Mechanical and durability characteristics of pervious concrete reinforced with mechanically recycled carbon fiber composite materials

A more durable pervious concrete was produced using mechanically processed carbon fiber composite scraps from the aerospace industry, referred to as cured carbon fiber composite materials (CCFCMs). The processed CCFCM were fiber-like shreds with large aspect ratios and were a composite of carbon fibers reinforcing the thermoset resin. CCFCMs were used as 0.5, 1, 2 vol% replacement of natural coarse aggregate in a low-porosity (well packed) pervious concrete with pea gravel. Mechanical and durability evaluation was performed compared to two baseline mixes, a neat mix with zero CCFCM (control) and a mix with 0.5 vol% replacement with commercial synthetic fibers (POLY-0.5). CCFCMs disturbed the packing arrangement of natural aggregate and resulted in higher porosity. Mechanical properties increased with more amounts of CCFCM due to bridging actions of high-aspect-ratio elements and reached similar or higher flexural strength than the control at 1 and 2 vol%. CCFCM had similar or higher mechanical properties than POLY-0.5, except the synthetic fibers increased the flexural toughness index by 85% compared to the maximum 53% increase by CCFCM. The most significant enhancement was with CCFCM-1 and 2 vol% in rapid freeze–thaw cycling and deicer chemical application evaluation. CCFCM-2 maintained 95% of its original mass and 77% of the initial dynamic modulus after more than 200 cycles. The incorporation of CCFCM as a replacement of natural aggregate shows a high potential for previous concrete while creating a new use for this high-volume waste from the automobile and aerospace industries for a circular economy.