《International Journal of Pavement Engineering》2012,13(6):477-487

In order to overcome reflective cracks, different techniques have been developed in the past, the most important of which is the use of geosynthetic materials. It has been proven in many studies carried out in this field that using geosynthetics can delay reflective crack initiation and reduce the speed of propagation. In this research, a laboratory simulation was performed on the cracked pavement with five types of geosynthetics. Each type was tested by tensile force. According to the stress strain graph, the secant modulus was achieved. Five types of geosynthetic-reinforced asphalt beams were tested under cyclic loading and a comparison of the results showed the effect of using geosynthetics and its modulus on increasing the loading cycles required for crack initiation and propagation. The results further showed that the pavements with thicker overlays are much more sensitive to the geosynthetics modulus. Moreover, crack growth rate, displacement at the bottom of the overlay, vertical displacement of the overlay and number of load cycles before failure were dependent on the geosynthetic modulus, and their relationship was studied. In this research, the effect of thickness on the above-mentioned parameters was also investigated.  相似文献   

    

《International Journal of Pavement Engineering》2012,13(3):214-223

The repeated load permanent deformation (RLPD) test is used to capture the permanent deformation characteristics of asphalt mixtures for prediction of pavement rutting. The full characterisation of permanent deformation behaviour as required by the National Cooperative Highway Research Program (NCHRP) Project 9-30A enhanced rutting model requires time-consuming RLPD tests at three temperatures – low, intermediate and high. This study investigates the application of time–temperature superposition (TTS) to reduce the material characterisation testing effort in the context of the NCHRP 9-30A models. Dynamic modulus and RLPD test data were collected for 27 mixtures, including mixtures from long-term pavement performance (LTPP) programme. The temperature shift functions obtained from dynamic modulus data were used to shift the associated RLPD test results at various temperatures to develop a master curve of cumulative permanent strain versus reduced number of loading cycles. The cumulative permanent strain curves at different temperatures collapsed fairly well into a single RLPD master curve for the evaluated mixtures, confirming the validity of TTS for the RLPD test. The TTS procedure was also applied individually to the test results at a single temperature to predict the permanent strains at the other temperatures. The results from the 27 mixtures suggest that the RLPD master curve obtained by testing only at the high temperature (LTPPBind high temperature at 50% reliability – 5°C) permits accurate and precise predictions of the permanent deformations at all other temperatures. RLPD testing at a single temperature has the real practical benefit of significantly streamlining the asphalt material characterisation testing programme.  相似文献   

    

《International Journal of Pavement Engineering》2012,13(3):268-286

Despite the general consensus among stakeholders on how useful the life cycle assessment (LCA) methodology can be in helping to reduce the environmental burdens of a road pavement, very few pavement LCA models have considered the entire pavement life cycle. This paper presents the development of a highly customisable LCA tool that provides an integrated, project-level approach that includes all six pavement life cycle phases. The developed tool encompasses six main modules, including extraction of raw materials and production; construction, maintenance and rehabilitation; transportation of materials; work-zone traffic management; usage; and end-of-life. Data regarding the Portuguese practise of pavement construction and management have been collected on site with certified Portuguese construction companies and complemented using published literature and databases. The research described in this paper provides a widely applicable pavement LCA model that will enable highway agencies, private companies and the construction industry to estimate emissions and environmental impacts during the project analysis period for road pavement. The use of the proposed tool for benchmarking current practises in pavement construction and management enhances the scientific basis for understanding where further efforts can be undertaken to promote sustainable pavement investment decisions.  相似文献   

    

