Biodeterioration of concrete in agricultural, agro-food and biogas plants: state of the art and challenges

Abstract

This article reviews the state of knowledge on the mechanisms of deterioration of concrete by agricultural and agro-industrial effluents, notably breeding effluents and biowaste valorised in anaerobic digestion plants. The main physicochemical characteristics of agricultural effluents are first listed in terms of components that are aggressive for cementitious materials. Then, the main mechanisms of deterioration of the cementitious materials exposed to the effluents are presented, as highlighted by laboratory studies (synthetic effluents and / or models, specific experimental devices) or with real effluents. The paper also points out the scientific and technical advances needed to improve the durability of concrete in these environments.

Cementitious materials in biogas systems: Biodeterioration mechanisms and kinetics in CEM I and CAC based materials

“…As for agricultural and agro-industrial buildings, concrete is the material the most commonly used for the construction of biogas plants. This is related not only to its low cost and ease of implementation but also to its air-and water-tightness and its good thermal inertia [5,6]. However, in digesters, structural concrete is directly in contact with both the liquid and gas phases of the digesting biowaste, which are aggressive to concrete [7,8].…”

“…The microorganisms involved may organize themselves as a biofilm on the surface of the material [27] and induce very high local concentrations of aggressive agents, accentuating the deterioration [7,28]. In this context, the concrete undergoes deterioration resulting in increased porosity and reduced impermeability, leading to a greater risk of reinforcement corrosion [6,29]. Damage to the structures could lead to both important economic and environmental impacts such recovery of a smaller amount of biogas, pollutant flows nearby the plant, and the need for repairs.…”

Evaluation of microbial proliferation on cementitious materials exposed to biogas systems

“…European policy currently supports the development of biogas systems to ensure the transition towards greener energy systems and the associated financial support has made the biogas sector a potentially attractive organicwaste recovery industry. In the dynamic biogas market, concrete has established itself as a suitable construction material thanks to its economic interest, its airtightness and its high thermal inertia [1,2].…”

“…However, in contact with biowaste, concrete structures are subject to deteriorations at every stage of biogas production because of the chemical compounds excreted by the microorganisms (volatile fatty acids, NH4 + , CO2, etc. [2][3][4] and because the biological compounds form biofilms at the concrete surface and may create very aggressive local conditions [3,5]. The impact of these deteriorations on biogas plants may be both economic (loss of productivity, repair costs, etc.)…”

Wide-range optical pH imaging of cementitious materials exposed to chemically corrosive environments

“…triggered by concrete -environmental interactions (e.g. aggressive solutions or gases), are directly associated with decreasing pH in the internal pore solutions and the external fluids [1][2][3][4]. In this perspective, detailed knowledge of pH distribution and associated pH gradients is crucial to gain a holistic process understanding of the different corrosion mechanisms and kinetics, to advance towards the development of sustainable concrete-based infrastructure.…”