350 



STATE BOARD OF AGRICULTURE. 



concentration of salts is possible a dense, nonporous siuface is essential." 

 This conclnsion is interesting even in its reference to the action of 

 alkali, ^vhich, however, is not a problem to be contended with in Michi- 

 gan soils. 



Owing to the fact that our investigations were not begun undl late in 

 the fall of 1914, we have not been able to place tile in drains and rejtort 

 as to its durability. In this respect, our findings, as already mentioned, 

 cannot be regarded as conclusive, since, to determine durability under 

 actual service conditions requires experiments extending over a period 

 of several j^ears. One marked characteristic of properly made concrete 

 tile is its resistance to the action of frost or alternate freezing and 

 thawing soil conditions. 



In our work we made experiments in manufacturing and hardening 

 tile and then tested specimens which were porous by causing solutions 



Fig.^l. — Disintegrated tile taken^f rom a drain 18 months after beingTJlaid. Subsequent invcstiga- 

 ^ tions proved that they were poorly made and placed in the ditch without being properly 

 hardened. Under such conditions disintegration is almost sure to follow. 



to percolate through the walls, thus endeavoring to determine what 

 changes took place in the solutions and in the tile. However, relatively 

 few of the tile used for test purposes were made in our laboratory. Most 

 of them w'ere samples sent in from different parts of the State, which 

 were not up to the average in displaying an observance of recognized re- 

 quirements of manufacture. These samples were accompanied by reports 

 giving information concerning the processes of manufacture, such as 

 mixtures, type of machine used and method of hardening; and a descrip- 

 tion of conditions under which they were placed in the ditch. Some of 

 them w^ere apparently sound and in good condition but others gave evi- 

 dence of having been poorly manufactured and, as a result, had under- 

 gone considerable disintegration. 



Chemical tests and analyses of the tile were made but gave no clue 

 as to the cause of the disintegration. Our experiments included placing 