《International Journal of Pavement Engineering》2012,13(8):710-720

Asphalt mixtures with similar percentages of air voids can have different morphologies and can age differently. Prediction of ageing behaviour without considering the influence of mixture morphology may thus lead to erroneous conclusions and non-optimal mix design. This article investigates the long-term field ageing of asphalt mixtures by incorporating mixture morphology. For this, a computational analysis on diffusion–reaction process has been conducted by implementing fundamental mechanism of ageing and conducting a parametric sweep of the morphology. To investigate the ageing gradient along the depth of asphalt mixture, diffusion controlled oxidative ageing on one dense and one open-graded field core was investigated. The proposed model based on the mixture morphology information was able to predict the aged viscosity better than the existing model. As mixture morphology is controllable, having insight into how the morphology parameter influences the mixture's ageing susceptibility can be of great value to its design.  相似文献   

    

《International Journal of Pavement Engineering》2012,13(4):402-416

Abstract

Rutting or plastic deformation is one of most frequently observed distress types in the wheel paths of flexible road pavements. This distress may cause the pavement structure to be attributable to early failure by expediting the deterioration due to load and environmental detrimental agents. Therefore, it is ideal to simulate the rutting performance of different asphalt mixtures in laboratory-controlled conditions before exposing them to aggressive field conditions. Different rutting simulation computer-controlled equipments are available to predict the mixture performance in laboratory at nearly similar conditions to actual in-service pavements. Cooper wheel tracking equipment is one such precise equipment. Mostly, the wearing course is likely to be damaged by this distress type in flexible asphalt pavements. Therefore, in this research study, thirty representative wearing course mixtures commonly used in road pavements were tested for rutting distress using Cooper wheel tracker. Three aggregate sources, three binders from two sources, five mixture gradations and two temperature conditions were included in the testing scheme. Mixtures were evaluated based on the terminal value of rut depth. Consistent ranking of mixtures has been observed for variable combinations of aggregates, binders, temperatures and gradations. Flakiness index (FI) of aggregates, binder penetration values, per cent coarse material retained on 4.75 mm sieve and temperature values are considered as independent variables based on past researches. The significance of these independent variables on the dependent variable of rut depth has been analysed by analytical tools of general full factorial design analysis. It has been concluded that temperature has highest significance for the rut depth prediction, followed by FI of aggregates, bitumen penetration value and percentage of coarse fraction.  相似文献   

    

《International Journal of Pavement Engineering》2012,13(1):41-48

Abstract

With the development of modified emulsified asphalt, cold recycling technique has the potential to be used in pavement layers closer to surface. Three modified emulsified asphalt binders were carefully prepared by adding Styrene–butadiene rubber (SBR) latex, styrene-ethylene–butylene-styrene (SEBS) copolymer and chloroprene rubber (CR) latex, respectively. In order to characterise how the properties of asphalt binder related to the rutting of cold recycling mix. The high temperature Dynamic Shear Rheometer (DSR) and Multiple Stress Creep Recovery (MSCR) tests were conducted under varying test temperatures ranging from 46 to 76 °C. An advanced cyclic creep test was conducted to study the rutting resistance of the full-depth pavement structures with cold recycling mix. According to the test results, the high-temperature performance were improved significantly by adding the polymer modifiers, and adding CR latex seems to be a more effective way to improve the rutting resistance of emulsified asphalt. Results from MSCR test under temperatures no less than 64 °C shows a better correlation with test results from the advanced cyclic creep test than the G*/sin δ from high temperature DSR test. Thus, by carefully choosing the test temperature and stress, the MSCR test shows promise to be a surrogate to the existing DSR test.  相似文献   

    

《International Journal of Pavement Engineering》2012,13(8):884-893

ABSTRACT

Engineered Cementitious Composites (ECC) with high ductility has been recognised to be a high performance and durable alternative to the construction material in civil engineering field. In this paper, ECC material was proposed to be applied on the long-span steel bridge deck overlay. Herein we studied the feasibility of this application via integration of ECC’s material performances and stress response of structure using finite element analysis. The results show that ECC material could overcome the brittleness of normal concrete, featuring high tensile strain/deformability capacity under tension/flexural load, as well as higher flexural strength and fatigue life, compared with normal asphalt/concrete materials. Furthermore, the self-healing capacity in ECC helps the crack seal itself, as a result, recovers its water permeability coefficient and resistance to chloride ion penetration to nearly the same level as undamaged ones. By integrating ECC’s flexural fatigue behaviour and finite element analysis, it can be concluded that ECC is feasible to be a candidate material for the steel bridge overlay. The application of ECC is expected to greatly extend the service life of steel bridge overlay meanwhile be with thinner thickness compared with normal bridge deck overlay structure, resulting in a more sustainable overlay.  相似文献   

