Hydrated lime (HL) is an active filler in some bitumens. Rheological models demonstrate that HL interacts with certain bitumens to develop an adsorbed (interactive) layer around the HL particles. The volume of this layer can be substantial, causing HL to have a much more substantial effect on the bitumen than inert fillers. The level of interaction between HL and bitumen is bitumen dependent. This interaction causes HL to strongly affect high-temperature rheology in certain bitumens, but it has less of an effect in others. The low-temperature stiffening effects of HL are less prominent, and a significant level of fracture toughening (at low temperatures) occurs through the addition of HL. The active nature of HL with certain bitumens is further verified by nuclear magnetic resonance. HL is considered a multifunctional additive with potential benefits to the binder and to the mixture that include resistance to deformation, low-temperature fracture toughening, and increased resistance to age hardening. HL may be competitive with some polymer additives.

Effect of hydrated lime on rheology, fracture, and aging of bitumen. Discussion. Authors' closure

Mesothelioma, a malignant cancer of the pleura, is almost exclusively associated with asbestos exposure.1 What will it take to eradicate this highly preventable cancer? Despite the scientific consensus that exposure to asbestos fibres causes deadly diseases, we continue to use asbestos in products designed ostensibly to improve quality of life. For example, asbestos is still used in automobile brake-linings, and in the chloralkali industry that produces chlorine for disinfecting water worldwide.2 Toxic asbestos remains the main material for some plastics and in domestic building products – especially in corrugated roof materials for housing in developing countries. \n \nRegional disparities persist in translating scientific knowledge of asbestos risks to policy for preventing cancers and other diseases. Most cases of mesothelioma are now found in countries producing asbestos and in developing countries using the products, where scientific knowledge of asbestos toxicity seems to have been lost in translation.3 It is in these countries, where affected populations are less likely to have access to prompt diagnosis, health care or litigation, that we will observe the next wave of mesothelioma cases.3 A perspective on three scientific translational gaps is presented here: (i) making policy decisions within the context of scientific uncertainty, (ii) the role of alternative assessments in selecting safer commercial materials, and (iii) the translation of scientific evidence into disease prevention. \n \nThe International Labour Organization’s Asbestos Convention, designed to protect workers from the well-known hazards of asbestos exposure, entered into force on 16 June 1989. Yet, nearly twenty-five years later, only 35 countries, 19% of 184 that are eligible, have formally ratified the Convention.2 In contrast, 154 countries (83% of those eligible) are Parties to the 1998 Rotterdam Convention on the Prior Informed Consent Procedure for Certain Hazardous Chemicals and Pesticides in International Trade.4 However, attempts to include chrysotile asbestos – the most common form used – in Annex III of the Rotterdam Convention have failed repeatedly, most recently at the sixth Conference of Parties due to resistance from seven countries, most of whom continue to produce, use, and export asbestos on a large scale (Fig. 1). The minority objection prevailed despite powerful testimony from the representative of the World Health Organization (WHO) that chrysotile and all forms of asbestos are carcinogenic to humans.6 Moreover, given the widespread use of chrysotile in domestic building products, it is impossible to safeguard hazardous exposures in occupational settings or to prevent environmental contamination that threatens the general population. Opposition to the proposal to regulate chrysotile asbestos under the Rotterdam Convention highlights three major gaps in the translation of scientific evidence to global disease prevention policy. \n \n \n \nFig. 1 \n \nAsbestos producers and consumers, 35 countries, 2011 \n \n \n \nThe first gap concerns making policy decisions within the context of scientific uncertainty. For example, the representative of one country claimed that there are insufficient scientific data to support listing asbestos under the Rotterdam Convention. This objection reflects a lack of understanding of the complexities of the scientific process and the inherent variability of factors that contribute to the relationship between toxic exposures and disease outcomes. There are small differences in the findings of observational studies of the effects of asbestos exposure. These are the result of complex interactions between asbestos exposure and genetic, environmental and social factors. Published research in this field includes studies contributed by laboratories that may have a conflict of interest with the asbestos industry.7 This complicates any assessment of the scientific evidence. In practice, a combination of different categories of evidence are used to reach policy decisions that protect the most vulnerable people.8 The proposed requirement of informed consent for the use of chrysotile is based on consistent and reliable evidence from numerous empirical and mechanistic studies conducted by independent scientists. \n \nThe second gap is the role of alternatives assessments in the selection of safer materials used in consumer products. For example, at least two representatives of countries opposing the international regulation of chrysotile asbestos claim that alternative materials have not been sufficiently researched to compare the risks to human health and the environment. Also, claims have been made that technical assistance is lacking for countries wishing to phase out asbestos use and replace it with safer alternatives. The scientific methods developed to address this issue – including materials’ life cycle assessment and functional equivalence – struggle with making comparisons across very different characteristics and potential health and environmental impacts. The assessment methods also have to compare a range of plausible disease endpoints. Whereas a particular material used in a consumer product may be linked to respiratory diseases, proposed alternatives may be linked to reproductive health effects, cognitive deficits or to cancers.9 Although there are legitimate scientific issues to be resolved with alternative assessments, they do not amount, in the case of asbestos, to reasons for stalling policy procedures that simply require informed consent. Inclusion of asbestos under the Rotterdam Convention would increase the pace of research to discover safer alternative materials and their adoption by key industries. \n \nThe third gap in the efficient translation of scientific evidence to disease prevention policy is the need to acknowledge trade-offs between public health, industrial development, economic advancement, employment and political autonomy. Representatives of countries opposing the listing of asbestos under the Rotterdam Convention acknowledge that this inclusion would not imply a ban on production, but argue that it would have a negative impact on international trade and contribute to unemployment. Without political consensus, regulations may be ineffective as detractors identify and use loopholes and backdoor trading to circumvent international policy. This has been the case, for example, with toxic electronic waste and the Basel Convention for controlling transboundary movements and disposal of hazardous wastes.10,11 Yet, forward-thinking countries manage to withstand pressure to protect economic interests at the expense of public health. This is exemplified by the implementation of California’s landmark safer consumer products regulations after five years of contemplation and debate surrounding these trade-offs.12 \n \nIt is possible to eradicate mesothelioma, but we must work harder to bridge the gaps between scientific knowledge and policy decisions that should protect people.

