Abstract: This research was Phase III of field investigations carried out over 12 years at a test section in southwest Washington State in an effort to quantify the contribution of geotextile separators to the long-term performance of pavement sections. Five different geotextile separators, as well as a control (soil-only) section, were installed in a test section covering two lanes with different base course thicknesses on a low volume but heavily loaded rural highway west of Bucoda, Washington. Phase I evaluated the performance of the separators during construction. Phase II and III were conducted to evaluate the performance of the separators 5 and 12 years after construction, respectively. Field and laboratory tests were conducted on the subgrade, granular base materials, and the geotextiles as part of the effort to correlate the performance of the pavement section to the presence of the geotextile separators. Falling weight deflectometer (FWD) testing was also performed at the site as part of the effort to quantify the performance of the pavement section. The laboratory tests indicated that the geotextiles successfully performed their separation function over the 12-year period. However, the soil-only sections had a minimal amount of intermixing at the base course/subgrade interface, indicating that the separation benefits of geotextiles may not be realized under relatively thick pavement sections. The FWD tests showed that the most significant increase in the subgrade moduli occurred in the first few months following construction. However, the soil-only sections exhibited behavior similar to the sections with geotextiles during the FWD testing, suggesting that for the relatively thick pavement sections, incorporation of geotextiles may not have provided a significant contribution to the overall performance of the section over the 12-year period. Some of the FWD results did suggest that geotextiles might contribute to an increase in the base course modulus over time.

Abstract: To achieve proper stability in base coarse materials, there is a variety of parameters to optimize. The response of the material is a combination of several factors, such as grading, water content, material strength, stress level etc. It is well known that the grading of a material is important for the stability and that a well graded material normally gives better stability than asingle sized or a less graded material. In the Norwegian guidelines for pavement design there are restrictions to ensure that the fines content is under a certain level to ensure a none-water susceptible material and hence avoid loss of bearing capacity during spring thaw. In this study the main focus is to study how the deformation properties, elastic as well aspermanent deformation behavior, are affected by different combinations of water content, grading and material strength. The grading of the material is based on the gradation curves for base course material in the Norwegian guidelines for pavement design, which is based on the fuller curve. Cyclic triaxial tests have been used to study the material behaviour in the laboratory.

Abstract: Subgrade restraint design is the use of a geosynthetic placed at the subgrade/subbase or subgrade/base interface to increase the bearing capacity or the support of construction equipment over a weak or soft subgrade. The conventional design criteria of unpaved roads require providing adequate base course or aggregate cover material to prevent bearing capacity type failure. Geogrids and high-strength woven geotextiles can increase bearing capacity of a pavement structure. Increasing the bearing capacity of subgrade soils can reduce required base course or treatment thickness. Several design methodologies exist for the use of geosynthetics in subgrade restraint for pavement construction. This paper evaluates currently available design approaches and design tools including related proprietary software. Comparative analysis results for different design approaches are also presented in this paper.

Abstract: In this paper, the responses of two different pavement structures (10 and 20 cm HMA layer), were analyzed under the steering, driving and trailer axles of an eighteen-wheeler truck during braking on a 6% downhill grade. The response of the asphalt pavement to the decelerated truck during the braking period was estimated at three different traveling speeds: 64, 32, and 3.2 km/h using the computer code 3D-Moving Load Analysis (3D-MOVE). Significant load redistribution, which occurs between the truck axles under deceleration, has been accounted for in the analysis. The time dependent behavior of the HMA layer as the truck approaches the stopping point is incorporated by using the complex shear modulus and the internal damping as a function of loading frequency. The base course and subgrade layers are treated as linear elastic materials with an internal damping assumed to be 5%. The non-uniform stress distributions at the tire-pavement interface were interpolated from measured contact stress distributions at various speeds made with the Kistler MODULAS Quartz Sensor Array by the Nevada Automotive Test Center (NATC). Braking forces at each tire were included as interface shear stresses with a distribution that was estimated by multiplying the vertical stress distribution by the calculated coefficient of friction between each tire and the pavement surface. The study reveals that rutting in the HMA layer is more prone under the steering single tire while shoving is mainly caused by the dual tandems driving tires.

