With the increasing use of mineral additions to partially replace Portland cement, reaction mechanisms and the effects of chemical attack on material properties change. A recent study examined magnesium attack on a model low-carbon cementitious paste, but the influence of Mg concentration on the observed mechanisms remains unclear. To investigate this, a low-carbon model cementitious paste was exposed to 5 and 50 mmol/L MgCl2 solutions for few months, as well as in pure water, to assess its impact on leaching kinetics and mechanical properties. The increase in MgCl2 concentration, leads to a comparable phenomenology, only the deterioration rate increases with higher Mg levels. When immersed in pure water, the Ca leaching of the paste is more progressive, and the degraded depth is slightly lower than that of magnesium attack. Immersion in pure water appears to generate larger pores compared to magnesium attack and a higher reduction in EPSIM is observed.

Microbially induced concrete deterioration can be observed in wastewater transport and treatment infrastructures. The attack on the concrete usually occurs due to the production of H2S and thus the subsequent biogenic formation of sulphuric acid. Calcium aluminate-based materials have demonstrated a better resistance to the biogenic acid attack compared to Portland cement-based materials and thus can be used as coatings to protect the supported concrete of the wastewater treatment plant. Early age deformations and movements of the protected substrate can cause cracks in the structure which might propagate into the coating. The presence of cracks might act as a pathway for aggressive agents to reach the supported concrete and thus alter the protective role of the coating. However, the precipitation of newly-formed phases inside the crack can possibly slow down or stop their penetration. To investigate the coupling of biodeterioration and cracking, cracked and uncracked coated specimens were exposed during 3 months to the BAC test which simulates the aggressive exposure conditions observed in sewer networks and can be developed for different types of cementitious materials and mineral coatings. The composite specimens were cracked with different width ranges using the three-point bending test; one between 150 and 200 μm and the other between 400 and 500 μm. The quantities of calcium and aluminum leached from the exposed surfaces of different specimens showed no influence of the crack on this durability indicator for both width ranges. The SEM-EDS observations demonstrated the presence of a newly-formed phase in the crack opening, close to the exposed surface of the coated specimens, which could possibly prevent more deterioration being a physical barrier to the penetration of aggressive agents.

The graphical abstract shows the workflow detailed in the article. The data from the SISE-Eaux database are first retrieved as two separate files: a PLV file containing location, date and identification, and a RESULT file containing the analysed data. These files then undergo a preprocessing step consisting of reformatting, annual aggregation and data harmonisation. This unified database is then used to find correlations between analysed parameters, plot geochemical maps and perform non-parametric tests across a large number of parameters.Ensuring drinking-water quality is essential both for safe human consumption and for preserving water supply infrastructures. In France, distributed waters interact with a diverse materials, including metallic pipes, cement-based linings, asbestos-cement pipes, and polymeric networks, making the assessment of water aggressiveness particularly important. This study proposes a dedicated workflow for exploiting the nationwide SISE-Eaux regulatory database to analyse and visualise spatial patterns of drinking-water chemistry and aggressiveness across France. The approach combines data preprocessing, harmonisation of analytical fields, calculation of aggressiveness indices, annual aggregation at the municipality scale, and municipality-level spatial attribution. Using data from 2020 to 2022, the study examines the geographical distribution of major chemical parameters and four complementary aggressiveness indices: the Langelier Index, Ryznar Stability Index, Larson-Skold Index, and Basson Index. The results highlight regional contrasts in water chemistry, especially for calcium, hydrogenocarbonates, sulphates, chlorides, and pH, in relation to geological context. They also show that the different indices do not provide identical classifications, confirming the value of a multi-indicator approach when interpreting water aggressiveness at the national scale. The proposed workflow should therefore be understood as a reproducible exploratory framework for supporting the large-scale interpretation of drinking-water chemistry and potential water-infrastructure interactions.HIGHLIGHTSNational-scale assessment of drinking water aggressiveness in distribution networks. Comparison of corrosion and scaling indices using operational monitoring data. Strong geological control on water chemistry and aggressiveness patterns. Identification of index discrepancies for highly mineralised waters. Decision-support approach for corrosion and scaling management in water networks.

