May 12,1923 
Effect of Decomposition on Concrete Tile 
495 
Tabl^ XXI. ^—Comparison of tile in peat with tile from stock pile at Coon Creek, tested 
Oct, 25, igzi 
Item. 
Per cent. 
Loss in weight. 
5-5 
17.8 
5-2 
10.4 
Loss in strength. 
Increase in porosity: 
Ends.:. 
Middle. 
1 Summary of Table XIX 
PKAT IN hAKB PRAIRIE DISTRICT 
On September 19,1921, a concrete tile line was examined on the NW. X 
and SW. X» sec. 29, township of Lake Prairie, about 10 miles northwest 
of St. Peter, Minn. In 1919, an 8-inch tile had been laid a short distance 
into a peat pocket about 1,200 feet long. The line was not completed. 
After eight months in the ground the tile was taken up and found to be 
very badly disintegrated on the bottom, as shown in Plate 6, B. New tile 
was laid in the fall of 1920 and the main completed. At the time of the 
examination it also showed signs of serious disintegration. No samples 
of the new tile were taken. Tests of the old tile showed physical condi¬ 
tions as summarized in Table XXII. 
Table XXII. —Absorption tests, bone-dry and boiling method, of concrete tile in peat 8 
months, and on bank i year, near St. Peter, Minn. 
Sample taken. 
No. I. 
No. 2. 
Top piece in mold. 
13.0 
16.6 
14. 6 
25-8 
19-3 
14. 6 
Center piece in mold. . 
Bottom piece in mold. 
Average. 
14.7 
19. 8 
All of the fragments of tile No. i were from the upper side. The upper 
and center fragments of tile No. 2 were from the partially disintegrated 
portion. The tile were apparently of about the same character originally^ 
a rather low grade without sufficient coarse aggregate. 
RKSurTS 
In addition to the 10 points brought out in the laboratory, the field 
studies indicate the following: 
(11) Concrete tile, as at present made, break down in all peat soils, no 
matter what the underlying mineral soil may be. 
(12) A high percentage of lime, even the presence of marl, is no guar¬ 
anty of immunity. 
(13) A high percentage of lime delays but does not stop the process of 
disintegration. 
(14) An acid subsoil aids in the disintegration. 
(15) The more porous the tile the more rapid the disintegration. 
(16) The presence of water is necessary for disintegration to take place^ 
