57 



Concrete in Columns. Light a candle at the bottom 

 of the column through the handhole and have a respon- 

 sible man look down into it from the top. Keep a 

 -ible man with his eye on each column after it 

 :>octed in this way and until it is run. 



Watch the mix going into the columns. If it is wet 

 enough to run and yet dry enough to stick, and the 

 column is obstructed by poorly designed steel, you en- 

 counter a bad combination that has to he taken care of. 

 Watch that your mix is of the right consistency and 

 tamp, tamp with I x 2-in. wooden sticks all the time. 

 The reinforcement must be concentric with the column. 



Use four tamps at once, one on each side of the 

 column. Use two at the very least if the concrete is 

 coming in very rapidly. Tap the column centering with 

 mallets while running, to work out air bubbles. 



Concrete in Running Water. When placing con- 

 crete into forms the exterior surface of which is ex- 

 posed to running water, use every precaution to make 

 the forms water tight. This is imperative, as running 

 will wash out the cement, and leave an aggre- 

 gate, good to use behind the mixer, but not in the 

 bottom of a column to support a structure. 



Concrete in Beams and Girders. Use care to se- 

 cure a good placement of concrete below the girder 

 steel on floor concrete. A batch of sand and cement 

 along the bottom of every beam will help a great deal. 



Top Surface. Use care to leave the top surface of 

 the floor while running in a level workmanlike manner. 

 Use a straight edge and guards if practicable. Snow- 

 shovels have been used to good advantage in leveling 

 floors. 



Floors Wet. Keep the floors wet after running con- 

 crete, r.arrel- filled with water with a partly plugged 

 bung-hole can be left out on the floor to keep it wet. 



Record of Concrete. On large work use some sys- 

 tem of marking the floor with the date on which it 



