May 12, 1933 
Effect of Decomposition on Concrete Tile 
487 
Table XIV .—Effect on concrete by treating repeatedly with weak peat water and with 
CO2 water 
Item. 
Sample i. 
Sample 3. 
Original weight (gm.).. 
I. 0000 
. 9684 
.8367 
• 7879 
• 7843 
•2157 
21. 5700 
1. 0000 
I. 0464 
. 9120 
• 9167 
. 8890 
.1110 
II. 1000 
Residue after treatment with 400 c. c. of peat water (gm.). 
Residue after treatment with 400 c. c. of CO2 water 0.016 normal 
strength (gm.). 
Residue after second treatment with peat water (gm.). 
Residue after second treatment with CO2 water (gm.). 
Total net loss (gm.). 
Total net loss (per cent). 
These experiments gave the first really constructive information. 
They showed that the powdered tile was powerfully acted upon by the 
peat waters, the amount of action depending upon the acidity of the 
peat water. In this action a semigelatinous mass was precipitated out 
of the solution, increasing the weight of the total solids. On treating 
with carbonic acid water, this gelatinous mass was removed and about 
as much tile dissolved as would have been the case had the tile not 
been previously treated with peat water. 
ACTION ON N:EAT CEMENT 
In order to ascertain if the decaying peat had any action on “neat’" 
cement a small quantity of the same cement as used in Table VII was 
mixed with water to make a stiff mortar. With this mortar small 
patties were made by first rolling the mortar into a ball by hand and 
working it thoroughly together. These balls were then flattened on 
glass into patties which were 2 inches across, one-half inch thick in the 
middle, and tapering to a thin edge. The upper surface was troweled 
with a spatula until the “laitance” was brought to the surface. The 
patties were then allowed to set in warm water for a week. 
After removal from the glass the patties were placed in a jar of peat 
and kept moist for three months in a warm place. At the end of that 
time the patties were broken and the fracture examined. It was found 
that on the lower side where the cement had been against the glass the 
peat solution had penetrated to about three thirty-seconds of an inch 
and the surface could be easily scratched with a knife. On the upper 
side, however, which had been packed by hand and then troweled, there 
was no sign of any acid penetration, and the surface was very hard and 
dense. 
There was no experimental work done to determine whether the 
resistant quality of the cement was due to the greater density of the 
mass, to the bringing to the surface of the “laitance,” or to some other 
cause not indicated. 
RESULTS 
In addition to the five principal points brought out in the preliminary 
studies, five additional ones are indicated in the later work. They are: 
(6) The setting of the partially decomposed tile on grinding and 
moistening. 
(7) The gelatinous compounds of organic matter and concrete. 
39363—23 - 4 
