Author: Painton, E T
First published: N/A
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Painton, E T
It may be stated in a general way that, for a given nature of sand and a given quality of cement agglutinant the strength of the resulting concrete increases when its compactness increases. The lack of compactness may be due in part to bad granulometry, which is a question into which it is not proposed to enter specifically in this paper; assuming that the best granulometric composition of the inert, component has been attained, lack of compactness may still be due to the fact that full advantage is not taken of the possibilities presented by the composition of the mixture, that air cavities remain in the concrete, either through the presence of mechanically enclosed
air bubbles, or through the gradual evaporation of superfluous water.
Psychology. To appreciate the conditions of the problem which we are studying to-night it is necessary to visualise the circumstances which surround buildings at the present time, the conditions under which we live, and the constructional materials in common use. All these circumstances have very direct bearing, not only upon the amount of noise which exists, but upon the extent to which people using buildings and living in houses, are uncomfortably conscious of this noise; in fact, it may not be too much to say that consciousness of noise is very much more important than noise itself.
Mr. D.A.G. REID, in a few words supplementing Dr. Glanville’s presentation of the paper, said that he might try to express in another form what he felt to be the value of the wet mortar test. It amounted practically to this, that if one had a strength-age curve for the wet mortar, and then immediately one had also a strength-age curve for a 1:2:4 concrete with a water-cement ratio of 60 per cent., and, with the aid of
a few general relationships, strength-age curves could be constructed for any other concrete made with that cement; and the strengths taken off from such strength-age curves would be correct to within about 10 per cent. If, however, any such operation were carried out with a dry mortar test, inevitably it seemed errors of 20 per cent. or more crept into the estimates. Of course, that could be got over if the mortar- concrete strength relationship were available for the particular batch of cement, but that contingency was not very likely. Dr. Glanville had mentioned the carrying out of
preliminary tests before the commencement of the main programme. The results of these tests had proved very instructive, and had been of considerable value in assisting in the interpretation of the results of the main series. Mr. Reid felt that this portion of the work would be of great interest to anyone connected with the testing of cements and concretes.