This research introduces a new approach to healing millimeter scale cracks in concrete using Lysinibaccilus Sphaericus Bacteria () encapsulated in cellulose fibers. Cracking in concrete, particularly macroscopic cracking, can cause premature structural failure and reduce its lifespan, which is a critical industry challenge. While bacteria encapsulated in cellulose fibers have been used to heal cement mortar, the studies are limited to heal much narrower cracks. In this study, we integrate , known for its strong biocalcification abilities, with the protective environment of cellulose fibers, which are renewable and sustainable, for healing millimeter scale cracks in ordinary cement concrete. To understand the healing process, we firstly used a 3D-printed polymeric scaffold for preliminary observations of calcite precipitation, demonstrating the potential of bacteria-induced calcification in a controlled environment before applying these insights to concrete. We then studied the self-healing of concrete. Through mechanical testing, we identified the optimal concentration of cellulose fiber as 0.45 % by volume of mortar. Approximately 2.38 × 10 bacteria were immobilized in each gram of cellulose fibers. With cellulose fiber encapsulated , the test results show up to 25 % increase in compressive strength and split tensile strength. After crack healing, the self-healing concrete still has higher mechanical strength than the undamaged control concrete. Particularly, the self-healing concrete was able to heal cracks up to 2.5 mm wide in fully wet environments and 1.5 mm wide in wet-dry conditions. This research also highlights the resilience of bacteria carried by cellulose fibers against harsh environmental conditions, including high temperatures at 160 °C, ensuring the durability and applicability of the proposed self-healing concrete in diverse climates. Integrating cellulose fibers encapsulated into concrete represents a significant breakthrough in addressing the perennial problem of concrete cracking, offering a promising avenue for constructing durable and maintenance-free structures.

中文翻译：

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纤维素纤维携带微生物对混凝土宏观裂缝的自修复

这项研究介绍了一种使用封装在纤维素纤维中的球形赖氨酸芽孢杆菌 (Lysinibaccilus Sphaericus Bacteria) 来修复混凝土中毫米级裂缝的新方法。混凝土裂缝，特别是宏观裂缝，可能会导致结构过早失效并缩短其使用寿命，这是一个严峻的行业挑战。虽然包裹在纤维素纤维中的细菌已被用来修复水泥砂浆，但这些研究仅限于修复更窄的裂缝。在这项研究中，我们将以其强大的生物钙化能力而闻名的纤维素纤维与可再生且可持续的纤维素纤维的保护环境相结合，用于修复普通水泥混凝土中的毫米级裂缝。为了了解愈合过程，我们首先使用 3D 打印的聚合物支架对方解石沉淀进行初步观察，证明在受控环境中细菌诱导钙化的潜力，然后再将这些见解应用于混凝土。然后我们研究了混凝土的自修复。通过机械测试，我们确定纤维素纤维的最佳浓度为砂浆体积的 0.45%。每克纤维素纤维中大约固定有 2.38 × 10 个细菌。测试结果显示，封装纤维素纤维后，抗压强度和劈裂抗拉强度提高了 25%。裂缝愈合后，自愈混凝土仍比未损坏的对照混凝土具有更高的机械强度。特别是，自修复混凝土能够在完全潮湿的环境中修复宽达 2.5 毫米的裂缝，在干湿条件下修复宽达 1.5 毫米的裂缝。这项研究还强调了纤维素纤维携带的细菌对恶劣环境条件（包括 160°C 高温）的恢复能力，确保了所提出的自修复混凝土在不同气候下的耐用性和适用性。将纤维素纤维封装到混凝土中是解决混凝土开裂这一长期问题的重大突破，为建造耐用且免维护的结构提供了一条有前途的途径。