Abstract: This paper presents the results of a recent investigation on the performance of four recycled concrete aggregates (RCAs). The materials, obtained by crushing concrete with compressive strength ranging from 15 MPa to 75 MPa, were reconstituted to satisfy the grading requirements for a subbase material. Triaxial specimens were tested under repeated loading one day after compaction. It appears that the original concrete compressive strength, the amount of softer material in the RCA, and the flakiness index of the RCA can significantly affect the resilient modulus. Degradation is mostly related to the crushing of softer and flaky materials within the aggregate matrix. In this regard, the Ten Percent Fines test is suitable as an evaluation test as it does not impose an excessive force on the RCA. The overall results indicated that RCA may be utilized as a subbase or base course material if it can be produced to consistently meet product quality standards.

Abstract: The objectives of this research study are to investigate the feasibility of using recycled concrete aggregate (RCA) as a base course material in asphalt pavement, to evaluate the physical properties of RCA, and to develop practical and reliable guidelines and specifications. The tasks included in this study are: literature review, a questionnaire to RCA producers, sample collection, laboratory testing, accelerated performance testing and pavement distresses monitoring, Falling Weight Deflectometer (FWD) test, theoretical analysis of pavement, and development of guidelines and specifications for the use of Florida RCA. The laboratory tests of RCA samples included: gradation, limerock bearing ratio (LBR), Los Angeles (LA) abrasion, soundness and sand equivalent, optimum moisture content, maximum dry unit weight, permeability, and impurities. The project also included the construction of three test sections of asphalt pavement at the University of Central Florida Circular Accelerated Test Track (UCF-CATT). Two sections of different thickness were constructed with RCA base and one section with limerock (LR) base. A total of 362,198 load repetitions were applied to the test sections. This is equal to 811,324 of 18 kips (80 kN), equivalent single axle load (ESAL). The pavement distresses of rutting, cracking, and settlement were monitored during the course of the performance moduli of RCA and LR for theoretical analysis of life expectancy. The findings in this project support the hypothesis that RCA can be used effectively as a base course when appropriate quality control techniques are utilized. Based on the information obtained in this study, a set of specifications for the use of RCA as a base course in flexible pavements was developed.

Abstract: The environmental impact of using petroleum-contaminated sand (PCS) as a substitute in asphalt paving mixtures was examined. An appreciable component of PCS is oily sludge, which is found as the dregs in oil storage tanks and is also produced as a result of oil spills on clean sand. The current method for the disposal of oily sludge is land farming. However, this method has not been successful as an oil content of <1% w/w is required, and difficulty was encountered in reaching this target. The reuse of the sludge in asphalt paving mixtures was therefore considered as an alternative. Standard tests and environmental studies were conducted to establish the integrity of the materials containing the recycled sludge. These included physical and chemical characterization of the sludge itself, and an assessment of the mechanical properties of materials containing 0%, 5%, 22% and 50% oily sludge. The blended mixtures were subjected to special tests, such as Marshall testing and the determination of stability and flow properties. The experimental results indicated that mixtures containing up to 22% oily sludge could meet the necessary criteria for a specific asphalt concrete wearing course or bituminous base course. To maximize the assay from the recycled material, the environmental assessment was restricted to the 50% oily sludge mixture. Leachates associated with this particular mixture were assayed for total organic residue and certain hazardous metal contaminants. The results revealed that the organics were negligible, and the concentrations of the metals were not significant. Thus, no adverse environmental impact should be anticipated from the use of the recycled product. Our research showed that the disposal of oily sludge in asphalt paving mixtures could possibly yield considerable savings per tonne of asphalt concrete, and concurrently minimize any direct impact on the environment.

Abstract: The Vermont Agency of Transportation (VAOT) conducted a two-phase study to quantify the resilient modulus and strength characteristics of its subbase material. In Phase 1, a literature review was done to determine the various methods available for indexing the shape, texture, and angularity of coarse aggregates. In the second phase, described in this report, a study was conducted to relate particle index to the mechanical resilient and shear properties of base course materials. The particle index as modified by the Michigan Department of Transportation used the complete gradation and was a good indicator of the crushed (angular) content of a given base course gradation. The particle index test also may be used to indicate resilient and shear properties of base course aggregate gradation.

