Use of impulse radar as a method for the non‐destructive testing of concrete slabs

The paper shows that Impulse Radar provides engineers and associated professions with an invaluable non‐destructive testing tool and when used in conjunction with other methods of testing, Impulse Radar has an important role to play throughout the complete lifecycle of a structure.     

The aeolian project: a MAB‐UNESCO investigation to promote sustainable tourism in the mediterranean area

The Aeolian archipelago is undergoing social and economical changes that threaten its natural and cultural patrimony, which is also the essence of a tourist appeal, as an image of uncontaminated sites, where nature's ancestral phenomena and seasonal rhythms are experienced. Salina island may serve as a prototype for exploring the possibility of implementing conservation strategies compatible with human needs, landscape preservation and sustainable economic development. By means of the CORINE methodology, “ecological sensitivity” (from a functional viewpoint) and “ecological vulnerability” (either physical or ecological) maps have been drawn to objectively quantify the environmental risk. Some final remarks are devoted to clarify the concepts of “environmental perception” and “citizens’ consent”.     

Risk‐minimizing approach to bid‐cutting limit determination

Intense price competition is quite common in the construction industry. In many markets, contractors have to cut their bids to compete, giving priority to winning enough contracts to sustain normal operation, and it is common to see a winning bid close to the expected project cost. While cutting bids not only gives up profits but also undoubtedly increases the risk of making a loss, the behaviour of contractors in intense competition is difficult to explain by existing academic bidding models. An approach to determining the lower limit of the bid for a project is proposed based on minimization of the overall loss risk defined by a probabilistic model. The approach can be used to prevent arbitrary over‐cuts in final bid decision where price competition is intense. Factors influencing the suggested bid‐cutting limit for a project are analysed. An illustrative example using real case data is provided.     

Decision‐making in a model‐based design process

Decisions early in the design process have a big impact on the life cycle performance of a building. The outcome of a construction project can be improved if different design options can rapidly be analysed to assist the client and design team in making informed decisions in the design process. A model‐based design approach can facilitate the decision‐making process if the design alternatives' performances can be evaluated and compared. A decision‐making framework using a performance‐based design process in the early design phase is proposed. It is developed to support decision‐makers to take informed decisions regarding the life cycle performance of a building. A scenario is developed in order to demonstrate the proposed framework of evaluating the different design alternatives' energy performance. The framework is applicable to decision‐making in a structured design process, where design alternatives consisting of both objective and subjective evaluation criteria can be evaluated.     

Inter‐agency transport planning: co‐ordination and governance structures

This article begins by clarifying the forms and means of co‐ordination peculiar to the governance structures of market, hierarchy and network. Co‐ordination in these structures is primarily achieved by competition, command and co‐operation, respectively. The case study focuses on co‐operation. It gives an account of how the administrative agencies of public roads, railways, civil aviation and coastal infrastructure work together in the Norwegian national transport planning process. The administrations take varying interest in the integrated plan and have different degrees of power in the co‐ordination process, which has caused some tension. The divergent co‐operation strategies chosen by the agencies are partly due to dissimilar sources of funding and organization models. These features and the degree of agency interest in the co‐ordination effort are influenced by the relative strength of market elements and hierarchical elements guiding their operations. It is therefore meaningful to explain the agencies' more or less co‐operative strategies by utilizing the concepts of governance structure and co‐ordination.     

Loan‐to‐value ratios in Sweden. The impact of financial deregulation

We ask how financial deregulation in Sweden during the 1980s affected housing finance by studying data on loan‐to‐value (LTV) ratios for home owners who moved recently. Accounting for the impact of demographic and economic determinants we find that LTV ratios were higher between 1985 and 1987 than in earlier and later years. This time pattern suggests that the deregulation of the mortgage institutions and the removal of the loan rate ceiling on banks in 1983 and 1984 were more important than abolishment of the bank loan ceiling in late 1985. They also indicate a decrease in loan demand and/or supply as early as 1988, i.e., well before the banking crisis.     

Finance‐based CPM/LOB scheduling of projects with repetitive non‐serial activities

Projects of repetitive non‐serial activities constitute a major category of construction projects which can be scheduled more conveniently using the line of balance (LOB) technique. Generally, scheduling activities such that the expenditures are always in balance with the available cash is a must to devise financially feasible schedules. The objective is to integrate a CPM/LOB model for a project of repetitive non‐serial activities with a cash flow model and utilize the integrated model to devise financially feasible schedules. The genetic algorithms (GAs) technique is employed to maximize the profit at the end of the project under the constraints of available cash. The optimization of the integrated models was demonstrated using an example project of 15 activities carried out at five units. The CPM/LOB model was validated against the results of a dynamic programming model in the literature and further by conducting a sensitivity analysis of the results of the integrated model. Finally, the model offers an effective financial planning tool for projects of repetitive non‐serial activities.     