The durability of wastewater treatment plants has been a major concern for decades due to their significant economic and health importance. Structures built with concrete are subject to severe deterioration linked to aggressive chemical and biological exposure conditions. Portland cement concrete is particularly vulnerable to such attacks leading to major damages in the structures. One of the strategies to protect this concrete from the effects of biodeterioration is applying a thin coating based on calcium aluminate cement. These materials were proved to have a superior resistance to biodeterioration compared to ordinary Portland cement. However, the cracks initiated in the protected structure that might reach the coating raise questions on its ability to fulfill its protective role. This paper aims to study the effect of the crack on the durability of the coating using a biological laboratory test, the BAC test, which simulates the real conditions encountered in a sewer system. The calcium leached from the specimens exposed to the biogenic sulfuric acid attack was monitored in two campaigns of the BAC test. Each campaign was performed on reference OPC-based uncoated specimens and coated specimens with the CAC-based coating: uncracked and cracked with two ranges of crack width between 150 and 200 µm and between 400 and 500 µm. The leaching results demonstrate that the protective function was not altered by the effect of the cracks when comparing the reference uncoated specimen to the coated ones. The SEM-EDS observations show the existence of a newly-formed phase in the few hundreds of micrometers from the exposed surface of the coated specimens. This phase was composed mainly of calcium, sulfur and aluminum and was probably a mix of AH3 and ettringite. The formation of this phase near and inside the crack opening could possibly act as a physical barrier that prevents further deterioration.

Air scrubbers installed in livestock buildings play a critical role in mitigating ammonia and particulate emissions, thereby improving air quality and helping to meet environmental regulations. However, concrete structures within these systems exhibit premature degradation, posing financial risks to farmers. The mechanisms behind this degradation, as well as the composition of the runoff water, remain poorly understood. This study aims to analyse runoff water compositions over 12 months and to evaluate the degradation mechanisms of two types of altered concrete: XA2 (exposed for 12 months) and XF1 (exposed for 10 years), through microstructural, chemical, and mineralogical analyses. Techniques used include inductively coupled plasma/optical emission spectrometry (ICP/OES), high-performance ion chromatography (HPIC), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Results showed that the runoff water contained ammonium in large amount (up to 995 mg/L), sulphates (up to 338 mg/L), and magnesium (up to 54.5 mg/L), all of which are aggressive to concrete. These components led to leaching and carbonation of the panels, with the XF1 concrete also suffering from sulphate attack (expansive secondary ettringite) and magnesium attack. The XF1 and XA2 type concretes exhibited degraded depths of 15 mm and 5 mm, respectively, after 10 years and 12 months of exposure. The findings indicate that air scrubbers create highly aggressive environments for concrete, highlighting the need for more suitable materials, such as calcium aluminate cement coatings, to improve durability and prevent structural failure.

Despite asbestos bans in many industrialized countries, asbestos cement (AC) waste remains widespread, mostly landfilled due to high neutralization costs. This study evaluates biochemical treatment to reduce asbestos cement mass through matrix dissolution. Experiments used AC monoliths exposed to lactic acid-producing Lacticaseibacillus paracasei ssp. paracasei cultures at 30°C, with a solid-liquid ratio of 10 g/L. Over 7 days of biodegradation, bacterial metabolism maintained acidic conditions, counteracting the pH increase from dissolving alkaline phases such as calcite and C3S, resulting in 17-25 % mass loss. X-ray diffraction analysis confirmed selective dissolution of the cementitious matrix while preserving asbestos fibers. Geochemical modeling with PHREEQC revealed an initial pH spike due to surface neutralization, followed by steady dissolution kinetics without surface passivation. However, increasing reactive surface area excessively, such as by grinding, leads to rapid pH rises that trigger calcite re-precipitation, reducing process efficiency; thus, grinding is discouraged. While this approach shows promise as a pre-treatment to reduce asbestos-cement waste volume prior to final inertization, limitations include pH control and challenges associated with scale-up. Overall, this biodeterioration process provides a laboratory-scale proof of concept that could inform the future development of sustainable and cost-effective strategies for asbestos waste management.

