INFLUENCE OF THERMOPLASTIC POLYMER TYPE ON INTERLAYER SHEAR STRENGTH BETWEEN EXOTHERMIC OVERLAYS AND EXISTING SUBSTRATES FOR RAPID BRIDGE DECK PROTECTION

Abstract

Interlayer bonding plays a key role in the long-term performance and durability of bridge deck overlay systems. Weak bonding between overlay and substrate layers can result in premature failures such as de-bonding[VS3.1], reflective cracking, slippage, and delamination. This study evaluated the influence of different thermoplastic fiber-reinforced polymer (FRP) tapes and woven polymer lattice systems on the interlayer shear strength (ISS) performance of asphalt-asphalt (A-A), portland cement concrete-portland cement concrete (PCC-PCC), and portland cement concrete-polymer concrete (PCC-PC) systems. In the pilot study, different thermoplastic FRP systems, including C-PA6, C-PA410, G-PETG, G-PP, and G-HDPE, were evaluated using the Louisiana Interlayer Shear Strength Test (LISST). In addition, lattice systems with different opening sizes were investigated in slab-scale specimens. The effects of polymer type, tack coat application, fiber orientation, heating condition, and lattice opening size were studied. The results demonstrated that polymer type and lattice geometry significantly influenced interlayer bonding performance. G-PETG exhibited the highest ISS performance in the asphalt pilot study specimens, while G-PP demonstrated the best performance in PCC-PCC specimens. In PCC-PC specimens, C-GPETG showed the highest ISS because of strong embedment within the polymer concrete overlay. For slab specimens, the 1 in. × 1 in. opening configuration consistently exhibited better performance than the 1 in. × 0.5 in. configuration. PETG-based systems showed better performance in concrete slabs, whereas HDPE-based systems performed better in asphalt slab specimens. Overall, the findings demonstrated that thermoplastic FRP reinforcement systems have strong potential for improving interlayer bonding and enhancing the durability of bridge deck overlay systems and multilayer pavement structures