This article is a summary of the most lively questions and answers for the University of Illinois Seminar on New Materials in Concrete Construction held December 15-17, 1971. Expansive cements have a indefinite shelf life as long as they are kept dry. Aluminum powder acts the same as expansive cements but the effect of the powder is immediate. To make your own shrinkage-compensating cement, the Japanese add calcium sulfo aluminate. For strength comparisons a modified cube is used. The sources for the fiber in fiber-reinforced concretes come from: for steel fibers, the National Standard Company and for glass, Owens Corning Glass Company and for synthetic fibers, E. I. du Pont. Battelle Development has patents based on spacing and so also does U. S. Steel. To regulate setting time for regulated set cements use an admixture at the job site. Type I can not be used because you don't get continued strength development if you load up Type I cement with too much accelerator. The water-cement ratio has no effect on setting time. Unexpended beads for synthetic aggregates can be easily expanded in hot water. It is cheaper to ship the unexpended materials than the expanded. Synopal has been as a concrete aggregate in Welland Canal. Of all the aggregates nothing is as bright. When drying polymer concrete by vacuum it is actually being thermally dried. Compressive strength is about 10 to 15 percent higher for radiation curing for reasons unknown. The depth that can be cured is 6 inches on either side. When taking about polymer latex-modified mortars, saran is anything with over 70 percent polyvinylidene chloride in the monomer. Some contain polyvinyl chloride and acrylates also. The latex that is to be used is about 3 to 4 gallons per bag of cement. In ferrocement, spacing of wire has no effect on cracking behavior. However, increasing the specific surface of wire per does decrease the crack spacing at failure. Welded mesh acts no differently than other kinds of mesh.