Molds are frequent indoor contaminants, where they can colonize many materials. The subsequent aerosolization of fungal spores from moldy surfaces can strongly impact indoor air quality and the health of occupants. The investigation of fungal contamination of habitations is a key point in evaluating sanitary risks and understanding the relationship that may exist between the fungal presence on surfaces and air contamination. However, to date there is no “gold standard” of sampling indoor air for such investigations. Among various air sampling methods, impingement can be used for capturing fungal spores, as it enables real-time sampling and preserves analytical follow-up. Its efficiency varies depending on several factors, such as spore hydrophobicity, sampling conditions, etc. Sampling devices may also impact the results, with recovery rates sometimes lower than filtration-based methods. The Coriolis µ air sampler, an impingement-based device, utilizes centrifugal force to concentrate airborne particles into a liquid medium, offering flexibility for molecular analysis. Several studies have used this device for air sampling, demonstrating its application in detecting pollen, fungal spores, bacteria, and viruses, but it is most often used in laboratory conditions. The present case study, conducted in a moldy house, aims to investigate the efficiency of this device in sampling fungal spores for DNA analysis in indoor environments. The results obtained suggest that the use of this device requires an optimized methodology to enhance its efficiency and reliability in bioaerosol research.

Corrosion of steel in concrete is one of the major deterioration mechanisms for reinforced concrete (RC) structures such as floaters of floating offshore wind turbines (FOWTs). As these are vital components of FOWTs, addressing corrosion is critical to ensure their durability with minimal maintenance. The existing literature indicates that RC in the tidal zone can experience premature corrosion. To mitigate this, galvanic cathodic protection (CP) is a well-known approach for protecting RC structures. Therefore, a field experiment in the tidal zone was conducted to study the behaviour of aluminum anode CP for RC with CEM I and CEM V cement types across two concrete surface textures, smooth and rough. The half-cell potentials (HCP) (for specimens without CP), mixed potentials and protection current (for specimens with CP) were monitored continuously. Furthermore, the effect of water levels and biofilm on corrosion characteristics of steel in concrete and the efficiency of CP was assessed. The findings highlighted that the biofilm on the concrete surface acts as a physical barrier, limiting the diffusion of oxygen – affecting the corrosion characteristics of steel embedded in concrete. This influence was distinctly observed in both protected and non-protected categories. In the protected category, the average protection current was found to increase upon biofilm removal for CEM I concrete - indicating that the CP is efficient/or working with or without biofilm on the concrete surface. Finally, this paper highlights the importance of understanding how the presence of biofilm on concrete surfaces can affect the corrosion characteristics of steel embedded in concrete.

This paper discusses the performance of calcium sulpho-aluminate (CSA) cement and a Sulphate-Resisting Portland Cement (SRPC) with a fly ash (FA) additive (i.e., a SRPC + FA binder system) in a ‘live’ sewer environment; it deepens the understanding of their deterioration mechanisms by using a laboratory test for simulated sewer conditions. It also studies the role of an iron-based additive (‘Hard-Cem®’, HC) in improving the performance of SRPC + FA concrete under a biogenic acid attack. The performance of 0.4 w/b concrete specimens of the three binders (CSA, SRPC + FA, and SRPC + FA + HC) with calcite aggregates in sewer exposure was assessed by visual observation, measurements of mass and thickness changes, and microstructural analysis for approximately 25 months. The laboratory test, i.e., the Biogenic Acid Concrete (BAC) test, was used to study the deterioration mechanisms of these binders in terms of leaching solution pH and standardised cumulative leached calcium and aluminium. The results indicate that CSA concrete had improved performance in the sewer environment, showing no mass loss and only about one-third of thickness lost in the SRPC + FA concrete over a 25-month exposure period in the sewer environment. The BAC test results complemented the field observations. The iron-based additive in sewer concrete slightly reduced mass loss, likely due to its better resistance to abrasion and erosion, but not due to any chemical influence, since it does not participate in hydration or dissolution reactions. The findings imply that CSA cement may represent a suitable alternative binder for concrete sewer construction. They also suggest that a surface hardener has limited benefits, except when it is under abrasive conditions. Further investigation is required, especially since CSA contains high amounts of sulphate, the effect of which is not well understood.