Abstract: In October 2000 the Mississippi Department of Transportation (MDOT) initiated a study to evaluate the long-term performance of lime-fly ash (LFA) stabilized soil as a base course material. This study entailed performing falling weight deflectometer (FWD) tests on both newer and older pavements and coring pavement at each FWD location to observe the condition of the layers, to obtain pavement thicknesses, and to perform unconfined compressive strength (UCS) testing. Visual observation, backcalculated modulus, and in situ structural layer coefficient values showed that MDOT LFA-stabilized soil base courses have highly variable material properties and thicknesses. Recommendations were made to increase the average LFA material property values and to reduce the spread in these values by increasing the required compaction of the LFA-stabilized soil base layer to 100% standard Proctor effort, setting the required in situ Proctor UCS at 400 psi, and reducing variability by either improving the current method of f...

Abstract: In an effort to quantify the contribution of geotextile separators to the long -term performance of pavement sections, falling weight deflectometer (FWD) testing was carried out over a 12-year period at a test section in southwest Washington State. Five different geotextile separators as well as a soil -only control section were installed in the test sec tion with a different base course thickness in the two lanes of a low volume but heavily loaded rural state highway. The performance of the separators was evaluated during construction and 5 and 12 years after construction. Field and laboratory tests wer e conducted on the subgrade, granular base materials, and the geotextiles as part of the effort to correlate the performance of the pavement section to the presence of the geotextile separators. As part of the most recent evaluation, the FWD results were analyzed using two recently developed interpretation methods, the FWD Area Program (version 2.0) and Evercalc Pavement Backcalculation Program (version 5.20). The results from the FWD Area Program generally showed a decrease in the adjusted deflections, and increases in the area parameter and subgrade modulus along the test section over the 12-year period. The greatest increase in subgrade modulus occurred in the six months following construction. The control sections exhibited behavior similar to the sections with geotextiles, suggesting that for relatively thick pavements, geotextiles separators may not provide a significant contribution to the long -term performance of the pavement. The Evercalc backcalculations indicated an increase in the adjusted pa vement and subgrade moduli over the 12-year period. The sections that contained geotextiles generally showed an increase in the base course modulus, however, some of the analyses showed little to no increase in the base modulus in the control (soil only) sections. The results suggest that geotextiles might contribute to an increase in the base course modulus over time. These findings were also correlated with the results of the field and laboratory investigations.

Abstract: This invention refers to a testing device which simulates the flowing pressure flushing the cracked asphalt pavement base. The device includes the mechanical system, data collecting system and the variable-frequency power source driving machine. The data collecting system includes the amplifier, data collector and the computer, while the mechanical system is made up of electric motor, continuous belt and the camshaft. The photoelectricity sensor is fixed beside the camshaft and on the camshaft there is the eccentric wheel, with which are linked the spring system, force sensor and the sample silo through the bar. The data collecting system will record and display the pressure and its active times. Add the load to the standard times, and it will evaluate the material's ability of anti-degradation through the mass loss. Through this device and its method we will get the relation between different flowing pressure, active times and base material's flushed quantity and the pump suction each time. The experiment's result is stable and believable. Meanwhile the results of different materials can be well compared, so it can be used to evaluated the ability of anti-degradation of half inflexibility road face base material.

Abstract: PROBLEM TO BE SOLVED: To provide a permeable subbase course material capable of improving the stability of a quality and the simplicity of a manufacture, a manufacturing method for the material and a permeable pavement. SOLUTION: The permeable pavement 1 for a roadway has a filter layer 3, a lower-layer subbase course material 4 or an upper-layer subbase course material 5 composed of the permeable subbase course material containing a blast-furnace annealing slag 7b or a steel-making slag 7a having a particle size of 5 to 40 mm in 50 to 90 mass% and a granulated blast-furnace slag 8 having the particle size of 10 mm or less in 50 to 10 mass% and a base course 11 and a surface course 12 on a subgrade 2 in succession. COPYRIGHT: (C)2005,JPO&NCIPI

Abstract: The contact condition between PCC surface layer and poor cement concrete base course directly influences the space between joints and the loading stresses in the pavement.Based on the directed shearing test in laboratory,the interfacial displacement and mechanics characteristics are analyzed systematically.The results can serve as reference for the design of PCC pavement with poor cement concrete base course.

