爆破振动对新浇筑混凝土强度的影响

为了分析爆破振动对新浇混凝土的影响,分别在混凝土模型浇筑后3、5、7、9、11 h进行爆破振动,通过声速仪对爆破前后混凝土的声速变化进行测量记录,同时在混凝土表面不同位置安装振动传感器用于测量振动幅值。结果表明:在爆源参数保持不变情况下,同一测点上的振动峰值随着凝固时间增加逐渐变大,说明混凝土在强度增长初期对爆破振动响应比较弱,随着水化反应进行,混凝土强度逐渐增长,其对爆破振动响应逐渐增强。另外,对于新浇筑混凝土,其内部有大量未水化水泥,即使在爆破振动作用下造成轻微的损伤,也能够完全愈合,而不影响后期强度,甚至强度因振捣作用有所提高,但也容易出现骨料下沉,导致底部强度高于上部。上述结果可为新浇混凝土在爆破振动下的安全标准提供参考。

Influence of blasting vibration on the strength of fresh concrete

In order to analyze the influence of blasting vibration on fresh concrete, the blasting disturbances were performed after the concrete models were produced 3, 5, 7, 9, 11 h respectively. The sound velocity of concrete was measured and recorded by a sound velocity meter before and after blasting, and the vibration amplitude was measured by the vibration sensors at different positions of the concrete surface. The results show that the vibration peak value grows with the increase of solidification time under the same vibration source parameters. At the initial stage of strength growth, the response of concrete to blasting vibration is relatively weak. With the hydration reaction, the strength and vibration response of concrete increases gradually. For fresh concrete, there is a large amount of unhydrated cement inside. Therefore even if blasting vibration causes slight damage, it can be completely healed without affecting the later strength. On the other hand, the blasting vibration may even cause coarse aggregate submerged, which will lead to the strength of concrete at the bottom exceeds that at the top. The results could provide reference for improving safety standards of concrete under blasting vibration.