Microbial Mediated Deterioration of Reinforced Concrete Structures

International Biodeterioration & Biodegradation 64 (2010) 748e754 Contents lists available at ScienceDirect International Biodeterioration & Biodegradation journal homepage: www.elsevier.com/locate/ibiod Microbial mediated deterioration of reinforced concrete structures Shiping Wei a,b,*, Mauricio Sanchez c, David Trejo d,**, Chris Gillis b a School of Ocean Sciences, China University of Geosciences, Beijing, China b Department of Plant Pathology and Microbiology, Texas A&M University, USA c Department of Civil and Environmental Engineering, Universidad de Los Andes, Bogota, Colombia d School of Civil and Construction Engineering, Oregon State University, Corvallis, OR, USA article info abstract Article history: Biogenic sulfuric acid corrosion is often a problem in sewer pipelines, compromising the structural Received 15 February 2010 integrity by degrading the pipeline’s concrete components. We investigated the microbial populations in Received in revised form deteriorated bridge concrete, with samples taken from bridge concrete both above the water level and in 5 September 2010 adjacent soils. Total counts of microbial cells indicated a range of 5.3 Æ 0.9 Â 106 to 3.6 Æ 0.3 Â 107 per Accepted 6 September 2010 gram of concrete. These values represent the range from slightly to severely deteriorated concrete. From Available online 28 September 2010 severely deteriorated concrete samples, we successfully enriched and isolated one sulfur-oxidizing bacterium, designated strain CBC3. This strain exhibited strong acid-producing properties. The pH of the Keywords: Concrete deterioration pure culture of CBC3 reached as low as 2.0 when thiosulfate was used as the sole energy source. 16S rDNA Bridge supports sequence analysis revealed that the isolated strain CBC3 was close to members of Thiomonas perometablis Thiomonas perometabolis with 99.3% identity. Fluorescent In Situ Hybridization (FISH) analysis of significant numbers of sulfur- Enrichment culture oxidizing bacteria from deteriorated concrete indicated that T. perometablis was the dominant acidophilic FISH bacterium, comprising 32.0% of the total active bacteria in the severely deteriorated concrete. Semi- continuous cultures of T. perometablis CBC3 and Thiomonas intermedia were used to evaluate the biodegradation of cement samples. A weight loss of up to 5.7% was observed after 3 months, compared with a weight loss of 0.3% in non-inoculated control. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction deterioration has begun to emerge. First, when sufficient moisture and nutrients are available sulfur-oxidizing microbes colonize Concrete corrosion has an enormous economic impact world- concrete surfaces. Alkaline-tolerant microbes participate in these wide, since most wastewater systems and bridges are concrete. early colonization events because the pH of non-deteriorated Corrosion severely compromises the structural integrity of these concrete surfaces is high (pH 12). Second, biogenic oxidation of concrete components, costing millions in repairs. Understanding of sulfur on concrete lowers the surface pH and creates conditions for the fundamental corrosion process and the causative agents will further microbial colonization by neutrophilic and/or acidophilic help us develop a corresponding strategy to inhibit the concrete organisms. Typically, Thiobacillus spp. (including Thiobacillus thio- corrosion process. parus, Thiobacillus novellus, Thiobacillus neapolitanus, Thiobacillus Microbiologically Induced Deterioration (MID) of materials intermedius and Thiobacillus thiooxidans) play key roles in these constitutes a significant problem in several industries, including the colonization events (Rigdon and Beardsley, 1956; Mori et al., 1992). wastewater treatment and transportation industries (Islander et al., Fungal species may also participate in these processes (Cho and 1991; Davis et al.,1998; Peccia et al., 2000; Vincke et al., 2001; Okabe Mori, 1995; Gu et al., 1998; Nica et al., 2000). Finally, microbial et al., 2007). An understanding of the biological and physicochem- growth further reduces the surface pH of concrete, thereby leading ical processes associated with microbiologically-induced concrete to significant biogenic release of polythionic and sulfuric acid (Rigdon and Beardsley, 1956; Milde et al., 1983; Sand, 1987; Diercks et al., 1991; Islander et al., 1991). This biogenic release of * Corresponding author. School of Ocean Sciences, China University of Geo- acid degrades the cementitious material in concrete, thereby sciences, 29 Xueyuan Rd., Beijing 100083, China. Tel.: þ86 10 82334704; fax: þ86 10 generating gypsum (CaSO4 of various hydration states) (Mori et al., 82320065. 