The purpose of this project, accomplished as part of NCHRP Project 4-8 of the same title, was to discover and describe possible areas of needed research which if successfully pursued would assist the highway materials engineer in development of procedures for the evaluation of aggregate properties and, in turn, would lead to the more efficient use of our aggregate supplies. A comprehensive series of statements of research problems was developed and categorized into four general areas of study which are: (I) Portland Cement Concrete (II) Bituminous Concrete and Related Materials (III) Base Course and Shoulder Materials (IV) General (involving at least two of the first three areas) The formulation of the research problem statements was based upon information obtained from an extensive literature survey, a Workshop Conference involving 51 “authorities” in various fields of aggregates, and a follow-up interview program. A total of 52 statements was developed with a total estimated cost of $5,499,500. A priority rating system was also developed and applied to each project. If only the top priority project in each of the four study areas were funded, the cost is estimated to be $670,000. The relative priority ratings indicate the significance of the problem statements. A solution to the priority one project of Group I, for example, relating to D-line cracking in concrete, would cure a persistent problem which engineers thought was solved. The major conclusion from this study is that the framework for selective aggregate research has now been developed and program funding is the next matter for concern. / M.S.

Plant growth regulators (PGR's) including metsulfuron plus mefluidide at 10 plus 140 g ha⁻¹, chlorsulfuron plus mefluidide at 20 plus 140 g ha⁻¹, imazethapyr plus imazapyr at 67.5 plus 2.5, 96.4 plus 3.6, and 115.7 plus 4.3 g ha⁻¹, ACP 2100 at 60, 120, and 180 g ha⁻¹, and DPX L5300 plus mefluidide at 10 plus 140, 20 plus 140, and 70 plus 140 g ha⁻¹ were applied to ‘KY 31’ tall fescue (<i>Festuca arundinacea</i> Schreb.). All rates of imazethapyr plus imazapyr, ACP 2100, and chlorsulfuron plus mefluidide afforded a significantly higher turf quality than metsulfuron plus mefluidide. ACP 2100 at 120 and 180 g ha⁻¹, imazethapyr plus imazapyr, DPX L5300 plus mefluidide at 70 plus 140 g ha⁻¹, and metsulfuron plus mefluidide gave the most consistent seedhead suppression. When treating seven month old tall fescue, DPX L5300 plus mefluidide did not adequately suppress seedhead elongation. Metsulfuron plus mefluidide, regardless of timing, caused excessive injury. All rates of imazethapyr plus imazapyr and the upper rates of ACP 2100 afforded the best turf quality followed by chlorsulfuron plus mefluidide in 1988 to ‘Rebel’ and both years to ‘KY 31’. Red fescue (<i>Festuca rubra</i> L.) quality was best with chlorsulfuron plus mefluidide and the high rate of DPX L5300 plus mefluidide. All other treatments resulted in a poorer quality turf. For all field studies on all turf types, in general, multiple applications were not practical and often caused excessive injury regardless of timing. Root studies conducted in the greenhouse revealed that with one application, imazethapyr plus imazapyr, ACP 2100, and DPX L5300 plus mefluidide provided root dry weights ranging from 0.5 to 0.7 g, which was greater than metsulfuron plus mefluidide, chlorsulfuron plus mefluidide, and the mowed check which afforded root dry weights of 0.1, 0.3, and 0.2, respectively. With two applications ACP 2100 and DPX L5300 plus mefluidide afforded 350, 1100, 200 and 200% greater root volume than metsulfuron plus mefluidide and chlorsulfuron plus mefluidide and 200, 630, 600 and 600% greater root dry weights. Three applications are not recommended. In laboratory studies using ‘KY 31’ tall fescue, mefluidide enhanced the uptake of ¹⁴C-DPX L5300 after 48 hours by as much as 11% and the translocation of ¹⁴C by 8.4% to the young leaves, 9.3% to the old leaves and 6.1% to the culm. Radioactive material concentrated in the tips of leaves. No significant accumulation of ¹⁴C occurred in the crown or roots. / Ph. D.

