In order to determine the degree of false set of Portland cement, I examined the change of the viscosity during the early setting of Portland cement with a B-type viscometer.
The results were as follows;
1. Determination of false set of Portland cement by B-type viscometer was easier and more exact than that by the original plunger.
2. In the case of false set of Portland cement artificially controlled, it was found by this method that the apparent viscosity change differs according to the cause of the false set.
It was found by this method that the apparent viscosity change differs according to the cause was measured by applying the various cause of false set artificially of the false set.
From this result, I concluded as follows.
The mechanism of false set of Portland cement due to weathering differes from that due to the addition of alkalicarbonate.

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There are many factors to be considered to evaluate the concrete strength from the rebound number by Schmidt hammer. These factors, some relating to the methods of measuring the number, and some relating to the qualities of concrete to be tested, were explained by many test data.
In conclusion, comparing the strength-hardness relation curves published by many researchers, it was recommended in determining the strength of concrete to make a safe decision by applying the relation curve which conforms well with the field conditions.

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In order to study the effects of prestrain and welding on the corrosion of ship structural rimmed steel, we have performed some experiments to decide the degree of corrosion by measuring the electrical resistance increment of test pieces.
The results obtained are as follows:
(1) Steel becomes more sensitive to corrosion as the amount of pre-strain increases.
(2) Particularly, the corrosion of steel which contains weldment is seriously precipitated.
(3) The effects of pre-strain on the corrosiveness of steel have been reduced by welding which produces a large quantity of heat such as union melt welding.
(4) The rim part of steel in more anticorrosive than the core part.

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In view of the importance of clarifying the fatigue phenomena of rubber vibration absorber, we investigated the behavior under constant torsional deformation using the hysterograph.
For the gum type stock, no change was observed in the amplitude of the torsional moment with the increase of repeated cycles, but for the tread type stock there appeared a considerable decrease. And in the latter case, it was interesting that the torsional frequency was very effective to the slope of the T-logN curve, while the temperature was not so effective.
The hardness of specimens with the longest life was about 50-65 Shore durometer in our experiment and the pause of operation had no great influence on the fatigue life of rubber vibration absorber.

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