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The asbestos paradox: global gaps in the translational science of disease prevention (vol 93, pg 359, 2015)

Day by day the call to solve traffic congestion problems is increasing. Subway tunnels and high-speed railway are commonly used for transportation. Therefore, tunnel construction induces soil movement, which in turn affects the stability and integrity of adjacent existing buildings. A series of numerical simulations have been established to investigate the effects of tunnel construction of the Greater Cairo Metro–Line 3-Phase-1 on adjacent pile cap foundations of Garage El-Attaba building. Many parameters have been investigated such as tunnel diameter and the distance between pile and tunnel at different tunnel axis and deep and shallow tunnel. After thorough analysis of the results’ simulation, it was found that the tunneling induces additional axial forces and bending moment as well as increasing axial settlement and lateral deflection. Moreover, the results obtained from the parametric study for the shallow and deep tunnel show that the tunnel depth has a much significant effect on piles responses. Finally, the tunnel diameter has an impact on pile responses as well as the pile cap foundation influenced by the tunnel when the tunnel is in very close vicinity of the pile, and its effect is modest to negligible if located far away from the buildings.

Influence of Cairo Metro Tunnel Excavation on Pile Deep Foundation of the Adjacent Underground Structures: Numerical Study

This book focuses on meeting funding needs for transportation infrastructure in the United States. Two main ideas are explored, the use of engineering economic analysis to determine the most efficient way to meet funding needs and how to ensure the availability of funding. Topics include: banking formulae for use in alternatives analysis; the use of project costs and benefits in economic analysis; the history of transportation financing; the use of bonds; and potential solutions for transportation funding in the future.

Engineering Economics and Finance for Transportation Infrastructure

Proceedings of a symposium sponsored by the Geotechnical Engineering Division. Geotechnical Special Publication No. 23.

Predicted and observed axial behavior of piles--results of a pile prediction symposium : proceedings of a symposium

Underground structures play an important role in achieving the requirements of rapid urban development such as tunnels, parking garages, facilities, etc. To achieve what is needed, new transportation methods have been proposed to solve traffic congestion problems by using of high-speed railway and subway tunnels. One of the issues in urban spaces due to tunnel excavation is considerable surface settlements that also induce problems for surface structures. There are a variety of published relationships concerned with field measurements and theoretical approaches to evaluating the amount of the maximum surface settlement value due to tunneling. This paper studies the ground surface settlement caused by the Greater Cairo Metro – Line 3 - Phase-1. This project was constructed by a slurry shield Tunnel Boring Machine (TBM). Therefore, this work consists of two parts. The first part presents the details of the project and monitoring results field and laboratory geotechnical investigations in order to determine the soil properties. The second part is to the comparison between the field measurements and theoretical approaches for surface settlement due to tunneling construction. At the end of the works, the results show that the more convenient methods which approach the field measurements, and the major transverse settlement occurs within the area about 2.6 times the diameter of the tunnel excavation. Doi: 10.28991/cej-2020-03091617 Full Text: PDF

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Prediction of Ground Settlement Induced by Slurry Shield Tunnelling in Granular Soils

