Abstract: A significant amount of recycled asphalt pavement (RAP) material is produced from flexible pavement rehabilitation projects. RAP can be used as a base course material for sustainable pavement construction. Performance of a pavement largely depends on the strength of its foundation, which consists of the subgrade and base course layers. Geocell was used in this study to increase the strength of RAP bases. Nine large-scale laboratory cyclic plate loading tests were conducted on unreinforced and geocell-reinforced RAP bases with three different thicknesses (150, 230, and 300 mm) over weak and moderate subgrades to investigate the influence of geocell confinement, base course thickness, base course strength, and subgrade strength on permanent and resilient deformations of RAP bases. The subgrade was prepared by mixing Kansas River sand with kaolin and compacted at weak [target California bearing ratio (CBR)=2%] and moderate (target CBR=5%) strengths. The test results showed that geocell confinement im...

Abstract: Performance of geogrid in gravel roads subjected to repeated loads was investigated through laboratory testing in the laboratory of faculty of engineering at Shoubra and finite element analysis. Twenty two laboratory model tests under cyclic loading were conducted on road sections consisting of base course layer with and without geogrid reinforcement overlaying weak subgrade. Parameters investigated included base layer thickness, grid aperture size, geogrid tensile strength, number of geogrid layers, and geogrid location. The experimental results indicated that the inclusion of one geogrid sheet placed at the base of course layer reduced the vertical deformation by about 18 to 64% depending on the base course layer thickness. The vertical deformation depth increased rapidly during the initial load cycles; thereafter the rate of settlement is reduced as the number of loading cycles increased. The most effective location of geogrid was found to be in the top quarter of the base course layer. When the results of the laboratory tests were compared with the analytical solution using finite element program ABAQUS, the FE results were in good agreement with the experimental test results.

Abstract: The objective of this study was to develop a methodology for quantifying the influence of geogrid on the performance of flexible pavement structures in a manner that would allow incorporation into Pavement Mechanistic-Empirical (ME) Design. The finite element technique was used to develop the geogrid-reinforced flexible pavement structure models, which focused on the characterization of the lateral confinement and vertical membrane effect of geogrid. A full-scale Soil Tank test was conducted to assess the validity of the developed geogrid-reinforced models by comparing the model predicted pavement responses (i.e., surface deflections, tensile strain at the bottom of asphalt concrete, and vertical stress distributions) to those tank test measurements. In general, the developed finite element models were capable of accurately predicting the responses of geogrid-reinforced and unreinforced pavement structures. It was found that the placement of geogrid increases the stiffness of base course and significantly reduces the vertical stresses around the geogrid layer, but cannot effectively reduce the tensile strain at the bottom of asphalt concrete. This indicated that the geogrid reinforcement is beneficial for reducing the rutting damage in base course and subgrade, but not effective in prolonging the fatigue life of flexible pavement. To quantify the influence of geogrid, the geogrid-reinforced flexible pavement structure was equivalent to an unreinforced flexible pavement structure with the modified material properties, which was based on a pavement response equivalency approach. The determined modified material properties was then input into Pavement ME Design software to predict the performance of geogrid-reinforced flexible pavement structures. Two case studies were conducted to predict the performance of two geogrid-reinforced pavement sections that were identified from the Long-Term Pavement Performance (LTPP) database. The predicted performance results (i.e., rutting depth and fatigue cracking area) were coincident with those field measurements, which validated the prediction accuracy of the proposed approach.

Abstract: Rigid pavements have an impact on the urban heat island (UHI) and hence the surrounding environment and human comfort. Currently, most studies use a mesoscale approach in UHI characterization of pavements. This study proposes a microscale approach that can be incorporated into a pavement life-cycle assessment (LCA). The heat flux of various concrete pavements containing layers of varying thermal diffusivity and inertia was simulated. The surface pavement radiative forcing (RFp) was developed as a metric for use in a pavement LCA. Additionally, the heat conducted and stored in each concrete pavement system was analyzed using an average seasonal day metric to understand the temporal pavement energetics. Of the various thermal cases, only a higher albedo surface significantly changed the RFp for a fixed climate. However, a time lag was induced by the thermal inertia of the base course, which decreased the amount of heat conducted out of the pavement at night by storing heat in the base course for a longer ti...

