多次振动荷载作用下新浇混凝土超声波波速变化规律试验研究

摘要

为研究多次振动对新浇混凝土性能的影响,设计新浇混凝土振动模拟试验,利用振动台对新浇混凝土施加多次振动荷载,测试其超声波波速,利用试验结果分析试块超声波波速的变化过程与规律.试验结果表明:新浇混凝土基准试块超声波波速经历了快速增长、缓慢增长和基本稳定3个阶段,振动试块经历了快速增长、缓慢增长、迅速降低和基本稳定4个阶段;振动试块在龄期48 h内超声波波速增长速率比基准试块大且其波速先达到峰值;在龄期3～7d内随着振动次数增加,振动试块超声波波速快速下降且该现象具有一定的累积效应,而基准试块超声波波速持续增长;龄期7d后,振动试块超声波波速逐渐趋于稳定,最终稳定值低于基准试块稳定值.%In order to study the influence of multiple vibrations on performance of new concrete,a new concrete vibration simulation test was designed.The vibration load was applied to the fresh concrete by shaking table.The ultrasonic wave velocity was measured during the test.The test piece was used to analyze changes of ultrasonic and regularity of wave velocity.The experimental results show that ultrasonic wave velocity of the new pouring concrete has experienced three stages:rapid growth,slow growth and basic stability.The vibration test block has experienced four stages:rapid growth,slow growth,rapid decrease and basic stability.The velocity of ultrasonic wave within 48 hours is larger than that of the reference test block and the wave velocity reaches the peak.During the period of 3 ～ 7days,the ultrasonic wave velocity of the vibration test piece begins to decrease with the increase of the number of vibrations.However,the ultrasonic wave velocity of the reference test block increases continuously.After 7 days of age,the ultrasonic wave velocity of the vibration test block is gradually stabilized and the final value is lower than that of the reference test block.