Study on Drying Shrinkage of Recycled Tyre Polymer Fiber Reinforced Concrete

To investigate the effect of recycled tyre polymer fiber (RTPF) on the drying shrinkage properties of concrete, dry shrinkage tests and analysis of the mechanism of fiber action were carried out on plain concrete, RTPF (volume fraction is 0. 1%, 0. 2%, 0. 4% and 0. 8%, respectively) concrete and 0. 1% polypropylene fiber (PPF) concrete. Results indicated that the slump of RTPF concrete with different contents decreases by 8. 1% ~62. 2%, and the air fraction increases by 11. 2% ~ 47. 9% as compared with plain concrete. The drying shrinkage rate of RTPF concrete increases rapidly at 0 ~7 d and then tends to be stabilized. The addition of RTPF reduces the early growth rate of the drying shrinkage of concrete. The drying shrinkage rate of concrete decreases initially and then increases with the increase of RTPF content. When the volume fraction of RTPF is 0. 2%, the concrete shows the minimum drying shrinkage rate. The drying shrinkage rates of RTPF concrete with different contents at 7 d and 28 d are 14. 2% ~ 36. 0% and 2. 9% ~ 27. 2%, respectively, which are lower than those of plain concrete. The drying shrinkage rate of PPF concrete is lower than that of RTPF concrete at the same volume fraction (0. 1%). In terms of the inhibiting concrete drying shrinkage, RTPF with a volume fraction of 0. 2% could replace PPF with a volume fraction of 0. 1% . The scanning electron microscope showed that RTPF could bond well with the concrete matrix and transfers the shrinkage stress of the concrete matrix. Finally, by comparing the test data and fitting value of drying shrinkage rate, a drying shrinkage calculation model suitable for RTPF concrete was obtained. © 2023 Northeastern University. All rights reserved.