Real Exposure Conditions Research Articles

Protective impact of Betanin against noise and scrotal hyperthermia on testicular toxicity in Wistar rat: Role of apoptosis, oxidative stress and inflammation

The heat exposure and white noise can induce damage on reproductive organs. The main objective of this study is to observe, if betanin administration could ameliorate oxidative stress, apoptosis and inflammation in testis of rodents following noise and scrotal hyperthermia exposure. Wistar rats were divided into 6 groups; control, betanin, noise, hyperthermia and two treatment groups. Scrotal hyperthermia model was performed by heat exposure of rat testicular (43 °C) for 15 min and 3 times per weeks for 14 days. Noise induction model was done following exposure of rats with 100-dB noise level for 14 days and 8 h daily similar to real exposure condition in human. Betanin was administrated at the sub-effective dose (15 mg/kg) by gavage route for 4 weeks (5 times a week) to male rats. The animals were euthanized and testis were dissected and stored at −80 °C. Then, the oxidative stress biomarkers (MDA and GSH), apoptosis (cytochrome c & Annexin V), and inflammatory cytokines (TNF-α & IL-6) were measured by the real time polymerase chain reaction (RT-PCR) of testis collected samples. The data output demonstrates the impact of noise and hyperthermia in testicular toxicity induction by mitigating oxidative damage, apoptosis and inflammatory mediators. Following treatment with 15 mg/kg per day of betanin, lipid peroxidation and GSH content have been modulated, and TNF-α and IL-6 gene expression has been declined. Our results revealed that in Wistar rats, betanin displays protective effects against noise and scrotal hyperthermia-induced acute testicular toxicity through the inhibition of oxidative stress, apoptosis, and inflammation.

Experimental evaluation of the temperature related behaviour of pigment based coloured BIPV modules integrated in a ventilated façade

Coloured BIPV installations require an accurate balance between aesthetic and energy aspects. This study explores the integration of Building Integrated Photovoltaic (BIPV) modules into building envelopes to enhance energy efficiency while maintaining aesthetic appeal. To achieve this goal, a real-scale mock-up was realized within the INFINITE project at the PV Integration Lab of Eurac Research to investigate the influence of aesthetic features (mainly given by different colors) on the energy performance of BIPV modules. Supported by an extensive monitoring campaign, this work delves into the performance of BIPV modules of five colors and finishes in both indoor and real exposure conditions. These modules serve as the outer layer of a prefabricated rain screen facade for building retrofitting. The study highlights that darker colors exhibit higher efficiency under standard test conditions but are also correlated with higher operating temperatures. Consequently, the differences in energy efficiency among the colors, observed during indoor tests, are significantly reduced when analyzing the energy produced under real exposure conditions. This observation underscores the intricate balance between maximizing energy generation and mitigating thermal stress on BIPV modules, while preserving aesthetic features. By providing empirical evidence of color-specific performance characteristics, this work offers insightful results for colored BIPV research and customized product optimization.

Kinetics and toxicity of nanoplastics in ex vivo exposed human whole blood as a model to understand their impact on human health

The ubiquitous presence of nanoplastics (NPLs) in the environment is considered of great health concern. Due to their size, NPLs can cross both the intestinal and pulmonary barriers and, consequently, their presence in the blood compartment is expected. Understanding the interactions between NPLs and human blood components is required. In this study, to simulate more adequate real exposure conditions, the whole blood of healthy donors was exposed to five different NPLs: three polystyrene NPLs of approximately 50 nm (aminated PS-NH2, carboxylated PS-COOH, and pristine PS- forms), together with two true-to-life NPLs from polyethylene terephthalate (PET) and polylactic acid (PLA) of about 150 nm. Internalization was determined in white blood cells (WBCs) by confocal microscopy, once the different main cell subtypes (monocytes, polymorphonucleated cells, and lymphocytes) were sorted by flow cytometry. Intracellular reactive oxygen species (iROS) induction was determined in WBCs and cytokine release in plasma. In addition, hemolysis, coagulation, and platelet activation were also determined. Results showed a differential uptake between WBC subtypes, with monocytes showing a higher internalization. Regarding iROS, lymphocytes were those with higher levels, which was observed for different NPLs. Changes in cytokine release were also detected, with higher effects observed after PLA- and PS-NH2-NPL exposure. Hemolysis induction was observed after PS- and PS-COOH-NPL exposure, but no effects on platelet functionality were observed after any of the treatments. To our knowledge, this is the first study comprehensively evaluating the bloodstream kinetics and toxicity of NPL from different polymeric types on human whole blood, considering the role played by the cell subtype and the NPLs physicochemical characteristics in the effects observed after the exposures.