Abstract: PROBLEM TO BE SOLVED: To provide a rolling compaction method for a subgrade base course when an artificial lightweight aggregate is used as a banking material SOLUTION: In this subgrade base course, the artificial lightweight aggregate obtained by baking, foaming, and sieving an expansible shale as the banking material, scrape-out thickness is controllably reduced, and the aggregate is compacted while repeating light rolling compaction several times COPYRIGHT: (C)2005,JPO&NCIPI

Abstract: PROBLEM TO BE SOLVED: To provide permeable pavement eliminating causes of a flood and a heat island phenomenon to solve a water problem and a heat problem by securing a sure permeating function in a paved road. SOLUTION: The permeable pavement 1 is constituted by forming a binder part 4 for joining a base course concrete part 2 and a surface layer concrete part 3 both formed of porous concrete and having permeability, at a boundary part 1X of the base course concrete part 2 and surface layer concrete part 3 so as not to block permeating holes 22, 32 opened to the surface of the base course concrete part 2 and the bottom face of the surface layer concrete part 3. COPYRIGHT: (C)2005,JPO&NCIPI

Abstract: A new design of concrete pavement is presented in this paper. After a rapid description of the current rigid pavement landscape, the new pavement is specified in terms of functions and material. From these specifications, we end up with a 6 cm-thick High-Performance Concrete (HPC) wearing course, reinforced with a welded-wire mesh, laying on a cracked hydraulic base course. The behavior in hot weather (risk of buckling) and cold weather (shrinkage-induced cracking) conditions is then examined. From these investigations a long-life wearing course is anticipated. Moreover, it is shown that the HPC carpet fits well with sustainable development requirements: it leads to a lower consumption of the non-renewable resource, and the noise generation is likely to be reduced, by comparison with present concrete pavement state of the art. A second paper to follow will present scale-1 applications and further investigations.

Abstract: This paper presents the first results of an experimental study aimed at evaluating the effectiveness of a rehabilitation method for low volume roads. The method suggests the usage of a steel reinforcing netting in order to improve the performance. It consist in reconstructing the surface layer placing a steel reinforcement in the interface between the new binder layer and the existing base course. This reinforcing method aims at making a road possibly support a sudden increase of number and load of vehicles quickly and with a modest maintenance. The research considered the problem from three points of view: real scale, by constructing and monitoring an experimental section; reduced scale, with laboratory tests reproducing the situations recorded in the experimental section; a finite element modeling using all the so gathered results. The findings show that although the steel netting is placed in the top layers of the pavement, it is still able to improve its resistance and its strain energy absorption ability consequent to the vehicles transit.

Abstract: The present invention provides a process for stabilizing the base course of a roadway through steps including admixing an asphalt emulsion and Portland cement with granulated base materials. The base course formed through this process is stronger and less permeable than base materials stabilized with either Portland cement or an asphalt emulsion alone. The method of base stabilization includes the steps of evaluating the base materials, designing a proportional mixture of the base materials and stabilizing agents, and forming a stabilized base course.

Abstract: PROBLEM TO BE SOLVED: To provide a pavement structure which can suppress a heat island phenomenon by making the structure carry water permeability and water retentivity, has a simple structure, and is easy in paving work. SOLUTION: The pavement structure 1 comprises a base course section 3 which is formed by being paved with crushed stones 5 into a predetermined thickness, and a pavement 4 which is provided on the base course section 3; the pavement 4 is composed of a water-retentive pavement material wherein at least crushed shells 6 and fine aggregate 7 are used as aggregate and which is formed by mixing the crushed shells 6 and the fine aggregate 7 into an asphalt emulsion resin as a binder. The pavement 4 which is formed of the water-retentive pavement material, has excellent water permeability and water retentivity, and reduces a rise in the temperature of a paved surface by the heat of evaporation of retained moisture so as to exert an effect of suppressing the heat island phenomenon. COPYRIGHT: (C)2005,JPO&NCIPI

Abstract: PROBLEM TO BE SOLVED: To provide railroad ballast, the ground of a structure, and construction methods thereof for effectively preventing the occurrence of frost heave on the railroad ballast and the grounds of various structures, effectively utilizing industrial waste and low in construction cost. SOLUTION: In this construction method, a construction material obtained by mixing clinker ash and a frost heaving material so that the weight ratio of the clinker ash to the total weight of the clinker ash and frost heaving material is ≥50% and COPYRIGHT: (C)2006,JPO&NCIPI

