Improving the physical properties of the concrete can assist in reducing moisture levels. The use of high compressive strength mix, low water to cement ratio and specific admixtures will improve the quality of the concrete slab for duration of its life.
The integration of pozzolans into the concrete mix design can be an excellent improvement to reduce water vapor emission and alkali. The specific amount of pozzolan to be included in the mix design must be balanced with the water to cement ratio, concrete curing process and long term compressive stength requirements. Regardless of the amount of pozzolan you use in your design, it will mix freely with the portland cement and water to create a cement like property. It becomes appart of the entire mix design.
In California, the Department of State Architect has specific requirements on pozzolans use and the amount of product to be used based on the batch plant and contractors experience. Other states may have similar requirements and should be explored prior to updating specifications for your next project.
Admixtures are one of a combination of products that will assist in reducing concrete moisture levels. No admixture alone can eliminate all concrete moisture, since all concrete cracks. Cracks allow moisture and dampness movement that admixtures cannot control.