Showing papers on "Asphalt published in 1996"

Tar sands extraction process

Abstract: A hot water extraction process for extracting bitumen from tar sands is taught wherein the tar sand is conditioned using an alkali metal bicarbonate, an alkali metal carbonate and a liquid hydrocarbon. A source of calcium and/or magnesium ions can also be added. The conditioning step replaces the step of conditioning using caustic soda previously used in tar sand extraction. The use of the alkali metal bicarbonate and carbonate and a liquid hydrocarbon substantially eliminates the production of sludge in tar sand extraction and maintains or improves bitumen recovery. The process allows for hot conditioning solution to be recycled to the process by use of a recycle storage tank.

Hot mix asphalt materials, mixture design and construction. second edition

Abstract: This textbook can be used for teaching undergraduate and graduate courses on Hot Mix Asphalt (HMA). The book should also prove useful to the practicing engineer. The second edition, in addition to the review and modification of each chapter to bring it up to date with the latest technology, includes information on Stone Matrix Asphalt, Superpave performance grade (PG) asphalt binders, Superpave mix design, and asphalt modifiers. The contents are organized in the following chapters: (1) Introduction; (2) Asphalt Refining, Uses, and Properties; (3) Aggregates; (4) Hot Mix Asphalt Mixture Design Methodology; (5) Characterization of Asphalt Mixtures; (6) Equipment and Construction; (7) Special Mixtures, Recycling, and Additives; (8) Performance/Distress of HMA; and (9) Maintenance, Rehabilitation, and Reconstruction of HMA. An index is provided.

Effect of Asphalt Film Thickness on Short- and Long-Term Aging of Asphalt Paving Mixtures

Abstract: It is generally believed that an asphalt paving mixture should have an adequate asphalt film thickness around the aggregate particles to ensure reasonable durability (resistance to aging) of the mixture. The minimum asphalt film thickness generally recommended ranges from 6 to 8 μm. However, no significant background research data are available in the literature to support these recommended minimum asphalt film thicknesses. Some states specify minimum asphalt film thickness for mix designs. This study was undertaken to quantify the relationship between various asphalt film thicknesses and the aging characteristics of the asphalt paving mix so that an optimum film thickness desirable for satisfactory mix durability could be established. Mixes prepared with asphalt binder film thickness ranging from about 4 to 13 μm were subjected to accelerated aging using Strategic Highway Research Program (SHRP) procedures to simulate both short- and long-term aging. Both the aggregate (RD) and the asphalt cement (AAM-1)...

Development of rubber and asphalt binders by depolymerization and devulcanization of scrap tires in asphalt

Abstract: Scrap tires in three forms—crumb rubber 60 minus mesh, crumb rubber 20 minus mesh, and buffed rubber—were subjected to depolymerization and devulcanization by applying heat, high shear, and a combination of both. Different reaction temperatures and times of reaction were applied. The reaction products were submitted to the testing of rheological properties by measurement of creep and recovery, viscosity, and some conventional tests. The amount of unreacted rubber and tendency to separation during the hot storage were also tested. Selected materials were evaluated according to SHRP specification and by the gel permeation chromatography. The results from the SHRP testing indicate that these materials are less temperature sensitive than conventional asphalts prepared from the same crude oil as the base asphalt. These materials were prepared in larger quantities and are being tested for their performance in paving mixes.

Effects of asphalt content and air void content on mix fatigue and stiffness

Abstract: The primary objective of most procedures for asphalt concrete mix design is to find an asphalt content that minimizes the possibility of stability failure while providing adequate fatigue and other durability characteristics. To date, the consequences of asphalt content selection and construction compaction on fatigue performance and flexural stiffness have not been thoroughly investigated and documented with experimental data. The results of laboratory-controlled strain flexural beam testing, (i.e., fatigue life and flexural stiffness) for one aggregate and asphalt cement combination, five asphalt contents, and three air void contents are presented. The results clearly indicate the benefits of a lower air void content on both fatigue life and initial stiffness. Increased asphalt content was found to increase fatigue life and reduce stiffness. Alternative models for predicting fatigue life and initial stiffness using asphalt content, air void content, voids filled with bitumen, and the volume concentrations of asphalt and aggregate were evaluated. Elastic-layer theory was used to simulate the effects of air void content and asphalt content on the fatigue life of several example overlays using the models for stiffness and fatigue life from the laboratory testing. The simulations indicated an increase in predicted pavement fatigue life for lower air void contents and higher asphalt contents. Example simulations of the effects of increased asphalt content and decreased air void content at the bottom of thick overlays indicated a marked increase in predicted fatigue life. It was also concluded that stiffness should not be included in regression for fatigue life models for mix design unless there is a clear understanding of the effects of other variables in the model that correlate with both fatigue life and stiffness.