Set‐point identification of a free‐fall triboelectrostatic separation process for plastic particles

Identification of the optimal operating conditions and evaluation of their sensibility to changes in certain critical factors are critical issues for the industrial application of electrostatic separation techniques. The aim of this paper is to validate an experimental procedure for optimising the selective sorting of non‐conductive constituents of granular industrial plastic wastes using a free‐fall triboelectrostatic separator.     

Payment and audit mechanisms for non private‐funded PPP‐based infrastructure maintenance projects

The introduction of a non private‐funded public–private partnerships (PPP) approach to the maintenance and operation of infrastructure facilities necessitates an equitable performance standard, a sensible penalty mechanism and a credible auditing system. Yet, with limited research on this type of scheme, it is not clear whether the payment and audit mechanisms can adequately gauge the performance of private partners and truly reflect the quality of service provided in their payment. The question is whether the reliability of the payment reduction and auditing mechanisms pertinent to the non‐private funded PPP infrastructure maintenance can be systematically verified. With reference to a case study in Hong Kong, field data have been collected and tested according to the sensitivity analysis and level of confidence. The results indicate that the level of payment reduction due to poor performance is fair and the audit frequency is adequate to reflect the overall performance of the service provider. The approaches adopted in this research should provide an objective basis for public and private partners to formulate a mutually acceptable and effective mechanism for non private‐funded PPP infrastructure maintenance contracts.     

Mini‐blasting for repair work

High chloride content of the concrete had led to corrosion of reinforcement in the brackets supporting the access balconies of a block of flats in Copenhagen; also affected were parts of the balcony decks and some wall panels. Widespread replacement of the suspect components was chosen, including re‐casting of the support brackets in situ. How the old concrete of the brackets was removed by controlled local blasting is described by a member of Demex consulting engineers, who acted as explosive demolition consultants to this project.     

Group‐level safety climate in the Australian construction industry: within‐group homogeneity and between‐group differences in road construction and maintenance

In modern organizations it is overly simplistic to assume that a uniform, organization‐wide climate for safety develops. Workgroup‐level safety climates are more likely to arise in decentralized organizations and their influence on occupational health and safety (OHS) behaviour is likely to be stronger when work is non‐routine, as in construction. The existence of workgroup‐level safety climates was examined in the Australian construction industry. A group‐level safety climate survey was conducted in a road maintenance and construction organization. The clear factorial structure produced in a larger sample of Australian defence logistics workers was not replicated and factors splintered, possibly due to the subject‐to‐item ratio in the construction study. However, the internal reliability consistency of the factors produced in the earlier pilot study was found to be acceptable for the construction industry data. Two requisite conditions for the existence of group‐level safety climates, i.e. (1) within‐group homogeneity; and (2) between‐group variation, were satisfied within the road construction and maintenance organization. The results indicate that distinct workgroup safety climates exist in construction, providing a theoretical explanation for why some workgroups perform better in OHS than others, despite having similar risk exposure.     

By‐products formation in catalytic combustion of aromatic compounds over a pt‐based catalyst

By‐products formation in the catalytic combustion of different aromatic compounds has been experimentally investigated. A commercial Pt‐based catalyst, in the shape of a short monolith, has been employed. Toluene, styrene, o‐xylene and cumene have been tested at low concentrations for conversions in the range 5–50%. The results confirm the formation of benzene in the combustion of toluene and styrene, as previously observed by other researchers, but in a very small amount; testing cumene, significant amounts of acetone have been found in the outlet flow. Some hypothesis about the reaction mechanism are put forward.     

Time‐dependent construction social costs model

Negative impacts of construction works on local traffic, environment and business have been pointed out by previous researchers. However, little work has been conductd on the quantification of such costs. A time‐dependent construction social costs (COSCO) model is developed for quantifying the negative impacts that result from construction operations during the field execution phase. The COSCO model is a simplified but practical model that calculates the construction social costs in a conservative way. A roadwork construction project is used to show the applicability of the COSCO model. It is found that the daily social cost was US$18?188–5.52 times the project construction cost. This is a striking illustration of management techniques for mediating the social costs of construction projects.     

Dispersion study for two‐dimensional modelling

Simulation of water quality variation in a particular river stretch or at a particular location with time requires mathematical modelling based on advection and dispersion phenomenon. In this context, estimation of an appropriate dispersion coefficient, which is a function of characteristics of a water body, is very essential and forms an important step in mathematical modelling. The tracer study conducted in this context on the river Ganga to estimate the dispersion coefficient is described in this paper with an analysis of data based on a stream‐tube approach. For the wide river Ganga, with a velocity in the range 0.3–0.5 m/s, the estimated transverse dispersion coefficient is 1.33 m²/s.     

