Significance and Use
4.1 As described in Guide C1894, the MIC of concrete is considered to be a three-stage process with the reduction in pH (Stage I) (for example, 12.5 > pH > 9-10), the establishment of biofilms which further lowers the pH (Stage II) (for example, 9-10 > pH > 4-6) and eventual deterioration due to biogenic acid exposure (Stage III) (for example, < ~4 pH). This standard provides standard test methods to assess the effects of different stages of MIC on concrete products and efficacy of antimicrobial products used in or on concrete.
4.2 The tests are performed in simulated exposure solutions containing well-controlled bacterial strains that are grown in the laboratory. These tests do not require an environmental chamber and are intended to be performed as benchtop tests in biosafety level 1 laboratory conditions. These tests are suitable for simulation of the Stage II and III of MIC because the pH range of the solution can be controlled within the ranges of each stage.
4.3 This standard provides three test methods.
4.3.1 Test Method A is suitable for assessing the efficacy of antimicrobial admixtures in delaying or preventing biogenic acidification in a nutrient-rich simulated wastewater exposure solution.
4.3.2 Test Method B is suitable for assessing the effectiveness of antimicrobial admixtures in a prescribed cementitious system (Option B1) or assessing the performance of different cementitious systems (Option B2) in delaying or preventing microbially-induced corrosion of concrete in the Stage II of MIC.
4.3.3 Test Method C is suitable for assessing the suitability of cementitious systems in delaying or preventing microbially-induced corrosion of concrete in the Stage III of MIC.
4.4 The results obtained by these test methods should serve as information to be used with Guide C1894 in, but not as the sole basis for, selection of a biologically-resistant material for a particular application. No attempt has been made to incorporate into these test methods all the various factors that may affect the performance of a material when subjected to actual service.
Scope
1.1 This standard presents test methods for the determination of the effects of biogenic acidification on concrete products and/or efficacy of antimicrobial products to resist microbially-induced corrosion (MIC) of concrete. In these tests, the biogenic acidification is achieved by sulfur-oxidizing bacteria (SOB) that can convert elemental sulfur or thiosulfate to sulfuric acid without the use of H2S gas.
1.2 This standard is referenced in the guideline document for MIC of concrete products. Guide C1894 provides guidance for microbially-induced corrosion of concrete products and an overview of where this test, and its options, can and should be used. This document is not intended to be a guideline document for MIC of concrete products.
1.3 This standard does not cover controlled breeding chamber tests, in which H2S gas is produced by bacterial activity and acidification is the result of the conversion of this H2S gas to sulfuric acid.
1.4 This standard does not cover chemical acid immersion tests, in which acidification is achieved by chemical sulfuric acid addition, not by bacterial activity. Testing protocols for chemical acid immersion are described in Test Methods C267 and C1898.
1.5 This standard does not cover tests that assess field exposure conditions or sewage pipe, concrete tank, or concrete riser network design.
1.6 This standard does not cover live trial tests where concrete coupons or other specimens are monitored in sewers.
1.7 The tests described in this standard should not be performed on concrete samples that have already been exposed to MIC conditions.
1.8 This standard does not cover concrete deterioration due to chemical sulfate attack, which is caused by the reaction of sulfate compounds that exist in wastewater with the hydration products of cement. Test methods for assessing sulfate attack are provided by Test Methods C452 and C1012/C1012M.
1.9 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.11 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