Abstract: Mechanical property variations of base course materials caused by freezing and thawing must be considered when designing subgrades in regions with seasonal freezing and thawing. In this stu...

Abstract: This paper examines the behavior of full-scale unreinforced and geotextile reinforced unpaved road using an indigenously developed full-scale laboratory accelerated pavement testing set up. The models of the unpaved road were subjected to 35,000 loading cycles of standard axle load. The effect of reinforcement on the vertical stress distribution at the base–subgrade interface was investigated. The test results show that the inclusion of geotextile significantly reduced the magnitude of vertical stress in the reinforced road as compared with the unreinforced road. This reduction of vertical stress magnitude is comparable to 9°–16° increases in the stress distribution angle; this may be attributed to stretching of the geotextile due to the tendency of lateral spreading of aggregates in the base course. The limited number of load cycles confirmed the lateral restraint of base course aggregates by the geotextile reinforcement and thus a reduction in the magnitude of vertical stress. The test results also confirmed about 22% reduction in base course thickness due to geotextile reinforcement, thus one step towards sustainability by saving of the expensive natural base course aggregate.

Abstract: : The U.S. Army Engineer Research and Development Center (ERDC) constructed a full-scale test section to evaluate the performance of geogrid-stabilized highway pavements. The test section consisted of two pavements composed of 3 in. of hot mix asphalt over a crushed limestone base course over a 6 CBR subgrade. One section was stabilized with Tensars TX5 multi-axial geogrid, and the second section was stabilized with a developmental geogrid referred to as TX8. Each section was instrumented with moisture probes, pore-water pressure probes, temperature probes, earth pressure cells, and asphalt strain gauges. Simulated truck traffic was applied using a heavy vehicle simulator (HVS) to evaluate the rutting performance and collect instrumentation response data. This report summarizes the material characterization and construction techniques, instrumentation response, and performance response of each section under simulated truck traffic. Comparisons are drawn to previous sections constructed and trafficked at ERDC without geogrids utilizing similar construction techniques and material properties.

Abstract: The invention discloses a one-time construction method for a structural slab and a surface layer of a large-area emery floor. According to the method, the structural slab and the surface layer of an emery floor are formed once, construction of the wear-resistant emery surface layer is performed between initial setting and final setting of concrete, a curing agent is used for curing after final setting, a finished product is well protected, the firm and wear-resistant floor about 3 mm thick is formed on a concrete structural layer, emery is scattered on fresh concrete of the structural slab directly, construction of a fine aggregate concrete leveling course is not needed, procedures are reduced, time is saved, a construction period is shortened, the cost is saved, clear height of a storey is guaranteed, load of the structural slab is reduced, phenomena such as hollowing, peeling, cracks and the like with the traditional method are avoided, by means of one-time forming of the structural slab and the emery surface layer of the floor, the emery surface layer and a base course are firmly bonded and not prone to hollowing or peeling, so that quality is guaranteed, and the floor is applicable to ground in industrial places, wharfs, parking lots, commercial stores, logistics warehouses, workshops and the like.

Abstract: Number of laboratory studies; have shown that geosynthetics reinforcement improves the performance of flexible pavement either by ex-tending the service life or by savings in base course thickness. In spite of the good laboratory evidence for the geosynthetics reinforced flexible pavement, the mechanism that enables and governs the reinforcement function is still unclear [1]. Cyclic laboratory test has been one of the ways, used for assessing/evaluating the soil-geosynthetic interaction mechanisms. In such a tests contribution of geosynthetics prop-erties, interface shear provided by geotextiles and interlocking provided by geogrids when used under or within the base course of flexible pavement are mainly concentrated. This paper reviews literature of laboratory model studies carried out by various researchers over the globe. This review indicates that, appreciable improvement due to geosynthetics reinforcement depends upon various factors viz. location of geosynthetics, geogrid aperture size, geosynthetics properties, mainly stiffness, variation of base course thickness and strength of subgrade soil. The findings of these laboratory studies are also correlated with the same nature of field studies finding.

