增强再生骨料固载混菌的混凝土裂缝自修复性能

Self-healing of concrete cracks by immobilizing non-axenic bacteria with enhanced recycled aggregates

  • 摘要: 为解决当前微生物载体与混凝土基体兼容性差和费用高等问题,提出了一种基于增强再生骨料固载混菌的裂缝自修复混凝土。首先明确再生骨料合理矿化增强时间及其对混凝土抗压强度的影响,然后考察基于增强再生骨料固载混菌的混凝土裂缝自修复效果及其裂缝填充物成分。试验结果表明:混菌矿化增强再生骨料的合理时间为7天,增强处理后再生粗骨料吸水率和压碎指标降低幅度分别达到27%和20%,混凝土抗压强度提高幅度达到12.9%;裂缝修复平均宽度和裂缝完全修复率经28天修复养护后均达到0.28 mm和60%以上,最大修复裂缝宽度达到1.26 mm;渗水系数比未修复时降低了99.7%以上;裂缝部位沉淀晶体呈规则方块状,晶体类型为方解石。

     

    Abstract: To solve the problems such as poor compatibility with the cementitious matrix and high cost of current bacterial carriers, a type of self-healing concrete by immobilizing non-axenic bacteria into recycled aggregate (RA) with enhancement was proposed. The reasonable enhancement time of RA and its effect on the compressive strength of concrete were first investigated. Then, the crack-healing capacity and the crack-filling precipitations of concrete immobilizing non-axenic bacteria were studied. The test results show that the reasonable enhancement time of the RA using biodeposition of non-axenic bacteria is 7 days. The water absorption and crushing index of recycled coarse aggregate (RCA) decrease by 27% and 20%, respectively. The compressive strength of concrete prepared with the enhanced RCA increases by 12.9%. After 28 days of healing, the average values of healed crack widths and completely healed percentages of cracks of the concrete specimens by immobilizing non-axenic bacteria into RA with enhancement are up to 0.28 mm and 60%. The maximum width value of healed cracks reaches 1.26 mm. The water permeability coefficients of the concrete specimens can decrease by up to 99.7% compared to that without crack-healing. The crack-filling precipitations of self-healing concrete by immobilizing non-axenic bacteria exhibit regular cubic shapes. The crystals of these precipitations are calcite.

     

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