146 CEMENT AND CONCRETE 



a hose, the mixing being continued until all parts of 

 the mass are of the same color and wetness. 



3) Carefully clean the molds and apply a thin film of oil 

 after using, so they will be ready for the next job. See 

 that they are absolutely clean before placing any con- 

 crete. 



4) Tile, block, etc., are made by thoroly tamping or press- 

 ing the concrete in the molds to be used. Any dry 

 mixture must be thoroly tamped to make dense con- 

 crete. 



5) Extreme care must be observed in removing the molds 

 to avoid cracking the product or causing it to get out 

 of true shape. Tapping the mold slightly will often 

 prevent failures. 



6) After the product has set for twenty-four hours, 

 sprinkle it carefully with water, repeating this fre- 

 quently for ten days. It should not be used for one 

 month or more. Where such products are made on a 

 commercial scale, they are often cured in a steam kiln. 



7) Write a report on each product made. Give the gen- 

 eral method of procedure and why. Carefully deter- 

 mine cost of materials in each. 



Project No. 3 



141. Sidewalk and Floors (Figs. 148 and 148-a). 

 Requirements: To prepare foundation, construct forms to 

 proper grade and position, and construct sidewalk and 

 floors of various kinds requiring a quaky mixture. 

 Tools Needed: Shovels, buckets, measuring box, screen, mix- 

 ing platform, trowels, edger, groover and float. Wood- 

 working tools suitable for constructing forms. 



