Download or read book Improving the Properties of Reclaimed Asphalt Pavement for Roadway Base Applications Through Blending and Chemical Stabilization written by Albert Marshall Bleakley and published by . This book was released on 2012 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reclaimed Asphalt Pavement (RAP) is produced by milling during resurfacing operations. Finding innovative ways to incorporate RAP into highway base course applications will provide both environmental and economic benefits by allowing in situ recycling of material for projects such as widening or shoulder addition. RAP is a well-drained granular material which is already on site, however 100% RAP is low bearing strength and creeps under load. The objective of this research was to develop methods to improve RAP's strength while reducing creep to an acceptable level through blending with high quality crushed limestone aggregate and/or by chemical stabilization with asphalt emulsion, Portland cement, or lime. RAP/aggregate blends with and without chemical stabilization were compacted by modified Proctor, Marshall, or gyratory methods, cured, and tested for strength and creep. Strength tests included limerock bearing ratio (LBR), a variant of the CBR test, unconfined compression, Marshall compression, and indirect tensile tests. Strength specimens were tested dry and soaked to evaluate retained strength. One dimensional creep testing was performed using seven day oedometer tests. RAP/aggregate blends have the potential to be used successfully as a base course material. Blends of RAP with 50% limerock base material attained a soaked LBR strength of 100 and acceptable levels of creep with the addition of 1% of either asphalt emulsion or cement. Blends of RAP with 75% or more limerock attained a soaked LBR close to 100 and low levels of creep without any chemical stabilizer. In general adding RAP to limerock blends increased the soaked retained strength and improved permeability compared to 100% limerock. Gyratory compaction achieved higher densities than modified Proctor or Marshall compaction and improved RAP's strength by a factor of two to three compared to modified Proctor compaction at the same density but had less effect on creep. Field testing is required to determine whether it is feasible to reproduce the gyratory compaction results on an actual construction site. Significant variability was noted between results with different blends, compaction methods, and stabilizing agents. Site specific performance testing should be conducted to establish the viability of blending RAP into a base or subbase.

Download or read book Improving the Properties of Reclaimed Asphalt Pavement for Roadway Base Applications written by and published by . This book was released on 2012 with total page 561 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this study was to improve Reclaimed Asphalt Pavement (RAP) strength in base course applications while reducing creep to an acceptable level using compaction techniques, fractionating, blending with high quality base course aggregate, and/or by chemical stabilization with asphalt emulsion, Portland cement, or lime. RAP/limerock blends with and without chemical stabilization were compacted by modified Proctor, Marshall, or gyratory methods, cured, and tested for strength and creep. Strength tests included limerock bearing ratio (LBR), unconfined compression, Marshall compression, and indirect tensile tests. Strength specimens were tested dry and soaked to evaluate retained strength. Seven-day one-dimensional creep testing was performed. Gyratory compaction produced higher densities than modified Proctor or Marshall compaction. At the same density, gyratory compaction improved RAP strength by a factor of two to three over modified Proctor but had less effect on creep. Modified Proctor moisture-density plots followed an S-shape without a clear optimum; modified Proctor may not be the best method to predict RAP compaction behavior. Fractionating RAP did not improve strength or creep unless RAP was remixed to match a maximum density curve. Fractionating did not produce acceptable LBRs or creep. RAP blended with limerock, cemented coquina, or reclaimed concrete aggregates showed improved LBR and creep performance. RAP/aggregate blends have the potential to be used as Florida base course. As the amount of aggregate blended with RAP increased, LBR increased and creep decreased. Creep behavior of blends with 75 percent aggregate was similar to 100 percent aggregate. Unstabilized blends with 50 percent aggregate did not produce LBR values over 100. Blends of 50 percent RAP/50 percent limerock stabilized with 1 percent of either asphalt emulsion or cement attained soaked LBRs over 100 and acceptable creep. Blends of RAP with 75 percent limerock attained soaked LBRs close to 100 and low creep without any chemical stabilizer. Adding RAP to limerock blends generally increased the soaked retained strength and improved permeability compared to 100 percent limerock.

