Microstructural Study of the Interface of Polyolefin Fibers Embedded in Self-Compacting Concrete Matrices with Bond Improver Admixture

Abstract

In recent years the plastic industry has developed a new type of synthetic macrofiber based on polyolefins that complies with the requirements of existing standards in considering contributions of fibers in the structural design of reinforced concrete (RC) elements. In meeting such requirements, the possibility of improving the results with lower fiber dosages by means of an admixture could provide new advantages. A previous study incorporated a bond improver admixture that increased the postcracking strength that appears after the first decrement of the load by 44%. At that time, the theoretical mechanisms of the admixture remained under discussion. The present research assessed the changes introduced by the bond improver admixture that enhance such residual flexural strengths. Pull-out tests and microstructural analysis of polyolefin fibers embedded in a concrete matrix of a previous study were taken as a reference. Therefore, specimens were manufactured with the same concrete mix and sizes. The bond improver admixture was added in some of them. Pull-out tests showed that the maximum load for extraction was lower with the admixture, although the overall energy of extraction was higher. Additional specimens were analyzed to assess the role of the bond improver admixture in the hydration process.