Environmental adaption of concrete: Environmental impact of concrete and asphalt pavements

Abstract: The object of the st udy has been to assess the environmen tal impact of concrete and asphalt road pavements. The assessment is based on the estimation of service life of road pavements and the envi ronmental burdens caused by their produ ction, use and disposal. Also taken into account is the influence of the pav ement on fuel consumption by traffic, noise, lighting requirements and dust formation. The functional unit studied is 1 km of pavement of the Tampere motor way assuming passage of 20 000 vehicles per day. The time scale is 50 years. On the basis of the results the environmental burdens of concr ete pavements significantly depend on the cement content of concrete. Consequently, the environmental profile of concrete pavement also significantly depends on the depth of the concrete layer. The envi ronmental burdens from paving and maintenance are rather low compared with those caused by produ ction processes of high-strength concrete. On the contra ry, the signif icance of lighting during 50 years is high. The dust emissions of the concrete pavement studied are mainly i nduced by abrasion and salting of the pavement. The significance of pavement materials, pavi ng, maintenance and lighting is low compared with the environmental burdens caused by traffic during 50 years. With respect to the effect of material properties of pavement on fuel consumpti on, it was assumed that the influence on fuel consumption related to the s urface texture is the same for both pavements, the difference in E-m odulus does not influence the fuel consumption for the heavy veh icles and that the measured differences in rolling resistance have no influence on fuel consumption. However, any difference in fuel consumption of traffic due to pavement materials would significantly affect the result. For example, a roughly 0.1 0.5% decrease in fuel consumption of traffic due properties of concrete pavement would bring "savings" in emissions of the same order of magnitude than those from all the other parts of the life cycle of concrete roads. On the basis of the results the environmental burdens of asph alt significantly depend on the bitumen content of asphalt. In additi on, the manuf acture of asphalt including

Nature and fate of oil sands fine tailings

Abstract: The chemical and physical properties of clay suspensions produced during oil production front oil sands are described. With a composition of approximately 70 wt% water (with some unrecovered bitumen) and 30 wt% solids (>90% less than 44 {mu}m in size), these clay suspensions consolidate very slowly. Clay aggregate or floc morphology has been shown to be a function of the water chemistry and can be manipulated to produce a tailings suspension that is easier to consolidate and dewater. Commercial oil sands processing has been going on in northeastern Alberta since 1967, and in that time approximately 250 million m of this difficult to dewater clay suspension has been produced. The reclamation options for this material (mature fine tailings) on a commercial scale are also outlined. 84 refs., 36 figs., 3 tabs.

Mechanistic evaluation of fly ash asphalt concrete mixtures

Abstract: This investigation was carried out: (1) to study the effect of fly ash on the mechanical properties of asphalt mixtures; and (2) to evaluate the effect of using fly ash in mitigating pavement distress and improving performance of asphalt concrete pavement. In this study, four groups of specimens with various fly ash contents were studied. The mechanical properties (resilient modulus, creep, permanent deformation, and fatigue) were determined at three different temperatures. Moisture damage tests were carried out. The VESYS model was used to predict pavement performance. Results from this study indicated that fly ash can be used as a mineral filler to improve resilient modulus characteristics and stripping resistance. The addition of fly ash did not significantly reduce field performance of asphalt concrete mix in terms of rut depth and present serviceability index but increase the amount of surface cracking in the pavement.

Variability analysis of hot-mix asphalt concrete containing high percentage of reclaimed asphalt pavement

Abstract: A research project was undertaken to evaluate the production and construction variability of hot-mix asphalt concrete (HMAC) containing large quantities of recycled asphalt pavement (RAP) material. Four construction projects were selected. Two of the projects used 35 percent RAP material, while the other two used 40 and 50 percent RAP, respectively. The projects differed in size with total hot-mix ranging from 12,000 to 30,000 tons. In all cases, dedicated RAP stockpiles were used. A series of tests were performed at both the hot-mix plant laboratory and the University of Texas (UT) asphalt laboratory. The tests at the plant included extraction, gradation, and asphalt content using nuclear gauge. A number of specimens were also compacted and shipped to the Texas Department of Transportation Materials and Tests Division for Hveem stability testing. Asphalt recovery, penetration, and viscosity tests for both HMAC and RAP were conducted at the UT laboratory. Each day, four sublots were sampled. The results o...

