Trade Journals for the Concrete Industry

It frequently occurs in practical construction work that the actual water content in a construction component is found to be substantially more than the target water content. If this is noticed – mostly for reasons of poor strength – then the cause generally becomes a subject of dispute. Was the water content already too great on delivery or was the consistency raised with water by wish of the construction site above the consistency ordered? For example, if an F3 concrete has been ordered with a 54 cm target after pumping, it then is “enhanced” with water. This is obviously “recognisably too soft concrete”, which the construction company is not permitted to install according to HGB § 377. In terms of water content, often only the water (intrinsic moisture + added water) is taken into consideration and the proportion of water from the admixture not recorded. However, the latter normally has to be taken into account with admixture content above 3 l/m3. This paper is concerned with determining water content by means of radar impulse technology and will describe experience gained both from practice and from a laboratory test series. Advice on suitability in practice will be given and the limitations of this measurement method pointed out.