    

《International Journal of Pavement Engineering》2012,13(7):747-760

ABSTRACT

This work numerically evaluates the role of material heterogeneity in the variability of fracture processes in Hot Mix Asphalt (HMA) materials. Specifically, the paper focuses on the heterogeneity induced by the spatial air void distribution within HMA specimens, and it uses a fracture test configuration to assess the differences produced by these distributions in the fracture response of the mixtures. The work initiated with an experimental stage that provided fracture, creep compliance and indirect tensile strength (IDT) test results and data on the heterogeneous distribution of air voids (AV) in HMA specimens. The outcome from this phase revealed that the air void content in HMA specimens significantly impacted the viscoelastic, tensile resistance and fracture response of the material. This stage also provided information on the typical internal distribution of AV within cylindrical HMA testing specimens. These experimental results were used in the development of computational Finite Element (FE) models that used the geometrical configuration of the semi-circular bending (SCB) test, and that incorporated cohesive surface contacts and stochastic Random Fields (RF) techniques. The cohesive contacts were used to simulate fracture within the computational specimens, while RF theory was used to indirectly account for the non-uniform spatial distributions of the air void phase and of the mechanical- and fracture-related material properties within the specimens. The numerical results suggest that HMA heterogeneity due to non-uniform air void distributions accounts for an important portion of the variability associated with fracture processes in HMA materials.  相似文献   

    

《International Journal of Pavement Engineering》2012,13(12):1385-1391

ABSTRACT

Massive sugarcane bagasse ash waste is generated from the combustion of fibrous residue of sugarcane . Also, highway reconstruction work generates large volume of reclaimed asphalt pavements that are disposed as waste . This paper present results of stabilization and laboratory evaluation of the characteristics of these wastes with a view to determine its suitability as flexible pavement material. The mixtures were subjected to reduced British standard light (reduced Proctor), British standard light (standard Proctor), West African standard and British standard heavy compactive efforts to determine the compaction characteristics, California bearing ratio, durability and water absorption characteristics of the mixes. Test results show that the properties of reclaimed asphalt pavements waste improved with sugarcane bagasse ash stabilisation. The maximum dry density decreased as the optimum moisture content increased with higher sugarcane bagasse ash contents in the mixes. Maximum California bearing ratio values of 28% (unsoaked) and 14% (soaked for 24 h) were recorded for 50% RAP + 50% SCBA mix that satisfied durability requirements and can be used as subgrade material in flexible pavement construction. This research is based on CBR determination. Further work may be encouraged to assess resilient modulus of this material under cyclic load.  相似文献   

    

《International Journal of Pavement Engineering》2012,13(6):628-637

ABSTRACT

The aim of this study is to investigate the impact of nanoclay and its combination with Styrene-Butadiene-Styrene (SBS) on fatigue behaviour of hot mix asphalt. With respect to four-point beam fatigue and Indirect Resilient Modulus at low and mid-temperatures, pairwise comparison was done over both aged and unaged modified specimens, including 6% nanoclay, 6% SBS, 2% nanoclay +4% SBS and 4% nanoclay +2% SBS. In addition, indirect tensile strength was performed at mid-temperature of 25 °C. The results indicated that nanoclay enhanced fatigue and thermal cracking resistance of unaged and aged mixes. It was found that, at low temperatures, SBS and nanoclay have negative effect on fatigue life and thermal cracking. Moreover, nanoclay was proved to improve fatigue performance of the SBS modified mixes at mid-temperature.  相似文献