Download or read book Improving the Properties of RAP for Base Course Application by Blending RAP with A 3 Soil and Chemical Stabilization Using Asphalt Emulsion and Portland Cement written by Rasha Riadh Salem AL-Obaydi and published by . This book was released on 2014 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this research was to evaluate the effects of adding a combination of two stabilizing agents to blends of reclaimed asphalt pavement (RAP) with A-3 soil for use in a pavement base course. The California Bearing Ratio (CBR) and Marshall Stability tests were conducted on the blends to evaluate strength. Marshall flow and one-dimensional creep tests were performed to evaluate deformation. The test procedure in this study included one RAP/soil blend (75% RAP with 25% A-3 soil by weight) with five cement contents (0.0, 0.5, 1.0, 1.5, and 2.0% of type IIII Portland cement) and five asphalt emulsion contents (0.0, 0.5, 1.0, 1.5, and 2.0% of asphalt emulsion) added as chemical stabilizing agents. 100% pure RAP and 100% pure A-3 soil were also tested for CBR, Marshall Compression and Creep in order to set as a baseline to evaluate the improvement when the stabilizing agents were added.Results from this study showed that the unstabilized blends did improve in the strength compared to RAP or A-3 soil alone, but the blends did not meet the strength requirement for a base course material. Several combinations of chemical stabilizing agents increased the soaked CBR strength of the stabilized blends to between 76 and 78, but did not meet the standard of 80. Increasing cement content led to a linear increase in strength and reduced creep while increasing asphalt emulsion showed peak strength and creep reduction at between 1% and1.5% followed by a decrease in strength and increased creep at higher emulsion content. A strong linear positive correlation was found between the CBR and Marshall stability while a very weak positive correlation was observed between creep strain rate (CSR) and Marshall flow.

Download or read book Recent Trends in Civil Engineering written by K. K. Pathak and published by Springer Nature. This book was released on 2020-09-27 with total page 1081 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the selected peer-reviewed proceedings of the International Conference on Recent Trends and Innovations in Civil Engineering (ICRTICE 2019). The volume focuses on latest research and advances in the field of civil engineering and materials science such as design and development of new environmental materials, performance testing and verification of smart materials, performance analysis and simulation of steel structures, design and performance optimization of concrete structures, and building materials analysis. The book also covers studies in geotechnical engineering, hydraulic engineering, road and bridge engineering, building services design, engineering management, water resource engineering and renewable energy. The contents of this book will be useful for students, researchers and professionals working in civil engineering.

Download or read book Feasibility of Reclaimed Asphalt Pavement RAP Use As Road Base and Subbase Material written by Edward J. Hoppe and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study was to investigate the current state of the practice with regard to the use of reclaimed asphalt pavement (RAP) material for road base and subbase applications and the potential for such use by the Virginia Department of Transportation (VDOT). To achieve the objectives of the study, a comprehensive review of the literature was conducted and the current state of the practice by other state departments of transportation was analyzed. The results indicated that the use of RAP in road base and subbase materials is viable and has been implemented by a number of transportation agencies. There seemed to be no major environmental concerns associated with using unbound RAP without chemical stabilization agents. Numerous sources of RAP are available in Virginia. Based on practices adopted by other state transportation agencies, the study recommends that VDOT allow the use of RAP in a road base material on highway construction projects. The study further recommends that the allowable percentage of RAP in a blend be phased in gradually to allow VDOT to gain familiarity with the materials and processes involved. Compaction testing could be performed with current methods while alternative procedures were analyzed for suitability. Once a standard specification has been developed, sites for long-term field studies will be identified to implement further the recommendations stemming from this study. There is a potential for significant economic benefits if RAP is used in base and subbase applications. Approximately 30% in material cost savings could be realized with a 50/50 blend of RAP and virgin aggregate. In addition, this application would likely result in a substantial reduction in the amount of RAP material currently stockpiled in Virginia.

Download or read book Full Depth Reclamation Mix Design for Portland Cement and Asphalt Emulsion Stabilized Blends written by Blnd Jasim Othman and published by . This book was released on 2014 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Full depth reclamation (FDR) is apavement repair method that uses in-place milling and recycling of existing asphalt to rehabilitate roads. The FDR process includes milling the existing pavement, blending the crushed pavement with underlying aggregate materials and chemical stabilizing agents to create a new stabilized base course. Usually a thin wearing course in placed on top of the stabilized base. The purpose of this research was to investigate the effects of a combination stabilizing agents added to different blends of reclaimed asphalt pavement (RAP) and high quality limerock aggregate base material on the strength and creep of blended materials. Strength and deformation of the blends were evaluated using the California Bearing Ratio (CBR), modified Marshall, and one-dimensional oedometer creep tests. Blends of RAP and limerock base were blended with Portland cements and asphalt emulsion in varying proportions. Blends in this study were prepared at 0%, 25%, 50%, 75%, and 100% RAP by weight. Specimen mixtures consisted of25, 50, and 75 percent RAP stabilized with 0.0, 0.5, 1.0, 1.5, and 2.0 percent Type I/Il Portland cement and 0,0, 0.5, .1.0, 1.5, and 2.0 percent Cationic Asphalt Emulsion (CSS-1H) by weight. The 0% RAP samples were controls of pure limerock aggregate; 100% RAP samples were controls of pure RAP. The objective of these projects was to obtain baseline data and to evaluate stabilizing, curing and testing techniques for chemically stabilized specimens. Increasing RAP content decreased the strength and increased the deflection of blends. For blends without chemical stabilization, only the 25% RAP/75% Iimerock blend achieved an average soaked CBR over 80. For chemically stabilized blends, increasing cement content always increased strength and decreased deflection. Asphalt emulsion stabilized blends showed peak strength (CBR and Marshall Stability) at 1% and 1.5% emulsion for 50% and 25% RAP blends. A very good correlation was found between soaked CBR and soaked Marshall stability with an average R2 of 0.73.

