A Case Study: Bacterial Surface Treatment of Normal and Lightweight Concrete - Biotechnologies and Biomimetics for Civil Engineering - page 353

Chapter 16
A Case Study: Bacterial Surface
Treatment of Normal and Lightweight
Concrete

H.K. Kim and H.K. Lee

Abstract Bacterial surface treatments for concrete have become increasingly
popular due to their strong potential to improve the durability of concrete struc-
tures for practical usage. Compared to bacteria inoculated into the cement matrix,
it is easier to provide the proper environment for bacteria when the bacteria are
applied onto the surface of the concrete. Moreover, the bacterial surface treatment
method has a number of advantages in comparison with conventional surface
treatment methods using polymer-based coating materials, including water
repellents or pore-blockers. Three advantages are as follows: (1) a similar thermal
expansion property between the microbially precipitated calcium carbonate and
the concrete surface, (2) environmentally friendly characteristics, and (3) the
potential for self-healing. A surface treatment, especially for lightweight concrete,
is very important to ensure good durability, as the durability of lightweight con-
crete is generally lower than that of normal concrete. In the present chapter, a
previous work of the authors, a study of the bacterial surface treatment of normal
and lightweight concrete (Kim et al. 2013 ) is reviewed and summarized. The
surfaces of normal and lightweight concrete specimens were treated with a liquid
medium containing bacteria. Macro- and micrographic assessments were done to
analyze the shapes and distribution of the calcium carbonate crystals. The capillary
water absorption of the concrete specimens was measured to evaluate the effects of
the bacterial precipitation of calcium carbonate on the moisture transport prop-
erties, as these properties were thought to affect the durability of the concrete.