Date of Award

6-1949

Document Type

Open Access

Degree Name

Bachelor of Science

Department

Chemistry

First Advisor

Charles B. Hurd

Language

English

Abstract

Excellent general discussions of the earlier literature concerning the rival crystallization and colloid theories as applied to the setting and hardening of Portland cement are found in Bogue (4, 5), Kuhl (21), and Lea and Desch (24). These authors, along with Steinour (41), have tried to resolve these apparently conflicting hypotheses in the light of more recent investigations and have clearly outlined those areas of conflict which need further clarification through continued research. Recent work by Hedin (16) has shown that when ion concentrations and ion activities in solution are changed by the addition, for example, of gypsum, a sufficiently high aluminate-ion concentration can be attained so that free silicic acid is coagulated. Through coagulation, the concentration of the calcium silicate in solution is kept very low. This suggests that lime may be absorbed by silica gel after which chemical reaction can take place. As reported by Steinour (41), Maffei showed that Freundlich and Langmuir isotherms vary in such a way that this process may be assumed to take place. Silica solutions with absorbed lime have shown no initial electron diffraction pattern attributable to crystalline products, but they soon give such products. Work such as this suggests that hydration passes through a colloidal-amorphous state which soon becomes a highly dispersed crystalline state. It has been shown, by the way, (of Steinour) that the gelatinous hydrated calcium silicate gel. These experimental results again suggest the application of the Haber theory to Portland cement.

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