THE LIFE OP PORTLAND CEMENT. 
BY G. G. AND A. J. WHEAT. 
Perhaps just a word in explanation of the title of this paper will not he 
amiss. We speak of Portland Cement as possessing life. We do this because 
the duration of its existence as Portland Cement is measurable. In contra- 
distinction we might speak of a material such as the Sioux Falls Quartzite as 
being dead, since no appreciable change takes place in the body of this Quartzite, 
all of the elements of the Quartzite being practically at a state of rest and re- 
sisting all disintegration by the ordinary weathering agencies. Perhaps our 
distinction may be somewhat arbitrary and we cheerfully invite helpful criticism. 
This subject has interested us for a number of years. We have taken inter- 
est in the advance in engineering construction made possible by the widespread 
production of Portland Cement. We have anticipated the conditions which have 
arisen and through the throes of which we are now passing. Portland Cement, 
one of the most valuable materials known to the engineering world, is being 
heavily overworked and is being crowded into fields of use where it is not fully 
competent to endure the conditions which it must meet. 
Without further preliminary we will give the results of some laboratory 
work and some suggestions concerning lines of research which to us seem to 
promise valuable results. We shall consider as our most sincere friend any 
fellow member who can or will show us that we are doing work in our investi- 
gations that is not correct. 
Early in this year we appeared before the Iowa Clay Workers at Des Moines. 
There we presented the following facts and suggestions: Portland Ce- 
ment construction or concrete does disintegrate With age. The places or condi- 
tions where this disintegration occurs are found to subject the concrete to one 
common agent of destruction. Where protected against the action of this agent 
and also not subject to some other destructive agent the concrete proves durable. 
The obvious explanation of the disintegration of the cement is the action of 
this one common agent, water. 
Disregarding the commonly advanced theory that concrete grows continually 
better under the action of water, we stated that the work of engineers and 
chemists shows plainly that there is a point of maximum strength reached in a 
very few months in light walled construction and in more massive work pos- 
sibly in a matter of a few years. Following this point of maximum strength 
the concrete is found to grow gradually and steadily weaker. 
Now in explanation of these facts we turned to the crystallization theory for 
a partial explanation of these phenomena of maximum strength followed by a 
decrease. The theory of crystallization offered as an explanation of the process 
of Portland Cement in setting seems to us inadequate to explain fully the process. 
(in; 