Abstract: The invention discloses a construction method of a crack-resisting cement stabilized crushed stone base course. The problems that at present, contraction fissures of a traditional cement stabilized crushed stone are many, the surface is prone to loosening after freeze-thaw, the defects of the construction mode exist in the construction side, and therefore large-area cracks and freeze-thaw are generated in the subsequent process of the road surface are solved. According to the key points of the technical scheme, the construction method comprises the following steps that (a), the crack-resisting cement stabilized crushed stone base course comprises a collected material, 3%-5% of cement and water, the curve of the screen hole size of the collected material and the passing percentage is in an S shape; (b), a mixture is mixed; (c), the mixture is conveyed; (d), the mixture is paved, specifically, square timber cushion blocks are put under a paver screed plate in advance, and mixture paving adopts two pavers to synchronously operate in an echelon formation mode; (e), the mixture is grinded; and (f), curing is conducted, specifically, a curing film or geotechnical cloth is covered to conduct hydrating curing, so that the surface of the cement stabilized course keeps a moist state all the time, and the cement stabilized crushed stone base course with the crack-resisting property being obviously improved is obtained.

Abstract: Transportation industries encounter substantial challenges with respect to ride quality and serviceability when they deal with expansive soils underneath roadway structures. These soils exhibit swell-shrink behavior with moisture variations, which cause surficial heaving on the pavement structure and cost billions of dollars for the maintenance of pavements. For the past four decades, a particular stretch of US-95 (Oregon line to Elephant Butte) exhibited recurrent swelling distresses due to the underlying expansive soils. Despite remedial measures that exhibited satisfactory results for most of the sections, recurrent damage still continued in few sections. Further research indicated that the problematic soils were located at a depth below 1.82 m. Conventional chemical remediation methods typically performed at a depth no greater than 0.9 to 1.2 m. To be able to address the adverse effects of this swell-shrink behavior of soil at a deeper depth, hybrid geosynthetic systems were proposed. Hybrid geosynthetic systems were successfully used to mitigate expansive soil swelling in railroad applications. Hence, this research study explored this idea of using hybrid geosynthetic reinforcement systems (geocell-geogrid combination) to mitigate differential pavement heaving resulting from underlying expansive soils. To evaluate the use of hybrid geosynthetic systems in reducing differential heaving from expansive subgrades, a large-scale box test was developed to simulate a pavement section with a base course and expansive subgrade (asphalt overlay was ignored). The surficial heaving on the base course reinforced with geocell, geogrid and hybrid geosynthetic reinforced system (HGRS) were measured over time and compared with the unreinforced case. The large-scale box test results showed that the geosynthetic systems significantly reduced the maximum surficial heave along with the differential swelling on the pavement section. HGRS exhibited better performance than geocells and geogrids. Numerical analysis using the finite element approach was conducted to study the response of other soil types not tested in the box. The numerical model was first calibrated using using the box test results and the calibrated model was used to change soil properties for two other soil types with different swelling charecteristics. In the numerical model, swelling behavior of expansive soils was simulated using material models that incorporate volumetric swelling and suction as a function of moisture content. The modulus of the unreinforced base was determined using laboratory tests while the modulus that for the reinforced sections was calibrated using large scale test data. The calibration of control model was performed by controlling the moisture percolation through subgrade. The improvement of reinforced models were quantified by higher modulus of reinforced base. These calibrated models were used to conduct a parametric study by varying the subgrade soil properties and their performance with respect to the modulus of reinforced base. The…