Fiber-modified asphalt concrete characteristics, applications and behavior (with discussion)

Abstract: Among the various techniques available for improving the properties of asphalt wearing courses, the addition of fibers has been taking on an increasingly prominent role. Today, the magnitude of what has been produced using these techniques along with the available information collected by monitoring in place behavior has enabled developing a thorough and significant assessment.

Aging and low-temperature cracking of asphalt concrete mixture

Abstract: Low-temperature cracking in asphalt concrete (AC) pavement is influenced by several factors broadly categorized as material, environmental, and pavement-structure geometry. Among the environmental ...

Roofing shingles and toner in asphalt pavements

Abstract: Existing information on the use of roofing waste in hot mix asphalt (HMA) was obtained from reviews of published and unpublished literature and interviews of cognizant individuals. Ground waste roofing is available from at least 3 locations in Texas. Laboratory testing was performed on HMA containing roofing manufacturing waste (new roofing) and consumer (tear off) roofing waste. Two types of HMA were modified with ground roofing and tested in the laboratory: dense-graded and coarse matrix-high binder (CMHB) surface mixtures. Roofing waste was added to HMA at 5% and 10% and the engineering properties of the resulting HMA mixtures were compared to untreated mixtures. Laboratory tests consisted of Hveem stability, indirect tension, resilient modulus at several temperatures, moisture susceptibility, Texas Department of Transportation static creep, air void content, and voids in the mineral aggregate (VMA). The findings indicate that roofing waste is a viable waste stream that has utility in HMA. It should be possible to incorporate 5% or less roofing waste into typical HMA paving mixtures and have a product that will meet the standard quality control specifications. Because of the relatively higher VMA and asphalt film thickness, a CMHB mixture may be more capable of accommodating roofing waste than a dense graded mixture. Standard procedures for mixture design and quality control appear satisfactory for HMA containing roofing waste. Materials specifications and construction guidelines for using roofing waste in HMA paving mixtures were developed. The use of waste toner (dry ink) in asphalt is briefly mentioned on pages 11-12.

The effect of asphalt composition on the formation of asphaltenes and their contribution to asphalt viscosity

Abstract: Interactions among asphalt components have significant effects on the performance of asphalt binder To understand those interactions, four asphalts, SHRP AAA-I, AAD-I, AAF-I, and AAG-I, were fractionated into three generic fractions according to Corbett's procedure and reblended into asphaltenes/aromatics/saturates ternary mixtures in various ratios Mixtures were oxidatively aged with atmospheric air at temperatures of 877, 933, and 988°C for 5 to 33 days The changes in chemical composition and physical properties were monitored using fourier transform infrared spectroscopy (FT-IR) and dynamic mechanical rheometry The formation of asphaltenes is a major factor in the hardening of asphalt with aging The data collected in this study indicate that the saturate content in the maltene phase has a profound impact on the contribution that asphaltenes have on the viscosity of aged asphalt The data also suggest that the aromatics fraction is solely responsible for the formation of asphaltenes as a

Evaluation of Voids in the Mineral Aggregate for HMA Paving Mixtures

Abstract: This study was undertaken to (a) reexamine the rationale behind the minimum voids in the mineral aggregate (VMA) values currently being used, and (b) quantify the relationship between various asphalt film thicknesses and the aging characteristics of the hot mix asphalt (HMA) mix, so that an optimum film thickness desirable for satisfactory mix durability could be established The optimum film thickness could then be used to establish VMA requirements Mixes prepared with asphalt binder film thickness ranging from about 4 to 13 microns were subjected to accelerated aging using Strategic Highway Research Program (SHRP) procedures to simulate both short and long term aging Both the aggregate (RD) and the asphalt cement (AAM-1) used in this study were obtained from the SHRP Materials Reference Library The aged, compacted mix was tested for tensile strength, tensile strain at failure and resilient modulus The aged asphalt cement was recovered and tested for penetration, viscosity, complex between various asphalt film thicknesses and the aging characteristics of the HMA mix, so that an optimum film thickness desirable for satisfactory mix durability could be established The optimum film thickness could then be used to establish modulus and phase angle Aging indices were obtained from these tests, and the relationship between film thickness and the aged mix/aged asphalt cement properties were determined using regression analysis For the particular aggregate/asphalt cement combination used in this study, it was found that accelerated aging would occur if the asphalt binder film thickness was less than 9 - 10 microns in an HMA mixture compacted to 8% air void content The minimum VMA required to accommodate this optimum asphalt film thickness and 4% air void content was also calculated

