RURAL ENGINEERING. 91 



Test of a 40-ft. reinforced concrete highway bridge, D. A. Abrams (Amer. 

 Soc. Testing Materials Proc, 13 {1913), p/;. SS4-,92;2, pgs. 2^).— A 3^ years' test 

 of 11 40-ft. reinforced concrete through-girder highway bridge with an 18-ft. 

 roadway, in which tlio bridge sustained unusual and excessive loading, is re- 

 ported in detail. 



Some properties of building materials, B. F. E. Keeling {Cairo 8ci. Jour.. 

 7 {1013), No. SO, pp. 97-103, fig. 1). — In this article the results of exiierinients 

 on the physical properties of sand-lime bricks and of walls made with them, and 

 also on some other properties of buildings, are reported. 



Results obtained with the autoclave tests for cement, II. J. Force {Amer. 

 fioc. Testing Materials Proc., 13 {1913), pp. 7.'fO-79G, figs. S).— This paper gives 

 the results of comparative tests of various brands of cement, some of which 

 tailed to pass and others of which pa.ssed the autoclave test previously noted 

 (,E. S. R., 2S, p. 290). 



On the ground that the grinding of the raw material and the proper burning 

 jilays a most important part in the quality of Portland cement, the author be- 

 lieves " that the failure of cement to pass the autoclave test is due very largely 

 to the coarser granules which do not become hydratetl when the cement is set 

 up, and that the failure of these granules to become fully hydrated is due to 

 tlieir chemical comi)osition, that is, the granules are composed largely of dical- 

 cium silicate with a smaller proportion of tricalcium silicate. Granules of this 

 composition fail to hydrate properly in the period of 24 hours, and consequently 

 when brought in contact with heat and pressure, together with moisture, slaking 

 of the dicalcium silicate is quickly brought about, with the result that a large 

 percentage of expansion occurs together with a proportionate decrease in tensile 

 strength. On the other hand, if the proportion of tricalcium silicate is largely 

 in excess of the dicalcium silicate, then we may expect a more stable product 

 and one which will show considerably less expansion under the autoclave test 

 and which should remain constant in volume in after years." 



Tests of natural concrete aggregates, .11. S. Greenman {Cement Era, 11 

 {1913), No. 8, pp. 41, 42; Amer.. Soc. Testing Materials Proc., 13 {1913), pp. 

 H28-833). — Results of tests are reported which indicate that both the laboratory 

 tests and carefully made field tests and inspections of aggregate present ways 

 and means of indicating what the natural aggregate, either fine or coarse, will 

 actually do in the concrete in place. 



Fine particles [in cement] estimated by rate of hydration, 11. S. Space- 

 man {Cement Era, 11 {1913), No. 7, pp. 83, 85; Amer. Soc. Testing Materials 

 Proc., 13 {1913), pp. 714-719). — Tests of a normal cement pas.sing the standard 

 specifications of the American Society for Testing Materials showed a definite 

 relation existing between fineness of grinding on one hand and rate and extent 

 of hydration on the other. 



Apparatus for determining consistency [of cement paste], C. M. Chapman 

 {Concrete-Cement Age, 3 {1913), No. 1, pp. 8, 9, figs. 3; Amer. Soc. Testing Ma- 

 terials Proc, 13 {1913), pp. 1045-1052, figs. 3).— A method for determining the 

 consistency of neat cement paste consists in depositing the mortar or concrete 

 in a form of suitable size and shape on a glass or metal surface, then removing 

 the form and noting the settling either with or without the assistance of a jar 

 or shock of the unsupported mass. A low form of large area is used for soft 

 wet mixtures, and smaller, taller forms for drier mixtures. 



The limits beyond which the method is useless lie between that consistencj^ 

 which is fluid enough to flow freely, and that wiiich is too stiff to alter its 

 form under the influence of a comparatively light .shock. 



Thermal activities of Portland cement during the period of setting, L. N. 

 Deals. Jr. (Amer. Soe. Testing Materials Proc., 13 {1913), pp. 720-739, figs. 9).— 