Associations between inhalation of typical volatile and semi-volatile organic compounds in e-waste dismantling workers with liver function damage

Studies in cell culture and animal models suggest hepatotoxicity of some volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), however, their effects in human populations under real exposure conditions have never been clarified. In this cross-sectional study, 224 participants, 38 e-waste dismantling workers and 186 subjects residing near to the dismantling sites in southern China, were evaluated for personal inhalational exposure to 72 VOCs and 91 SVOCs according to site-specific atmospheric chemical concentrations and personal exposure time. Additionally, their serum samples were subjected to liver function tests (LFTs), including total protein (TP), albumin (ALB), globulin (GLB), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), and bilirubin. Linear regression analysis of the VOC/SVOC levels against the LFTs results indicated that VOC exposure was negatively associated with the TP, ALB, GLB levels (indicating liver-specific protein synthesis functions), while positively associated with AST, ALT, GGT activities (marking liver damage). Somehow, SVOC exposure appeared to be positively associated with not only AST and ALT but also TP and ALB. These findings were supported by the quantile g-computation analysis and confirmed in the Bayesian kernel machine regression model. This study indicates that simultaneous inhalation of VOCs and SVOCs may impair human liver functions.

Effect of accelerated weathering on pyrolysis kinetics and ignition characteristics of typical thermal insulation materials

Thermal insulation materials are widely installed on external walls because of their excellent properties. However, thermal insulation materials are often exposed to air and sunlight as external facades fall off, which can lead to weathering and potential fire risk. Especially, weathering may cause changes in pyrolysis and combustion characteristics of thermal insulation materials, which is of great significance for understanding fire. To simulate real exposure conditions, typical thermal insulation materials (expanded polystyrene) were weathered by accelerated weathering for 25, 45, 90, 135 and 180 days. Pyrolysis characteristics of unweathered and weathered materials were researched by thermogravimetric analysis, Fourier transform infrared (FTIR) spectrometric technique and cone calorimeter experiments. The kinetic parameters were estimated and optimized using Coats-Redfern and Shuffled Complex Evolution methods. Subsequently, the correlation between weathering time and kinetic parameters was obtained. The functional groups were detected by FTIR. Finally, the ignition time was measured. The results showed that the color of materials changed and the chalking appeared as accelerated weathering increased. Activation energy decreased from 324.44 kJ/mol to 91.04 kJ/mol, and pre-exponential factors reduced from 52.31 lns−1 to 10.72 lns−1. The intensity of vibration bands was strengthened. Ignition time was shortened by 119 s, indicating that weathered EPS is more easily ignited.

PECULIARITY OF MARKER GENES’ EXPRESSION IN BANK VOLES CLETHRIONOMYS GLAREOLUS CHARACTERIZING ECOTOXICITY EFFECTS OF THE TERRITORY CONTAMINATED WITH DIOXINS

To assess the ecotoxicity of low doses of dioxins is almost impossible without considering the in uence of real exposure conditions on these substances’ properties. The best approach to take these into account is the biomonitoring of the initial toxic e ects’ manifestation. We studied bank voles from population naturally exposed to dioxins, the summer-born adults and overwintered functional groups of animals di ered by dioxin body burden. Dioxin-free samples of a vivarium bank voles’ line served as a control. Initial e ects of ecotoxicity were characterized by transcriptional levels of genetic markers: ahr, cyp1a2, keap1, dnmt1, dnmt3a, dnmt3b, LINE-1 and B1-SINE. Summer-born functional group had signi cantly higher expression levels of ahr, keap1, dnmt3a and dnmt3b genes versus their control group. Overwintered functional group had elevated expression levels of cyp1a2 and keap1, but no changes were found versus controls for dnmt1, LINE-1 and SINE B1. The increased expression of marker genes in dioxin-exposed voles was quite well associated with toxic process’ mechanisms - their formation and progression under exposure of several generations to low sub-toxic doses. The data obtained will contribute to the development of a biomonitoring method for assessing the initial e ects of dioxin ecotoxicity.