A prediction methodology for the dynamic modulus of in-place aged asphalt mixtures (with discussion)

Abstract: By incorporating the results of recent studies on the field-aged viscosity of conventional asphalt cements into the revised model, a new predictive methodology is presented that allows for the evaluation of dynamic modulus of mixtures exhibiting any degree of binder aging. A sensitivity study showed the reasonable performance of the predictive methodology for evaluating the dynamic modulus of in-place aged asphalt mix layers of any thickness at different environmental conditions.

Hot Mix Asphalt Rubber Applications in Virginia

Abstract: Four test sections using asphalt rubber hot mix were placed in Virginia from 1990 to 1993. These installations were to familiarize contractors and Virginia Department of Transportation personnel with the construction process and compare the performance of different types of mixes containing ground tire rubber. The MacDonald and Rouse wet processes were used successfully. Dense graded surface mixes, a gap-graded surface mix, and a base mix were manufactured. A stress-absorbing membrane interlayer was also used on one project in an attempt to deter or eliminate various types of cracking. The asphalt rubber mixes have performed as well as the conventional mixes over the short term. More evaluation time is needed to determine if long-term performance of the asphalt rubber mixes is superior to conventional mixes. The asphalt rubber mixes cost 64 to 102 percent more than conventional mixes. This cost would probably decrease if substantial quantities were placed.

Hot-Mix Asphalt Segregation: Measurement and Effects

Abstract: Segregation of hot-mix asphalt (HMA) has been associated with poor pavement performance. As a result, a nondestructive test method that could quickly identify segregation and be easily included in field testing would be useful to agencies. A study was conducted of four HMA mixtures with five levels of segregation. All levels of segregation for each mix were characterized by gradation, asphalt content, density, and air voids. The segregated mixes were tested with an air permeameter and a nuclear moisture/density gauge. In addition, thermal imaging equipment was field-tested on an existing pavement, at a hot-mix asphalt plant, and at a paving project to determine its overall effectiveness in detecting segregation. Preliminary wheel-tracking tests with the PURWheel tracking device were used to evaluate segregated mixture performance.

Investigation of stone matrix asphalt mortars

Abstract: The use of stone matrix asphalt (SMA) has continued to increase in the United States since its initial application in 1991. This preference for SMA has been linked to its ability to withstand heavy traffic without rutting. The antirutting capability of SMA is normally accredited to the presence of a stone-on-stone aggregate skeleton in the mixture. However, the mortar in an SMA mixture is also important. The mortar is composed of fine aggregate, filler, asphalt cement, and a stabilizing additive. Work to characterize SMA mortars is detailed. For testing purposes, the mortar was broken into separate phases, total mortar and fine mortar. The fine mortar was tested using the Superior Performing Asphalt Pavements system (Superpave) binder tests. The total mortar was tested using the bending beam rheometer, resilient modulus, indirect tensile test, and Brookfield viscometer. The results indicate that the fine and total mortars are closely related. In addition, it was determined that at least some of the Superpave tests can be used to characterize SMA mortars. It is recommended that further testing be completed and specification criteria be established for the mortar.

Initial CAL/APT Program: Site Information, Test Pavement Construction, Pavement Materials Characterizations, Initial CAL/APT Test Results, and Performance Estimates