Web‐based integrated project control system

This paper presents a system that supports project time and cost control in an integrated manner. The system utilizes object‐oriented modelling to represent the process of project delivery. A set of control objects is designed to map the process of project control. Eighteen key indicators are considered to represent the resources utilized in each control object and serve as sensors to highlight problematic areas associated with unfavourable performance. A Three‐Tier Client/Sever computer system is designed to implement the developed system. Daily, weekly, monthly and/or yearly, period‐by‐period, and cumulative to‐date project performance reports are generated to provide the status at project, control object and resource levels. An example drawn from the literature is analysed to allow for comparison with the results obtained using the proposed methodology. The example also serves the purpose of demonstrating the use of the proposed system and illustrating its essential features.     

Fabric‐reinforced cement,folded plate

Vistarp Karbhari and Robert Nicholls, Professor of Civil Engineering at the University of Delaware, show that sandwich panels, having fabric‐reinforced cement mortar faces with triangularly folded cores, can be designed to maximize flexural stiffness per unit material cost. The authors suggest that a wide variety of loading conditions could be satisfied from stock sheet, folded to structural engineers’ individual designs.     

Numerical parametric investigation of infiltration in one-dimensional sand–geotextile columns

Geotextiles are routinely used in separation and filtration applications. Design of these systems is currently based on saturated properties of the geotextiles and the surrounding soils. However, in the field, soil and geotextile can be in an unsaturated state for much of their design life during which they are essentially hydraulically non-conductive. Periodic wetting and drying cycles can result in rapid and large changes in hydraulic performance of soil–geotextile systems. The writers have reported the results from physical water infiltration tests on sand columns with and without a geotextile inclusion. The geotextile inclusions were installed in new and modified states to simulate the influence of clogging due to fines and to broaden the range of hydraulic properties of the geotextiles in the physical tests. This paper reports the results of numerical simulations that were undertaken to reproduce the physical tests and strategies adopted to adjust soil and geotextile properties from independent laboratory tests to improve the agreement between numerical and physical test results. For example the paper shows that the hydraulic conductivity function of the geotextile must be reduced by up to two orders of magnitude to give acceptable agreement. The lower hydraulic conductivity is believed to be due to soil intrusion that is not captured in conventional laboratory permeability tests. The calibrated numerical model is used to investigate the influence of geotextile and soil hydraulic conductivity and thickness as well as height of ponded water at the surface on wetting front advance below the geotextile and potential ponding of water above the geotextile due to a capillary break mechanism. A simple analytical model is also developed that predicts the maximum ponding height of water above the geotextile based on two-layer saturated media and 1-D steady state flow assumptions. The analytical model is used to generate a design chart to select geotextiles to minimize potential ponding of water above the geotextile. Ponding can lead to lateral flow of water along the geotextile in reinforced wall, slope, embankment and road base applications.     

Experimental investigation on pressure–leakage relation for high-density polyethylene pipe

ABSTRACT

Leakage control decision-making analysis needs a deep recognition of the pressure–leakage relationship. In this study, leakage behavior in High-Density Polyethylene (HDPE) pipes is investigated by a semi-industrial pilot-scale. Accordingly, some experiments were conducted on circular, longitudinal and circumferential slits for studying the effect of diameter, thickness, and material of pipes, forms, and dimensions of the leak opening, the surrounding environment, and temperature. New equations are presented to estimate the discharge coefficient for orifices and longitudinal slits in HDPE pipes. Leakage value from a longitudinal slit depends on elastic or plastic behavior of the leak area, to distinguish this, a new criterion has been introduced between elastic and plastic behaviours of the longitudinal slit. Results show that, for same leakagel area and pressure, the leakage rate of circumferential slits is generally more than orifices and less than longitudinal slits. Results of this study can be utilized for estimating the leakage rate.     

Optimum mix design of enhanced permeable concrete – An experimental investigation

Permeable pavement, due to its high porosity and permeability, is considered as an alternative to traditional impervious hard pavements for controlling stormwater in an economical and friendly environmental way. Permeable concrete normally made of single-sized aggregate bound together by Portland cement, using restrictedly as a pavement material, because of its insufficient structural strength. Aimed at developing a new type of permeable concrete with enhanced structural strength, various mix designs were attempted and their effects on the compressive strength and permeability of permeable concrete were investigated in this research. The optimum aggregate and mix components design were consequently recommended for enhanced permeable concrete.