A literature survey on Ultra High Performance Fibre Reinforced Concrete (UHPFRC) reveals that the applications until now have remained limited. This is because although it has proved to have outstanding mechanical properties such. as the compressive strength of 150-250 MPa and flexural strength of 25-50 MPa, UHPFRC has a highcosting issue as well as shortage of mix design procedure and of structural design guidelines. Therefore, the following works are carried out in this PhD study. The mix design of UHPFRC is first studied. A mix design procedure based on the 'Excess Paste Model' is proposed to' design the preliminary mix proportions. The superplasticiser dosage and excess paste volume significantly influence the workability as well as the mechanical properties of UHPFRC. Optimisation of superplasticiser dosage and excess paste volume leads to the optimum mix proportions by reducing the water-binder ratio and finally enabling achievement of high strength. The by-products of industry such as Ground Granulated Blast-Furnace Slag (GGBS), Pulverised Fuel Ash (PFA), and glass cullet are studied to replace cement and silica sand in UHPFRC. These replacements help to reduce the cost. The replacement of cement by GGBS and PFA also lessens the environmental impact caused by the cement producing industry. The sustainability of UHPFRC is therefore improved. The mechanical properties of UHPFRC are investigated experimentally by testing cube specimens for compressive strength and prism specimens for flexural strength, fracture energy and flexural toughness. There is no significant difference of compressive strengths between two sizes of specimens, Le. 50 mm cube and 100 mm cube, but a considerable difference of flexural strengths between 40x40x160 mm specimens and 100x1 00x350 mm specimens is found. The origin of this size effect issue on flexural strength is therefore investigated by using different loading arrangements, extracting small specimens from large specimens, and various sizes and shapes of specimens. Two factors are found to contribute to this size effect. These are the boundary surface layer and the ratio of the total crack-surface area to the cross section area of beam specimens. Paving flags with the lower half of thickness comprising UHPFRC with 2.0% fibres are fabricated as an outcome product of the studies on mix proportions and mechanical properties. These 400x200x30 mm UHPFRC paving flags are cast using a 'Hydraulic press' technique replicating a factory's typical casting procedure. The flexural strength and fracture energy of UHPFRC paving flags are then examined to compare with those of ordinary concrete paving flags. These flexural strengths and fracture energies are used as input parameters for finite element analysis (FEA) models of pavements using these paving flags. The structural behaviour of pavements using ordinary concrete paving flags and pavements using UHPFRC paving flags positioned on sand bedding and sub-base layers are studied using both laboratory experiments and FEA models. The FEA model of UHPFRC pavement is then used to predict the structural behaviour when the thickness of flag, the thickness and elastic modulus of sub-base layer vary. The following novel and major outcomes from this PhD study contribute to the development of UHPFRC: • Systematic investigations of mix proportions and mechanical properties of UHPFRC help the users to select the raw materials, mix proportions and curing regime suitably for the structures required. The results on the effect of specimen size on the flexural behaviour of UHPFRC suggest that UHPFRC large-scale beams should be trialied carefully before use; • An application of UHPFRC for very high performance crack-resistant paving flags using in pedestrian pavements has been studied by both experimental and FEA methods. The potential benefits obtained from using UHPFRC paving flags compared with ordinary concrete paving flags include: (1) UHPFRC paving flags can be made thinner and lighter, resulting in the reduction of health and safety concerns during handling and placing and also the reduction in transportation costs; (2) increase of pavement service life and lead to reduced maintenance costs; (3) reduction of liability claims arising from uneven pavements.

