ウエザリング法によるアルミナセメントの長期強度の推定

アルミナセメントの研究 (第5報)

抄録

In spite of the great importance for the maintenance of the aluminous cement buildings there have been only a few papers concerning the changes of the mechanical properties extending long times.
This paper deals with the possibilities of finding out the method of prediction of the mechanical strength of aged mortar as early as possible.
The results of the studies on the changes of the structure of hydrated aluminous cement during aging showed that the decomposition of aluminum hydrate, which took an important part in the mechanical strength, was accelerated remarkably by the cycle of wetting and drying as well as by exposing to sunlight.
It was considered that the change of the strength of hydrated aluminous cement during long age may be found rather in a short period by an accelerated test using weather-meter, a well known apparatus for testing the aging effect of organic products.
A good many specimens of aluminous cement mortars were subjected to weather-meter test, under 40% relative humidity at 35°C. During the test extending about 100 days they were exposed alternatively to the attacks of arc light and water spray (8min/hr, 1 atm nozzle).
Every 5 days the crushing strength were measured to compare with those of naturally aged mortar.
It was confirmed that the curve of weather-meter test was quite similar in form to that of natural aging, giving, however, in the first 30 days the change as large as that occurred in 3 years of natural aging.; both curves showed no change of strength therafter. The statistical consideration of the experimental data indicated that 10 days of the artificial weathring corresponded to a year in natural aging. Thus, the change of the mechanical strength of hydrated aluminous cement may be predicted by using weather-meter test which gives the values of natural aging test 30 times or more earlier.