22 BULLETIN 249, U. S. DEPARTMENT OF AGRICULTURE. 



The proper method of handling the cement is sometimes con- 

 siderably affected by the requirements which the specifications pro- 

 vide regarding tests. Some specifications require that the cement 

 shall be held until the results of the 28-day test are reported, while 

 others permit its use as soon as it has satisfactorily passed such 

 tests as may be made within seven days. If any tests of consequence 

 are required and the sampling is not done until the cement arrives at 

 the nearest railroad station, it will be necessary either to unload and 

 store it or pay demurrage charges. This difficulty may be overcome to 

 some extent by placing an inspector at the cement plant to collect and 

 forward samples to the testing laboratory as soon as the cars are 

 loaded. The testing may then be begun while the cars are en route. 



Another plan sometimes employed to lessen the demurrage and 

 avoid rehandling is to purchase bin-tested cement and have the cars 

 loaded under the supervision of an inspector. When this is done, the 

 cement may be used as soon as it arrives on the work, but the custom 

 of cement manufacturers to make a slight additional charge for bin- 

 tested cement may entirely offset the economical advantages gained by 

 its use. 



No matter what the arrangements for testing the cement may be, 

 provision should usually be made for storing near the work sufficient 

 cement to keep the mixer going for four or five days, in case that 

 shipments are delayed, as frequently happens. 



In general, the most satisfactory method of hauling the materials 

 for the concrete is by means of an industrial railway constructed 

 along one shoulder of the road, though this method is not always the 

 most economical. Teams, traction engines with trailers, and motor 

 trucks with or without trailers have each been frequently used for 

 this purpose, and are no doubt each economically best adapted to 

 certain sets of conditions. But all of these are objectionable from a 

 construction standpoint on account of the damage which they usually 

 do to the subgrade. 



Among the advantages possessed by an industrial railway for haul- 

 ing the concrete materials are : 



(1) Materials may be delivered without disturbing the subgrade. 



(2) The railway may be readily operated along the shoulder of a 

 newly laid pavement, which makes it practicable to prosecute the 

 work at any desired point. 



(3) Hauling is affected comparatively little by Aveather conditions. 



(4) Where there is sufficient work to keep an industrial railway 

 outfit busy, it is usually economical, especially whore the size of 

 the projects is such that the railway can be operated continuously 

 throughout a season on the panic project. The purchase of an indus- 

 trial railway outfit, however, usually involves a greater outlay of 

 capital than is desirable for a single project. 



