Flexural Creep and Recovery of Fiber-Reinforced SCC - Testing Methodology and Material Performance

Abstract

Deferred strain and cracking under sustained loading can be more prominent in self-consolidating concrete (SCC) used in repair applications than conventional concrete given its higher paste content. Flexural creep and subsequent creep recovery were monitored over 19 months tests for SCC, fiber-reinforced SCC (FR-SCC), fiber-reinforced conventional vibrated concrete (FR-CVC), and fiber-reinforced self-consolidating mortar (FR-SCM). Synthetic and steel fibers were used. Expansive agent (EA) was employed in FR-SCC with synthetic fibers. Fiber volumes of 0.5% and 0.8% were used in FR-CVC/FR-SCC and FR-SCM, respectively. Restrained shrinkage was also determined. The overall creep performance was based on the control of deferred deflection, crack opening, and strain in steel and concrete. The use of fibers enhanced creep performance by 5 to 7 times compared to SCC. FR-SCC with steel fibers provided 45% higher creep performance than FR-SCC with synthetic fibers. The incorporation of EA in FR-SCC enabled 80% additional enhancement of creep performance. The FR-SCC and FR-SCM mixtures exhibited crack widths lower than 0.2 mm at service loads as high as 70% of nominal load. The creep recovery of the FR-SCC was on the order of 20% to 70%, regardless of mixture type. Flexural creep and restrained shrinkage tests indicated similar tendencies of concrete performance. The best performance was obtained for the FR-SCC made with EA, followed by FR-SCC, then SCC and FR-SCM.