微生物沉积碳酸钙修复水泥基材料表面缺陷

RESTORATION OF DEFECTS ON THE SURFACE OF CEMENT-BASED MATERIALS BY MICROBIOLOGICALLY PRECIPITATED CaCO_3

用涂刷技术,以琼脂作为载体将菌株和营养物质固载于水泥石表面,创造菌株生长、酶化和碳酸钙沉积的微环境,7d后能在水泥石表面紧密附着生成厚度100μm左右的碳酸钙膜,其表面吸水率可以降低到覆膜前的15%以下;同时将高浓缩菌株与砂基材拌合,并混合尿素和Ca2+,制备成浆体,注入到水泥石人造裂缝中,通过定时滴加修复营养液的方法,逐渐在裂缝砂粒之间矿化沉积出碳酸钙,最终将砂粒紧密胶结在裂缝内,达到裂缝修复的目的,28d抗压强度可恢复至84%,效果显著。通过涂抹工艺和注入工艺的实现,可在材料表面原位矿化沉积出方解石,增强了微生物修复在实际工程中应用的可操作性。

A CaCO3 layer was produced by brushing immobilized bacteria and nutriments onto the cement paste surface after 7 d. The deposited layer was about 100 μm and bound with the surface tightly. A carrier was used to immobilize the bacteria with agar, which could provide a microenvironment for bacterial growth, urea digestion and CaCO3 deposition. The experimental results show that the capillary water absorption of the treated specimens is 85% lower than that of the untreated specimens. Furthermore, by injecting ...