Concrete Durability Improvement in a Sulfate Environment Using Bacteria

Using carbonate-producing bacteria is a promising novel technique to improvement of concrete characteristics. Durability of concrete in harsh environments such as sulfate exposure has been constantly an important issue. The intention of the current study is evaluation of durability improvement of concrete containing bacteria exposed to sulfate environment. To do so, seven groups of 70-mm concrete prisms were made using two different bacterial strains accompanied with mixing water; the effects of sulfate solution exposure on durability properties of tested specimens including mass variation, volume variation, water absorption, and compressive strength were then determined. Furthermore, seven groups of concrete discs with 100 mm diameter and thickness of 50 mm were prepared from the aforementioned batches to investigate the chloride permeability of bacterial concrete by rapid chloride permeability test (RCPT). The results indicated that bacteria incorporation in concrete reduces mass variation, volume variation (in higher ages), and water absorption; it also increases the compressive strength of the specimens. The results also showed that the 28-day compressive strength of the bacteria-containing concretes is about 20% more than that of the control specimens. Moreover, bacterial concrete have lower chloride penetration in comparison with the control specimens. (C) 2015 American Society of Civil Engineers.