Laboratory Durability Testing of Preservative-Treated Wood Products

Recently, certain European standards have allowed for the classification of the biological durability of chemically modified wood and preservative-treated wood, including treated products, but necessary methods for representative sampling and testing are lacking. Instead of sampling from products that can contain areas of varying durability, this study aimed at testing full-size products. Sections of untreated and preservative-treated terrace decking and palisades were incubated with pure cultures of brown and white rot fungi. Instead of mass loss, the decayed cross-sectional area was determined. The spatial distribution of decay and wood moisture content was investigated. After 16 weeks of incubation, all untreated product specimens showed signs of decay independent of the test fungus. The treated specimens were less affected. The mean and the maximum decayed cross-sectional areas were well correlated, for both the total and the sapwood cross-sections. The wood moisture content after incubation was always favorable for fungal decay, but highest where the specimens were in direct contact with the malt agar. Different infestation pathways became evident: (1) from the sapwood mantle, (2) via radial checks, and (3) from the end-grain. The latter should be prevented in order to better mimic real outdoor exposure conditions.

A study on the chemical profile and the derived health effects of heavy-duty machinery aerosol with a focus on the impact of alternative fuels

The combustion of petroleum-based fossil fuels is associated with a high environmental burden. Several alternative fuels, including synthetic fuels (e.g., gas-to-liquid, GTL) and biofuels (e.g., rapeseed methyl ester, RME) have been studied in the last few years. While the advantages for the environment (sustainability of biofuels) are well known, research on the resulting health effects from combustion aerosols of these alternative fuels is still scarce. Consequently, we investigated the chemical combustion profile from three distinct fuel types, including a petroleum-based fossil fuel (B0) and two alternative fuels (GTL, RME) under real exposure conditions. We sampled particulate matter (PM2.5, PM0.25) and the gas phase from heavy-duty machinery and evaluated the general pattern of volatile and semi-volatile organic compounds, elemental and organic carbon as well as a range of transition metals in the size segregated PM and/or gas phase. The use of comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry enabled us to classify distinct methylated PAHs in the PM samples and its high abundance, especially in the fine fraction of PM. We found that (methylated) PAHs were highly abundant in the PM of B0 compared to GTL and RME. Highest concentrations of targeted aromatic species in the gas phase were released from B0. In summary, we demonstrated that GTL and RME combustion released lower amounts of chemical compounds related to adverse health effects, thus, the substitution of petroleum-based fuels could improve air quality for human and the environment.

Long-Term Deformations and Mechanical Properties of Fine Recycled Aggregate Earth Concrete

Earth-based materials are currently receiving high attention, as they are considered as sustainable. In addition, the reuse of waste materials and more particularly recycled aggregates can boost circular economy while reducing landfilling and mineral resource depletion. Incorporating recycled aggregates in earth concrete can be an innovative way to valorize them. However, investigations are required concerning their long-term behavior. Such an aspect is more important when fine recycled aggregates are considered. In this paper, the vulnerability to long term deformations of natural sand (NS) and recycled sand (RS) earth concrete mixtures is examined under real exposure conditions. Autogenous shrinkage, drying shrinkage, basic creep and drying creep of the different mixtures were monitored for a period of two months. Specimens were then subjected to compressive tests in order to evaluate their residual strength. Furthermore, the destructive tests were monitored in parallel with the acoustic emission (AE) technique. The results show an increase in the rate of drying creep and shrinkage for RS earth concrete mixtures. In addition, NS and RS earth concrete mixtures subjected to drying, with and without loading, reported a strength development in comparison to the reference mixtures. However, the Young’s modulus reported its lowest value for drying shrinkage of both mixtures. Regarding the AE technique, the distribution of its activity reflected the higher rate of damage of dried specimens in the pre-peak region.

Statistical Treatments of Chloride Threshold and Corrosion Propagation Rate

The variability found in real structures is a function of the “intrinsic” variability of the material itself, of its aging with time and of the external climatic conditions, and, therefore, it is normal that the chloride threshold and the corrosion rates could vary spatially in the same structure or temporarily as the concrete ages. In present communication, some statistical distributions of chloride threshold are discussed, as well as the variability of the corrosion rate in real exposure conditions. In all both cases, the values found in laboratory specimens are in the same range than those found in real structures. The chloride threshold can vary from 0.2% to around 3% by weight of cement depending on the corrosion potential, which, in turn, depends on the particular condition of the steel bar in each structure. The corrosion rates show to be below 0.1 µA/cm2 when the steel is passive and values above 1 µA/cm2 are seldom found in real structures. The high variability when considering all choices may impact in a prediction of residual life of several decades of difference which aims into the need for the assessment of a specialized engineering judgement in function of the quality of the concrete and the exposure class.

