Tan Xiaoyong,Zhang Jiupeng,Guo Dong,Sun Guoqing,Zhou Yingying,Zhang Wenwu
Cracks are the main challenges for asphalt pavement, which should be timely repaired. One of the most commonly used repairing methods is to fill the binding materials into cracks, but the repeated repairing ability is insufficient. The self-healing microcapsule technologies provide
the potentials for enhancing the repeated repairing ability of filling materials. Therefore, the microcapsule core material was selected from sunflower oil in this study, and the capsular wall material was selected from melamine-urea-formaldehyde resin, which was used to prepare the microcapsule
by using in-situ polymerization method. Three kinds of microcapsules with different particle sizes were prepared by adjusting the emulsifier dosage and core wall ratio. The microstructure, molecular structure, thermal stability, and dispersion features were further studied, and the
effects of microcapsules with different particle sizes on the repeated repairability of the filling materials were evaluated via the fatiguerepair-fatigue test. In addition, the traditional regenerative microcapsules were compared to determine the optimal particle size range for sunflower
oil microcapsules. According to the experimental research, it was thus concluded that the emulsion droplet size distribution was most concentrated when the emulsifier content was 0.7%; and when the core-wall ratio was 1.3:1, the microcapsules had uniform particle size and good dispersion effect.
When the microcapsule emulsification rate was 900 rpm and microcapsule content was 2%, then the repeated repair effect for the microcapsule crack filling materials was optimal. The sunflower oil type microcapsule therefore meets the filling temperature requirement for the filler.
Honglei Chang,Xiuyu Liu,Zhengkun Guo,Feng Guo,Jian Liu
Concrete, a widely utilized construction material, is prone to micro-cracking due to external loads and environmental factors, leading to water infiltration and structural deterioration. Conventional repair methods are time-consuming, whereas self-healing mechanisms typically necessitate prolonged durations to become effective. This study investigates the self-sealing performance of concrete blended with novel water-absorbent capsules containing superabsorbent polymers (SAP). The capsules were designed to prevent premature SAP expansion during the mixing and curing stages, thereby enhancing the material's self-sealing capability upon crack formation. The research evaluated the capsules' waterproofing performance, expansion characteristics, and dispersion, followed by permeability tests on concrete specimens with through-cracks. The effects of multiple factors, including capsule dosage, SAP content, water-cement ratio (w/c), and different molding methods (cast-molded and press-molded), were examined. The results demonstrated that double-walled capsules containing 5 % SAP achieved the optimal balance of waterproofing and swelling behavior. Compared to other mixtures, press-molded concrete incorporating 5 % capsules and 7 % SAP showed the most robust self-sealing capacity, reducing permeability by up to 55.2 % over 60 min and 95.7 % over 540 min separately, significantly outperforming cast-molded specimens, which showed a maximum reduction of 65.1 %. X-ray Computed Tomography (XCT) analysis confirmed that the SAP within the capsules absorbed water and expanded, filling cracks and reducing crack volume by 12.6 % when exposed to a 5 % CsCl solution. These findings highlight the potential of water-absorbent capsules as an effective strategy for autonomous crack sealing in concrete structures. The press-molded method, in particular, provides better control over capsule breakage and SAP release, leading to more effective and prolonged sealing performance.
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