Development and Construction of Low-Cracking High-Performance Concrete (LC-HPC) Bridge Decks: Construction Methods, Specifications, and Resistance to Chloride Ion Penetration

The development, construction, and evaluation of Low-Cracking High-Performance Concrete (LC-HPC) bridge decks are described based on laboratory test results and experiences gained through the construction of 14 LC-HPC bridge decks. The study is divided into three parts covering (1) an evaluation of the chloride penetration into concrete using long-term salt-ponding tests, (2) a comprehensive discussion of specifications for LC-HPC construction and standard practices in Kansas, and (3) the description of the construction and the preliminary evaluation of LC-HPC bridge decks in Kansas. This report emphasizes the construction process; a companion report provides a detailed discussion of the influence of material properties on the performance of LC-HPC bridge decks. The first portion of the study involves evaluating the effect of paste content, curing period, water-cement (w/c) ratio, cement type and fineness, mineral admixtures (ground granulated blast furnace slag and silica fume), a shrinkage reducing admixture (SRA), and standard DOT bridge deck mixtures on chloride penetration into solid concrete, tested in accordance with AASHTO T 259. The evaluation includes a total of 33 individual concrete batches and 123 test specimens. The results indicate that for concrete containing only portland cement, reductions in paste content result in increased permeability. A reduced paste content and increased w/c ratio result in increased permeability, whereas the presence of mineral admixtures (ground granulated blast furnace slag and silica fume) and longer curing periods result in decreased permeability. Concrete made with medium or coarse ground Type II cement has greater permeability than concrete made with Type I/II cement. It is not clear how the presence of an SRA affects concrete permeability. LC-HPC mixtures have lower permeability than standard DOT mixtures. The second portion of the study describes the specifications for the LC-HPC and Control bridge decks in Kansas. The focus is on the construction methods, including the evolution of the specifications over time. The third portion of the study details the development and construction of 14 LC-HPC and 12 conventional Control bridge decks built in Kansas. The design details, construction experiences, and lessons learned from the LC-HPC bridge decks are described in detail, and an overview of the materials is presented; the design and construction data for each Control deck is provided; and initial crack survey results are evaluated for various construction-related parameters. The results indicate that that successful LC-HPC bridge deck construction is repeatable and that clear and consistent communication between the contractor, owner, and testing personnel is vital for successful construction of LC-HPC decks. Preliminary evaluation of cracking indicates that at early ages, LC-HPC decks are performing better than the Control decks, as well as earlier monolithic decks in Kansas

Development and Construction of Low-Cacking High-Performance Concrete (LC-HPC) Bridge Decks: Construction Methods, Specifications, and Resistance to Chloride Ion Penetration

The development, construction, and evaluation of Low-Cracking High- Performance Concrete (LC-HPC) bridge decks are described based on laboratory test results and experiences gained through the construction of 14 LC-HPC bridge decks. The study is divided into three parts covering (1) an evaluation of the chloride penetration into concrete using long-term salt-ponding tests, (2) a comprehensive discussion of specifications for LC-HPC construction and standard practices in Kansas, and (3) the description of the construction and the preliminary evaluation of LC-HPC bridge decks in Kansas. This report emphasizes the construction process; a companion report provides a detailed discussion of the influence of material properties on the performance of LC-HPC bridge decks. The first portion of the study involves evaluating the effect of paste content, curing period, water-cement (w/c) ratio, cement type and fineness, mineral admixtures (ground granulated blast furnace slag and silica fume), a shrinkage reducing admixture (SRA), and standard DOT bridge deck mixtures on chloride penetration into solid concrete, tested in accordance with AASHTO T 259. The evaluation includes a total of 33 individual concrete batches and 123 test specimens. The results indicate that for concrete containing only portland cement, reductions in paste content result in increased permeability. A reduced paste content and increased w/c ratio result in increased permeability, whereas the presence of mineral admixtures (ground granulated blast furnace slag and silica fume) and longer curing periods result in decreased permeability. Concrete made with medium or coarse ground Type II cement has greater permeability than concrete made with Type I/II cement. It is not clear how the presence of an SRA affects concrete permeability. LC-HPC mixtures have lower permeability than standard DOT mixtures. The second portion of the study describes the specifications for the LC-HPC and Control bridge decks in Kansas. The focus is on the construction methods, including the evolution of the specifications over time. The third portion of the study details the development and construction of 14 LC-HPC and 12 conventional Control bridge decks built in Kansas. The design details, construction experiences, and lessons learned from the LC-HPC bridge decks are described in detail, and an overview of the materials is presented; the design and construction data for each Control deck is provided; and initial crack survey results are evaluated for various construction-related parameters. The results indicate that that successful LC-HPC bridge deck construction is repeatable and that clear and consistent communication between the contractor, owner, and testing personnel is vital for successful construction of LC-HPC decks. Preliminary evaluation of cracking indicates that at early ages, LC-HPC decks are performing better than the Control decks, as well as earlier monolithic decks in Kansas