Download or read book Improved Mix Design Evaluation and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content written by Randy Clark West and published by Transportation Research Board. This book was released on 2013 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Report 752: Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content describes proposed revisions to the American Association of State Highway and Transportation Officials (AASHTO) R 35, Superpave Volumetric Design for Hot Mix Asphalt, and AASHTO M 323, Superpave Volumetric Mix Design, to accommodate the design of asphalt mixtures with high reclaimed asphalt pavement contents.

Download or read book Improving Durability of Asphalt Mixes Produced with Reclaimed Asphalt Pavement Rap by Enhancing Binder Blending written by Hawraa Kadhim and published by . This book was released on 2019 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reclaimed Asphalt Pavement (RAP) has been favoured over virgin materials in the light of the unstable cost of virgin asphalt binders, shortage of quality aggregates, and compelling need to preserve the environment and natural resources. Mixes containing up to 20% RAP are commonly considered to have similar behaviour to virgin mixes. However, during the production process of HMA with RAP, the blending between aged and virgin binders would be partial, which would create heterogeneity in distribution of the aged recycled binder and the soft virgin binder in the HMA-RAP mixes. Hence, it is important to control the blending process between old and new binders to obtain more homogenous mix. Therefore, the main objectives of this research are to examine the kinematics of blending of aged and virgin binders by considering the time-temperature effect during mixing and silo-storage, and assess the thermo-mechanical behaviour of Hot Mix Asphalt (HMA) containing RAP at different blending states. The asphalt mixes used in this research were produced and collected at two plants (Plant 1) and (Plant 2) located in Ontario, Canada. Two Marshall mixes were produced and collected from Plant 1 including a surface course HL-3 containing 15 percent RAP and a base course HL-8 containing 30 percent RAP. These mixes were labelled as 1HL-3 and 1HL-8 respectively. In addition, two Marshall mixes were produced and collected from Plant 2 including a surface course HL-3 containing 20 percent RAP and a base course HL-8 containing 40 percent RAP. These mixes were labelled as 2HL-3 and 2HL-8 respectively. To investigate the impact of storage time on the blending progress and achieving a cohesive final binder, the mix samples were collected as a function of storage time in the silo. The first sampling was done immediately after production (t = 0-hour), and then at several time intervals of silo-storage; i.e., at 1, 4, 8, and 12 hours. In case of Plant 2, the samples were additionally collected after 24-hour of storage time. All samples were then kept in a storage room at 7ʻC until the day of compaction to minimize any further blending between aged and virgin binder. To understand the blending phenomena and its effect on the performance of the pavement, a multi-scale investigation is carried out. The blending was examined in terms of micro-mechanical and rheological properties. The microstructure of the blending zones were examined under The Environmental Scanning Electron Microscope (ESEM). In addition the effect of the silo-storage time on the rheology of the binders was investigated. The results indicate that increasing the interaction time and temperature between the aged and virgin binder significantly results in a better blending. The performance of RAP-HMA with respect to the silo-storage time was examined using Dynamic Modules Test, Thermal Stress Restrained Specimen Test (TSRST), Rutting Test, and Flexural Beam Fatigue Test. The experimental data indicates that samples collected after 12-hour of silo storage exhibited a reduction in the stiffness due to better blending of aged and virgin binder. In addition, the 12-hour samples showed enhancement in their fracture temperature, rutting depth, and fatigue life, accompanied with a better blending between their aged and virgin binder. On the other hand, the samples that collected after 24-hour silo-storage had a higher stiffness in comparison with the 8 and 12-hour samples. Moreover, the AASHTOWare Pavement Mechanistic-Empirical Design was utilized to examine the effect of the 12-hour silo-storage time on the long term performance of the pavements. Four pavement structures have been designed for this purpose. These pavements have the same structure of their granular A, granular B, and the subgrade. Yet, the first layer (surface course and base course) is a silo-storage time-dependent. The long-term field performance prediction indicates a slight improvement with the 12-hour pavements (Plant1 12hrs and Plant2 12hrs). However, it should be noted that AASHTOWare Pavement Mechanistic-Empirical Design does not appear to properly capture the effect of blending in the pavement performance. The collected experimental evidences unveils correlations between time-temperature effects and mixture performance. Based on these findings, the research provides practical recommendations to the professionals of the Canadian asphalt industry for a better use of RAP. Ultimately, this research recommends a 12-hour silo-storage time for the RAP-HMA for better performance and durability of the mixes.

