Bridging Crystals of Different Types

The experiments were carried out using a supersaturated calcium sulfate solution a = 1.8 and the time of contact t = 1000 s and with the applied compressive force,/ of either 1 or 10 dyn. The results of the experimental studies showed in aU cases a sharp transition from contacts with a strength 

Probability of Bridging (IV ) of Different Crystals in Supersaturated Calcium Sulfate Solutions (a = 1.8 f = 1000 s) 

Results summarized in Table 6.7 indicate that the formation of crystallization contacts was facilitated by the applied compressive force,/ In the case of the same applied force, the probability of contact formation depended on the crystallographic orientation of the gypsum crystals. The effect of compressive force on the probability of bridging must be primarily related to the properties of the gypsum crystals. Among all materials used in the study, gypsum was the softest with stress-dependent solubility its concentration therefore increased in the contact zone. 

The studies conducted indicate that the fine disperse filler added to mineral binders did not act solely as a substrate support for the hydration nuclei, but played an important role as an active structure-forming element and took direct part in the contact formation process. 

5 Effect of Chemical Modifiers and the Solution Composition on Crystallization Contacts 

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