Mineral Admixtures, Curing, and Concrete Shrinkage – An Update

Work currently underway at the University of Kansas to evaluate free shrinkage of concrete as a function of the length of curing prior to drying, mineral admixtures as a replacement for portland cement, and aggregate type is presented. Silica fume, ground-granulated blast furnace slag (GGBFS), and fly ash at two levels of replacement are evaluated with a high-absorption coarse aggregate (2.5 to 3.0%) and a low-absorption coarse aggregate (less than 0.7%). The results show that when cast with a high-absorption coarse aggregate, the addition of either silica fume or GGBFS results in a reduction in shrinkage at all ages, while the addition of fly ash increases early-age shrinkage and does not have a significant effect on long-term shrinkage. For mixtures containing a low-absorption coarse aggregate, the addition of silica fume or GGBFS results in increased early-age shrinkage if the specimens are only cured for seven days. These same mixtures exhibit reduced shrinkage at all ages when the curing period is doubled from seven to fourteen days. In either case the addition of fly ash increases shrinkage at all ages. Based on these results, it appears that the high-absorption limestone provides internal curing water, which results in a reduction in the shrinkage of mixtures containing GGBFS or silica fume

Low-Cracking, High-Performance Concrete Bridge Decks: Case Studies over First 6 Years

David Darwin, JoAnn Browning, Will Lindquist, Heather A. K. McLeod, Jiqiu Yuan, Miriam Toledo, and Diane Reynolds, "Low-Cracking, High-Performance Concrete Bridge Decks: Case Studies over First 6 Years", Transportation Research Record (No. 2202) pp. 61-69. Copyright © 2010 AGE Publications. DOI: 10.3141/2202-08.Cracks in concrete bridge decks provide easy access for water and deicing chemicals that shorten the life of the deck, and field surveys show that the problem has become progressively more severe since at least the 1980s. A two-phase, 10-year Pooled Fund study to minimize cracking in bridge decks is now under way. Twenty bridge decks have been constructed in the program to date. Comparison with conventional decks shows that the techniques embodied in low-cracking, high-performance concrete (LC-HPC) bridge deck specifications have been highly successful in reducing cracking in bridge decks. The results also show that highslump high-strength concretes result in greater cracking in bridge decks than low-slump, moderate-strength concretes and that concrete temperature control and early application of curing counteract the negative effects of casting concrete under high-temperature conditions. Early owner and contractor buy-in is needed for successful LC-HPC bridge deck construction, and top performance requires the adherence to all aspects of the specifications

Protestant women in the late Soviet era: gender, authority, and dissent

At the peak of the anti-religious campaigns under Nikita Khrushchev, communist propaganda depicted women believers as either naïve dupes, tricked by the clergy, or as depraved fanatics; the Protestant “sektantka” (female sectarian) was a particularly prominent folk-devil. In fact, as this article shows, women’s position within Protestant communities was far more complex than either of these mythical figures would have one believe. The authors explore four important, but contested, female roles: women as leaders of worship, particularly in remote congregations where female believers vastly outnumbered their male counterparts; women as unofficial prophetesses, primarily within Pentecostal groups; women as mothers, replenishing congregations through high birth rates and commitment to their children’s religious upbringing; and women as political actors in the defence of religious rights. Using a wide range of sources, which include reports written by state officials, articles in the church journal, letters from church members to their ecclesiastical leaders in Moscow, samizdat texts, and oral history accounts, the authors probe women’s relationship with authority, in terms of both the authority of the (male) ministry within the church, and the authority of the Soviet state

Genome-Wide Association Study in BRCA1 Mutation Carriers Identifies Novel Loci Associated with Breast and Ovarian Cancer Risk

BRCA1-associated breast and ovarian cancer risks can be modified by common genetic variants. To identify further cancer risk-modifying loci, we performed a multi-stage GWAS of 11,705 BRCA1 carriers (of whom 5,920 were diagnosed with breast and 1,839 were diagnosed with ovarian cancer), with a further replication in an additional sample of 2,646 BRCA1 carriers. We identified a novel breast cancer risk modifier locus at 1q32 for BRCA1 carriers (rs2290854, P = 2.7×10-8, HR = 1.14, 95% CI: 1.09-1.20). In addition, we identified two novel ovarian cancer risk modifier loci: 17q21.31 (rs17631303, P = 1.4×10-8, HR = 1.27, 95% CI: 1.17-1.38) and 4q32.3 (rs4691139, P = 3.4×10-8, HR = 1.20, 95% CI: 1.17-1.38). The 4q32.3 locus was not associated with ovarian cancer risk in the general population or BRCA2 carriers, suggesting a BRCA1-specific associat

Genetic fine mapping and genomic annotation defines causal mechanisms at type 2 diabetes susceptibility loci.