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The following thesis is a summary of work undertaken over a five year period investigating the potential of one method of remote measurement to evaluate the geometrical properties of highway surface textures. The character and configuration of surface textures contribute significantly to the safety and serviceability of highway pavements. A synopsis of current evaluation methods is considered followed by a detailed consideration of close range photogrammetry in its application to surface modelling. Close range photogrammetry is used to construct models based on the Delaunay triangulation algorithm. The outputs from these models are evaluated initially against the benchmark standard of the Mean Texture Depth (MTD) derived from the Volumetric Sand Patch (VSP). The approach addresses a significant range of surfacings at varying mesh spacings and in several contexts with results and conclusions presented at the macro and in some instances the micro scale. Images were collected within laboratory and field contexts and compared for models of surfaces at locations in Scotland, areas of mainland Europe and along the eastern seaboard of the United States of America. Images were post processed using ImageMaster™ proprietary photogrammetric software at varying mesh spacings and Triangular Irregular Networks (TIN) generated for subsequent analysis and manipulation in other spatial and surface analysis software including ArcGIS ™ and Digital Surf Mountains Map ™ Premium surface analysis software. The integrity of the TINs is evaluated against TINs of a group of surfacing materials generated from photogrammetry and a ZScanner™ 800 handheld 3D laser scanner with a stated resolution of 50 microns. The thesis does not simply present photogrammetry as an alternative to traditional volumetric methods of estimating MTD but also as a convenient method of generating an array of surface information that may be compared to functional parameters in recognised British, European and International Standards.

This thesis considers Warm Mix Asphalt in Ireland. It was sponsored by the National Roads Authority to explore sustainable materials and technologies. This material is typically mixed and laid at least 20°C lower than conventional Hot Mix Asphalt. This reduction in temperature reduces fuel consumption and fume emissions during manufacture and laying. A review of current literature found that harmonized European standards have to be revised to make them compliant with the Construction Products Regulation. Although the Regulation places greater emphasis on the durability of road construction products there is no specific harmonized test method to asses this. This prompted the research in this thesis that considered the durability of WMA. The laboratory study assessed four WMA proprietary additives i.e. CWM, Advera, Rediset LQ and a long chain hydrocarbon wax. This was added to HRA, SMA14, SMA10 and AC20. A Control Hot Mix Asphalt (HMA) was included for each mixture. Testing was carried out in accordance with European Standards. This included Compactibility, ITSM Stiffness and ITFT fatigue. A new durability test called the Dragged Ravelling Test (DRT) was developed. This is based on a dragged tyre / surface interaction. A technique using 3D modelling was developed a new parameter called Rut Depth3D to quantify durability. The research has found that the performance of WMA is comparable to HMA using the test methods described and materials assessed. WMA can be used in both surface courses and lower layers. This research has developed methods of data extraction which allow more accurate prediction of road surface durability.

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Pavement researchers have increasingly focused on reducing production and compaction temperatures in order to improve the environmental and economic impacts of hot mix asphalt, without adversely affecting the workability, durability and performance of asphalt pavements. The introduction of innovations and technologies in the form of warm mix asphalt will lead to substantial environmental improvements and economic prosperity. Moreover, in order to maximise the benefits of such technology, the inclusion of higher percentages of reclaimed asphalt pavement materials in warm mix asphalt allows the development of a more sustainable and cost-effective pavement structure. This thesis studies the characterisation of warm asphalt mixtures with the addition of reclaimed asphalt pavement materials. The effect of warm additives Sasobit, Rediset WMX and Rediset LQ on the viscosity of bitumen was investigated in detail. Furthermore, the effect of these additives on the rheological properties of bitumen was also identified using a dynamic Shear Rheometer. In fact, there is a point of controversy among pavement engineers about the performance of warm mix asphalt in terms of fatigue; therefore, firstly, the fatigue performance of warm-modified bituminous binder was investigated in detail. Fatigue test were conducted in dynamic Shear Rheometer using a time Sweep method and data were modelled using the viscoelastic continuum damage approach. After proving that warm additives such as Sasobit and Rediset WMX improved the fatigue life of asphalt binder, emphasises were paid to investigate nano-mechanical properties of warm modified bituminous binders and mix. Therefore this study also presents an investigation into the impact of warm additives on topography, modulus, deformation and adhesion of warm-modified bituminous binders using atomic force microscopy with the peakForce quantitative nano-mechanical mapping modality. The effect of production temperatures on the performance of warm mix asphalt was further investigated. Nanoindentation, which is an advanced technique, was used to study the effect of warm additives on the nano-mechanical