回弹读数趋于稳定状态时的压强临界值

选取C20,C30,C40,C50共4种强度等级、尺寸均为100mm×100mm×300mm的混凝土试件,在5,10,15,20,25,30,40kN共7个压力等级下测量其回弹值,并通过比较回弹值与压力之间的关系,得出混凝土试件回弹值趋于稳定时的压强临界值约为0.25kN/cm2.将试验结果与原混凝土无损检测规程比对后发现,原无损检测规程在制定测强公式时规定的试件承受压力并不能确保回弹值的正确读取.所得结果可为混凝土无损检测规程的再版修订提供新的依据.

Critical Value of Pressure in Stable Rebound Readings

The concrete rebound values were calibrated at 7 different load degrees, i.e. 5,10,15,20,25,30 and 40kN. The concrete strength grade was C20,C30,C40,C50,and specimen size was 100mm×100mm×300mm. The relationship between rebound value and load was researched. Results show that the critical value of pressure is about 0.25kN/cm2 when rebound values are stable. Comparing tested value with inspecting technical specification, it is found that the rebound value could not be measured correctly at the load in accordance with currently used technical specification. The results could provide a new basis for revised edition of rebound inspecting technical specification.