Flexural and compressive creep behavior of UHPFRC specimens

Abstract

[EN] The long term behavior of Ultra High Performance Fiber Reinforced Concrete (UHPFRC) is analyzed in this study. The experimental campaign covered creep in compression and creep in flexure in cracked state. Three types of specimens were cast: cylindrical specimens (empty set100 x 200 mm) for compressive creep and shrinkage, and prismatic specimens type regular "R" (150 x 150 x 600 mm) and type slim "S" (150 x 40 x 600 mm) for flexural creep in cracked state. Specimens R were notched up to 50 mm in depth to weak the central section and then pre-cracked until 0.65 mm of Crack Mouth Opening Displacement (CMOD). Specimens S were pre-cracked unnotched until a loss of 50% of stiffness was observed. Flexural creep tests were performed during 270 days under load, and until 360 days the compressive tests. Measurements from three experimental sources were obtained: CMOD, compressive strains on top of prismatic specimens and longitudinal compressive strains in cylindrical specimens. Creep coefficients and parameters related with deferred deformations velocity were obtained from all three sources. Creep coefficients under flexure at 270 days ranged from 0.62 to 1.20 in the tensile zone, and from 0.72 to 0.90 in the compressive zone. Creep coefficient in compression at one year was 1.07, which is consistent with values found in the literature. Deferred deformations velocities at early ages were greater in specimens R than in specimens S, and a secondary creep stage was achieved in all specimens after 210 days of sustained loading.