526 Report of Farmers' Institutes 



Platform: 8 feet by 12 feet, of 1-inch matched lumber, four 2-inch by 4- 

 inch scantling. 



fSand screen: Mesh i/4-inch by 5 or 6 inches, nailed to a wooden frame 2 

 feet by 5 feet and set at an angle of 45 degrees. 



Material 



Gravel, sand, cement, water. \Mien screening what is called " bank-run 

 gravel," that is, gravel running from a fine sand to stones 1^^ inches in 

 diameter, all stones passing through the screen will be i/4-inch or less in 

 diameter, and are classified as sand. All other stones not passing through 

 the screen are classified as gravel. Crushed hard stones may be used in place 

 of gravel. 



Proportions 



A 1-3-5 mixture, that is, 1 cubic foot of cement (1 sack of cement), 3 cubic 

 feet of sand and 5 cubic feet of gravel, will make about 5 cubic feet of 

 concrete. 



For engine foundations, fence posts, silos, troughs, and foundation walls 

 use a l-2%-4 mixture. 



Mixing 



Thorough mixing together of the sand, gravel, and cement, before adding 

 the water, is necessary. After mixing, form the dry materials into a crater, 

 pouring the water on the board in the center, and shoveling the mixture into 

 the water from the inside. Continue this metliod until the mixture is soft 

 and mushy. 



General Rules 



1. Concrete should not be mixed ahead. 



2. To unite new concrete to concrete already hardened, wet the surface of 

 the hardened concrete thoroughly and cover with grout, made of water and 

 cement to tlie consistency of cream; apply tlie new concrete at once. 



3. Large stones may be used in concrete foundations provided the stones 

 are wet thoroughly before placing in the wall. 



4. Salt is injurious to concrete. 



