Comparison of Destructive Methods to Appraise the Mechanical Integrity of a Concrete Surface

peer reviewedDepending on the technique being used, the concrete removal operation prior to repair can be harmful to the residual concrete skin left on the structure. Whenever a tight bond between the repair and the old concrete is required, the soundness of the prepared surface should thus be assessed. Although this is widely recognized, there is no standard method intended to characterize the integrity of a concrete substrate after concrete removal. This paper presents the results of an investigation intended to assess and compare quantitatively different test methods, namely the Schmidt rebound hammer, the pull-out test and the pull-off test, to evaluate superficial mechanical integrity of a substrate after concrete removal operations. Although it does not yield a precise evaluation of compressive strength, the Schmidt rebound hammer test is recognized as a useful tool for performing quick surveys to assess concrete uniformity. The pull-off test is very well correlated with the splitting-tensile test, but it is not suited for vertical and overhead surfaces. The Capo pull-out test has limited interest for surface preparation, as it is applicable to flat surfaces only. Conversely, the accelerated pull-out test showed interesting potential as a simple and relatively rapid means for assessing the mechanical integrity of a concrete surface prior to repair for any type of concrete surface. More work is definitely required to refine the procedures and develop performance criteria. Nevertheless, it appears from the results generated in this study that the combination Schmidt hammer / pull-off test could fill the needs for the evaluation of horizontal surfaces after concrete removal, while the combination Schmidt hammer / accelerated pull-out test could be used effectively on vertical and overhead surfaces.Coopération scientifique WBI/Québe

Recovering from COVID-19 Building Closures: Guidance Document

While the country comes to terms with the inevitable impact that SARS-CoV-2, the virus that causes COVID-19, will have on our lives and communities, public health authorities remain focused on breaking the chain of transmission. Managing the risk has resulted in widespread closures of businesses, schools, universities, resorts, and other facilities deemed “non-essential.” Practically speaking, this means closing buildings and ceasing operations. For building owners and operators, this poses a significant challenge to protect their assets and to ensure they are ready to reoccupy once the pandemic subsides

Evaluation of Urinary Pesticide Biomarkers Among a Sample of the Population in the United States

Pesticide use in the United States continues to attract negative public attention. In recent years, this attention has focused on the effects that chronic, low-level pesticides may have, especially on children and various sub-populations. Over the past decade, studies have attempted to correlate negative health effects with detections of pesticide biomarkers in biological media. The current research investigates biomarker of exposure levels in a sample of the United States population. Data from the 2001-2002 NHANES dataset (n=11,039) was evaluated. The detection frequency of urinary biomarkers of exposure and the geometric mean from the NHANES pesticide dataset (n=3,152) were determined. Of the 18 specific pesticide biomarkers, three were detected in more than 50% of the sample: 79% had a detectable level of 3,5,6-trichloropyridinol, a biomarker of chlorpyrifos, with a geometric mean of 2.07 µg/L (C.I: 1.98-2.17); 53% had a detectable level of paranitrophenol, a biomarker of methyl parathion, with a geometric mean of 0.367 µg/L (C.I.: 0.346-0.389); and 77% had a detectable level of 3-phenoxybenzoic acid, a biomarker of permethrin, with a geometric mean of 0.336 µg/L (C.I.: 0.320-0.352). These levels fall within the range of other epidemiological and biomonitoring studies investigating background levels of biomarkers in the general population. The association between the detection of a biomarker and variations in mean height and weight of children aged 6-11 was evaluated. No significant results were found when evaluating these differences for 3,5,6-trichloropyridinol exposure. Paranitrophenol associated with shorter children at age 8 [Non-Detect=134.3 cm and Detect: 130.9 cm (p=0.046)] and taller children at age 11 [Detect=153.7 cm and Non-Detect=149.9 cm (p=0.022)]. Heavier children associated with 3-Phenoxybenzoic Acid at age 7: [Detect=28.61 kg and Non-Detect=25.26 kg (p=0.009)]. Clinical chemistry biochemical concentration comparisons were made between individuals that had a detectable level of the biomarker in urine and those that did not. Two biochemicals had a significant difference across all three biomarkers: cholesterol and sodium. The biochemical levels with significant difference between detects and non-detects for the biomarkers were not elevated above clinical reference values. Overall, there is insufficient evidence to suggest a relationship between background pesticide exposures in this sample and negative health effects

Recovering from COVID-19 Building Closures: Guidance Document

While the country comes to terms with the inevitable impact that SARS-CoV-2, the virus that causes COVID-19, will have on our lives and communities, public health authorities remain focused on breaking the chain of transmission. Managing the risk has resulted in widespread closures of businesses, schools, universities, resorts, and other facilities deemed “non-essential.” Practically speaking, this means closing buildings and ceasing operations. For building owners and operators, this poses a significant challenge to protect their assets and to ensure they are ready to reoccupy once the pandemic subsides

Workplace Cleaning for COVID-19: Guidance Document

Critical and essential workplaces operating during this pandemic need to implement procedures to reduce the risk of workers, contractors, vendors, customers, and members of the community becoming infected on their premises. Outside of healthcare and paramedical facilities, the infrastructure and standard practices of infection prevention and control have not been commonplace. Establishing enhanced routine cleaning and disinfection procedures in offices, factories, warehouses, call centers, grocery stores, and other non-healthcare workplaces is a critical step in reducing exposures and infections