62 ANNUAL REPORT 
Roman cement mortar. (3) Portland cement mortar. (4) One part 
Portland cement and two parts lime. (5) Cement and slag mortar. (6) 
A patent frost proof mortar. 
All mortars were one part cementing material to two parts of sand. 
The walls were torn apart during the following summer. Their con- 
clusions were: (1) That lime for a cementing material is entirely unsuited 
for cold weather construction. (2) That Roman cement can be used with 
fairly good results in brick masonry, but is not safe for rubble masonry 
construction in freezing weather. (3) That Portland cement mortar is 
not seriously affected in freezing weather and is especially good when 
used with salt. (4) That mortar mixed with warm water (77 degrees 
F.) showed about the same loss of strength as when cold water was used. 
(5) The frost proof cement and the Portland cement with salt showed 
very little loss of strength when frozen. (6) That dry brick and stone are 
necessary to safe construction under freezing conditions. 
THE EFFECT OF HEAT UPON MORTAR. 
M. Devol, of the Paris Testing Laboratory, made tests with briquettes 
of I cement to 3 of sand. They were allowed to harden in air from 
24. hours to 30 days, and then placed in water at 177 degrees F. and kept 
from 2 to 7 days. Six brands of Portland cement were used. 
They resisted hot water at that age and gained about the strength in 7 
days in hot water that they gained in cold water in 28 days. But when 
placed in hot water before being completely set, disintegration set in. 
Cements containing free lime when placed in hot water swelled, warped 
and cracked. 
