Study on Flexural Properties of PA Fiber Shot-concrete for Tunneling
Shot-concrete is often used as the initial lining in tunnel construction.Therefore,it is required to have good toughness and crack resistance.Polyamide(PA)fibers can improve the compression bending and tensile bending properties of concrete,but the enhancement effect on the flexural strength and toughness of concrete is not yet clear.Based on experimental research,the influence of PA fiber content on the flexural strength and toughness of concrete was analyzed to determine the optimal dosage of PA fiber.Meanwhile,the basic mechanical properties differences between the samples prepared in the laboratory and on site were compared.The results showed that the optimal dosage of PA fiber was 0.7％;When the sample is in a high strain state,its toughness will decrease when the PA fiber content is 1.00％;Before reaching the design strength,the sensitivity of toughness to PA fiber content is lower.But when the specimen reaches the ultimate state,the sensitivity of toughness to PA fiber content will significantly increases.
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