We performed fine mapping of 39 established type 2 diabetes (T2D) loci in 27,206 cases and 57,574 controls of European ancestry. We identified 49 distinct association signals at these loci, including five mapping in or near KCNQ1. 'Credible sets' of the variants most likely to drive each distinct signal mapped predominantly to noncoding sequence, implying that association with T2D is mediated through gene regulation. Credible set variants were enriched for overlap with FOXA2 chromatin immunoprecipitation binding sites in human islet and liver cells, including at MTNR1B, where fine mapping implicated rs10830963 as driving T2D association. We confirmed that the T2D risk allele for this SNP increases FOXA2-bound enhancer activity in islet- and liver-derived cells. We observed allele-specific differences in NEUROD1 binding in islet-derived cells, consistent with evidence that the T2D risk allele increases islet MTNR1B expression. Our study demonstrates how integration of genetic and genomic information can define molecular mechanisms through which variants underlying association signals exert their effects on disease

Biomedical colonialism or local autonomy?: local healers in the fight against tuberculosis

Analiza el papel de los agentes médicos autóctonos y sus conocimientos en las campañas antituberculosas contemporáneas en el África subsahariana. Sitúa la medicina contemporánea, llevada a cabo en África en la herencia cultural de la medicina colonial, para comprender el marco histórico en el que se desarrollaron, a partir de los años setenta del siglo XX, las estrategias de la Organización Mundial de la Salud de promoción y desarrollo de las medicinas 'tradicionales'. En los proyectos sanitarios analizados, se evalúan las prácticas médicas locales y se entrenan a los agentes autóctonos para integrarlos en actividades estrictamente biomédicas: identificación de síntomas, remisión a hospitales o supervisión de tratamientos farmacológicos.The article explores the role played by indigenous medical agents, and their knowledge, within contemporary tuberculosis campaigns in sub-Saharan Africa. To understand the historical framework within which the World Health Organization devised its strategies to promote and develop traditional medicine as of the 1970s, the article contextualizes contemporary medicine as a cultural legacy of colonial medicine. Under the public healthcare projects analyzed in the article, local medical practices were assessed and indigenous agents trained so they could take part in strictly biomedical activities, like symptom identification, referrals to hospitals, or supervision of drug treatments.Trabajo realizado para la obtención del Diploma de Estudios Avanzados (DEA) en el programa de doctorado Salud: Antropología e Historia, bajo la dirección de la profesora Rosa María Medina Doménech

An original phylogenetic approach identified mitochondrial haplogroup T1a1 as inversely associated with breast cancer risk in BRCA2 mutation carriers

Introduction: Individuals carrying pathogenic mutations in the BRCA1 and BRCA2 genes have a high lifetime risk of breast cancer. BRCA1 and BRCA2 are involved in DNA double-strand break repair, DNA alterations that can be caused by exposure to reactive oxygen species, a main source of which are mitochondria. Mitochondrial genome variations affect electron transport chain efficiency and reactive oxygen species production. Individuals with different mitochondrial haplogroups differ in their metabolism and sensitivity to oxidative stress. Variability in mitochondrial genetic background can alter reactive oxygen species production, leading to cancer risk. In the present study, we tested the hypothesis that mitochondrial haplogroups modify breast cancer risk in BRCA1/2 mutation carriers. Methods: We genotyped 22,214 (11,421 affected, 10,793 unaffected) mutation carriers belonging to the Consortium of Investigators of Modifiers of BRCA1/2 for 129 mitochondrial polymorphisms using the iCOGS array. Haplogroup inference and association detection were performed using a phylogenetic approach. ALTree was applied to explore the reference mitochondrial evolutionary tree and detect subclades enriched in affected or unaffected individuals. Results: We discovered that subclade T1a1 was depleted in affected BRCA2 mutation carriers compared with the rest of clade T (hazard ratio (HR) = 0.55; 95% confidence interval (CI), 0.34 to 0.88; P = 0.01). Compared with the most frequent haplogroup in the general population (that is, H and T clades), the T1a1 haplogroup has a HR of 0.62 (95% CI, 0.40 to 0.95; P = 0.03). We also identified three potential susceptibility loci, including G13708A/rs28359178, which has demonstrated an inverse association with familial breast cancer risk. Conclusions: This study illustrates how original approaches such as the phylogeny-based method we used can empower classical molecular epidemiological studies aimed at identifying association or risk modification effects.Peer reviewe

An index to assess the health and benefits of the global ocean

The ocean plays a critical role in supporting human well-being, from providing food, livelihoods and recreational opportunities to regulating the global climate. Sustainable management aimed at maintaining the flow of a broad range of benefits from the ocean requires a comprehensive and quantitative method to measure and monitor the health of coupled human–ocean systems. We created an index comprising ten diverse public goals for a healthy coupled human–ocean system and calculated the index for every coastal country. Globally, the overall index score was 60 out of 100 (range 36–86), with developed countries generally performing better than developing countries, but with notable exceptions. Only 5% of countries scored higher than 70, whereas 32% scored lower than 50. The index provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.This is the publisher’s final pdf. The published article is copyrighted by the Nature Publishing Group and can be found at: http://www.nature.com/nature/index.htm