ABSTRACT

Variations in the design requirements of prestressed concrete girders lead to variations in their geometry and section profile, thereby influencing the characteristics of the waves which form the working principles of the various NDT techniques, and thus possibly shield the presence of air void. Thus, an experimental plan was adopted to study the effect of the changes in parameters like the cover to the duct, the material of the duct, the number of strands, and diameter of the duct on the efficiency of Ultrasonic Pulse Velocity (UPV), Ground Penetrating Radar (GPR) and Infrared Thermography (IRT) (active and passive) to detect a simulated void in a grouted duct. Seven 150 × 150 x 750 mm specimens were prepared with duct embedded in concrete. Both steel (inner diameter 106.6 mm) and plastic (inner diameter 105 mm and 86 mm) ducts were used. Three specimens had 3 strands, three specimens had 5 strands, and one specimen had 8 strands. It was found that the efficiency of GPR increased with the increase in the number of strands and duct diameter. Active IRT is highly efficient for the detection of voids than Passive Thermography. The presence of steel strands influenced UPV results.

摘要

预应力混凝土梁设计要求的变化会导致其几何形状和截面轮廓的变化，从而影响构成各种无损检测技术工作原理的波浪特性，从而可能屏蔽空气空隙的存在。因此，采用实验方案研究了管道覆盖物、管道材料、股数和管道直径等参数变化对超声波脉冲速度（UPV）效率的影响，探地雷达 (GPR) 和红外热成像 (IRT)（主动和被动）检测灌浆管道中的模拟空隙。7 个 150 × 150 × 750 毫米的试样是用嵌入混凝土的管道制备的。使用了钢（内径 106.6 毫米）和塑料（内径 105 毫米和 86 毫米）管道。三个试样有3根，三个试样有5根，一个试样有8根。发现探地雷达的效率随着股数和管道直径的增加而增加。与被动热成像相比，主动 IRT 检测空隙的效率更高。钢绞线的存在影响了 UPV 结果。