Improvement of photoprotection with sunscreen formulas containing the cyclic merocyanine UVA1 absorber MCE: In vivo demonstration under simulated and real sun exposure conditions in three randomised controlled trials

AbstractBackgroundChronic sun exposure induces skin damage leading to skin ageing and skin colour heterogeneity with hyperpigmented spots. In this process ultra violet A (UVA) rays highly contribute, especially long‐UVA (UVA1) supporting the need for an efficient photoprotection over the whole UV spectrum. A new UVA1 filter, methoxypropylamino cyclohexenylidene ethoxyethylcyanoacetate (MCE), with a pic of absorption at 385 nm, has been recently approved for use in sunscreen products.ObjectiveThree randomised clinical studies were performed to evaluate the additional photoprotection afforded by a sunscreen formula containing MCE compared to state‐of‐the‐art sunscreen lacking absorption in the longest UVA1 wavelengths. Two studies were performed on European volunteers with UV‐controlled (UVA1, ultra violet B (UVB) + UVA) exposures and one on Indian volunteers under real sun exposures.MethodsThree intraindividual trials (two randomised UV‐controlled and one real sun) were conducted on a total of 62 healthy subjects with Fitzpatrick III–IV and individual typology angle (ITA°) values between −18° and 35°. The MCE at 2% was formulated in a state‐of‐the‐art sun protection factor 30 sunscreen reference allowing to enlarge the absorption profile up to 400 nm. UV‐induced pigmentation was assessed by colorimetric measures and visual scoring at different time points after a single exposure to UVA1 (Study 1) or repeated exposures to daily UV radiation comprising both UVB and UVA (Study 2) or under real sun (Study 3).ResultsWhatever the study exposure condition (UVA1, UVB + UVA, real sun), the level of pigmentation was increased as attested by colorimetric parameters (decreased luminance L* and ITA° values) and visual scorings. In the three studies, the comparison showed higher prevention of hyperpigmentation with the sunscreen enlarged in the longest UVA1 wavelengths with MCE compared to the state‐of‐the‐art sunscreen. No side effects were reported.ConclusionsMCE is a valuable UVA1 filter to improve photoprotection over the entire UV spectrum in state‐of‐the‐art sunscreens and limits the impact of UVA1 rays.

No Alteration Between Intrinsic Connectivity Networks by a Pilot Study on Localized Exposure to the Fourth-Generation Wireless Communication Signals.

Neurophysiological effect of human exposure to radiofrequency signals has attracted considerable attention, which was claimed to have an association with a series of clinical symptoms. A few investigations have been conducted on alteration of brain functions, yet no known research focused on intrinsic connectivity networks, an attribute that may relate to some behavioral functions. To investigate the exposure effect on functional connectivity between intrinsic connectivity networks, we conducted experiments with seventeen participants experiencing localized head exposure to real and sham time-division long-term evolution signal for 30 min. The resting-state functional magnetic resonance imaging data were collected before and after exposure, respectively. Group-level independent component analysis was used to decompose networks of interest. Three states were clustered, which can reflect different cognitive conditions. Dynamic connectivity as well as conventional connectivity between networks per state were computed and followed by paired sample t-tests. Results showed that there was no statistical difference in static or dynamic functional network connectivity in both real and sham exposure conditions, and pointed out that the impact of short-term electromagnetic exposure was undetected at the ICNs level. The specific brain parcellations and metrics used in the study may lead to different results on brain modulation.

Experimental Alternative to the Determination of the Thermal Dependence of the Complex Modulus of Asphalt Mixes in Dry Tropical Areas