properties of asphalt mixture phases, aggregate, interfacial transition zone (between aggregate and binder) and mastic. The nanoindentation results were used: firstly, to evaluate the effect of production temperatures and warm additives on the mixture phases; of warm mix asphalt; secondly, the nano-mechanical properties of interfacial transition zone were used to propose a new method to evaluate the degree of bonding between aggregate and binder in the mixture and, thirdly to evaluate the effect of each phase on the overall fatigue performance of warm mix asphalt. The aggregate-binder bond is one of the main factors that affect the durability of asphalt mixtures. This can be investigated based on the energy required to fracture the adhesive bond between binder and aggregate. In this thesis, the effect of warm additives on the adhesive bond strength of an aggregate-binder system was investigated using the pull-off test. Furthermore, the contribution of warm additives in improving the work of fracture has been linked to the adhesion force determined using atomic force microscopy and work of indentation approach. The fatigue life of WMAs was further investigated using a dynamic Shear Rheometer to study the effect of warm additives, production temperatures and binder grade. It was found that the level of reduction in the production temperatures and binder grade highly affect the fatigue performance of warm mix asphalt. Moreover, as Nanoindentation has shown to have the potential to characterise the properties of mixture phases, those properties can help in understanding the overall fatigue behaviour of warm asphalt mixture and show how improving nano-mechanical properties of interfacial transition zone and mastic can reflect the significant improvement in the fatigue life of asphalt mixtures. It is therefore recommended that highway agencies should specify a minimum production temperature for warm mix asphalt to reach acceptable mixture stability in terms of fatigue performance, taking into account the binder source and grade. Two issues regarding the inclusion of reclaimed asphalt pavement materials in asphalt mixtures need to be further investigated: the fatigue behaviour of reclaimed asphalt pavement materials mixes and the degree of blending between reclaimed asphalt pavement and virgin materials. The level of blending between virgin and reclaimed asphalt pavement materials was investigated under the scope of this thesis. The level of blending was investigated based on the nano-mechanical properties of mastic and interfacial transition zone measured using nanoindentation. Results were validated using scanning electron microscopy and the overall performance of warm mix asphalt incorporating reclaimed asphalt pavement materials in terms of stiffness and fatigue. Accordingly, a simple protocol is proposed to obtain a complete blending between reclaimed asphalt pavement binder and virgin binder, which is a key component of suitable practices in the pavement industry. The implications of this work for industry are that, firstly, warm additives offer a superior performance in producing asphalt mixtures that have better fatigue performance than traditional hot mix asphalt. Moreover, the study revealed that warm additives improve the strength bond between aggregate and binder. Secondly, highway agencies are advised to specify a minimum production temperature for warm mix asphalt to reach acceptable mixture stability. A complete blending between reclaimed asphalt pavement and virgin materials can be achieved using the proposed protocol; therefore a more sustainable and cost-effective pavement structure can be constructed.

Efficient operations of highways are inevitably critical for the sustainable, fast and safe transportation of people and freight. Effective maintenance in particular is of primary importance for ensuring that a highway meets operational and safety standards and offers efficient services to its users. Road surface or pavement maintenance comprises of required actions for planning rehabilitation strategies and maintenance activities over a highway network, having as an objective to keep the network in an acceptable functional and structural condition. Therefore, pavement condition assessment and prediction of deterioration become mandatory prerequisites for deciding on maintenance programming and budget allocation. Improved models of that category would better decisions on maintenance activities and allocation of resources. In this context, this PhD research focuses on the development of novel, efficient models for assessing existing condition and predicting future damage of pavements. Particular research efforts include introduction of an approach for assessing existing pavement condition, as well as the development of new post-treatment pavement deterioration models. New tools and methods are developed for that purpose: first, a new method for assessing existing pavement structural health, using the dynamic stiffness modulus is introduced and evaluated. Next, a Bayesian duration based model is developed in an effort to predict remaining service life of pavements, following rehabilitation actions. A subsequent model is developed for forecasting asphalt cracking initiation, again following maintenance activities; this model is based on Artificial Neural networks. Explanatory parameters are identified in all models; these include treatment activities, weather and structural characteristics of pavements. A qualitative comparison of BDM and ANN techniques reveals conceptual differences: BDM refers to the temporal behavior of pavement deterioration while attempts to forecast the probability of deterioration given a set of inputs. On the other hand, the quantitative comparison yields strong statistical similarities between the outcomes of the two models, with respect to estimating post treatment deterioration timing.