Research on mechanical properties, permeability and abrasion resistance of fibers modified recycled aggregate pervious concrete

Recycled aggregate pervious concrete are made by cement, water and recycled aggregates, which conforms to the concept of sustainable development, can be used to construction of the sponge city, and has important social and economic benefits. In order to study the application of fiber in recycled aggregate pervious concrete (RAPC), RAPC was prepared with waste prefabricated pavement concrete as the source of recycled aggregate, natural concrete pervious concrete (NAPC) was prepared as a comparison. Two series of fibers added in RAPC were designed, which contained 0.3%, 0.6%, 0.9%, 1.2% polypropylene fiber (PF), and 0.2%, 0.4%, 0.6%, 0.8% carbon fiber (CF) by volume fraction, respectively, RAPC without PF and CF showed as control group. With the experiment on test cubes under standard maintenance, compressive strength, splitting tensile strength, the continuous porosity, the permeability coefficient and the abrasion resistance were measured. The results showed that: 1) Compared with NAPC, the continuous porosity and permeability coefficient of RAPC are lower than those of NAPC, the compressive strength of RAPC has improved by 29.33%, the splitting tensile strength has reduced by 18.12%, the mass loss ratio of RAPC has improved by 11.26%; 2) By adding the fibers to RAPC, the continuous porosity with different volume fractions of fibers varies in a certain range. The continuous porosity of RAPC containing PF ranges from 18.6% to 20.8%, and that of RAPC containing CF ranges from 19.2% to 21.7%. In general, the permeability coefficient changes in a small rang with the changing of fiber content. The permeability coefficient of RAPC with PF ranges from 3.87-4.17 mm/s, and the permeability coefficient of RAPC containing CF ranges from 4.02 - 4.16 mm/s. The effects of PF and CF on the continuous porosity and permeability coefficient of RAPC are similar. 3) By adding PF in RAPC, compressive strength of RAPC is lower than that of control group. By adding CF in RAPC, compressive strength of RAPC increased first and then decreased with the increase of CF content. When the amount of CF up to 0.4%, the compressive strength reached a maximum value of 9.2 MPa which is higher than 14% that of control group. The splitting tensile strength increased first and then decreased with the increase of fiber content. For PF, when the amount of PF up to 0.6%, the compressive strength reached a maximum value of 2.0 MPa which is higher than that of control group (52.67%). For carbon fiber, when the amount of CF up to 0.4%, the compressive strength reached a maximum value of 1.78 MPa which is higher than that of control group (35.88%). 4) PF is better than CF for improving abrasion resistance. When the amount of PF up to 0.9%, the abrasion resistance reached a minimum value, which is lower than that of control group (41.2%). When the amount of CF up to 0.4%, the abrasion resistance reached a minimum value which is lower than that of control group (29.4%). 5) With the application of optimization theory, the optimum amount of PF in RAPC is 0.6%, and the optimal amount of CF in RAPC is 0.4%.The results can provide reference for the promotion and application of fiber-modified concrete and recycled aggregate pervious concrete. © 2019, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.