Abstract: PROBLEM TO BE SOLVED: To provide permeable pavement hardly causing separation between a surface layer and a base course before construction without impairing permeability, and facilitating reinforcement even if separation occurs after construction. SOLUTION: The permeable pavement 1 has a permeable base course concrete part 5 formed of porous concrete, and a permeable surface layer concrete part 6 formed of porous concrete and laid on the upper part of the base course concrete part 5. The permeable pavement 1 has anchor parts 7 comprising bottomed anchor holes 71 passing from the surface to the bottom face of the surface layer concrete part 6 and reaching at least the surface of the base course concrete part 5, and mortar 72 injected in the anchor holes 71 from the bottom parts to the openings and hardened. COPYRIGHT: (C)2005,JPO&NCIPI

Abstract: Geogrid products placed in pavement base layers apparently improve performance. Currently the only way to prove this is by evaluating full -scale roadways or laboratory-scale models of a pavement system, which is time-consuming and expensive, making them impractical on a project- or product-specific basis. Isolation of the improvement mechanism is difficult due to the multiple variables present in each component of the pavement system. The bending stiffness index test has been developed to isolate and measure geogrid performance in the base layer of a pavement system. The objective of this paper is to evaluate and refine the bending stiffness index test described by Sprague et al. (2004). The effects of the apparatus and testing variations on the test results are addressed through a series of tests . The results show that the measured bending stiffness for a compact ed base course alone is consistent with published values. In addition, the bending stiffness can be measured with enough resolution to distinguish an increased stiffness when the base course is reinforced with a geogrid. Also, the measured bending stiffnes s can be used to compare the effects of different geogrid products. The ability to distinguish the effect of a geogrid and to compare different geogrids decreases as the confinement stress on the base course increases.

Abstract: PROBLEM TO BE SOLVED: To prevent the occurrence of base course deformation in a labor-saving track in which a sleeper is supported by a grouting layer formed on a base course. SOLUTION: A surface drainage layer 3 formed of nonwoven fabric is formed on the surface of the base course 2, and a drain pipe 8 is laid between the surface drainage layer 3 and a track side ditch 12. A check valve 10 is mounted to the drain pipe 8, and the drain pipe 8 is filled with water. Moisture in the surface of the base course 2 is thereby sucked by the surface drainage layer 3, then led into the drain pipe 8 by the principle of siphon and discharged to the track side ditch 12 via the check valve 10. Consequently, even if the base course 2 receives a train load, base course soil does not flow out. COPYRIGHT: (C)2005,JPO&NCIPI

Abstract: As the presence of difference between the deflection measured and calculated according to the elastic layer theory, synthetic modified deflection coefficient F is put forward. In the present design specification of asphalt pavement, the number of structure layer is not taken into account in the present F. Moreover the flexible base course is seldom used. A new regression formula of F is suggested according to the full-scale tests in the field.

Abstract: The dynamic modulus of hot mix asphalt can be determined according to the different combinations of testing temperature and loading frequency. The superposition rule is adapted to get the master curve of dynamic modulus for each hot mix asphalt. There are couple of different methods to get the shift factor which is a key for making the master curve. In this paper, Arrehnius, 2002 AASHTO, and experimental method was employed to get the master curve. Evaluation of dynamic modulus for 25mm base course of hot mix asphalt with granite aggregate and two asphalt binders(AP-3 and AP-5) was carried out. Superpave Level 1 Mix Design with gyratory compactor was adopted to determine the optimum asphalt binder content(OAC) and the measured ranges of OAC were between 4.1% and 4.4%. UTM was used for laboratory test. The dynamic modulus and phase angle were determined by testing on UTM, with 5 different testing temperature(-10, 5, 20, 40, & ) and 5 different loading frequencies(0.05, 0.1, 1, 10, 25 Hz). Using the measured dynamic modulus and phase angle, the input parameters of Sigmoidal function equation to represent the master curve were determined and these will be adopted in FEM analysis for asphalt pavements. The shift factor and activation energy for determination of master curve were calculated.

Abstract: In the last years, the pavement rehabilitation techniques in Brazil have been improved. New types of recycling appear every year but the problems frequently associated with these techniques and materials should be used in considering its mechanic behavior. In Brazil, two kinds of recycling asphalt pavement have been used in the last five years: foamed asphalt and recycled base course with cement. The recycled base course with cement technique has success because it is very easy and the costs are economical, however, the standards and proceedings recommend that the roadway should not be opened to traffic for seven days. Therefore, this is a big obstacle for using this technique, because it is almost impossible to close part of highway for a week. The time to get the necessary performance is a critical element for adopting this technique even if the cost is lower when compared with others. This paper presents the results of research to study the resistance behavior of specimens of the recycling of the asphalt pavement with Portland cement in terms of the time. Some tests were done: compressive strength, indirect tensile and creep static. The samples were tested after 3, 6 and 12 hours after the mixture of the materials with cement Portland.