The biodeterioration of concrete elements in sewer systems and their repair is of significant economic and societal concern. However, the available test methods to assess the performance of cementitious materials under the relevant conditions are insufficiently validated. In the present study, two biological test methods and a standardised chemical test were applied to two sewer repair mortars and a reference mortar, and the performances of these materials were compared in a severely deteriorating sewer environment. In both biological tests, the induction period was considerably shorter than that of the field, and time-resolved recording of durability indicators enabled to determine deterioration rates in the steady-state regime, which compared reasonably well with each other and with the behaviour in the sewer environment. The chemical test does not allow to obtain a deterioration rate, and the observed relative performance differences of the mortars deviated from the results of the biological tests.

In order to find an alternative to the more heavily regulated titanium dioxide (TiO2 P25) and to reduce the concentration of nitrogen oxide (NOx) in indoor environments, gold nanoparticles-decorated ZnO composite materials (Au/ZnO, 1 wt% Au) were successfully prepared by photodeposition (PD) or urea depositionprecipitation (UDP) methods. The resulting Au/ZnO catalysts showed excellent photocatalytic performance (around 40 %) for the degradation of 400 ppb nitrogen dioxide (NO2) at a laboratory reactor scale under UV-A irradiation as low as 0.1 W/m2 at 50 % relative humidity. The high activity was attributed to the Au-ZnO heterojunction formation, which significantly promoted the transfer of photogenerated holes from ZnO to Au and the water oxidation process on Au nanoparticles, improving the NO2 photocatalytic oxidation reaction due to a higher generation of OH center dot radical. The NO2 degradation was also investigated under realistic indoor visible light irradiation with NO2 concentrations found indoors (40 and 100 ppb). This work showed the prospects of applications of Au/ZnO materials in the field of indoor photocatalytic purification and gave a new insight into the study of ZnO-based composites for the photocatalytic degradation of NOx.

The durability of cover concrete in the submerged zone for floating offshore wind turbines is closely associated to the performance of the cement type used, which also plays a key role in the environmental impact of their construction and operation. A real-world study is conducted by simulating the concrete cover, submerging cementitious materials at a depth of 27 m in Banyuls-sur-Mer, located on the Mediterranean coast of France. The objective was to identify the short-term interactions between cementitious materials, biofilm developing at their surface, and seawater after 30- and 90 days exposure, with emphasis on, (i) the influence of cement type on the microbial composition of biofilm, and (ii) the influence of biofilm and seawater on the microstructural, chemical composition, and mineralogical changes within the cementitious matrix. After 30 days of exposure, scanning electron microscopy coupled to energy dispersive spectroscopy detected the formation of Mg- rich, S-rich, and Cl-rich zones in CEM I and CEM III concrete, while CEM V exhibited the same zonation after 90 days. These findings were corroborated by electron probe microanalysis. After 90 days of exposure, regardless of the cement type, calcium carbonate precipitated at the concrete-biofilm-seawater interface, predominantly in the form of aragonite crystals, as identified by X-ray diffraction analysis. In CEM I concrete, a brucite layer formed immediately beneath this CaCO3 deposit. The bacterial and eukaryotic diversity was identified using 16S rRNA and 18S rRNA sequencing, revealing diverse and dynamic communities over time. The macrofouling species, marine polychaetes (or serpulids), have been identified and considered to be biomineral in origin.