Abstract: The effect of unsaturated soils on pavement performance is examined through a case history involving a narrow pavement constructed on an at-grade section. The pavement function was for bicycle and pedestrian traffic in a recreational project in Oklahoma City, Oklahoma. The pavement section consisted of asphalt concrete surface course underlain by aggregate base on a prepared subgrade. Following construction, and during a very dry weather cycle, the pavement experienced a total of 3237 m of predominately longitudinal cracking and surface undulation. A reconnaissance of the pavement extent (5.58 km) indicated that 68 percent of the cracking occurred in one pedological soil series. A geotechnical study was performed that included: pavement core and base course tests, hand auger and continuous Standard Penetration Test borings, index and engineering property tests and filter paper method soil suction testing. Examination of an average yearly water balance prior to and following pavement construction revealed that shrinkage rather than heave was the crack controlling mechanism. Estimates of field capacity were made from water balance calculations. The Thornthwaite Moisture Index (TMI) and the Soil Moisture Deficits (SMD) were estimated for the period prior to and following construction by comparisons of monthly rainfall and monthly potential evaporation resulting in indications of potential shrinkage and cracking. A characteristic curve was developed from the total suction measurements using the filter paper method. Analysis of available information indicates that the change in the total suction was responsible for soil shrinkage. Suction changes were determined through suction versus depth profiles over time to predict the initial and final suction input and using initial calculated suction from the characteristic curve(s). Finally it was shown that the change in suction, resulting in lateral shrinkage of the soil, caused lateral forces that easily exceeded the tensile strength of the asphalt concrete and aggregate base courses.

Abstract: This report gives the results of a study of the properties of unbound aggregate base materials using both laboratory testing data from full scale field tests in Illinois, Georgia, and Texas, and a model of cross-anisotropic elastic materials to characterize the behavior of the base materials under traffic loads. Using the cross-anisotropic model, the stress distribution in a base course is more realistic than that developed when the aggregate base is considered to be linear and isotropic. The stress distribution based on cross-anisotropic analysis is not only more correct, but it is also more favorable to the unbound aggregate in that significant tensile stresses are found not to occur. The analogy is presented in this report that the response of the aggregate base to the load is as if the stress distribution directly under the wheel load due to anisotropy acts as a moving column under the wheel in which the aggregate essentially produces its own confinement and does not enter into tension. Other findings in this report include the following: (1) The unbound aggregate base material should be modeled as nonlinear and cross-anisotropic to account for stress-sensitivity and the significant differences between vertical and horizontal moduli and Poisson's ratios. (2) The International Center for Aggregates Research (ICAR) laboratory testing protocol is efficient and precise and should be considered as a candidate to model the unbound aggregate base. The protocol uses three stress regimes and ten stress levels within each regime to determine stress sensitivity and cross-anisotropy. A system identification method is used to select the five material properties based on the test results necessary to properly characterize the aggregate base and to satisfy the requirements of elastic work potential theory. (3) The Fast Industrial Process Controls cell is efficient and should be used to characterize unbound aggregate bases. The ratio of the diameter to the specimen height is 1:1. While testing of such sample sizes is discouraged in the literature, improvements made to the IPC cell minimize frictional development between the sample and loading platens resulting in minimal constraint at the sample ends. This is verified in the report based on comparative triaxial testing and finite element analysis. (4) The ICAR testing protocol is an excellent tool for both unbound aggregate characterization and comparative analysis of materials. A compaction study on two very different aggregates (uncrushed river gravel and crushed limestone) was performed in which the aggregates were subjected to impact, kneading gyratory compaction. The difference in the tendency of the compaction techniques to produce varying levels of particle orientation (which affects anisotropy) was evident in the degree of anisotropy measured.

Abstract: In order to better simulate the dynamic effects of a rolling wheel travelling over an asphalt pavement, and to better understand the initiation and growth of cracks in bituminous pavement layers, a wheeltracking fatigue simulation facility was developed. This experimental facility permitted the testing of large slab specimens (305×305×50mm) using dynamic wheel loadings. The slab specimens were supported on a soft elastomeric foundation that simulated overlay behaviour on top of a weak pavement structure. Digital photography and image analysis techniques were utilised to monitor the initiation and propagation of fatigue cracks on the bottom of these slabs. Two standard Irish mixtures, a Dense Base Course Macadam (DBC) and Hot Rolled Asphalt (HRA), were evaluated with the fatigue simulation facility. Crack damage was seen to initiate on the bottom face of the slab specimen in a direction parallel to the direction of wheel travel. These cracks would interconnect to form a full width crack that propa...

