Assessment of Deviations in Concrete Properties Quantified Under Laboratory Conditions and from the Construction Site

The durability of a concrete structure ultimately depends on the quality of the cast concrete, whereby especially the edge zone of the manufactured concrete segments is crucial for environmental exposures. In order to ensure that the concrete provides sufficient resistance to these exposures, the corresponding material properties must be quantified according to the so-called performance-based durability design. However, the quantification of these properties is carried out using mainly standardized concrete test specimens, cast and cured under optimized laboratory conditions. On the other hand, the real structure is built under different in situ and curing conditions. This may lead to a deviation of the concrete properties achieved at the construction site in contrast to those determined in the laboratory. In this context, systematic investigations were conducted to assess this deviation. To accomplish the studies, separately manufactured test specimens, as well as dummy walls (4 m^2), were cast at different construction sites. The separately manufactured test specimens were cured in the laboratory following current standards. The wall was cured in its formwork for a defined number of days (mostly 7 days). Subsequently, drill cores were taken and compared to the laboratory samples in terms of the corresponding material properties (compressive strength, chloride migration and carbonation rate of the concrete). As a result, the core drill samples underperformed the laboratory-cured samples, indicating that the performance achieved at the construction site tends to be lower than that of laboratory specimens.     «

The durability of a concrete structure ultimately depends on the quality of the cast concrete, whereby especially the edge zone of the manufactured concrete segments is crucial for environmental exposures. In order to ensure that the concrete provides sufficient resistance to these exposures, the corresponding material properties must be quantified according to the so-called performance-based durability design. However, the quantification of these properties is carried out using mainly standardi...     »