Abstract: The measuring-value sensor according to the present invention for the measurement of extensions, for example in concrete or shotcrete, consists of a support member, having an extension stiffness value that is lower than the extension stiffness value of the material diameter displaced by the sensor. Transverse elements are located at either end of the support member, which induce the impact. By combining sufficiently large transverse elements that have a relatively high flexural strength and a support member that has the above-mentioned very low extension stiffness value it is made sure that extensions in the concrete are forced completely and without obstruction upon the support member by means of the transverse elements, so that when measuring the extension of the support member, the extension of the concrete is measured directly and without any distortion. The support member is suitably a hollow profile of aluminum or a plastic material, into which an additional profile, e.g.