Abstract: Ground-penetrating radar (GPR) was used to identify the variability in layer thickness for 13 general pavement study sites in North Carolina. Two data sets were collected for each of 11 sites and one data set was available for 2 additional sites. Asphalt thicknesses varied over a wide range, but the standard deviation for asphalt layers less than 6 in. (15.24 cm) thick was 1 or less. GPR results were consistent with North Carolina typical base course thicknesses, whether that base be asphalt, dense-graded aggregate, or cement-treated aggregate. Variability in base course thickness was greater than variability in the surface layer. The effects of changing layer thicknesses from the mean thicknesses to the mean 1 standard deviation were examined by backcalculation and by calculating overlay thickness requirements with the North Carolina Department of Transportation overlay design procedure. Overlay thickness requirements typically changed by 3.8 mm (0.15 in.) over the range of layer thicknesses. Backcalcula...

Abstract: The author of this article examines the causes and potential cures of asphalt pavement rutting. He explains that rutting on the asphalt pavement surface commonly is the result of an unstable asphalt mix, heavy vehicle traffic, and high pavement temperatures. He notes that this type of rutting is often observed at intersections, bus stops, freeway off ramps, or under extreme loading situations on airport runways or dock loading facilities. He explains how an engineer can determine if rutting in the asphalt pavement surface is due to distress throughout the entire pavement structure or due to failure in the asphalt layer only. He suggests that asphalt mixes can be designed to resist rutting with the proper selection of materials, good construction practices, and use of appropriate mix design methods. Good compaction practices during construction will improve rut resistance by increasing the interlock of aggregate particles in the mix.

Abstract: The in-service behaviour of a standard Irish Dense Base Coarse Macadam mixture (DBC) was evaluated by using the material to overlay a road section, which was based upon a weak pavement structure. The response of the layer under a fully laden dual axle truck was examined using a series of pressure cells and asphalt strain gauges that were embedded in the test section. The section was traversed repeatedly until a network of fatigue cracks was observed on the road surface. The transverse horizontal tensile strain was found to be the most critical parameter in initiating pavement damage. INTRODUCTION Full scale test facilities offer particular advantages over simulated laboratory programmes: the effects of size, construction, substructure, boundary and loading conditions correspond more closely to the actual on-site conditions than can be simulated directly with model experiments. However, it is seldom possible to control temperature and moisture when using such facilities and consequently there are always inherent disparities when attempting to relate laboratory and in-situ test data. Recent investigations have focussed on the mechanical performance of standard bituminous mixtures using uniaxial fatigue tests [1-3] and fatigue wheel tracking laboratory tests [4]. The present paper describes a full scale accelerated loading performance test on a 20mm Dense Base Coarse Macadam [6] which overlaid a peat based forest access roads [5]. Such forest roads generally have a weak pavement structure, which consists of a surface dressed granular base and a subbase (±0.5m deep) that overlay deep peat foundations. In general, peat (a soft biogenic deposit) provides a poor foundation for roads as it is frequently weak [7] and compressible, particularly after prolonged dry periods [8]. Various damage assessment procedures are used to evaluate the structural integrity of a pavement, for example the monitoring of crack initiation and propagation and permanent deformation on the pavement surface. In-situ material properties can be evaluated by measuring surface deflections with a Falling Weight Deflectometer (FWD), while internal stresses and strains can be monitored by use of appropriate transducers that are located at critical positions within a pavement structure. Environmental factors such as the moisture level in the subgrade and the pavement temperature can also be monitored. The present research has characterised and quantified the in-situ mechanical performance of a standard Irish Dense Base Course Macadam (DBC) by measuring surface strains, crack growth and subgrade stresses at incremental levels of fatigue cycles under controlled load conditions. LAYOUT AND CONSTRUCTION OF TEST SECTION A suitable section of a forest access road was identified for the experiment. Figure 1 shows a schematic representation of the monitoring section, the dimensions of which are 3.3m (road width) by 35m (length of overlaid area). A central area in the outer wheel path was selected for instrumentation with pavement transducers, the detailed layout of which is shown in Figure 2. FWD points were marked over the test area to measure the global pavement response. Crack monitoring grids were randomly spaced in the outer wheel path over 15m along the section. A total of 19 grids were marked out to monitor cracking. Four permanent deformation cross section measurement positions were identified, two at both ends of the crack monitoring strip. The traffic counter was located at the end of the test section. The counter had to be placed as far away as possible from the crack monitoring and permanent deformation measurement positions since counter cables had to be machined into the overlay which could induce initial defects. 0m 5m 10m 15m 20m 25m 30m 35m Traffic counter Permanent deformation measurement cross section Crack monitoring area FWD deflection point Instrumented area (detail in Fig.2) 1 2 3 4 North Overlay chamfer Figure 1. Layout of experimental road pavement section. Road center 460