Abstract: One of the key goals in the EU White Paper is to reduce carbon emissions in transport by 60% by 2050.Consequently, during the past years an effect on the environment became a decisive factor in selecting materials andtechnologies for road construction and rehabilitation. Cold recycling is a reasonable solution in asphalt pavement rehabilitationbecause it is economical and old asphalt pavements can be reused. This technology differs from others bymixing temperature. Besides, cold recycling does not require additional heating. These benefits result in wide applicationof cold recycling around the world. In Lithuania, cold recycling has been used for more than 15 years. Both technologies,i.e. cold in-plant recycling and cold in-place recycling, were used. In both technologies reclaimed asphaltpavement (RAP) is bound with bituminous binders (foamed bitumen or bitumen emulsion), hydraulic binders (cement)or a combination of bituminous and hydraulic binders depending on the base course specifications. This paper focuseson the Lithuanian experience in cold recycling of asphalt pavements using different types of cold recycling and binders. DOI: https://doi.org/10.3846/enviro.2017.153

Abstract: This paper presents a review of unbound recycled materials, specifically recycled asphalt pavement (RAP) and recycled concrete aggregate (RCA), as road base course for sustainable highway construction. A total of fifteen recycled materials were collected for characterization and testing from across the USA. Compaction characteristics and resilient moduli of these samples were determined and predictive equations were derived. Test sections were constructed using recycled materials in the granular base layers at the MnROAD test facility. Large-Scale Model Experiments (LSME) replicating field-scale conditions were also conducted and scalability of various scale modulus measurements was investigated. When compared to conventional base course, RAP and RCA experienced higher modulus. Discussion includes mechanical and durability characteristics, and leaching behavior. Sustainability evaluation of material alternatives in a project is described.

Abstract: The aim of this research was to model rutting of modified stone matrix asphalt concrete pavements. Four mixes were investigated, including two modified with different percentages of styrene–butadiene–styrene (4 and 6%), one modified with cellulose fibres and one unmodified mix. Dynamic creep tests were performed on specimens of each mix to obtain material parameters of the creep power law used for rutting modelling purposes. For each mix, a model was developed and then a finite-element method was used to estimate the rut depth of a pavement structure by incorporating realistic material properties for the base course, subbase course and subgrade beneath the asphalt concrete pavement surface. Results of applying static and repeated loads on modelled pavement show that the rut depth of static loading is greater than a repeated one. Moreover, a pavement made from asphalt concrete modified with 6% styrene–butadiene–styrene would have the least rut depth followed by the 4% mix, the unmodified mix and the cellul...

Abstract: This study focuses on in-situ and laboratory evaluation of modified drilling waste materials (MDWMs) applied on base course construction. Cement treated drilling waste materials have been used on a limited basis for full-depth base repair on Texas Department of Transportation (TxDOT) low volume roads. A road inspection was made of full-scale county roads that were constructed with the MDWMs. Field test results measured by the falling weight deflectomer (FWD) showed reasonable in-situ strengths. The MDWM section had stiffness values similar to those typically observed for newly constructed flexible bases. The old, in-service flexible base adjacent to the MDWM section exhibited values half those of the MDWMs. Cores removed from the field also had significantly higher strength values than the lab-molded samples. Moreover, the other non-TxDOT low volume county roads using MDWMs exhibited good field performance. From this observation, it is concluded that this material clearly has some unique engineering properties which has the ability to gain strength with time though weak initially and there is the potential applicability used in the low volume roadway.

