Om Materialprøvningens Udvikling i Norden
Og om Statsprøveanstaltens Virksomhed

170 shelf in the cement premises. The result of the compression- tests after 28 days appears from Table X above. It appears from this that while the moler mortar increases at any rate a little in strength when left in a very moist room instead of in comparatively dry air the very opposite is the case with the unmixed lime mortar which after 28 days has attained a crushing strength 3 times as large when stored in comparatively dry air as when preserved in very moist air. The figures further show that in a mortar with 5 per cent calcic hydrate about half of the latter can be replaced by moler without the strength particularly de- creasing in a room where the degree of moisture is that of the cement premises — and the degree of moisture is here about 65 per cent — while in a very moist room much is gained in strength on employing moler in the named quantity. The named 2 mortars were further employed for adhesion experiments. The Laboratory had formerly made adhesion experiments in the well known way of masoning together crosswise 2 bricks and then pulling them from each other after the lapse of a certain time. To pull them away from each other the primitive appa- ratus, shown at p. 78 in fig. 28, was employed supplied with some small screws indicated in the figure and recommended by v. d. Kloes in »Baumaterialienkunde« 1900, p. 154. S are the bricks seized by claws K the uppermost of which is suspended in a dynamometer again fastened to the beam D. The lower claw is pulled downwards when a man turns by hand the shaft A, and another at the same time pulls the free end of the rope T wound some times round the shaft A. The shaft is turned by means of a small fly-wheel attached to it. This apparatus has proved appropriate in several cases, the shaft A belongs to an extant machine and the trestles B can be placed, as shown on the figure, on both sides of the shaft and the controlled dynamometer M where the pull exercised for the over- coming of the adhesion is displayed. In the case before us the adhesion experiments were, how- ever, made in the following well known way: Common bricks were employed; they were masoned together 3 and 3, the lower beds against one another, so that in each set one header-side of the middle brick projected beyond the two others. The bricks were left in the cellar of the Laboratory