Fracture and fatigue strength of grouted macadams

Grouted macadams form a class of material which provides significant advantages in comparison to both concrete and conventional asphalt, having both rut resistance and a degree of flexibility. This paper presents a series of laboratory tests on several grouted macadam mixtures, for stiffness, fatigue and low temperature fracture. The variables explored include binder grade and content, aggregate size and gradation, and grout strength. Although the material is found to perform fundamentally as an asphalt, there are several significant differences in the form of fatigue behavior found compared to that usually expected from an asphalt. In particular the effect of varying binder content is found to be markedly different. The results are discussed in terms of optimizing mixture design in order to obtain the most desirable combination of properties (stiffness, fatigue strength, low temperature fracture resistance). Discussion is also presented regarding the possible role of grouted macadams as base or binder courses within highway pavements, and the conclusion is drawn that they are likely to provide an economical solution in many circumstances owing to their superior mechanical properties

The effect of using rest periods in 4PB tests on the fatigue life of grouted macadams

Four-point bending tests are commonly used to assess the fatigue resistance of bi-tuminous bound materials that are used in road pavements. However, it is difficult to establish a reliable relationship between the laboratory test results and the field performance of the mate-rial. In order to predict the real life of the pavement, shift factors are normally used to convert the fatigue results obtained in the laboratory onto the actual fatigue life of the material in the field. Those shift factors depend on the type of test used, the testing conditions and the type of mixture used. In this study, an attempt was made to establish a shift factor for grouted mac-adams, based on four-point bending fatigue test results carried out with rest periods between the loading cycles. The result obtained was used to define a fatigue criterion for pavement design with grouted macadams

Fused and spiro nitrogen heterocycles of quinuclidine and its C-nucleosides

Quinuclidin-3-one (1) was used as a versatile intermediate for the synthesis of fused and spiro quinuclidine and its C-nucleosides. The reaction of 1 with formalin and secondary amines namely; morpholine, piperidine, and piperazine afforded the corresponding Mannich bases 2-4 in acid medium. Quinuclidino[3,2-b]pyran 5 has been synthesized via a selective cyclocondensation reaction between Mannich base of quinuclidinone hydrochloride 2 and malononitrile. The transformation of 1 with formalin and methylamine in molar ratio (1:20:2) afforded the spiro compound 7. Ring expansion of 2 under Schmidt reaction conditions gave the 1,3-diazabicyclo[3.2.2]nonanone derivative 6. Eventually, the synthesis of C-nucleosides 10, 12-14 were achieved by using aldohexoses and aldopentose catalyzed by zinc chloride, while, the bis-quinuclidine derivative 15 was obtained by using sodium carbonate. Newly synthesized compounds were characterized by IR, 1H NMR, and mass spectral data

Assessing the feasibility of impregnating phase change materials in lightweight aggregate for development of thermal energy storage systems

This paper assesses the feasibility of impregnation/encasement of phase change materials (PCMs) in lightweight aggregates (LWAs). An impregnation process was adopted to carry out the encasement study of two different PCMs in four different LWAs. The leakage of the impregnated/encased PCMs was studied when they were submitted to freeze/thawing and oven drying tests, separately. The results confirmed that, the impregnation/encasement method is effective with respect to the large thermal energy storage density, and can be suitable for applications were PCMs cannot be incorporated directly such as asphalt road pavements.The authors acknowledge the funding given by Centre for Coordination and Regional Development Committee (CCDR-C) through the research project CENTRO-07-ST24_FEDER-002020 "Environmentally-Friendly Aeronautical Transport Systems Integrated Program (EFATRAS)", http://efatrasubi.wordpress.com. Supply of Expanded Clay materials by ARGEX - Argila Expandida, S.A and Cork materials by Sofalca - Sociedade Central de Productos de Cortica, Lda are also acknowledged

A laboratory study on cold-mix, cold-lay emulsion mixtures

This paper describes laboratory experiments and presents results for the performances of cold-mix, cold-lay emulsion mixtures. The main objective of the experiments was to evaluate and improve the properties of the cold mixtures. The mixture properties evaluated were: volumetric properties, indirect tensile stiffness modulus (ITSM), repeated load axial creep and fatigue. These properties were compared with conventional hot asphalt mixtures not containing any waste/recycled materials. To optimise the performances of the mixtures, a target of ITSM value of 2000 MPa was selected. At full curing conditions, the stiffness of the cold mixes was found to be very similar to that of hot mixtures of the same penetration grade base bitumen (100 pen). Test results also show that the addition of 1–2% cement significantly improved the mechanical performance of the mixes and significantly accelerated their strength gain. The fatigue behaviour of the cold mixes that incorporated cement was comparable with that of the hot mixtures

Socioeconomic, environmental, and geographic factors and US lung cancer mortality, 1999–2009

Background The American Cancer Society estimates that about 25% of all US cancer deaths will be due to lung cancer – more than from cancers of the colon, breast, and prostate combined. Methods We ascertained county-level age-adjusted and age-specific death rates and 95% confidence intervals from the Centers for Disease Control and Prevention Compressed Mortality File. Multiple regression analyses were used to estimate the strength and direction of relationships between county poverty, smoking, fine particulate matter (PM2.5) air pollution, and US Census divisions and race- and sex-specific lung cancer deaths. Results Poverty, smoking, and particulate matter air pollution were positively and significantly related to lung cancer deaths among white men, but of these, only poverty and smoking were significantly associated with lung cancer deaths among white women. Residence in the South Atlantic, East South Central, and West South Central US Census divisions at the time of death was significantly associated with lung cancer deaths for both white men and white women. As with white men, poverty and smoking were associated with lung cancer deaths among black men, but of these, only adult smoking had a statistically significant association among black women. Conclusions The results support the need for further research, particularly in high-risk areas, to better differentiate factors specific to race and sex and to understand the impact of local risk factors

Influence of guided mode absorption on the effectiveness of GaN-on-sapphire photonic crystal light-emitting diodes

Enhanced light extraction from photonic crystal light-emitting diodes etched into the device surface is described. Finite difference time domain modeling indicates that scattering or absorption at the substrate-epilayer interface is the dominant limiting process

Quasicrystals: Making invisible materials

All-dielectric photonic quasicrystals may act as zero-refractive-index homogeneous materials despite their lack of translational symmetry and periodicity, stretching wavelengths to infinity and offering applications in light wavefront sculpting and optical cloaking.Comment: 5 pages, 2 figure

Lack of validity of self-reported mammography data

This qualitative literature review aimed to describe the totality of peer-reviewed scientific evidence from 1990 to 2017 concerning validity of self-reported mammography. This review included articles about mammography containing the words accuracy, validity, specificity, sensitivity, reliability or reproducibility; titles containing self-report, recall or patient reports, and breast or ‘mammo’; and references of identified citations focusing on evaluation of 2-year self-reports. Of 45 publications meeting the eligibility criteria, 2 conducted in 1993 and 1995 at health maintenance organisations in Western USA which primarily served highly educated whites provided support for self-reports of mammography over 2 years. Methodological concerns about validity of self-reports included (1) telescoping, (2) biased overestimates particularly among black women, (3) failure to distinguish screening and diagnostic mammography, and (4) failure to address episodic versus consistent mammography use. The current totality of evidence supports the need for research to reconsider the validity of self-reported mammography data as well as the feasibility of alternative surveillance data sources to achieve the goals of the Healthy People Initiative