Investigation of Fiber-Reinforced Self-Consolidating Concrete

About the report:

The rising cost of materials and labor, as well as the demand for faster construction, has prompted development of cheaper, faster alternatives to conventional building techniques.  Self-consolidating concrete (SCC), a high-performance concrete characterized by its ability to flow without segregation under its own weight, promises to speed construction while reducing the need for skilled labor.  However, experience has shown that SCC may be prone to shrinkage cracking, which may compromise its durability.  In conventional concrete, fiber reinforcement has been used to control cracking and increase tensile and flexural strength. 

This study evaluated the feasibility of fiber-reinforced SCC (FR-SCC) for structural applications.  Tests were conducted in the laboratory to assess the fresh and hardened properties of FR-SCC containing various types and concentrations of fibers.  The results indicated that an SCC mixture can be prepared for use in transportation facilities that combines the properties of a high flow rate and some residual strength that would be beneficial for crack control.  The residual strength is contributed by the internal fibers and provides load-carrying capacity after initial cracking of the concrete.  At optimum fiber additions, FR-SCC mixtures can have the same fresh concrete properties as traditional SCC mixtures.  FR-SCC also demonstrated a considerable improvement in the residual strength and toughness of a cracked section, which is expected to lead to the control of crack width and length.  The improved performance of the FR-SCC cracked section indicated that it can be expected to have more durability in service conditions than would an identical SCC with no reinforcement. 

The study recommends that the Virginia Department of Transportation’s Structure & Bridge Division evaluate FR-SCC in field applications such as link slabs and closure pours in continuous concrete decks; formed concrete substructure repairs; or prestressed beams where end zone cracking has been an issue.  In such applications, construction with FR-SCC has the potential to be faster than with SCC, as traditional steel reinforcement may be reduced or eliminated, yielding reduced labor and materials costs for reinforcement placement.  Enhanced public and worker safety may result from the reduction of overall construction time and required maintenance of traffic.  The next step toward implementation of this technology would involve coordination with VDOT’s Materials Division and Structure & Bridge Division to create special provisions or standard specifications regarding the use of FR-SCC and to identify candidate projects for field trials.

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