Modeling spacing factor requirements and measuring water permeability in hydrated Portland cement paste

摘要

Small, well-dispersed air voids in hydrated cement paste can improve workability, reduce bleeding and segregation, and improve resistance to freezing and thawing. To characterize the air void system in cement paste, not only the amount and size of air voids are important, but their distribution (spacing factor) is also significant. This thesis investigates the frost action mechanism in cement paste and how the spacing factor closely relates with it. Also, this thesis provides detailed information about testing the cement pasteu27s water permeability by using a falling head permeameter on saturated samples.Paper one is a sensitivity study from an existing modeling system for determination of maximum spacing factors. Conclusions are drawn by analyzing the existing mathematic model and comparing the theoretic values with experimental values.Paper two describes work conducted in the development of a method to test water permeability of saturated hydrated cement paste. This is a cost effective method to test the water permeability, since the work is achieved by revising of existing Ballim oxygen test. From test results and observations, several apparatusu27 revisions have been completed. Some recommendations are provided for further improvement of the test apparatus.