RURAL ENGINEERING. 689 



Irrigation pocket book, or facts, figures, and formulas for irrigation engi- 

 neers, compiled by II. B. Buckley {London, New York, Calcutta, and Bombay, 

 1913, 2. ed., pp. Jf83, pi. 1, figs. SO). — This, the second edition of this pocket book, 

 contains about GO pages of " facts, figures, and formulas " concerning irrigation 

 engineering which did not api>ear in the first edition (E. S. R., 29, p. 289). 



Drainage and irrigation: Method and cost of manufacturing sand cement 

 with results of tests of the modified cement, L. E. Sale (Engin. and Contract., 

 JfO {1913), No. 23, pp. 623-628, figs. 6).— This article describes the methods of 

 manufacturing sand cement employed by the United States Reclamation Service 

 at the Lahontan Dam and gives the results of tests of the modified cement in 

 regard to sand and cement ingredients, tensile and compression strength, poros- 

 ity of mortars and concrete, and effect of hot water and allcali. 



In the sand or so-called "silt" the elements silica and alumina were found 

 to predominate, while the cement analyses showed a high lime content and also 

 sulphuric anhydrid. It was found that an amount of silt, up to 25 per cent of 

 the volume of the sand used, tends to increase the strength and imperviousness 

 of the concrete, it being unnecessary to wash the sand on this account. 



Cement replaced by silt, and the two only mechanically mixed, decreased the 

 strength of the concrete in direct proportion to the increase of silt, and too fine 

 grinding of the blend resulted in a flash set. The ideal product was found to 

 consist of a mixture of 50 per cent silt and 50 per cent Portland cement, ground 

 until an average of 82 per cent passed a No. 200 sieve. Sand cement concrete 

 required more mixing and more water than pure Portland cement concrete, and 

 after being placed in forms cracked and disintegrated unless watered constantly 

 for a period of from one to three weeks, depending on the weather. It was 

 further found that hot water could not be used in mixing. The flour in the silt 

 is thought to combine chemically with certain elements in the cement, thus 

 increasing the strength. 



From the alkali test it is concluded that an impervious concrete which will re- 

 sist alkali action can be made with sand cement without resort to "alkali proof" 

 compounds or waterproofing materials such as soap, alum, etc. It is further 

 concluded that sand cement concrete is essentially a warm weather concrete. 



Pressure tests of jointed concrete pipes {Engin. News, 70 {1913), No. 23, 

 pp. 1126, 1121, fig. 1 ) . — Tests are reported of the resistive qualities under severe 

 internal pressure conditions of lines of 63, 84, and 48 in. reinforced concrete pipe 

 of 1:1^; 2^ mixture and having special "lock joints". The pipe is cast in 

 4 ft. lengths and is provided with a bell end and a groove on the inside of the 

 pipe at the joint. In making the final joint the reinforcements of the adjoining 

 pipes are overlapped in the internal groove, and the groove filled up flush with 

 the inside of the pipe by pouring in a cement grout. In addition there is a 

 specially prepared plaster interior cover to the joint. 



The 63-in. pipe withstood an internal pressure of 54 to 56 lbs. per square inch 

 and the 84-in. pipe an internal pressure of 65 lbs. per square inch without leak- 

 age through pipe or joints. The 48-in. pipe withstood 40 to 55 lbs. internal 

 pressure for 48 hours without leakage. A steady increase of pressure in this 

 pipe up to 90 lbs. per square inch caused sudden failure at that point. 



Small cube pavements of Monroe County, [New York], W. G. PIargeb 

 {Engin. Rcc, 68 {1913), No. 23, pp. 624-626, figs. 7).— Service tests and cost 

 data are reported of surfacing country roads with 2-in. blocks of vitrified clay 

 ash, vitrified shale, and concrete. 



It was found that the cube form of pavement is flexible under frost action, thus 

 making it suitable as a surfacing on a macadam base. It is stable under trafiic 

 and can be successfully held in place with a macadam or gravel shoulder without 

 the formation of a rut. It gives a satisfactory surface in wet and dry weather, 

 and can be laid late in the season, requiring comparatively simple inspection. 