Abstract: The use of commercially produced Carbon-Negative aggregates from Carbon8 (a British company which applies patented Accelerated Carbonation Technology (ACT) to solidify waste residues producing useful eco-friendly aggregates) is being investigated in the Caribbean islands of Trinidad, Tobago and St. Lucia. Typical construction of the subbase layer of pavements in the Caribbean include layers of virgin aggregate material (gravel, pea gravel) on which the base course layer is located. These materials are usually unbound granular (crushed stone, crushed slag, crushed concrete, slate) or cement-bound. Permeable Pavement Systems (PPS) have emerged over the years using various quality of subbase materials including large pieces of rocks and concrete. For the first time in the Caribbean, the design, construction and implementation of such pavement systems is being carried out. The novel pavement systems consist of permeable or pervious concrete paving blocks and the Carbon-Negative aggregates in the sub-base as an innovative and effective method of providing structural pavements, whilst allowing urban stormwater runoff to infiltrate naturally into the pavements (mimicking the hydrologic cycle) into the base/sub-base reservoir for urban runoff attenuation and an overall reduction in stormwater discharge. These pavement systems are being considered to reduce the overall carbon footprint on the construction and implementation phase of pavements, in addition to reducing surface water flooding in several towns and cities across these Caribbean Small Island Developing States (SIDS). The project includes ongoing experimental assessment of the Permeable Pavement Systems (PPS) using Carbon-Negative aggregates versus conventional pervious pavements from a water quality, structural integrity and hydraulic perspective. Stormwater is being collected from various towns and cities across the islands and applied uniformly over the pilot scaled permeable pavements using a rainfall simulator. The permeable pavements stormwater treatment efficacies are being evaluated for the removal and retention of nutrients (total nitrogen and total phosphorus), heavy metals (zinc, lead, copper, cadmium), suspended solids and turbidity. The hydraulic performance, flow through and clogging patterns of these pavements are also being measured over a simulated 10-year period of sediment loading. Load bearing and deflection test are being carried out on the various pavement designs to assess its structural integrity and load bearing capacity. Static and dynamic loads applied representing the maximum contact pressure varying from 0.03 to 1.7 MPa over the cross-sectional area of 0.2 m2 (permeable pavement surface area). These contract pressures represent various loads from heavy vehicles, cars, pallets and handling equipment of industrial areas (ports).

Abstract: The invention discloses plant-growing concrete and a construction method thereof. The plant-growing concrete comprises base course concrete positioned at the bottom and surface course concrete positioned at the top; the base course concrete is formed by spray spreading of a plant-growing concrete substrate material; the surface course concrete is formed by spray spreading of the plant-growing concrete substrate material mixed with grass seeds; and the plant-growing concrete substrate material comprises the following raw material components in parts by weight: 5-15 parts of phosphorus slag, 75-85 parts of clay, 0.01-0.1 part of polypropylene fiber, 0.01-0.1 part of a water retention agent and 60-80 parts of water. The plant-growing concrete disclosed by the invention utilizes the phosphorus slag and other solid wastes, the raw materials are wide in source and low in price, high strength of the base course concrete can be ensured, and phosphorus and other elements required by growth of plants can also be provided; by adopting the polypropylene fiber, the anti-scouring performance and the anti-crack performance of the plant-growing concrete are further improved; and the construction method of the plant-growing concrete disclosed by the invention is simple and convenient, and a mechanical spray spreading mode can be adopted directly to reduce the labor intensity of workers, improve the working efficiency and then reduce the project cost.

Abstract: The invention provides a method for evaluating the freezing resistance of a semi-rigid base course material by utilizing dynamic compressive resilient modulus and relates to a method for evaluating the freezing resistance of the semi-rigid base course material, aiming at solving the problems that the freezing resistance of the semi-rigid base course material cannot be effectively evaluated at present so that the strength of a road surface cannot be evaluated and integrated damages of a road surface structure are caused. The method comprises the following steps: 1, determining the dynamic compressive resilient modulus of a comparing test piece; 2, determining the dynamic compressive resilient modulus of a test piece to be detected; 3, calculating a dynamic compressive resilient modulus loss ratio FRI of the test piece to be detected which is frozen and thawed for (i+1) times. The freezing resistance of the semi-rigid base course material is evaluated by adopting the dynamic compressive resilient modulus loss ratio and damages of an inner structure of a mixture can be sensitively reflected; damage conditions caused by freezing and thawing effect under an actual condition can be more accurately characterized. The method for evaluating the freezing resistance of the semi-rigid base course material by utilizing the dynamic compressive resilient modulus can be obtained.

Abstract: Synopsis This chapter assesses the use of sewage sludge ash (SSA) in road pavement applications, dealing with its use in unbound, hydraulically bound and bituminous bound forms. As unbound capping or subbase, the material is not the most suitable because of its fine grading and as such, minimal work is available in this area. In hydraulically bound layers, SSA has been mixed with fresh concrete and subsequently hardened and crushed to produce a base course material and has also been used as a partial fine aggregate component in rigid pavement surface concrete slabs. The material has most commonly been used as a bituminous bound mineral filler and fine aggregate component, including in a number of full-scale projects. An environmental assessment dealing with the leaching behaviour of road pavements containing SSA is also included.

