Experimental study to evaluate the impact of bubble defects on the interfacial bonding properties of the self-compacting concrete filling layer

Abstract The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS III slab ballastless track structure. This study sought to enhance technical standards for evaluating interfacial bonding properties by suggesting the use of the splitting tensile strength to evaluate the impact of bubble defects. Specimens were fabricated through on-site experiment. The percent of each area of 6 cm 2 or more bubble defect was 0 in most of specimens. When the cumulative area of all bubble defects reached 12%, the splitting tensile strength value was 0.67 MPa, which exceeded the minimum required value of 0.5 MPa for ensuring bonding interface adhesion. Furthermore, when the cumulative area of all bubble defects reached 8%, the splitting tensile strength value was 0.85 MPa, which exceeded the minimum required value of 0.8 MPa, thereby overcoming the negative impact of each area of 10 cm 2 or more bubble defect. Additionally, keeping the cumulative area of each area of 6 cm 2 or more bubble defect below 6% ensured adequate bonding strength and reduced the occurrence of specimens with lower splitting tensile strength values.