Impact of cracks on distribution of chloride-induced reinforcement corrosion

Surface crack width is regulated in codes to limit corrosion of reinforcement bars in concrete. However, the influence of surface crack width on corrosion damages is not directly inferable from previous research.In this work, data on corroded cracked concrete specimens in chloride environments was compiled. Detailed information was included, such as crack and pit locations, local corrosion pattern, etc. Five hypotheses on the influence of transversal cracks on corrosion damage were formulated, and statistical methods were used to test them on the dataset.Transversal cracks were good indicators of the position of corrosion pits. The corrosion rate of the pit increased in proximity of a crack. With time, pits grew in depth at a slower rate but increased in number. No clear correlation between surface crack width and corrosion damage was found. Results point out discrepancies in the collected data, arguing for the need of well-defined procedures for assessing crack and corrosion damage.Further, the statistical treatment allowed for identification of bias in existing data, which was used as a research planning tool to provide guidance on the design of additional experiments. Thus, recommendations for future experimental work required to reduce the bias are given

Greater body mass index is a better predictor of subclinical cardiac damage at long-term follow-up in men than is insulin sensitivity:a prospective, population-based cohort study

To examine whether lower insulin sensitivity as determined by homeostatic model assessment (HOMA-%S) was associated with increased left ventricular mass (LVM) and presence of LV diastolic dysfunction at long-term follow-up, independently of body mass index (BMI), in middle-aged, otherwise healthy males

Concluding destructive investigation of a nine-year-old marine-exposed cracked concrete panel

This study undertaken on a nine-year-old cracked concrete panel further investigates the impact of cracks on the corrosion performance of conventional steel reinforcement in marine-exposed concrete to explain observed monitoring data. The present data covers seven 1.80 m long (12.6 m) reinforcing bars embedded in good quality concrete (w/b = 0.40 and cover >75 mm). Each bar was crossed by two horizontal cracks (surface crack widths 0.20–0.30 mm). The investigation showed no corrosion on the surface of the reinforcing bars, in either cracked or uncracked areas. Two of the seven reinforcing bars were instrumented in the vicinity of the cracks. Extensive corrosion was found in the interior of all instrumented parts of these bars. This may explain the monitoring data despite the lack of corrosion on the exterior surface of the two instrumented rebars. However, with no other weaknesses, the remaining conventional rebars showed no impact from the cracks

Concluding destructive investigation of a nine-year-old marine-exposed cracked concrete panel

This study undertaken on a nine-year-old cracked concrete panel further investigates the impact of cracks on the corrosion performance of conventional steel reinforcement in marine-exposed concrete to explain observed monitoring data. The present data covers seven 1.80 m long (12.6 m) reinforcing bars embedded in good quality concrete (w/b = 0.40 and cover >75 mm). Each bar was crossed by two horizontal cracks (surface crack widths 0.20–0.30 mm). The investigation showed no corrosion on the surface of the reinforcing bars, in either cracked or uncracked areas. Two of the seven reinforcing bars were instrumented in the vicinity of the cracks. Extensive corrosion was found in the interior of all instrumented parts of these bars. This may explain the monitoring data despite the lack of corrosion on the exterior surface of the two instrumented rebars. However, with no other weaknesses, the remaining conventional rebars showed no impact from the cracks.publishedVersio

Electrical resistivity measurements in steel fibre reinforced cementitious materials

This paper reports results from experiments aimed at better understanding the influence of fibre dosage and fibre geometry on the AC frequency needed to determine the DC resistivity of cementitious materials containing steel fibres. Impedance spectroscopy and DC galvanodynamic measurements were performed on mortar prisms with varying fibre reinforcement to determine the matrix resistivity (related to ionic current within the pore solution) and composite resistivity (accounting for both ionic current and electronic current through the fibres). The results showed that adding steel fibres did not significantly affect the DC nor the AC matrix resistivity of the mortar prisms. However, the steel fibres yielded a drastic reduction of the frequency associated to the AC matrix resistivity from ∼1 kHz in plain mortar to ∼1 Hz in steel fibre reinforced mortar. These findings revealed the need to adequately adjust the frequency in AC resistivity measurements of steel fibre reinforced cementitious materials

Copenhagen comorbidity in HIV infection (COCOMO) study:a study protocol for a longitudinal, non-interventional assessment of non-AIDS comorbidity in HIV infection in Denmark

Abstract Background Modern combination antiretroviral therapy (cART) has improved survival for people living with HIV (PLWHIV). Non-AIDS comorbidities have replaced opportunistic infections as leading causes of mortality and morbidity, and are becoming a key health concern as this population continues to age. The aim of this study is to estimate the prevalence and incidence of non-AIDS comorbidity among PLWHIV in Denmark in the cART era and to determine risk factors contributing to the pathogenesis. The study primarily targets cardiovascular, respiratory, and hepatic non-AIDS comorbidity. Methods/design The Copenhagen comorbidity in HIV-infection (COCOMO) study is an observational, longitudinal cohort study. The study was initiated in 2015 and recruitment is ongoing with the aim of including 1500 PLWHIV from the Copenhagen area. Follow-up examinations after 2 and 10 years are planned. Uninfected controls are derived from the Copenhagen General Population Study (CGPS), a cohort study including 100,000 uninfected participants from the same geographical region. Physiological and biological measures including blood pressure, ankle-brachial index, electrocardiogram, spirometry, exhaled nitric oxide, transient elastography of the liver, computed tomography (CT) angiography of the heart, unenhanced CT of the chest and upper abdomen, and a number of routine biochemical analysis are uniformly collected in participants from the COCOMO study and the CGPS. Plasma, serum, buffy coat, peripheral blood mononuclear cells (PBMC), urine, and stool samples are collected in a biobank for future studies. Data will be updated through periodical linking to national databases. Discussion As life expectancy for PLWHIV improves, it is essential to study long-term impact of HIV and cART. We anticipate that findings from this cohort study will increase knowledge on non-AIDS comorbidity in PLWHIV and identify targets for future interventional trials. Recognizing the demographic, clinical and pathophysiological characteristics of comorbidity in PLWHIV may help inform development of new guidelines and enable us to move forward to a more personalized HIV care. Trial registration ClinicalTrials.gov: NCT02382822

Levels of SARS-CoV-2 antibodies among fully vaccinated individuals with Delta or Omicron variant breakthrough infections

SARS-CoV-2 variants of concern have continuously evolved and may erode vaccine induced immunity. In this observational cohort study, we determine the risk of breakthrough infection in a fully vaccinated cohort. SARS-CoV-2 anti-spike IgG levels were measured before first SARS-CoV-2 vaccination and at day 21–28, 90 and 180, as well as after booster vaccination. Breakthrough infections were captured through the Danish National Microbiology database. incidence rate ratio (IRR) for breakthrough infection at time-updated anti-spike IgG levels was determined using Poisson regression. Among 6076 participants, 127 and 364 breakthrough infections due to Delta and Omicron variants were observed. IRR was 0.29 (95% CI 0.15–0.56) for breakthrough infection with the Delta variant, comparing the highest and lowest quintiles of anti-spike IgG. For Omicron, no significant differences in IRR were observed. These results suggest that quantitative level of anti-spike IgG have limited impact on the risk of breakthrough infection with Omicron