Abstract: Asphalt pavements can be built so that they last for the foreseeable future, with minor surface work from time to time The design life being discussed now is 50 years for what is called"perpetual pavement" Built on a solid base, asphalt that is thick enough will resist traditional fatigue-caused cracking that results eventually in total failure of the pavement A cross-section of conventional pavement shows that it has roughly one-third the hot-mix asphalt topping and that it is designed much more simply than the perpetual pavement's hot mix asphalt (HMA) mixture United Kingdom researchers discovered the "curing curve" of asphalt pavements, where the stiffening of the upper and lower layers as they cure has different effects on pavement life By refining the thicknesses of the top and bottom layers, they could design a pavement which maximized the sturdiness of both French scientists developed extremely stiff asphalt binders in high modulus asphalt concrete (HMAC) to reduce the amount of asphalt needed HMAC provides a good base California scientists have worked on elasticity in a project on the I-710 freeway, using full-depth asphalt concrete pavement with a thin upper lift that acts as a protector to the structural layers and can be cheaply and easily milled off and replaced Texas devised a similar design but using a more mechanistic approach New Jersey used the perpetual pavement approach on rehabilitating a rundown roadway that still had sturdy foundations Florida researchers are working on ways to model slow-growing cracks that seldom penetrate more than three inches into the surface to better understand what makes cracks speed up

Abstract: The objectives of this licentiate thesis are to evaluate existing material models used for fatigue life evaluation of an asphalt concrete pavement. Different Continuum Damage Mechanics (CDM) models are also evaluated, and the results are compared to results obtained with traditional methods. A standard Swedish base course mixture (AG22/B180) has been used in this work. The aggregate used in the mixture was mainly gneiss with some small portions of diabase. The binder was a standard B180 without modifications, and it was manufactured from Venezuelan crude oil. Static creep tests, frequency sweep tests, constant strain rate monotonic tests and cyclic fatigue test (tension and compression) were performed on specimens cored from laboratory manufactured plates. Four 100 mm diameter specimens were cored from each plate using portable coring equipment. After coring, speciemens were cut, resulting in speciemns with a height equal to 200 mm (2:1 ratio). The tests were performed using a dynamic servo hydraulic test machine, UTM-25 (Universal Testing Machine-25 kN). (A)

Abstract: PROBLEM TO BE SOLVED: To provide a waterproof construction method for an asphalt pavement, capable of causing no environmental pollution, and constructing or repairing an asphalt pavement road having both high adhesive force and waterproof performance, and high quality in a short construction period. SOLUTION: An adhesive and waterproof layer 83 of asphalt is formed between a bed 6 and an upper layer 7 of asphalt mixture having open grading aggregate by laying an asphalt sheet. The layer 83 is mainly composed of asphalt, and works as an adhesive material between the layers, and also works as a waterproof layer for preventing rainwater permeating into a drain layer formed by the asphalt mixture having open grading aggregate from leaking to the bed side. Thus, scattering of chemicals is prevented so as to prevent environmental pollution, drying work is eliminated not to require wait time, and further the adhesive and waterproof layer 83 having uniform thickness is formed without air bubbles.

