土木工程与力学学院知识库

~混凝土作为工程建设使用量最大的建筑材料，其质量直接影响到工程的质量。为了保证混凝土的质量和对已有混凝土结构的评估鉴定，需要对混凝土进行检测。回弹法作为混凝土质量无损检测方法中的一种，因其操作简单，测量精度高等优点被广泛采用。按回弹能量可将回弹仪分为轻型、中型、重型回弹仪。其中编入国家规范的有2.207J、4.5J与5.5J能级回弹仪。2.207J能级回弹仪适应于60MPa以下强度的混凝土，对高强度混凝土也能够有效的测量。规范指出，可用标称动能为4.5J或5.5J的回弹仪检测C50～C100的混凝土抗压强度。本文应用多种方法对2.207J、4.5J与5.5J三种回弹仪的检测效果进行分析，并比较4.5J与5.5J能级回弹仪对C50～C100等级混凝土检测精度，这将对进一步了解和使用回弹仪具有重要的现实意义。
本文采用2.207J、4.5J与5.5J三种不同回弹能量的回弹仪对强度范围为31.5MPa～87.4MPa的311个混凝土试块进行检测，通过对约1000个检测数据的回归分析，建立了幂函数方程，曲线的误差满足规范要求。对高强混凝土，通过反回归分析与一倍剩余标准差分析回弹值的变化，5.5J能级回弹仪与4.5J能级回弹仪相比，使用重复性更好，测量精度更高。

~Concrete, the most used building material in engineering construction, has a direct impact on the quality of the project. To ensure the quality of the project or to evaluate and evaluate existing concrete structural components, the concrete must be inspected.As one of the non-destructive testing methods for concrete quality, rebound method is widely used because of its simple operation and high accuracy. According to the impact energy, the rebound instrument can be divided into light, medium and heavy resilience instruments. Among them, 2.207J, 4.5J and 5.5J level resilience instruments are included in the national standard. The 2.207J level rebound instrument is suitable for the concrete with less strength below 60MPa, and it can also effectively measure the high strength rebound instrument. It is pointed out that the concrete compressive strength of C50 to C100 can be measured by a rebound tester with a nominal kinetic energy of 4.5J or 5.5J. In this paper, using a variety of methods for 2.207J, 4.5J and 5.5J three rebound hammer detection effect is analyzed, and compare the 4.5J and 5.5J level rebound hammer of C50～C100 concrete precision grade, it will has important practical significance to further understand and use hammer.
In this paper, 311 concrete test blocks with 31.5 MPa ~ 87.4 MPa were tested using 2.207 J, 4.5 J, and 5.5 J impact energy reflectors. The power function equation was established by regression analysis of about 1,000 test data. The calculated error satisfies the specification requirements. In the high strength concrete detection, the change of the rebound value is analyzed by the inverse regression and the double remaining standard deviation. Compared with the 4.5 J energy level rebound instrument, the 5.5 J energy level rebound instrument uses better repeatability and higher measurement accuracy.