质疑“回弹法检测混凝土抗压强度”

Questions on utilizing method of schmidt for testing strength of concrete

材料的硬度和强度不是同一个概念。同一种匀质材料的硬度和强度之间有一定的相关性,而不同材料的硬度和强度之间不能建立相关的关系;同样水胶比的砂浆和混凝土是不同的材料,砂浆的硬度最多只可能与砂浆强度有一定的联系,而相同水胶比的砂浆强度和混凝土强度的关系却依浆骨比和砂率的不同而异;混凝土碳化层和该混凝土更是不同的材料,混凝土碳化层的硬度和内部混凝土的强度没有关系,再基于碳化层的硬度引进"折减系数"来推算混凝土的强度,在概念上是错误的。

Hardness is an intrinsic physical property of a material conceptually different from its strength.It is possible that a certain empirical correlations between hardness and strength for the same material, but the correlation between hardness of a material and strength of another has no physical sense thus it can not be established.Mortar and concrete with the same W/C ratio are different materials.Hardness of given mortar can be used, to some extent, to estimate its strength,but it can not be used to evaluate strength of concrete with the same W/C ratio, because relationship between strength of concrete and of mortar with the same W/C ratio is various depending on paste to aggregate ratio and/or sand to aggregate ratio. Moreover, the carbonation layer of concrete surface and internal concrete have quite different mechanical properties, and no relationship is yet established between the hardness of carbonation layer and strength of internal concrete.It is conceptuall wrong to use deduction factor of strength based on thickness of carbonation layer.