The population and economy in the State of Qatar have been increasing significantly in the past 10 years. Accordingly, traffic loading has also increased rapidly, which merits consideration of the design and construction of long-lasting pavement structures that require minimal maintenance. This study started with an investigation of the feasibility and performance of the current asphalt pavement materials and structures being used in the country. This investigation utilised the analysis approach implemented in the Mechanistic-Empirical Pavement Design Guide (M-E PDG) software. The results evidenced how effective it is to replace the conventional unmodified 60-70 Pen bitumen with polymer-modified PG76-10 bitumen for pavements in Qatar and other countries in the region with similar climatic conditions. In addition, the results showed that the use of perpetual pavement structures is a viable option economically and that they are much more accommodating of increase in traffic loading, without causing excessive damage, than conventional pavement structures. The study also concentrated on the assessment of the long-term performance of different full-scale perpetual trial sections by conducting several field tests. The field performance evaluation results showed slightly low resistance to rutting, high IRI values, to some extent, and low stiffness during summertime when the temperature is high. These distresses and deteriorations are expected given the huge traffic loading and the big difference in temperature between seasons in Qatar. Then several field cores, field mixtures, and laboratory mixtures were tested and evaluated in order to assess the performance of different asphalt concrete mixtures against rutting, fracture, temperature susceptibility and fatigue damage. The conducted tests were useful to characterise and assess the performance of the mixtures against several major distresses. The results indicated that resistance of asphalt concrete mixtures to rutting was mainly affected by the bitumen grade, aggregate source and aggregate gradation. A well-designed mixture that uses polymer-modified bitumen (PMB) can achieve the high rut-resistance of asphalt mixtures either with Gabbro or limestone aggregates. The use of polymer-modified bitumen reduced the temperature and frequency susceptibility on the stiffness and rut-resistance. According to these results, it is obvious that rutting and cracking would not be major distresses for asphalt mixtures in Qatar if the mixtures were designed following a Superpave mix design with the appropriate content of polymer-modified bitumen. However, given the current mixture design system in Qatar, which utilises very low bitumen content, fatigue damage or cracking in general is a main distress, and its characterisation should be investigated in depth. The traditional methods to interpret fatigue tests data are not sufficient to characterise and evaluate mixtures against fatigue damage. Therefore, two advanced fatigue characterisation approaches were performed on the raw data obtained from the fatigue test of specimens prepared from different mixtures. The analysis of the fatigue tests focused on calculating the dissipated energy (DE) and obtaining damage characteristics curves following a comprehensive viscoelastic continuum damage (VECD) approach. The test results showed that the use of the VECD approach has major advantages over obtaining DE results only. However, the predicted fatigue life (Nf) for each asphalt mixture was affected by the uncertainty associated with fatigue tests as well as with model parameters. Therefore, it was important to develop a probabilistic analysis approach that accounts for the uncertainty and the variability associated with fatigue tests and analysis, respectively. To that end, a novel probabilistic analysis approach has been proposed in the last chapter of this study for predicting the performance of asphalt mixture against fatigue damage. The VECD characterisation approach was used in the development of this probabilistic analysis model. The random variables (RVs) of the fatigue life (VECD-Nf) model (|E*|LVE, a, b and α) were generated following normal distribution functions. However, it is suggested that more specimens should be tested in the future to specify the true distribution functions for the RVs. In conclusion, it is clear that the fatigue life results of the probabilistic analysis approach were much more consistent and reliable than those of the deterministic analysis approach. This probabilistic approach coupled with VECD results is very practical and useful for engineers and will be beneficial to predict fatigue cracking resistance of asphalt mixtures in the field.

M.Tech. (Engineering: Civil) / Please refer to full text to view abstract

After natural/man-made disasters, a major challenge faced by governments is to ensure a speedy recovery of roads and transportation networks. In order to achieve this, a new road recovery priority (RRP) model has been developed to identify key issues and their inter-relationships giving a better understanding of factors that govern prioritisation across the affected regions. Interviews are conducted with experts in road reconstruction and maintenance organisations to investigate respondents’ evaluation and understanding of the RRP model in terms of its ease of use, usefulness, comprehensiveness, applicability, feasibility and structure. A questionnaire survey is conducted to investigate the impact of the important proposed affecting factors that can be critical for successful implementation and application of the RRP model in the road rehabilitation sector. A field survey is carried out to collect data which are essential to determine parameters in the model’s application. Four case studies are carried out to investigate the RRP model’s application in a variety of road conditions. The application of this model may solve the problem of decision making in road recovery priority determination in a hierarchical manner so that the recovery process can be accomplished from an urgent repair need to a lower recovery priority.

Transportation is a central component to most political, economic, social and environmental issues throughout most inhabited societies. The concerns of transport have become widely acknowledged. It is broadly accepted that promoting alternative forms of transport such as walking, cycling and public transport use is one solution to tackle environmental concerns. Although, delivering, implementing and developing transport strategies to reduce car usage is still highly debated. Transport stakeholders (e.g. planners and policymakers) have long strived to reduce car usage. Many studies have attempted to develop strategies or understand triggers that might encourage and promote a reduction in car use. Despite this, the car usage has typically intensified and alternative forms of transport have become marginalised or discouraged when compared to the car. This research investigates travel attitudes and behaviours of individuals along a specific urban travel corridor within an area of Birmingham, UK. It explores socio-demographic factors using a mixed methods approach that incorporated questionnaires, travel diaries and interviews. This work identified a series of transport measures conceived upon different urban demographic characteristics in order to meet different individuals’ transport need. A significant finding from this work indicated there was an appetite amongst the sampled participants to be willing to reduce their car use if the right transport strategies were introduced. Initially the results from the questionnaire suggested age influenced car use the most, however, other demographic characteristics (e.g. gender and deprivation) were found to be an influential factor.