Due to the complex biogeochemistry of marine sedimentary systems, the burial depth of sedimentary electrodes significantly influences their bioelectrochemical activity. This study investigates the impact of burial conditions on sedimentary microbial electrodes in oxic and suboxic zones of reconstructed sedimentary systems was investigated. Carbon-felt electrodes were deployed in laboratory reactors filled with fresh marine sediments and seawater under three different exposure conditions. The results showed that the placement of electrodes, whether in sediments or in seawater, profoundly affected both the electrical current (anodic or cathodic) and the microbial communities colonizing the electrode biofilm. Electrodes placement in the transition zone between the oxic and suboxic zones led to the formation of microbial electrodes with hybrid bioelectrochemical properties. Analytical and numerical models were developed to calculate the ratio of anodic and cathodic surfaces operating at the scale of these sedimentary microbial electrodes.

The management of corrosion in reinforced concrete (RC) structures is crucial for addressing the challenges posed by aging infrastructure, particularly in marine environments where the aggressiveness of seawater can severely impact durability. This study explores a novel approach known as BioGalvanic Cathodic Protection (BGCP), inspired by Benthic Microbial Fuel Cells, for the electrochemical maintenance of RC exposed to marine corrosion. BGCP utilizes electroactive microorganisms naturally present in marine sediments to form bioanodes on conductive materials, which provide protective electrical currents to partially submerged RC structures. A pilot study involved a 3-m-high concrete pier, which was partially immersed in natural seawater and sediments with embedded bioanodes. The current distribution from the BGCP system to the steel was monitored for over a year under various configurations, including changes in steel surface area and the number of bioanodes, while simulating tidal variations and monitoring ambient temperature. Results indicated that BGCP effectively demonstrated cathodic prevention for passive steel, with improved performance observed when multiple bioanodes were utilized. Indeed, the total current density received by the steel was in the range of [-0.2;-2 mA/m2] at all times. The current distribution varied with tidal changes, peaking at the air/water interface. A notable correlation emerged between temperature and current output, suggesting better performance at elevated temperatures. Although CP has not yet been achieved on actively corroding steel, BGCP offers significant potential for delaying corrosion initiation through the development of a selfsustaining and environmental-friendly technology.

Calcium aluminate-based materials have shown high resistance to the chemical and biological attack in sewer systems and thus are used to protect Portland cement-based structures and increase their durability. In this direction, a protective calcium aluminate-based coating, designed to be sprayed in a thin layer onto newly built wastewater infrastructures, was developed by Imerys Aluminates. The question arises of the ability of the coating to maintain its protective function when a crack is initiated in the concrete support and possibly propagates into the coating. Several phenomena may develop and condition the behavior of the cracked aluminous coating, including the self-healing of the cementitious material and the penetration of micro-organisms to reach the substrate. To study this coupling of cracking and biodeterioration in the lab, a method for the generation of representative cracks was developed. The three-point bending test was performed on these coated mortars to initiate cracks with a specific opening width, to be maintained after unloading. Then, to understand the mechanisms of biodeterioration, cracked and uncracked specimens were exposed to the BAC test which reproduces biodeterioration conditions observed in sewer environments. The biodeterioration process was monitored in terms of analyses of the composition of the leached solutions to quantify the calcium and aluminum leaching. The superior resistance of the coated substrates was significantly proven. The presence of a crack in the coated substrates has no influence on the leaching species for the specific duration of the test.

In contact with natural waters, concrete can be exposed to the action of magnesium. Mg-attack on the cement paste leads to dissolution of cementitious phases and formation of brucite, hydrotalcite and/or magnesium silicate hydrates (M-S-H). The knowledge of the properties of the latter is limited. In binders with supplementary cementitious materials, M-S-H formation is favoured over that of brucite because of the lower contents of portlandite. To investigate the effects of a magnesium attack on such binders, a low Ca/Si model cement paste was immersed in a 5 mmol/L MgCl2 solution for several months. Energy-dispersive spectrometry analyses coupled with X-ray diffraction and electron probe microanalyses showed Ca leaching, Si preservation and Mg enrichment of the altered zones of the pastes corresponding to the dissolution of C-S-H and formation of M-S-H and amorphous silica. The Mg-enriched zone showed a lower residual Young's modulus than the sound zone as measured by microindentation.

