Investigation of Properties of High-Performance Fiber-Reinforced Concrete: Very Early Strength, Toughness, Permeability, and Fiber Distribution

About the report:

Concrete cracking, high permeability, and leaking joints allow for intrusion of harmful solutions, resulting in concrete deterioration and corrosion of reinforcement in structures. The development of durable, high-performance concretes with limited cracking is a potential solution for extending the service life of concrete structures. Further, the use of very early strength durable materials will facilitate rapid and effective repairs, reduce traffic interruptions, and decrease long-term maintenance work.

The purpose of this study was to develop low-permeability durable materials that could achieve a very early compressive strength of 3,000 psi within 10 hours. Within the scope of this work, various proportions of silica fume and fly ash and steel and polypropylene fibers were used to evaluate crack control and post-cracking performance. Other characteristics including toughness, residual strength, water permeability of cracked concrete, and fiber distribution were also examined.

The study showed that very early strength durable concretes can be achieved with proper attention to mixture components (amounts of portland cement and accelerating admixtures), proportions (water–cementitious materials ratio), and fresh concrete and curing temperatures. Fiber-reinforced concretes with steel fibers had considerably higher toughness and residual strength compared to concretes with polypropylene fibers. Permeability work showed that minor increases in crack width caused large increases in infiltration of solutions. Further, the addition of fibers can facilitate crack width control. An investigation of fiber distribution showed preferential alignment and some clumping of fibers in the specimens and highlighted the need for appropriate specimen size selection, sufficient mixing time, and proper sequencing of concrete ingredients into the mixer for a uniform random fiber distribution.

The results indicated that very early strength and durable fiber-reinforced concrete materials can be developed to improve the condition of existing and new structures and facilitate rapid, effective repairs and construction. The addition of fibers enables cracking control. Optimization of mixtures for strength and durability at different ages for specific applications is recommended.

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