The research was aimed at the development of an optimal road fund allocation model for road maintenance to three road agencies in Ghana. The objective was to compare a novel model by multicriteria analysis (MCA) with deterministic outcome and a model based on preferential analysis to determine optimality. The deterministic model was efficiency based with quantitative analysis from a decision maker’s perspective whilst the approach by preferential analysis was equity based with qualitative analysis from stakeholder perspective. The input parameters of the deterministic model were based on the value function method (VFM) and the concept of efficiency frontier. It determined a scaler index for the proportionate allocation of road fund by road type. It was based on a set of attributes including road length, traffic, pavement roughness and percentage of work achievement. The concept of efficiency frontier was used to sub divide the proportion of funds allocated by road type into economic efficiency and equity components based on the Net Present Value/Capital, Vehicle Operation Cost (VOC) and income. The values of the selected attributes were generated from the outputs of HDM-4 analysis. The model based on the preferential analysis was set on the Analytical Hierarchy Process (AHP). It involved pairwise comparison of defined criteria and sub criteria by stakeholder priority at national, district and community levels. Priority vectors were estimated for road fund allocation into efficiency and equity proportions by road type. A comparison of the outputs of the two models on the basis of the impact on pavement roughness performance indicated the stated preference based model yielded better impacts than the model with deterministic approach. It was concluded that road fund allocation based on a well logically determined value judgement with mathematical analysis yields better results.

This thesis reports an investigation into the relationships between the tyre strain feature and tyre operating conditions based on finite element analysis and experiments for the development of a strain-based intelligent tyre system, which could estimate the tyre operating characteristics for optimising vehicle dynamics control and improving vehicle safety. A 175/505R13 tyre is adopted as the subject of this study. An efficient and effective material property determination procedure is developed for investigating the rubber and reinforcement material properties by experiment. Considering the possibility of the absence of tyre composite profile due to proprietary protection by tyre manufacturer, a novel imagebased method is developed to capture the tyre geometry feature from the tyre product cut cross-section. Both the 2D and 3D finite element tyre models are created in the commercial finite element code ABAQUS. The generated finite element tyre models are validated with experimental data and then adopted to construct the comprehensive relationship between tyre strain feature and tyre operating characteristics. Experimental validation of these estimation models are implemented based on a custom designed test system. Finally, some recommendations are presented for improving the capability of the finite element tyre model and the strain-based intelligent tyre test system.

A study of the factors affecting the packing and porosity of particles has been made and a general theory for the combining of aggregates of varying shapes and sizes in order to achieve minimum porosity is proposed. Arising out of this theory experiments have been carried out from the results of which graphs have been prepared to enable the determination of the optimum percentage of fine material for maximum density in two component systems. A method for extending the application of these results into the province of the design of multicomponent systems of both the continuous grading and intermittent grading types has been devised, and in the latter type the inherent gaps in the grading have been related to measured void characteristics. From another graph the value of porosity appropriate to any such mixture can be estimated. The theory and relevant graphs are believed to be of general application in the fields of mixtures comprising aggregates of any shape or combination of shapes whether these be dry aggregates, wet aggregates, bitumen or tar coated aggregates or concrete aggregates, and to cover all possible environmental conditions of the particulate mass such as the applied compactive effort and boundary effects.

The strategic and local road networks are together the United Kingdom’s most valuable infrastructure assets. Roads deteriorate over time as a function of traffic and the environment and must be maintained appropriately to preserve their asset value in order to help support the economy. Furthermore, well maintained roads reduce road user costs via lowering vehicle operating costs, reducing accidents, delays and litigation. Amongst other projections, climate change indicators suggest there will be warmer wetter winters and an increase in extreme weather events such as heavy rains. Increased heavy rainfall events will adversely influence the road infrastructure and place more demands on maintenance. The inherent risks in highway infrastructure assets and those associated with future climate predictions must be better understood and incorporated within decision support models to enable highway engineers and asset managers make better, more informed decisions regarding infrastructure maintenance. By combining the risk management process and drainage network analysis this study explored the risks and their potential impacts within a road network. This resulted in a proposed methodology for the identification of parts of a network to be most at flood risk. Data in respect of the risks and their probability of occurrence, for use within the model was obtained through a questionnaire completed by highway drainage engineers at various locations in the UK.