Abstract: The stress intensity factor(SIF) at the crack tip is an important index to judge the crack development.In this paper a finite element analysis model of 20-node isoparametric elements was established by the FEM software ABAQUS and the crack at the bottom of the semi-rigid base course was numerically analyzed with the singularity isoparametric elements method and fracture mechanics theory.The effect of pavement parameters on base crack was studied and the change of the stress intensity factor(K_1 and K_2) in the course of base crack propagation was discussed.The life of crack propagation was estimated.The results reflected the pavement structure and performance for anti-crack design.

Abstract: Aiming at cutting-slippage between surface and semi-rigid base of asphalt pavements, interlayer cling-materials are studied. Then lots of laboratory experiments for cutting-slippage are carried out with shear testing instrument. Last, some technical means including SBR cling-materials are recommended to prevent cutting-slippage between base and surface.

Abstract: For over 10 years, “full depth, cold recycling” of deteriorated asphalt pavement in road rehabilitation projects has expanded. Recycled asphalt pavement RAP, is now accepted as an inexpensive, available and environmentally acceptable aggregate material for incorporation into road structures. In-place, full-depth, cold recycling eliminates purchasing and hauling of new materials and disposing of old asphalt, with substantial savings. Despite the cost and environmental benefits, use of cold, in-place RAP, many times does not provide adequate strength to the base layer. In the USA and others countries like Australia, “recycling with stabilization” has quietly expanded. Led by innovative commercial companies and encouraged by the Department of Transportation’s (DOTs) Federal Highway Administration, materials such as: cement, lime, asphalt emulsion and enzyme stabilizers are commonly added to the blend of RAP and underlying granular material to increase strength. New experiences in mixing sub-grade soil with RAP and stabilizing the blend shows strength increases of 2 to 3 times, while further reducing costs of rehabilitation by lowering purchase and transport requirements for base layer materials. The increased CBR of RAP and soil combinations further reduces the need for increase thickness of the base course material before repaving. The new recycling process of increasing milling depth to include 30% to 50% underlying soil with the RAP and stabilizing the mix with liquid enzyme will be presented. Results from government field projects and independent laboratory work, as well as economics will be reviewed. The stabilization process includes the steps of loosening the road surface, pulverizing the soil to prepare a uniform bed, distributing the stabilizer solution on the prepared bed, mixing the soil with the enzyme solution uniformly in a one-pass operation that is followed by shaping and compacting. Recycling equipment improvements have increased the cost benefits of this new practice of recycling with enzyme stabilization.

Abstract: Moisture beneath pavements leads to premature pavement distress which can include pumping, faulting, and cracking. This article presents a cost/benefit approach to using separation geotextiles to ensure long-term pavement performance. The authors describe how a geotextile is used to prevent the mixing of two adjacent material layers. A geotextile's structure and properties ensure separation of granular materials without compromising the movement of fluids between layers. The authors report on the limited number of studies on the performance of separation geotextiles; overall these studies demonstrate that while geotextiles do provide performance improvement, placing an exact value in terms of % improvement in design life of a pavement is very challenging. However, geotextile cost remains less than the cost of 1 in. base course aggregate and separation geotextiles typically prevent contamination of several inches of base layer. Thus, the benefits clearly outweigh the costs.

Abstract: In the paper, The thesis is prepared in combination with "Study on crazing-resistance performance of bituminous mixture pavement "as approved by Henan provincil Communications Department,Low temperature crazing-resistance strength and construction technology of pitch rubber spall bituminous mixtures is explored by means of indoor test and field test and analysis of strength-forming mechanism, thereupon which it is submitted scientifically that "asphalt-rubber macadam"is used for mending the cracked bituminous pavement arising from the fatigue and as the bituminous surface course and the lower surface course of semi-rigid type base course pavement, Not only could reduce greatly the reflex of semi-rigid type base unit material, but also it is possible to lengthen the service life of pavement.

Abstract: With the finite element method, the effect on asphalt pavement with changing the thickness and modulus of semi-rigid base course was studied. The results show that the mechanics function and the using life of asphalt pavement can be improved through properly increasing the thickness of semi-rigid base course and increasing the thickness and modulus of bottom base course. The conclusions are helpful to practical construction.