Abstract: PURPOSE: A cement concrete road paving method using soil as some of materials and a cement block manufacturing method are provided to heighten the utility value of eco-friendly and helpful soil by securing optimal stiffness when using soil as some of materials for road pavement or a block. CONSTITUTION: A cement concrete road paving method using soil as some of materials comprises the steps of mixing one or two out of yellow ocher, red ocher, white clay, and black soil plastic-worked to remove organic matters with cement, water, and a dispersant, paving the mixture in a thin layer of 1-5cm on the base course paved with an ordinary concrete tamping method, tamping on the upper part with a roller, before or after curing the surface, mixing water, emulsion resins, yellow ocher, white cement, a dispersant, and silica fume, and spraying on the surface to reinforce the surface or spraying liquid hardener to reinforce the surface. A cement block manufacturing method comprises the steps of putting materials for a base course out of materials for road pavement in a regular form, vibrating under pressure to form a lower layer of a block, inputting materials for an outer layer into an upper layer, vibrating under pressure, and taking out from the form and moist-curing or vapor-curing.

Abstract: This investigation was conducted to develop and demonstrate permeable base course materials using coal combustion products (CCPs) for highways, roadways, and airfield pavements. Three types of CCPs—two high-carbon, high-sulfate flue-gas desulfurization (FGD) by-products and a variable-carbon fly ash—were evaluated for no-fines or lowfines concrete as a permeable base material. This report summarizes the work completed for this two-year project. A total of 56 mixtures were proportioned and manufactured in the laboratory in this research. Mixture proportions for the base course materials were developed using a twostep experimental optimization process. The first step involved developing mixture proportions for permeable base course materials containing no CCPs. A total of 26 mixtures were produced in the first step. The optimum mixtures developed from the first step of the experimental process were used as candidate mixture proportions for the second step of the optimization process. The second step of the mixture optimization included various combinations of the three CCPs for developing mixtures for base course materials. Specimens from each mixture were made using roller-compacted concrete (RCC) technology in accordance with ASTM C 1435. Three different series of ten base course mixtures were developed and tested based on the structure of the base course: dense-graded, intermediate-graded, and open-graded. Each mixture was evaluated for both strength and durability properties. The strength properties that were evaluated consisted of compressive strength (ASTM C 39), flexural strength (ASTM C 78), and splitting tensile strength (ASTM C 496). Durability properties consisted of drying shrinkage (ASTM C 157), resistance to sulfate exposure (modified ASTM C 1012), and resistance to rapid freezing and thawing (modified ASTM C 666). Based on the mixture proportions established in the laboratory, four prototype opengraded base course mixtures containing one source of CCP were manufactured at a commercial ready-mixed concrete plant. A full-scale base course mixture was produced for a construction demonstration, which was held in conjunction with a technology transfer educational workshop conducted in Green Bay, Wisconsin, in September 2002. The base course mixture was open-graded to maximize drainage capability. The base course mixture was made by replacing approximately 50 % of the cement with one of the sources of CCP evaluated for this project. Adequate compressive and flexural strength were achieved from the mixture used for the demonstration.

Abstract: The bad effect to cement concrete pavement influenced by joint sawing and temperature has been analyzed from a new perspective.The interaction between the surface course and the base course causes three basic failure types,which lead to further failure of pavement.Such basic failures can be avoided when setting a kind of intermediate layer between the surface course and the base course,and as a result the failure of pavement can be reduced to the utmost.

Abstract: PURPOSE: A patterning porous concrete paving method is provided to reduce working hours by using a stencil or pattern sheet on a porous concrete surface tamped by a roller, to express various colors and shapes without lowering stiffness, to have natural beauty, and to enlarge frictional force. CONSTITUTION: A patterning porous concrete paving method comprises the steps of: leveling a subgrade and paving a base course; forming a porous concrete layer by using a mixture composed of aggregate for general concrete, pulverulent waste concrete, slag, etc. as aggregate, then paving 1 cubic meter of the aggregate on the basis of the optimal compaction with a mixture by mixing 200-450 kilograms per a cubic meter of cement, 80-150 kilograms per a cubic meter of water and an admixture(a water reduction agent) in less than 2 percent of the amount of cement used and tamped by a roller; sprinkle 200 kilograms of water per 100 square meters of the porous concrete paved and installing a stencil; after mixing general cement or white cement, water, etc. at a certain ratio per a cubic meter of the aggregate on the basis of the optimal compaction, then sprinkling and finishing evenly; and removing the stencil and curing the surface.

