Evaluation of the freeze-thaw resistance of concrete incorporating waste rubber and waste glass

In this paper, a systematic evaluation of the freeze-thaw (F-T) resistance of concrete containing waste rubber (WR) and/or waste glass (WG) was performed. Fine aggregates were replaced separately with crumb rubber (CR), glass powder (GP) and a mixture of both, and substitution rates varied from 0 to 15 % by volume. All mixtures were subjected to 25, 50, 75 and 100 F-T cycles, respectively. After reaching the desired number of F-T cycles, changes in the appearance, mass, dynamic modulus, degree of internal damage, and compressive strength of the degraded mixtures relative to the pre-freeze-thaw (Pre-F-T) condition were observed or measured. Results indicated that compared with plain concrete, rubberized concrete had superior F-T resistance but lower Pre-F-T strength. Although glass concrete may be less impressive than rubberized concrete in F-T resistance, it offered better mechanical strength and a denser microstructure. However, the incorporation of GP failed to mitigate the apparent damage and mass loss of concrete in F-T environments. Besides, the long-term F-T durability of glass concrete may be questioned, as evidenced by a sharp deterioration in nearly all of its parameters during 75-100 F-T cycles. For the combined mixtures, 15% CR and 10% GP have been proved to be a reasonable combination for maximizing the F-T resistance of concrete. Finally, scanning electron microscopy (SEM) was employed to reveal the mechanisms of CR and GP action in F-T environments at the microscopic level. In summary, CR and GP are materials worth considering in concrete preparation to improve its F-T resistance.