Tunnel construction will inevitably change the surrounding soil’s original stress and displacement fields, affecting the surrounding piles. In addition, the lateral displacement of the soil at the subway tunnel’s face is symmetrically distributed along the tunnel’s central axis, which is greater in the center and smaller on both sides. Therefore, the protection of existing piles and providing a reasonable reinforcement plan have become the focus of attention. Taking a section of Tianjin Metro Line 3 as the research object, this paper studies the influence of the shield tunnel excavation process on the existing pile foundation through three-dimensional finite element simulation. The model has been verified through field monitoring data. Then, parameter analysis has been carried out for two reinforcement measures: grout reinforcement and isolation pile construction. According to the research results, the impact of shield construction on the pile foundation is mainly within the range of twice tunnel diameter to the pile foundation from the front and back of the tunnel face. In addition, the grouting reinforcement has better control of the vertical displacement of the existing pile foundation. The construction of isolation piles can better control the lateral displacement of the existing pile foundation. Have certain reference significance for similar projects.

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Numerical Study on the Reinforcement Measures of Tunneling on Adjacent Piles

In the construction of mountain tunnels, biased and water-rich strata are often encountered. During tunnel excavation, the fluid–solid coupling has a great influence on the stability of the surrounding rock. This effect will be more severe when the terrain is biased. The bias tunnel points out the asymmetric load of the rocks which are surrounding the tunnels through the drilling or construction process due to the topographic situation. These loads can cause inverse actions during tunnel construction. Therefore, the effect of fluid–solid coupling on the displacement field, stress field, and seepage field of the tunnel surrounding rock under different biased terrains are studied in this paper. In the context of the Youzishu tunnel project, the numerical model is established to define the degree of terrain bias. Besides, the concept of bias coefficient is introduced. To achieve what is needed, 10 sets of increasing bias coefficients are obtained, by changing the inclination of the terrain to study the influence of formation bias degree on tunnel excavation in water-rich formations. After an in-depth analysis of the simulation results, it is found that the influence of fluid–structure interaction cannot be ignored. By analyzing ten groups of data under different working conditions, the biased terrain will aggravate this effect. As far as the displacement field of the surrounding rock is concerned, the biased formation has a greater impact on the deeply buried side than on the shallow-buried side, and has a greater impact on the vault than on the arch bottom. In addition, by analyzing the stress field and seepage field of the surrounding rock, a similar result can be obtained: the influence of formation bias on the deeply buried side is greater than that on the shallow-buried side, and the biased terrain will increase the pore pressure outside the tunnel lining and increase the water inflow. Finally, the locations where the displacement, stress, water pressure, and water inflow are the largest during the tunnel excavation process are found by the simulations and analyzed. Thus, attention can be paid to these locations, permitting a focus on protection during the construction process.

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Study on the Mechanical Behavior of Fluid-Solid Coupling in Shallow Buried Tunnels under Different Biased Terrain

An inclined straight combination support pile can play a better role in deep foundation pit support, especially for the protection of adjacent structural pile foundations. We take a section of the construction of a deep foundation pit project in Wuhan City, Hubei Province as the research object. This paper studies the influence of inclined and straight combination support piles on the bending moment and displacement behavior of adjacent pile foundations during the construction of foundation pits under the influence of different factors such as distance from the excavation surface, pit angle effect, inclined pile tilt angle, pit depth to width ratio, and construction conditions on the adjacent pile foundation using a three-dimensional finite element model. According to the research results, as the distance from the excavation surface increases, the bending moment of the adjacent pile foundation decreases, and the closer the pile is to the foundation pit, the greater the horizontal displacement of the pile; the bending moment and displacement of the pile foundation are supported by the pit angle effect. Moreover, the pile bending moment increases with the increase of the pit depth–width ratio, and the maximum displacement point of the pile body gradually moves down from the middle of the pile body to the bottom of the pile foundation as the excavation depth of the pit increases. In addition, the minimum displacement of the adjacent pile foundation is at the top of the pile, and the maximum displacement is at the middle of the pile. Finally, compared with the static analysis, the whole process of dynamic simulation can reflect the dangerous working conditions in the project construction process, and make a more complete safety control construction plan for the project construction process.

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Mo’men Ayasrah

Papers

Prediction of Ground Settlement Induced by Slurry Shield Tunnelling in Granular Soils

Influence of Cairo Metro Tunnel Excavation on Pile Deep Foundation of the Adjacent Underground Structures: Numerical Study

Numerical Study on the Reinforcement Measures of Tunneling on Adjacent Piles

Study on the Mechanical Behavior of Fluid-Solid Coupling in Shallow Buried Tunnels under Different Biased Terrain

Impact Study of Deep Foundations Construction of Inclined and Straight Combined Support Piles on Adjacent Pile Foundations