The effects of shape, age and curing on conversion factors were investigated for a series of nine lightweight concretes (LC) and one normal weight concrete (NC) covering the strength range from 15 to 70 MPa. The experimentally obtained conversion factors between standard cylinders and cubes (1.17 to 1.26) correlate much better with the factor given for NC (1.23) in Model Code 90, EN 1992 and EN 206 than with the one for LC (1.10). This may result in an overestimation of the strength class, if cubes are tested only as it is common in e.g. Austria and Germany. The question arises, if deviating conversion factors for LC are needed at all. The experimental findings will be explained by means of the by lightweight aggregate determined strength limit (flc,lim) and changes in crack pattern in the course of the hydration. The conversion factor for NC is the better fit as long as the strength of lightweight aggregate is not the limiting factor. Above this limit the conversion factor decreases and approaches the one given for LC in EN 1992. In practice, this will only apply for a few LC. The conversion factor between water storage and dry curing is the same for LC and NC.    «

The effects of shape, age and curing on conversion factors were investigated for a series of nine lightweight concretes (LC) and one normal weight concrete (NC) covering the strength range from 15 to 70 MPa. The experimentally obtained conversion factors between standard cylinders and cubes (1.17 to 1.26) correlate much better with the factor given for NC (1.23) in Model Code 90, EN 1992 and EN 206 than with the one for LC (1.10). This may result in an overestimation of the strength class, if cu...    »