Download or read book Laboratory and Field Evaluation of Cement Treated Reclaimed Asphalt Pavement Blends as Roadway Base Material written by Soheil Nazarian and published by . This book was released on 2012 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reclaimed asphalt pavement (RAP) and granular base materials were collected throughout Texas to evaluate the properties of RAP and RAP blended with virgin or salvage aggregates for roadway base course application. Mixes containing RAP of 100 %, 75 %, and 50 % and treated with Portland cement of different dosages were utilized in a comprehensive laboratory testing program. The factors that affect the properties of cement-treated RAP mixes are identified and a mix design model based on typical RAP and granular base materials in Texas was proposed. The design model was verified by the data from the initial field trial on actual construction projects. The feasibility of using a modulus-based procedure for quality assurance/quality control during construction is discussed.

Download or read book Sustainable Polymers from Biomass written by Chuanbing Tang and published by John Wiley & Sons. This book was released on 2017-02-17 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offering a unique perspective summarizing research on this timely important topic around the globe, this book provides comprehensive coverage of how molecular biomass can be transformed into sustainable polymers. It critically discusses and compares a few classes of biomass - oxygen-rich, hydrocarbon-rich, hydrocarbon and non-hydrocarbon (including carbon dioxide) as well as natural polymers - and equally includes products that are already commercialized. A must-have for both newcomers to the field as well as established researchers in both academia and industry.

Download or read book AASHTO Guide for Design of Pavement Structures 1993 written by American Association of State Highway and Transportation Officials and published by AASHTO. This book was released on 1993 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt: Design related project level pavement management - Economic evaluation of alternative pavement design strategies - Reliability / - Pavement design procedures for new construction or reconstruction : Design requirements - Highway pavement structural design - Low-volume road design / - Pavement design procedures for rehabilitation of existing pavements : Rehabilitation concepts - Guides for field data collection - Rehabilitation methods other than overlay - Rehabilitation methods with overlays / - Mechanistic-empirical design procedures.

Download or read book Cold recycled Bituminous Concrete Using Bituminous Materials written by Jon A. Epps and published by Transportation Research Board. This book was released on 1990 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: This synthesis will be of interest to pavement designers, construction engineers, and others interested in economical methods for reconstructing or rehabilitating bituminous pavements. Information is provided on the processes and procedures used by a number of states to recycle asphalt pavements in place without application of heat. Since 1975 a growing number of state highway agencies have reconstructed or rehabilitated asphalt pavements by recycling the old pavement in place. This report of the Transportation Research Board describes the processes used for cold in-place recycling, including construction procedures, mix designs, mixture properties, performance, and specifications.

Download or read book Cement Stabilization of Aggregate Base Materials Blended with Reclaimed Asphalt Pavement written by Ashley Vannoy Brown and published by . This book was released on 2006 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of the ANOVA performed on the UCS data indicate that UCS decreases from 425 to 208 psi as RAP content increases from 0 to 100 percent and increases from 63 to 564 psi as cement content increases from 0.0 to 2.0 percent. Similarly, the final dielectric value decreases from 14.9 to 6.1 as RAP content increases from 0 to 100 percent and decreases from 14.0 to 5.8 as cement content increases from 0.0 to 2.0 percent.

Download or read book Reclaimed Asphalt Pavement written by Imad L. Al-Qadi and published by . This book was released on 2007 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Illinois has been recycling Reclaimed Asphalt Pavement (RAP) material into hot-mix asphalt (HMA) since 1980, this research project seeks to determine the appropriate level of contribution that should be given to the residual asphalt binder in RAP.

