Abstract
Abstract This paper investigates the effect of curing time and aggressive environmental exposure on the mechanical performance of impregnated Carbon Fabric Reinforced Cementitious Matrix (CFRCM) composite. Following the recently published IIC-ES AC434 guidelines, saltwater, distilled water, alkali and acid resistance are investigated together with freeze-thaw cycles. Mechanical characterization is based on tensile uni-axial tests under deformation control of rectangular-base prismatic specimens. 28- and 60-day curing times are considered for the control environment as well as for saltwater and alkali resistance. Deformation is monitored via digital acquisition. Besides uni-axial tests, experimental results comprise optical and scanning electron microscopy, crack pattern analysis and failure mechanism assessment. Focus is set on the determination of the design limits for the composite system at failure for the tested environments and curing times. In particular, a comparison is drawn with established design criteria already coded for FRP systems, which introduce the concept of safety (or partial) factors. Environmental conversion factors are also defined and calculated on a statistical basis in a twofold manner, as a mean to determine the design strain and strength limits of exposed specimens from the control (unexposed) data. It is found that they provide a convenient method for assessing the composite vulnerability to the aggressive environments at different curing times.
Highlights
Fabric Reinforced Cementitious Matrix (FRCM) composite stands out as a new class of material available to the structural engineer for designing reliable and cost-effective strengthening and retrofitting systems for concrete and masonry structures
The effect of the aggressive environment and of the curing time on the mechanical performance of impregnated carbon-FRCM prismatic coupons is assessed according to the ICC guidelines
Aggressive environments may significantly reduce the design limits and should be carefully considered; in particular, the seawater and the alkaline environments are especially demanding in terms of performance degradation, while distilled water and hydrochloric acid produce no statistically significant effect; freeze-thaw cycles induce a small beneficial effect
Summary
Fabric Reinforced Cementitious Matrix (FRCM) composite stands out as a new class of material available to the structural engineer for designing reliable and cost-effective strengthening and retrofitting systems for concrete and masonry structures. A wide variety of materials may be adopted for the reinforcing fabric which may be grouped under several criteria: conventional materials, such as steel or glass, high-modulus materials, such as aramidic fibers (Kevlar), carbon fibers or synthetic polymers (Zylon, better known as polyphenylene-benzobisoxazole or PBO), low-modulus (polypropylene) or even natural fibers (straw, cellulose, hemp). All these technologies may be labeled together under the common heading of continuous fiber reinforcing material (CFRM), as opposed to randomly distributed discontinuous fiber reinforced materials, such as fiber reinforced concrete (FRC) [6, 22]
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