Abstract: The invention discloses a water-permeable pavement with a purifying function. The water-permeable pavement comprises a water-permeable concrete surface course, a nonwoven geotextile course, a water-permeable foam concrete base course, a cement-lime stabilized soil base course and an original dirt road base course from top to bottom in sequence, wherein water collecting and draining pipes are arranged in the water-permeable foam concrete base course. According to the water-permeable pavement, a traditional gravel course is replaced by water-permeable foam concrete, nonwoven geotextile is laid between the water-permeable foam concrete base course and the water-permeable concrete surface course, and the nonwoven geotextile not only has favorable water permeability, but also can block solid pollutants in rainwater, maintain the load-carrying property of the overall structure and effectively prevent the development of reflection cracks; the water-permeable foam concrete can filter out fine solid pollutants in rainwater, and the acidic environment in the water-permeable foam concrete can enrich various microbes to purify organic pollutants in rainwater; and the water-permeable foam concrete also has a favorable thermal-insulation property, and can protect the pavement structure at lower temperature and provide a favorable living environment for the microbes.

Abstract: The UK has adopted the concept of sustainable development and the construction industry is playing a key role in improving the efficient use of materials. The aim is to minimise the waste generated and maximise quantities of materials reused or recycled, minimising raw material consumption. Using Reclaimed asphalt pavement (RAP) is a rehabilitation technique which involves recycling materials from asphalt layers that have already been in service. This reduces the use of new bitumen and aggregates and avoids disposal. However, UK pavements constructed prior to 1980 or surfaced in the late 1980’s may contain tar, a carcinogenic substance that cannot be reheated and, therefore, cannot be recycled into hot mix asphalt (HMA). Recycling these pavements into unbound materials is also prohibited; consequently, disposal or cold recycling are the two available options. Cold recycling of asphalt is a proven technique that reduces material disposal and raw material and energy consumption. The reduction in energy consumption is largely achieved by avoiding aggregate drying and mixing of the material at ambient temperature. In this sense, using cold recycled bound materials (CRBMs) becomes the most economic and sustainable option. However, despite the increasingly common use of CRBM in roads, the specifications for the use of these materials in airfields are under-developed and there is no guidance to ensure that pavement design with these materials is trustworthy. This is the reason why this Thesis focuses on airfield pavement design with CRBM. The aim of this investigation is to develop a design methodology to use CRBMs in airfield pavements. For this purpose, the objectives were to review past experience on performance of these materials, measure and analyse the effect of key variables on performance to establish material limitations and develop a design methodology, proposing design guidance for airport authorities and practitioners. To achieve the project aims and objectives, a literature review was carried out focusing on pavement engineering, airfield pavement design and CRBM. The objective was to gain sufficient knowledge on key areas to conduct the research. Based on this literature review it was decided to use foamed bitumen as the cold technology and Kenlayer as pavement analytical design software. It was also found that the current design methodology for using CRBM in airfields is to conservatively equate material properties to those of a HMA commonly used in airfield base course (HDM50). Therefore, this practise should be analysed to decide if it is correct or if it can be improved. Subsequently, a laboratory programme was established to analyse CRBM mechanical properties and, therefore, understand the material’s behaviour and performance under cyclic loading. RAP, fly ash, cement and foamed bitumen were used to manufacture laboratory specimens, compacted with a gyratory compactor. These specimens were tested to analyse densities, air voids, stiffness, strength, permanent deformation and fatigue. For developing a new design methodology, Kenlayer was used to analyse strains and stresses within the airfield pavement. The first step was to ascertain Kenlayer adequacy and establish inputs related to loading, traffic and subgrade condition. For this purpose, 96 case studies were analysed with HMA, with different aircraft types, traffic and subgrade conditions. These cases were compared to those of a well-established airfield design guide, namely DMG 27. Then the software could be used to model pavements containing CRBM and with the knowledge gained in the laboratory about its behaviour, establish layer thicknesses to bear traffic during the pavement design life. With the results obtained from the laboratory investigation it was concluded that CRBM mixes have acceptable properties for use in airfield pavements. Resistance to permanent deformation, fatigue, temperature susceptibility and durability results show that these materials give reasonable performance; however, they differ from conventional hot mixes. Thus, current practice can be improved, justifying the need for design guidance for using CRBM in airfields. As fatigue is one of the main failure modes in asphalt mixtures and flexible pavements, a deeper study into fatigue behaviour of CRBM was carried out using Indirect Tensile Fatigue Tests (ITFT) in strain control mode and Wheel Track Test (WTT). The results showed different failure mechanisms for CRBM from those of HMA; thus, a new failure criterion was established. In HMA the failure criterion of 50% stiffness reduction is related to the appearance of macro cracks. CRBM develops dispersed micro-cracking that lowers the mixture stiffness without producing macro cracks until late in the material’s life. Macro cracks only tend to appear at 70% stiffness reduction; therefore, this was established as new failure criterion for CRBM. Once CRBM properties were defined, the pavement structure could be modelled. The results obtained from HMA modelling showed that the software and the inputs selected were appropriate for this investigation. Then the HMA base properties were substituted with CRBM properties obtained in the laboratory. The results showed that DMG 27, Chart 7, can be used for designing airfield pavements using CRBM increasing the base thickness by 9%, with a minimum Dry Lean Concrete (DLC) layer of 150 mm. A deterioration analysis was also carried out with the design software. In this case the aim was to analyse how strains distribute within the CRBM layer and how this affects the pavement life. With these analysis, it was highlighted how different CRBM behaves compared to HMA. Strains distributed linearly within the HMA layer; however, this does not happen with the CRBM. Moreover, this analysis showed how fatigue data can be used to obtain a more accurate pavement life taking into account different strain levels. Nevertheless, the study carried out here is based on laboratory performance of one type of CRBM. There is need for further investigation to establish a relationship between fatigue behaviour in the laboratory and the field and confirm how micro cracking affects the bearing capacity of the CRBM layer, establishing shift factors to optimise CRBM layer thickness. Moreover, the laboratory study has been carried out analysing CRBM in the same way as HMA; therefore, further study is needed to analyse the adequacy of the testing methodology. Also, modelling has been done comparing one CRBM to one HMA, namely HDM50; therefore, further investigation is needed to open the model to other HMA. Consequently, the design guidance presented here is a first step towards an airfield pavement design guide and further study is needed to optimise it.