Abstract: An asphalt pavement construction method capable of building high-quality asphalt pavement roads or the like in a short time without causing environmental pollution, wherein an asphalt sheet (10) obtained by forming asphalt into a sheet is used when an asphalt mixture layer is laminated on a base or an existing pavement surface, that is, after an asphalt sheet (10) for forming a bonding layer is laid on an asphalt mixture layer laminated on the base or the existing pavement surface, an asphalt mixture layer is laminated on the sheet as an upper layer.

Abstract: Recycling of asphalt concrete is increasingly used as a major rehabilitation method in Japan because it can conserve natural resources, reduce costs and save energy In this study, reclaimed asphalt concrete from Tokyo International Airport was evaluated for use in four types of base materials : recycled granular material, recycled cement stabilized material, recycled cement-emulsified asphalt stabilized material and recycled hot-asphalt stabilized material The results of laboratory tests indicated : 1) These materials can satisfy base course and subbase requirements, and 2) they are sensitive to temperature and water

Abstract: PROBLEM TO BE SOLVED: To provide a permeable pavement structure capable of easily passing rainwater which has fallen on a road face through ground and excellent in durability and applicable for a heavy traffic road. SOLUTION: This permeable pavement structure 10 allows rainwater which has fallen on a road face 11 to penetrate through the base course layer 13 and the subgrade layer 14 and return into the ground. It is constituted of a pavement layer 13 having dynamic stability of 3,000 times/mm or more and a permeability coefficient of 1×10-2 cm/see or larger as the whole layer, a base course layer 13 having 2N/mm2 or higher bending strength and 1×10-3 cm/sec or more permeability coefficient, and a subgrade layer 14 having K30=0.2 N/mm3 cm/see or larger bearing force on the subgrade face and 1×10-3 cm/sec or larger permeability coefficient. A vertical ditch having a specified width is formed in the subgrade layer 14 and a granular material is filled therein. In this way, drain trenches 21 under the subgrade face are formed at every specified distance in the direction of vertical section of the road.

Abstract: Through investigation,comparison and observation on testing road,the author indicates:it can produce better anti-cracking action as well as economic effect to use material of graded stone upper base course for transition course between bituminous pavement and semi-rigid base course.

Abstract: Based on the pavement condition,overlay information and general performance equation presented by Tongji University,the authors counter?deduce effective thickness coefficients ( f ) and effective thickness of existing asphalt pavement surface course By variance analysis,the significant factors affecting f are determined as the pavement condition before overlay( PCI t ),existing surface course thickness ( oldh ) and base course type Then,the prediction model of effective thickness coefficients ( f ) is developed by regression analysis,of which different base course types have different regression parameters Making use of the model,the authors predict and analyze effective thickness coefficients and effective thickness with different pavement structural combination

Abstract: PROBLEM TO BE SOLVED: To provide a pavement structure in a sidewalk which stores rainwater which has fallen on the pavement below the surface course for efficient use. SOLUTION: An impervious sheet 15 is laid to form a recessed shape between the subgrade and the base course 17 and a granular material 16 is filled in the recessed part to show 30% or more in aggregate porosity and form a base course 17 provided with a strength having 30 or more in a modified CBR and 1×10-1 cm/sec in permeability coefficient. Further, a nonwoven fabric 18 is laid on the surface of the base course 17 and sand cushion is laid and then, water permeable blocks 20 having 1×10-2 cm/sec or more in permeability coefficient to form a surface course 27. Rainwater which has passed through the surface course 27 and penetrated to the lower side is stored in a recessed rainwater storage tank 21 filled with the granular material 16.

Abstract: PURPOSE: A paving process is to provide a clean surface of a dense grade permeable thin layer of concrete applied to a base course by using small particles less than 1.5mm and to maintain the successive permeability thereof due to a few void clogging. Further, the process is also to provide easy material handling and simple construction with a water to cement ratio of 15-30% composed of dense particles. CONSTITUTION: A process comprises a step of paving a crushed stone base course on a sand filter layer under highest possible compacting with an optimized moisture content by a roller, a step of forming permeable concrete for the base course, where any one or more than two aggregates of crushed stones, pulverized waste concrete, recycled aggregate, slag passing 100% by weight through a sieve of 40mm, 0-30% through a 5mm sieve, 0-10% through a 2.5 sieve respectively are used, a mixture of 200-400kg cement, 80-150kg water and an admixture(a water reducing agent) within 2% used cement by weight is paved on the crushed stone base course prepared at the former step and compacted, and a step of paving and compacting a less than 2 cm thin layer of dense permeable concrete with a mixture of 1.5mm-0.04mm granulated aggregate to the permeable concrete surface for the base course of the former step.

