This paper presents the results of a study on the effects of Hydropel, one of waterproofing admixtures, on the strengths, absorption, shrinkage and resistance to sulphates of mortar and concrete and on the bleeding of concrete.
　From the results, it may be observed that Hydropel entrains so much air that the workability of either mortar or concrete is improved considerably, consequently resulting in reduction of bleeding, and that Hydropel-treated mortar and concrete are less absorptive than plain mortar and concrete. It may be also noticed that Hydropel has prominent adverse effects which reduce the strengths and increase the shinkage of mortar and concrete by considerable amount.
　The authors conclude that Hydropel may be employed as an admixture for the concrete, of which major function is assumed to be waterproofing, and suggest that the present dosage of Hydropel recommended by the producer contains too much adverse effects to be employed in concretes for marine structural members required to have high strengths.