逐层回弹法评定火灾后混凝土抗压强度的试验研究

Experimental Study on the Assessment of Compressive Strength of Fire-damaged Concrete by Layer-by-layer Rebound Method

目的研究火灾后混凝土抗压强度与混凝土不同深度处的平均回弹值之间的关系,建立逐层回弹法评定火灾后混凝土抗压强度的专用测强曲线和计算公式.方法通过采用逐层回弹法对不同火灾温度条件下的混凝土试块进行逐层切割回弹试验,得到火灾后混凝土不同深度处的回弹数据,利用分层回弹数据的变化趋势和混凝土的实测强度来拟合火灾后混凝土的专用测强曲线和计算公式.结果表明按逐层回弹法建立的火灾后混凝土测强曲线和计算公式具有良好的精度,同时该方法考虑了不同深度处的回弹值与混凝土强度之间的相关关系,使得本文提出的测强曲线更接近实际.结论逐层回弹法可以应用于火灾后混凝土的强度评定,该法满足工程精度的要求,可以为火灾后混凝土结构的检测鉴定提供新的依据.

To assess the residual strength and deteriorated depth of flre-damaged concrete, layer-by-layer rebound method is developed in this paper. A number of concrete specimens were tested at different elevated temperatures. The test of rebound hammer was carried out layer-by-layer on the heated specimens, and the test data of different depth were obtained, Based on the data of rebound numbers and the measured values of compressive strength of concrete, the relationship between the compressive strength and the rebound numbers in diverse depths of concrete subject to fire which has been established by layer-by-layer rebound method. What＇s more, the special strength curves and empirical equations are fitted. Since the method can consider the correlation of concrete strength and values of rebound hammer in different depth of concrete, it can not only predict the residual strength of fire-damaged concrete, but also provide data for estimating the deteriorated depth, which makes the assessment more applicable to the practical situation. In a word, the layer-by-layer rebound method is a brand new way to predict the residual strength of fire-damaged concrete. It is applicable to the damage assessment of concrete subject to fire and the corresponding accuracy is enough for the requirement of engineering.