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Mechanical analyses were also made of typical samples of pumice from various localities. The following general conclusions from the results so far obtained are taken from an interim report supplied to the Building Research Committee : — (a) Pumice concretes can be made which would bo suitable for precast partition slabs to comply with British Standard Specification 492 (1933). Some pumice concretes would make precast blocks for walls which would comply with British Standard specification No. 834 (1939), but further experimental work is needed before it can be definitely stated what are the requirements in the mix used : (b) The drying shrinkage and moisture movement are usually, but not always, excessive unless a very lean mix is used : (c) There are large differences in the moisture movements of concretes with different pumice aggregates, though they have the same proportion of cement: (d) Pieces of pumice themselves do not have any appreciable moisture movement and the movement must be due to the cement in the concrete : (e) Lean-mix concretes made with suitable pumice aggregates can have a comparatively dry drying shrinkage and moisture movement: (/) The compressive strength of pumice concrete is very low unless a rich mix is used. The strength of very lean mixes is extremely low : (g) Pumice gravels of the " all-in " type, as usually used, arc not well graded and contain too much fine material and dust: (h) As with ordinary concrete, the strength is increased by keeping the amount of water down, though the mix must not be too dry. Dry pressure mixes are usually rather too dry, and vibrated fairly dry mixes should give the strongest concrete : (i) The failure in the concrete when it is crushed occurs on the surface of the pumice pebbles with lean mixes, there being a weak bond on that part of the surface of each pebble which was at the bottom, during the setting of the cement. This is evidently due to the water in each piece of pumice going to the bottom and weakening the cement bond there. Richer mixes fail through the pumice pebbles : (j) Aggregates of Rotorua pumice give a concrete which is stronger but heavier than that made with alluvial pumice : (k) Replacing the pumice fines with silica sand increases the strength of the concrete and the density can be kept reasonably low. This concrete can be nailed and holds the nails very well: (I) Pumice concretes have a low modulus of elasticity, being about one-quarter of that of ordinary concrete : (m) Reinforced beam tests have shown that a strong structure can bo made with pumice concrete, but very little data are available as yet, except that derived from tests in conjunction with precast floor units described below. Precast Light-weight Concrete Fbor Units.—The objects of this investigation were — (a) To obtain a comparison with two previous floors which were constructed of ordinary concrete of a density of about 156 lb. per cubic foot: (b) To determine the factor of safety and the load factor for the system when subjected to the New Zealand Code domestic load of 40 lb. per square foot of floor area. The range of the investigation was small and consisted of testing the materials used and also testing similar units separately. The actual test of the floor consisted in applying one and a half times the design load twice and removing, then applying one and a half times the design load, taking deflection readings each time, and then supplying a further load till failure. The conclusions from the test were as follows : — (a) The units stood all handling and assembling stresses, but required more careful handling than plain concrete units : (b) " T-beam " action is fully developed : (c) The assembled floor shows a safety factor of 4 and a load factor of 6. DAIRY RESEARCH INSTITUTE (N.Z.) Dairy Research, Management Committee.—Mr. A. Linton (Chairman); Sir T. Rigg; Messrs. R. A. Candy, C. A. Duncan, H. E. Johnson, A. J. Murdock, W. Linton, W. E. Scott, G. M. Valentine, Dr. E. Marsden (Secretary); Professor W. Riddet (Director). The Committee met on five occasions during the year to review work in progress and to consider new projects. In addition, a combined meeting of the Dairy Research Management Committee, the New Zealand Dairy Board, and the Board of Governors of the Massey Agricultural College was held on the Bth December, 1944, to discuss matters of mutual interest. During the year Messrs. W. M. Singleton and J. Murray resigned from the Committee. Mr. Singleton was a member of the Committee from its inception in 1927, and Mr. Murray was first appointed in 1930. Mr. G. M. Valentine was appointed by the Dairy Division, Department of Agriculture, to succeed Mr. Singleton ; and Mr. W. Linton was appointed by the New Zealand Dairy Factory Managers' Association as its representative on the Committee, vice Mr. Murray. Research work was limited mainly to the conduct of projects concerned with New Zealand's war effort. Some attention has been given to the part the Dairy Research Institute will play in the post-war development of the dairy industry. The following subjects have engaged the attention of the staff over the past year Dry-butterfat Production. —The large-scale production of dry butterfat was not resumed during .the year, but, as requested by the United Kingdom Government, the installation of the standby plant at Frankton was continued by the Internal Marketing Division, and the Institute has cooperated in arranging the layout of the plant and in the design of the various items of equipment. In view of the improvement in the war situation, the installation is not now being continued to completion.

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