Abstract: Author(s): Harvey, John; du Plessis, Louw; Long, Fenella; Shatnawi, Shakir; Scheffy, Clark; Tsai, Bor-Wen; Guada, Irwin; Hung, David; Coetzee, Nick; Riemer, Michael; Monismith, C L. | Abstract: This report, an interim report covering the work completed on the CAL/APT Project during the period June 1994 through July 1995 presents the results of laboratory tests on the pavement materials, and evaluates a number of different pavement-materialscharacterization and pavement-performance-prediction procedures. This information as well as additional data to be acquired subsequently will be used for complete analyses of response of the first two pavement sections (four test sections) to accelerated loading with the Heavy Vehicle Simulator (HVS). Experience gained from test-section construction suggests that the following guidelines might be of use for the construction of highway pavements by Caltrans: Reduce the length of mix that can be laid down prior to beginning compaction, Increase the minimum compaction thickness, especially for placement over cold existing surfaces and during night construction, Require simultaneous construction of adjoining lanes where feasible and, Install lateral confinement such as curbs or other similar devices prior to mix compaction where possible and economically feasible. Extensive analyses of the fatigue performance and resulting influences on subgrade strain of both the drained (ATPB) and undrained sections have been conducted. These analyses assumed the pavement to be represented as a multi-layer elastic solid and utilized a series of models for both fatigue and rutting. The predicted fatigue life is larger for the drained pavement than for the undrained pavement. This is due primarily to the increased stiffness of the ATPB compared to that of the aggregate base it replaces. However, the relative performance of drained and undrained pavements may be different under field conditions especially if severe moisture conditions reduce the effectiveness of the asphalt treatment. An increase in load from 40 to 100 kN (9,000 to 22,500 lb) causes a much larger reduction in the subgrade rutting life than predicted for the fatigue life.

Consideration of Hot Mix Asphalt Thermal Properties During Compaction

Abstract: A computer program was developed at the University of Minnesota to predict asphalt concrete cooling times for road construction during adverse weather conditions. Cooling models require extensive experimental data on the thermal properties of hot-mix paving materials. A sensitivity analysis was performed to determine which thermal properties affect pavement cooling times significantly. The results indicated that more information on asphalt thermal conductivity and thermal diffusivity is required. Two suitable test methods for determining these properties at typical paving temperatures and densities were developed, and preliminary results for dense-graded and stone-matrix asphalt (SMA) mixes agreed well with values reported in the literature.

Oil coagulant products and methods of use therefor

Abstract: Oil coagulant compositions, and methods of using such compositions to coagulate the oil that has been spilled on water are prepared from a thermal reaction utilizing an oil component selected from the group consisting of glycrides, fatty acids, alkenes and alkynes, and a copolymer component. Representative polymers include, for example, isobutyl methacrylate polymers, and representative oil components include, for example, glycerides such as those derived from a drying oil such as linseed oil. The composition of the present invention floats on the water surface and coagulates oil independent of both agitation and temperature, and can be used in both salt and fresh water. After the coagulant has coagulated the spilled oil, the floating coagulated oil can be readily removed from the water by mechanical means such that at least 99.9 % of the oil is removed from the water and only a faint trace of oil remains in the water. An alternate way of using the composition is to incorporate it into a porous substrate, which substrate is then applied to the spilled oil. Preferably, the porous substrate is a floatable material, enabling the product to keep afloat Group 5 oils or asphalt.

Effect of Segregation on Fatigue Performance of Asphalt Paving Mixtures

Abstract: The main objective of this research was to investigate the effect of segregation on fatigue performance of asphalt paving mixtures. Segregation in asphalt concrete pavements occurs when coarse material is concentrated in some areas of the pavement and fine materials in others. Segregation has been one problem that has resulted in poor performance in many pavements. Materials used in the study included gravel, natural sand, and an AC-20 asphalt cement. Aggregates were selected to meet the Indiana Department of Transportation specification for a No. 8 binder with a maximum aggregate size of 1 in. (25 mm). To simulate various levels of coarse and fine segregation, four artificially segregated mixtures were prepared in addition to the control asphalt mixture. Slabs were compacted for the five mixtures using the Purdue linear compactor. These slabs were cut into beams that were used to test for the fatigue properties of the five segregated asphalt concrete mixtures. Limits of fatigue were examined when flexural stiffness was one-third and one-half of the initial stiffness at 200 load applications. Results of the investigation indicated that the fatigue life of segregated asphalt concrete mixtures was significantly affected.

Consumable asphalt containers and method of reducing fumes from a kettle of molten asphalt

Abstract: A consumable container is molded from a composition comprising 40 to 90 weight % of an asphalt and 10 to 60 weight % of a polymer material, which advantageously can include a first polymer such as PP that imparts heat resistance and a second polymer such as EVA that imparts toughness and impact resistance. This molded asphalt/polymer material preferably has an unnotched Izod impact strength of at least 2 joules. The container is consumable - it can be melted along with roofing asphalt held in the container without adversely affecting the properties of the asphalt and without requiring undue mixing. The composition also can be used to reduce fumes normally emitted from a kettle of molten asphalt, e.g., as measured by a reduction of the visual opacity of the fumes by at least 25 %, a reduction of the hydrocarbon emissions of the fumes by at least 20 %, or a reduction of the total suspended particulates emissions of the fumes by at least 15 %. The container may be used, e.g., to hold roofing or paving asphalt or a recyclable petroleum-derived material, such as used motor oil. In one embodiment, the container composition may include one or more ingredients to improve the quality of paving-grade asphalt.

