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

Concrete cracking, high permeability, and leaking joints allow harmful solutions to intrude into concrete, resulting in concrete deterioration and corrosion of reinforcement. The development of durable concrete with limited cracking is a potential solution for extending the service life of concrete structures. Optimal design of very early strength (VES) durable materials will facilitate rapid and effective repairs and thus reduce traffic interruptions and maintenance work. The purpose of this study was to develop low-cracking durable materials that could achieve a very early compressive strength of 3,000 pounds per square inch within 10 h. Various proportions of silica fume, fly ash, steel fibers, and polypropylene fibers were used to evaluate concrete durability and postcracking performance. In addition, toughness, residual strength, permeability of cracked concrete, and fiber distribution were examined. VES durable concretes could be achieved with proper attention to mixture components (amounts of portland cement and accelerating admixtures), proportions (water–cementitious material ratio), and fresh concrete and curing temperatures. Permeability values indicated that minor increases in crack width, greater than 0.1 mm, greatly increased infiltration of solutions. Adding fibers could facilitate control of crack width. An investigation of fiber distribution showed preferential alignment and some clumping of fibers in the specimens and highlighted the need for sufficient mixing and proper sequencing of the addition of concrete ingredients into the mixer to ensure a uniform random fiber distribution. Results indicated that VES and durable fiber-reinforced concrete materials could be developed to improve the condition of existing and new structures and facilitate rapid, effective repairs and construction.