Abstract: Numerous ongoing research projects at the Recycled Materials Research Center of the University of New Hampshire include Project 13/14 whose goal is to develop standard American Association of State Highway and Transportation Officials (AASHTO) materials specifications for the use of recycled materials in highway and transportation facility construction. This paper describes the ongoing study of six different materials that were selected for participation. The materials are: glass gullet in base course; reclaimed concrete aggregate in unbound base course; reclaimed concrete aggregate; fly ash as an embankment material; asphalt shingle waste; and reclaimed asphalt pavement.

Abstract: An investigation of limestone base course aggregates was performed to ascertain if strength and stiffness changes in carbonate aggregates could be evaluated for the purpose of quantifying their effects on the base structural layer coefficient used in pavement design. One of the goals of this approach was to develop a laboratory test or series of tests, which the Florida Department of Transportation might use to quantify or predict strength and stiffness gains, that could be generally applied to a range of materials types given field operating conditions. Materials of varying carbonate content were selected, prepared at optimum moisture content and compacted by modified proctor for testing at different ages after curing by two methods (soak and moisture room). Replicate specimens were prepared with 1.0% lime and tested for the purpose of accelerating cementation or modifying clay contained in the aggregate to simulate observed increases in field based strength performance. Limerock Bearing Ratio, cohesion and angle of internal friction, triaxial resilient modulus, and gyratory shear tests were performed and evaluated. Based on the data accumulated with this study, carbonate content does not necessarily relate to higher strength gain. This does not mean that high carbonate content materials cannot achieve cementation and greater strength, rather that the series of tests included in this report were unable to quantify and/or accurately reproduce the effect of cementation within a curing time of 60 or less days. However, it does suggest that use of a higher layer coefficient for high carbonate aggregates strictly based on percent carbonates may not be appropriate.

Abstract: installation of the :MR.F. Ash-amended bituminous was to be used in the base course and binder course of the pavement profile. Significant environmental and structural testing was perfo lll1ed prior to construction. Environmental and structural testing was also perfo lll1ed simultaneously with the construction process. Environmental testing comp leted in 2000 included: analysis of stack emissions from the bituminous plant, evaluation of breathing zone particulates at the bituminous plant, and analysis of surface water runoff from the ash­ amended bituminous. Structural testing included trial mix design parameters. The road was also instrumented to collect water that may infiltrate through the ash-amended bituminous. Environmental testing to be completed in 2001 includes: evaluation of impacts to soils adjacent to the roadway and evaluation of infiltration water collected in the under-pavement collectors. Post-construction pavement testing is also to be completed in 2001. This paper presents the initial results of environmental and

Abstract: In August 1997, the loading test with a concrete pavement was carried out at the Public Works Research Institute (PWRI). From this experimental result, the permanent deformation of the base course surface by cyclic loading was confirmed. In this study, the estimation method of permanent deformation of base course surface was suggested based on the theory of elasticity and the repeated tri-axial compression test result of granular base course material and subgrade material. And then, the analytical result was compared with the experimental result. As the result of comparison, the estimated value and the measured value agreed well, and the adequacy of this estimation method was confirmed in this paper.

Abstract: This paper reports the findings of a project on evaluating the performance of recycled concrete aggregate (RCA) for use as a base material under hot mix asphalt pavements and as an aggregate in portland cement concrete pavements. Nine design sections involving hot mix asphalt and portland cement concrete pavements were constructed at the University of Central Florida's Circular Accelerated Test Track to evaluate the performance of the pavement sections made with RCA under actual dual-wheel loading. Laboratory tests performed on concrete specimens made of different percentages of RCA and virgin aggregate (VA) showed that the higher the percentage of RCA material, the lower the compressive, flexural, and tensile strengths. Despite having lower compressive strength than VA concrete, 100% RCA concrete had a compressive strength of 35 MPa (5,070 psi), which was well above the target strength of 25 MPa (3,630 psi). Trenching of the flexible pavement test sections and petrographic examination of the hardened concrete showed that after a simulated life expectancy of 3.04 years for asphalt sections and 4.2 years for concrete sections, RCA has performed at least equally to VA.