Polymer enhanced asphalt

Abstract: The present invention relates to an asphalt composition prepared from bitumen (asphalt), linear and non-linear copolymers of styrene and butadiene, and elemental sulphur. The present invention compositions are useful for industrial applications, such as hot mix asphalts used with aggregates for road paving, and repair.

Asphalt paver with remixing conveyor system

Abstract: An improved asphalt paver having a remixing conveyor system that is adapted to substantially or entirely eliminating segregation in hot mix asphalt material delivered to the asphalt paver. The remixing conveying system includes at least one pair of parallelly spaced, oppositely pitched, counter-rotating hydraulically driven feed augers having remixing blades that intermittently displace portions of the hot mix asphalt material generally transversely to the direction that the feed augers convey the hot mix asphalt material from a hopper of the asphalt paver to spreading augers near the rear of the machine. Elongate members over the feed augers provide protection from impact forces and overloading and enhancing lateral extraction of hot mix asphalt material from the hopper. An optional feed screen provides flow control of the hot mix asphalt material in the hopper. A kit is provided for converting existing asphalt paving machines to have desegregating capability. A method is provided for substantially or entirely eliminating segregation in hot mix asphalt material delivered to an asphalt paver.

Quantitative analysis of aggregate based on hough transform

Abstract: Deformations in asphalt pavements continue to create problems for pavement agencies. One factor that has been identified as contributing to the potential of asphalt concrete to deform is the angularity of particles in the asphalt and aggregate mix. A new video-based method of measuring angularity based on the properties of the Hough transform, a powerful mathematical tool commonly used to detect long straight lines in video images, is presented. The method detects and measures the length of any straight edge in a two-dimensional image of a particle that is then used to quantify the particle angularity. The technique resolved three different test patterns independent of size and angle of rotation. Seven sands were analyzed with the method. The results were consistent with the known qualities of the sands. Although still limited as an engineering application, shape analysis of aggregate by video imaging has the potential to provide insight into the mechanisms of pavement deformation and may provide a basis for specifications or guidelines for the use of manufactured and natural sands in asphalt concrete.

Development of Solid Properties and Thermochemistry of Asphalt Binders in the 25−65 °C Temperature Range

Abstract: The effects of temperature and composition on the rheology of asphalt binders is of practical importance. The asphalt binder should be solid enough at higher temperatures to prevent the asphalt from flowing, and it should be fluid enough at lower temperatures to prevent the asphalt from cracking. In this work it is shown that there is a transition from a higher temperature Newtonian fluid phase to a lower temperature viscoelastic fluid phase at 45 °C in the vacuum residue of Arabian medium/heavy crude oil that is associated with the heptane insoluble asphaltenes. The asphaltene content must be greater than 15 wt % for this transition to occur. Solid properties increase by a factor of 3 beyond the phase boundary. The low-frequency dynamic viscosity increases by a factor of 5. The transition is first order with an enthalpy change on heating of 0.5 cal/g. The position of the phase boundary in a temperature−composition diagram can be predicted by calculating points at which the free volume of the asphaltenic ...

Modified Cold In-Place Asphalt Recycling

Abstract: Cold in-place asphalt recycling has been shown to be a technically sound, cost-effective, environmentally friendly method of strengthening and maintaining a wide range of deteriorating asphalt pavements. The overall process combines testing and mix design procedures, milling, processing and mixing units with microprocessor control of emulsion addition, compaction, placement of a wearing surface and quality assurance testing. In laboratory work and a number of Ontario projects during the past 3 years it has been shown that modification of the cold in-place process to incorporate new aggregate results in an improved recycled binder course with closer voids and stability control. These findings address observed conventional cold in-place asphalt recycling problems such as high residual asphalt cement content (flushing), fine mix (high percent passing 4.75 mm and 75 μm), rutting (low initial stability with emulsion system), and adequacy of in-place material thickness. Structural equivalency factors for cold i...