacture factors; the inside of the concrete itself exist cracks. e crack shrinks
Summary
Received 25 April 2021; Revised 29 July 2021; Accepted 13 August 2021; Published 19 August 2021. E test results show that the axial creep deformation and creep strain of the thermal insulation shotcrete specimens increase with the increase of the number of drying and wetting cycles under normal temperature water bath condition. E thermal insulation shotcrete axial steady-state creep rate increases nonlinearly with the increase of the number of drying and wetting cycles under different stress levels. When the number of adjacent cycles is 0–3, the average increase is larger, and the axial steady-state creep rate of thermal insulation shotcrete for 28 cycles increases with the increase of water bath temperature. E instantaneous deformation modulus of thermal insulation shotcrete decreases logarithmically with the increase of the number of drying and wetting cycles, and the total deterioration degree of the average instantaneous deformation modulus increases gradually, but the deterioration degree between adjacent cycles decreases successively. When the water bath temperature is 40°C, the fracture degree of the specimen increases first and decreases with the increase of the number of cycles
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