Abstract: It is a consensus that salt heaving and frost heaving are typical distresses in the sulfate saline soil subgrade. To further investigate the mechanic response of pavement structure in sulfate saline soil area, a finite element(FE) model was established based on fluid-structure interaction(FSI) model in this paper. Then the mechanic response of the asphalt pavement under traffic loads, salt heaving and frost heaving was simulated and analyzed. It is shown that only under salt heaving and frost heaving, the tensile strength of asphalt surface course was seriously inadequate and that at the bottom of semi-rigid base course were negative, which may be helpful to crack resistance at the bottom of base courses. Besides, traffic loads could help to dramatically counteract displacement, tensile stress and strain. However, as a whole, in sulfate saline soil area, asphalt courses should strengthen crack resistance and foundation treatment.

Abstract: Construction and rehabilitation of road infrastructure in Indonesia require about 1.2 million tons of asphalt per year, approximately 100% used of petroleum asphalt. Only a half of asphalt demand can be provided domestically, while about 600 thousand tons have to be imported from abroad. Indonesia has natural asphalt with a quite large deposit but has not been fully utilized. Lack of availability of asphalt and the increasing demand of the domestic market will give effect to an increase in bitumen cost in the domestic market. Somehow, this is not a sufficient condition due to the rising cost of road infrastructure. This study aims to determine the effect of using a layer of asphalt concrete pavement asbuton to rigid pavement (PR-modification). Stressing that occur in rigid pavement, asphalt concrete layer and base course measured by using LVDT and for the subgrade using soil pressure transducer. Using asbuton on asphalt concrete will have more benefit on improving the stability of the marshall. The maximu...