1992), and possibly ettringite (3CaO$Al O $CaSO $12H Oor ** Corresponding author. Tel.: þ1 541 737 9304; fax: þ1 541 737 3052. 2 3 4 2 $ $ $ E-mail addresses: [email protected] (S. Wei), david.trejo@oregonstate. 3CaO Al2O3 3CaSO4 31H2O), which possess expansive properties. edu (D. Trejo). The conversion of concrete to gypsum and ettringite weakens the 0964-8305/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.ibiod.2010.09.001 S. Wei et al. / International Biodeterioration & Biodegradation 64 (2010) 748e754 749 structural integrity of concrete, and eventually can lead to structural Situ Hybridization (FISH) provides an alternative approach towards failure. quantitative population analysis in these environments (Schrenk MID of the concrete of sewer systems provides the most thor- et al., 1998; Edwards et al., 1999; Hernandez et al., 2002; Okabe oughly studied example of biogenic concrete deterioration. The pH et al., 2007; Peccia et al., 2000), and studies using this approach of undeteriorated concrete is approximately 12; little microbial have suggested that sulfur-oxidizing microorganisms likely are activity occurs at such a high pH (Sand et al., 1987). However, the responsible for promoting sulfuric acid production in sulfide rich pH of alkaline concrete surface is gradually reduced by carbonation environments. To visualize the biodeterioration, a chemical method and neutralization of hydrogen sulfide, which buildup in the sewer is often used to assay the released gypsum (Minteny et al., 2000; systems (Zhang et al., 2008; Nielsen et al., 2005; Matos and Aires, Vincke et al., 1999; Aviam et al., 2004), and a simulation chamber 1995; Lahav et al., 2004). Biological oxidation of hydrogen sulfide is used to assay the weight lost (Sand et al., 1987; Mori et al., 1992; can occur at the sewer surface exposed to sewer atmosphere Vincke et al., 1999). Here, we used both traditional and molecular (Vollertsen et al., 2008). When the pH approaches neutral, different biology methods to characterize the active acidophilic bacteria aerobic and autotrophic Thiobacillus sp. colonize the concrete growing on concrete found in a deteriorated bridge support envi- surface and contribute to a successive oxidation of reduced sulfur to ronment. Specifically, we report the results of our systematic dissociated sulfuric acid (Devereux et al., 1989; Islander et al., 1991), analysis of the microbial contribution to concrete deterioration at which causes corrosion of the concrete. T. thioparus is the first to a bridge site in Texas. We find that the acid-producing bacteria colonize new pipe surface, but disappear as corrosion becomes likely play an important and underappreciated role in the concrete severe (Rigdon and Beardsley, 1956). When the pH continues to fall deterioration process. to moderate or weakly acidic conditions, T. novellus, T. neapolitanus and T. intermedius become established on the surface of concrete 2. Materials and methods (Milde et al., 1983; Sand, 1987). At pH below 5, T. thiooxidans start to grow and produce high amounts of sulfuric acid, causing the pH 2.1. Site selection and characterization drop as low as 1.5 (Sand and Bock, 1984). A positive correlation between the cell number of T. thiooxidans and the level of corrosion A bridge that spans the Navasota River in Texas (N305201000 and has been noted under these conditions (Milde et al., 1983). The E961103300) was selected as a case study. The field work included sulfuric acid produced by Thiobacillus sp. reacts with calcium collecting three concrete samples (concrete is made of mixing hydroxide presenting in concrete to form gypsum and ettringite. cement sand and water at weight ratio of 2:2:1) from the bridge The ettringite is an expansive product that leads to rising internal exhibiting slight to moderate surface deterioration (Fig. 1). The pressure that results in cracking. With the removal of the deterio- deteriorated and non-deteriorated concrete samples were collected fl rated materials by sewage ow, the concrete corrosion accelerates from the surface of the wall by scraping with a clean metal chisel (Mori et al., 1992). and transferring them to separate, sterilized containers. Non- Several approaches to addressing MID of concrete have been deteriorated concrete was collected from top of the wall as pursued. For example, protective coatings that create a physical a control. Samples were taken in May, 2008 to take into account barrier between corrosion susceptible concrete and the biologically variations in temperature. active environment have been employed. However, coatings can delaminate over time because of either improper preparation of the 2.2. Sample fixation concrete surface or inadequate and improper application in the field. Moreover, deterioration inducing bacteria can penetrate Immediately after

Load more