74 



chine and run the hose in. Keep the mixer and hose 

 running and the water will overflow, carrying the loam 

 with it. 



Waterproofing is done in many ways but it is now 

 quite generally recognized that a concrete impervious 

 to water may be obtained by very careful grading 

 of the aggregate, and use of a rich mixture. As rich 

 mixtures are nearly always used in reinforced con- 

 crete work in order to obtain necessary strength and 

 adhesion to the bars, it would seem that by the use 

 of a properly graded aggregate, impervious concrete 

 might always be obtained. In practice, however, it is 

 seldom practicable to obtain such ideal aggregate and 

 very often it is advisable to waterproof. There have 

 recently been placed upon the market a large number 

 of prepared substances for waterproofing concrete by 

 mixing with the concrete. These substances give good 

 results. 



Weight of Materials. The following data will be 

 of use in making a rough check on quantities : 



Granite measures 12 cu. ft. to the ton. 



Crushed Granite measures 20 cu. ft. to the ton. 



Broken Stone measures 20 cu. ft. to the ton. 



Sand measures 20 cu. ft. to the ton. 



Coal (soft, broken) ....measures 40 cu. ft. to the ton. 



Weight of Cast Iron. To -find the weight of cast 

 iron plates: Multiply the length in inches by the width 

 in inches by the thickness in inches and divide by 4. 

 The result will be the weight of the plates in pounds. 



CONCRETE INSPECTION. 



Inspection work can be separated into two classes, 

 but the duties of each class are the same, the difference 

 lying mainly in the fact that in the one case the in- 

 spector reports to the concern for whom the work is 

 done and in the other he reports to the concern doing 

 the work. In may cases the duties of the inspector 

 are performed by those who have other duties assigned 



