PMID- 34640062
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20211016
IS  - 1996-1944 (Print)
IS  - 1996-1944 (Electronic)
IS  - 1996-1944 (Linking)
VI  - 14
IP  - 19
DP  - 2021 Sep 29
TI  - Microbial-Induced Carbonate Precipitation Improves Physical and Structural 
      Properties of Nanjing Ancient City Walls.
LID - 10.3390/ma14195665 [doi]
LID - 5665
AB  - The preservation and restoration of heritage sites have always been of key focus 
      in the field of cultural relics. Current restoration methods mainly involve 
      physical or chemical techniques, which are in many cases intrusive, destructive, 
      and irreversible. Hereby, we introduce a novel biological strategy 
      (microbial-induced carbonate precipitation (MICP)) to repair natural and 
      simulated surface cracks on six hundred years' old wall bricks (part of the 
      Nanjing City Min Dynasty ancient wall, China). X-ray micro computed tomography 
      (X-ray micro-CT) was employed to non-destructively visualize the internal 
      structure of the MICP-treated brick cubes. The results showed that MICP can 
      effectively repair both natural and simulated cracks present on the brick's 
      surface. The compressive strength of the MICP-treated brick cubes was 
      significantly higher than that of the untreated control cubes (33.56 +/- 9.07 vs. 
      19.00 +/- 1.98 kN, respectively). MICP significantly increased the softening 
      coefficient and decreased the water absorption rate (p < 0.05), indicating that 
      the water resistance of the wall bricks can be improved after treatment. The 3D 
      images from X-ray micro-CT, a method that could non-destructively assess the 
      internals of such cultural structures, showed that MICP can effectively repair 
      ancient relics, promoting durability and limiting degradation without affecting 
      the structure. X-ray diffraction analyses showed that MICP generates the same 
      calcite form as that of original bricks, indicating that MICP filler is 
      compatible with the ancient city wall brick. These findings are in line with the 
      concept of contemporary heritage preservation.
FAU - Mu, Baogang
AU  - Mu B
AUID- ORCID: 0000-0002-5589-5345
AD  - School of Civil Engineering, Southeast University, Nanjing 211189, China.
AD  - Key Laboratory of Urban and Architectural Heritage Conservation of Ministry of 
      Education, Southeast University, Nanjing 210096, China.
FAU - Gui, Zheyi
AU  - Gui Z
AD  - School of Civil Engineering, Southeast University, Nanjing 211189, China.
FAU - Lu, Fei
AU  - Lu F
AD  - School of Civil Engineering, Southeast University, Nanjing 211189, China.
FAU - Petropoulos, Evangelos
AU  - Petropoulos E
AD  - School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
FAU - Yu, Yongjie
AU  - Yu Y
AUID- ORCID: 0000-0002-6454-8986
AD  - School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
AD  - School of Applied Meteorology, Nanjing University of Information Science & 
      Technology, Nanjing 210044, China.
LA  - eng
GR  - 2019YFC1520700 and 2019YFC1520901/National Key R&D Program of China/
PT  - Journal Article
DEP - 20210929
PL  - Switzerland
TA  - Materials (Basel)
JT  - Materials (Basel, Switzerland)
JID - 101555929
PMC - PMC8510088
OTO - NOTNLM
OT  - MICP
OT  - X-ray micro-CT
OT  - ancient wall bricks
OT  - restoration of cultural relics
COIS- The authors declare no conflict of interest.
EDAT- 2021/10/14 06:00
MHDA- 2021/10/14 06:01
PMCR- 2021/09/29
CRDT- 2021/10/13 01:09
PHST- 2021/08/31 00:00 [received]
PHST- 2021/09/26 00:00 [revised]
PHST- 2021/09/26 00:00 [accepted]
PHST- 2021/10/13 01:09 [entrez]
PHST- 2021/10/14 06:00 [pubmed]
PHST- 2021/10/14 06:01 [medline]
PHST- 2021/09/29 00:00 [pmc-release]
AID - ma14195665 [pii]
AID - materials-14-05665 [pii]
AID - 10.3390/ma14195665 [doi]
PST - epublish
SO  - Materials (Basel). 2021 Sep 29;14(19):5665. doi: 10.3390/ma14195665.