Current pavement design methods do not allow for the reduction of early deformation of the surface layers of bituminous pavements in the city of Ouagadougou. Weather conditions combined with traffic, particularly during heat waves, are factors. The temperature at the surface of the bituminous pavement can reach 62˚C but the complex modulus associated with this temperature is not taken into account in the design, hence the interest in proposing laws of dependence of the complex moduli is taken into account in the maximum temperatures of the pavement surface. The objective of this paper is to propose an experimental method to determine the temperature dependence of the complex moduli of asphalt mixes for temperatures between 40˚C and 70˚C. This experimental method consists of performing axial compression tests on cylindrical asphalt specimens. It was applied to three different formulas of bituminous mixes, intended for the wearing course, obtained from mixes of crushed granites, granular classes 6/10, 4/6 and 0/4, pure bitumens of grade 50/70, 35/50 and modified bitumen of grade 10/65. The comparative study of the experimental results obtained with the results of a semi-empirical methodology revealed a root mean square deviation from the mean of between 6.58% and 14.8% of the norms of the complex moduli (modulus of rigidity) of the asphalt mixes for a fixed frequency of solicitations of 10 Hz. The consistency of these results with data from the literature led to the initial conclusion that asphalt mixes formulated with 35/50 and 10/65 bitumen would have better compressive strength than those formulated with 50/70 bitumen, for exposure temperatures between 40˚C and 70˚C. This experimental approach could be an alternative to the complex modulus test for determining the modulus of rigidity for design purposes under real pavement exposure conditions in the city of Ouagadougou during heat waves.

Evolution of TSA/TSZ coatings: a review on recent advances on cold gas spraying for steel corrosion protection

Abstract For decades, zinc- and aluminum-based coatings have been considered the best material choice for steel corrosion protection since they may act as a protective barrier and show sacrificial behavior. These coatings are often prepared by galvanizing methods. However, their application by thermal spraying techniques (wire arc spraying, WAS and flame spraying, FS) has been proved as a cost-effective solution for the preparation of long-term corrosion-resistant coatings. This review selectively collects the most relevant information about the application and performance of these two techniques on Zn and Al coatings for corrosion protection. The report summarizes separately the Zn and Al data from the effect of the spraying parameters on coating properties on the one hand, and the results shown in long-term studies carried out in relevant and real exposure conditions, on the other. Finally, this review includes a description and comparison of the most recent advances found out with the novel and emerging spray technique, cold gas spray, for the deposition of Zn and Al coatings for corrosion protection purposes. Nevertheless, the use of this technique has not reached the stage of wide industrial application yet and therefore its long-term performance is unknown, which suggests that there is still room for further development.

Challenges in quantification of photocatalytic NO2 abatement effectiveness under real world exposure conditions illustrated by a case study

Health risks due to NO2 exposure commonly exceed acceptable levels in modern societies. Among the measures to reduce such risks, photocatalytic materials present a promising technology. However, while the pollutant remediation of such materials has been extensively validated in laboratory studies, the performance under real world environmental exposure conditions is still subject to controversy. Indeed, a comparison of available in-situ monitoring studies manifests non-conclusive and highly scattered results regarding the photocatalytic effectiveness observed. The reasons for this behaviour must be carefully explored in order to prevent non-efficient photocatalytic applications from being put into practice on a larger scale. This paper presents a comprehensive large-scale study for assessing the photocatalytic NO2 remediation by active pavements in a street of Madrid (Spain), comprising different in-situ monitoring techniques. The discussion is enriched by relating the obtained results to those of other large-scale studies. The discrepancies between these results may be traced back to different circumstances, among them the distance between the active pavement and the pollutant concentration sampling inlet, as well as to significant site-specific and time-dependent variations of pollutant concentrations and climatic parameters. Under due consideration of these influences, for materials with relatively high initial effectiveness, it was concluded that in most such applications, the average NO2 removal effectiveness, if evaluated at a typical inlet height of Air Quality Stations (3 m), will not exceed a value of 4% (averaged over a sufficiently large number of measurement points in the area of application and a sustained amount of time, i.e. several months). When considering more realistic human exposure conditions (lower heights and daytime), it might be justified to assume somewhat higher average effectiveness.

Multi Self-Healable UV Shielding Polyurethane/CeO2 Protective Coating: The Effect of Low-Molecular-Weight Polyols.

We prepared a series of polyurethane (PU) coatings with defined contents using poly(tetramethylene oxide)glycol (PTMG) with two different molecular weights (i.e., Mn = 2000 and 650), as well as polydimethyl siloxane (PDMS) with a molecular weight of Mn 550. For every coating, maximum adhesive strength and excellent self-healing character (three times) were found using 6.775 mol% mixed with low-molecular-weight-based polyols (PU-11-3-3). Defined 1.0 wt% CeO2 was also used for the PU-11-3-3 coating (i.e., PU-11-3-3-CeO2) to obtain UV shielding properties. Both the in situ polymerization and blending processes were separately applied during the preparation of the PU-11-3-3-CeO2 coating dispersion. The in situ polymerization-based coating (i.e., PU-11-3-3-CeO2-P) showed similar self-healing properties. The PU-11-3-3-CeO2-P coating also showed excellent UV shielding in real outdoor exposure conditions.