Floating Offshore Wind Turbines (FOWTs) are designed to harness the energy produced by wind. Since these structures are in deep waters, the engineering and dynamics of steel and or concrete structural elements (floaters, chains, mooring, etc.) is important to ensure significant performance. The durability of concrete in submerged zones is affected by biological and chemical deterioration mechanisms, with the latter being controlled by transport of aggressive ions. The influence of concrete on biodiversity developing on its surface plays a significant role as it contributes to the overall environmental footprint of the structure. The aim of this experimental research was to identify the surface interactions between cementitious materials such as concrete, biofouling at their surface, and seawater on short-term exposure. CEM III concrete specimens were submerged at a depth of 27m at SOLA station, Banyuls-sur-mer, France. The microstructural and chemical changes in the cementitious material were analysed with scanning electron microscopy coupled to energy dispersive spectroscopy (SEM-EDS) and electron probe micro analysis (EPMA). The results of SEM-EDS analysis showed the formation of three zones, namely, magnesium-rich, sulfur-rich, and chloride-rich zones. Using Environmental DNA analysis, bacterial diversity was identified, revealing high abundances of alphaproteobacteria and gammaproteobacteria, and 18s rRNA sequencing unveiling a diverse eukaryotic community.

Exposure of concrete to various acids can hardly be overstated due to the widespread use of concrete in the construction industry. The effect of selected factors on the degradation of ordinary Portland cement (OPC 53 grade) paste and mortar exposed to acetic acid is investigated in this paper. Various test parameters such as mass loss, loss in cross-sectional area, relative dynamic elastic modulus (RDEM), loss in flexural and compressive strength are used to assess the selected factors and the results obtained are analysed to determine the most favourable test conditions for degradation, that can be adopted for developing an accelerated test method. The factors used for the investigation are replenishment of acid solution, concentration of acid solution, ratio of surface area of specimen to volume of liquid acid solution (S/L), shape of the specimen and nature of the specimen. This paper also investigates the interrelationships among test parameters and adopts interpretation of acid consumption to assess the aggressiveness of the acid solution. It was found that renewing conditions and high concentrations of acid solution (0.5 M) indicate rapid degradation. The aggressiveness of 0.125 M acetic acid solutions in renewing conditions is about 5 times that of non-renewing conditions respectively. The rate of degradation is inversely related to S/L ratio. Cylindrical specimens have a marginal increase in degradation than prismatic specimens. It is preferable to evaluate acid attack on mortar specimens rather than paste specimens due to higher loss in cross-sectional area and relative dynamic elastic modulus (RDEM).

Many concrete structures in aqueous environments suffer leaching, affecting their microstructure and durability. The resulting chemical and mineralogical degradation are difficult to predict over the long term and for environments of varying chemical composition, especially for severely degraded cement matrices. This is mainly because of the lack of chemical and thermodynamic data on the degraded phases formed during these attacks. In this context, this study aims to evaluate the chemical changes of leached ordinary Portland cement (OPC) paste by combining experimental (batch experiments) and modelling (thermodynamic equilibria calculations) approaches. The ground OPC paste was gradually added to an acetic acid solution. pH and chemical compositions of the solution were monitored throughout the experiment. The solid fraction was characterised over time, with particular attention paid to the phase obtained during the first additions. The latter was found to be an amorphous aluminosilicate gel (Al/Si = 0.3), with major contributions from Si Q4 and AlIV (obtained by 29Si and 27Al NMR analyses respectively). Existing databases (MINTEQ 3.0, Thermoddem, Cemdata) were first used in the thermodynamic simulation of the experiment using PhreeqC, which showed discrepancy with the experiment in the early stages of the attack. They were then improved by the addition of the Si-Al gel identified experimentally. The incorporation of the new phase enabled to better fit the experimental data. The calculated equilibrium constant of the gel at 20 degrees C (log Kgel = 0.37) was consistent with the equilibrium constants of similar Si-Al phases already explored in the literature.