Influence of Sulfur Ions on Concrete Resistance to Microbiologically Induced Concrete Corrosion

Abstract

Concrete biodeterioration is defined as the damage that the products of microorganism metabolism, in particular sulfuric acid, do to hardened concrete. The combination of sulfur compounds and sulfur-dependent microorganisms is the origin of the process, because sulfates are found in certain groundwater, sewer and in sea water, additionally, some sulfur compounds are natural constituents of Portland cement. Along with this, the common presence and activity of microorganisms plays a very important function in the whole spectrum of degradation processes such as biodeterioration of metals and concrete. We report here the development of a possible biodeterioration resistant concrete. We assume that the elimination of sulfur compounds and acid reactive materials in the Portland cement and aggregates will prevent the formation and action of the biogenic acids that cause dissolution of calcium-containing minerals [for a narrative in Spanish see (Rendon, ¿Que es el biodeterioro del concreto? Revista Ciencia de la Academia Mexicana de Ciencias, Vol. 66 Num. 1. http://www.revistaciencia.amc.edu.mx/images/revista/66_1/PDF/Biodeterioro.pdf, 2014)]. This study was carried out on site inside a wastewater sewer drainage in Mexico City. Concrete samples whose main characteristic was being formulated without any sulfur or sulfates in its composition as well as reference concrete samples made with Ordinary Portland Cement (OPC) were used for the experiment. The weight changes and surface changes of both concrete samples were valuated after 7-month exposition to the biodeterioration process. The results obtained on site suggest that both the composition of concrete and duration of aggressive environment are very important. This possible biodeterioration-resistant concrete could give a viable solution to the long known problem of microbiologically induced concrete corrosion (MICC) a typical case of biodeterioration. Furthermore, we recommend the Portland type cement Mexican norm (ONNCCE, Organismo Nacional de Normalización y Certificación de la Construcción y Edificación, S.C. (2004) Norma Mexicana (NMX – C – 414 – ONNCCE - 2004) Diario Oficial de la Federación 27 de julio de 2004, 2004) which does not take into consideration the concrete biodeterioration variable and its mechanism, to be reviewed in this aspect, or at least that a warning be issued as a key measure to mitigate biodeterioration in sewer concrete infrastructure.