Local Neighbourhood Image Properties for Exposure Region Determination Method in Nonuniform Illumination Images

During image acquisition, nonuniform illumination regions are produced due to several factors, such as improper environment lighting and inappropriate capturing device setting. Applying contrast enhancement methods with the same enhancement concept to the whole image can over enhance or under enhance nonuniform illumination image. Thus, different and specific enhancement concepts should be applied to different regions in nonuniform illumination image. This concept requires identification of those different regions. Almost all existing methods that introduced the region determination process can only detect two different regions, namely, dark and bright, which inadequately represent the real exposure condition because the methods only consider intensity criteria to determine the regions. For this problem, a new method used for the accurate detection of nonuniform illumination regions is proposed. Different illumination levels affect not only the intensity but also the details in an image. Thus, three image attributes, namely, intensity, entropy and contrast, which are evaluated locally in detecting the regions, must be considered. For the detection to be on par with that in humans, the three attributes are combined with a rule-based method for the identification of illumination regions. Experimental results involving evaluation from research experts demonstrate that the proposed method qualitatively detects different illumination regions (i.e., over-exposed, well-exposed and under-exposed) in a nonuniform illumination image more accurate than the state-of-the-art methods.

Variability of in-situ testing in wall coating systems - Karsten tube and moisture meter techniques

To meet customers' demand and adequate levels of satisfaction, there are various reasons for the need of proactive maintenance and knowledge about in-service performance of building façades. From this perspective, performing inspections depends on the in-service appraisal's reliability and the presence of monitored and measured parameters along the life cycle under real exposure conditions. Water, the major in-service deterioration agent, has different origins and transport mechanisms through façades, including wind-driven rain, ground moisture, and wetting/drying of surfaces, resulting in various chemical and/or physical-pathological phenomena. Thus, water resistance is considered highly relevant due to its significant influence on the durability of coating systems. This study presents results of an investigation concerning the water resistance of in-service wall coating systems, focusing on conventional and industrial renders and adapting appropriate techniques for field analyses, namely Karsten tube and moisture meter. In-service parameters (water absorption under low pressure and surface moisture) are assessed, and the techniques' sensitivity is analysed considering exposure and inspection conditions, roughness, coating and finishing types, and existing anomalies. The capacity of these techniques to monitor in-service performance is also discussed, and in-service performance criteria are proposed.

Effect of Static Magnetic Field of Electric Vehicles on Driving Performance and on Neuro-Psychological Cognitive Functions.

Human neuropsychological reactions and brain activities when driving electric vehicles (EVs) are considered as an issue for traffic and public safety purposes; this paper examined the effect of the static magnetic field (SMF) derived from EVs. A lane change task was adopted to evaluate the driving performance; and the driving reaction time test and the reaction time test were adopted to evaluate the variation of the neuro-psychological cognitive functions. Both the sham and the real exposure conditions were performed with a 350 μT localized SMF in this study; 17 student subjects were enrolled in this single-blind experiment. Electroencephalographs (EEGs) of the subjects were adopted and recorded during the experiment as an indicator of the brain activity for the variations of the driving performance and of the cognitive functions. Results of this study have indicated that the impact of the given SMF on both the human driving performance and the cognitive functions are not considerable; and that there is a correlation between beta sub-band of the EEGs and the human reaction time in the analysis

Influence of cracking on the capillary absorption and carbonation of structural lightweight aggregate concrete

This paper aims to study the influence of the presence of cracks on the capillary absorption and carbonation resistance of structural lightweight aggregate concrete (LWAC) and to compare its behaviour to normal weight concrete. For this purpose, the effect of artificial and natural cracks on LWAC with different w/c and types of aggregates was analysed. Artificial and natural cracks in the range 0.1–0.3 mm were induced by the notch method and bending tests, respectively. Results show that the influence of artificial cracks on the studied durability properties was not significantly affected by the aggregate type. However, when LWAC was subjected to natural cracks, there was greater participation of the more porous aggregates. For crack widths greater than 0.1 mm, the resistance to CO2 diffusion was less affected by the crack characteristics. Depending on the relationship between carbonation depth and crack length, the estimated carbonation rate under real exposure conditions can increase more than 80% in cracked concrete.