Strength Characteristics of Organo-Mineral Composites

Chemical studies of the cured organo-mineral composition end products by IR spectroscopy showed that the ratio of triisocyanurates, disubstituted ureas, amines, sodium carbamates, carbonates, phtha-lates, and methacrylates, as well as the composition of the silicic acid 

In the aging process of cured compositions, their compression strength noticeably increases, more so for compositions with lower waterglass silica modulus. For example, o-p of cured compositions with M = 1.35-2.35 after 15 days of aging increases 4r-5 times, whereas the compositions with M = 2.35-3.0 show only 1.8-2 times growth of this index. The compression strength is reduced to a minimum with introduction of waterglass with M = 3.2. 

The influence of the waterglass silica modulus on physical and mechanical properties of organo-mineral composites is explained mainly by change in the composition of the products of reaction of 

Compression strength increase in compositions with low-modulus waterglass is observed over 30 days. The rate of achieving maximum strength increases with silica modulus, but absolute values of this index are reduced considerably. For ex unple, the maximum strength of cured composites with M = 3.2 is achieved in 2 days but is only IMPa, whereas for the composites with M = 1.35 the maximum strength is reached over 30 days but reaches 49 MPa. 

This character of specimens o-p dependence on time can be connected with prolonged chemical or physicM structuring or with the purely physical process of moisture loss by the specimens. The kinetics of moisture loss by the specimens under hold-up in air in normal conditions was investigated to test the last assumption. Moisture loss was assessed by the change over time in specimen mass relative to initial specimen mass. It was established that the rate of moisture loss during hold-up in the air gradually reduces, but even at 30 days it rem dns important and the maximum moisture loss by specimens was 11.9%. 

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