Download or read book Novel Methods for Adding Rejuvenators in Asphalt Mixtures with High Recycled Binder Ratios written by Fan Yin and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objective of this study was to explore three novel rejuvenator application methods using the emulsion and foaming technologies and determine their impacts on the workability and long-term cracking resistance of high-reclaimed asphalt pavement (RAP) asphalt mixtures. To that end, a comprehensive experimental plan was developed, which consisted of four supplementary experiments focusing on rejuvenator characterization, foaming measurements of rejuvenators and rejuvenated asphalt binders, RAP pretreatment and marination evaluations, and mixture performance testing, respectively. Test results indicated that adding rejuvenators for RAP pretreatment improved the overall quality characteristics of RAP. Among the three rejuvenator application methods evaluated for RAP pretreatment, the emulsion method was found more effective than the spray-on and foaming methods. Marinating the pretreated RAP had a notable impact on the rheological and chemical properties of the extracted RAP binders, but it did not significantly affect the workability, appearance, and color consistency of RAP. Adding rejuvenators, in general, improved the workability and cracking resistance of high-RAP mixtures, although the improvement in mixture performance test results, in some cases, was not statistically significant. Among the different rejuvenator application methods, pre-blending the rejuvenator into the virgin binder (with or without foaming) provided slightly better or equivalent rejuvenating effectiveness and thus, mixture performance properties, than adding the rejuvenator for RAP pretreatment. Based on the findings of the study, it was recommended that asphalt contractors continue to use the pre-blending method of adding rejuvenators for the design and production of high-RAP mixtures due to performance and ease of operation considerations.

Download or read book Engineered Frameworks for Evaluating the Use of Recycling Agents in Surface Asphalt Mixtures for Virginia written by Jhony Habbouche and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, several state highway agencies have introduced special provisions and specifications to allow the use of higher contents of reclaimed asphalt pavement (RAP) in asphalt surface mixtures. The challenges associated with high RAP mixtures can be addressed through the use of additives such as recycling agents (RAs) and/or softer binders. Currently, there are no specific guidelines or specifications available to evaluate the acceptability of RAs in Virginia. The purpose of this study was to evaluate the short- and long-term effectiveness of RAs in improving the performance of asphalt mixtures, particularly those with high RAP contents. Another objective of the study was to establish a performance-based framework to determine the acceptability of a specific RA product for inclusion in the Virginia Department of Transportation’s Approved Product List. Both objectives were achieved by benchmarking recycled binder blends (Phase I) and mixtures (Phase II). These were then compared in terms of laboratory performance to commonly used virgin asphalt binders and mixtures in Virginia. Moreover, a comprehensive review of the literature and information from state departments of transportation and RA suppliers on the current state of the practice regarding the use of recycled materials and RAs in asphalt mixtures was summarized. Component materials, including three virgin asphalt binders, RAP and aggregate materials from three different sources, and six RAs, were collected and tested. Phase I involved testing virgin and RAP binders; combinations of virgin binder and RAP binder; and combination of virgin binder, RAP binder, and RAs. A total of 26 binder blends were evaluated at various aging conditions through numerous rheology- and chemistry-based tests. In Phase II, 10 asphalt mixtures were designed and evaluated for durability, resistance to rutting, and resistance to cracking at various aging conditions. Cross-scale evaluation of asphalt binder and mixture testing data was established. Finally, preliminary verification was performed using data collected from various field trials constructed in Virginia. Based on the binders and mixtures tested in this study, the effectiveness of RAs in improving the properties of asphalt binder blends is specific to the product being used and to the targeted temperatures or conditions. Moreover, RAs can enhance the performance and increase the use of recycled materials in asphalt mixtures provided that the correct and suitable dosage of RA product is determined through a performance-based testing framework. The study recommends the following: (1) adopting the streamlined frameworks presented in this study to determine the acceptability of a given RA; (2) further validating the presented framework using different component materials; (3) employing balanced mix design tests to assess the performance characteristics of surface mixtures (with A and D designations) with RAs and drafting a roadmap; (4) collecting and further evaluating the field performance of all trials involving high RAP, RAs, and/or softer binders; (5) investigating the availability and activity of binders, especially with RAs, in RAP materials; (6) evaluating and establishing a protocol to assess the consistency of RAP materials; and (7) quantifying the environmental and economic impacts of using surface mixtures with high RAP contents and/or RAs.

Download or read book Rice Husk Ash Stabilization of Reclaimed Asphalt Pavement written by Kolawole J. Osinubi and published by . This book was released on 2012 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of a reclaimed asphalt pavement (RAP) and rice husk ash (RHA) mixture in the construction of pavements has benefits in not only reducing the amount of waste materials requiring disposal but can also provide construction materials with significant savings over new materials. The paper presents results of the laboratory evaluation of the characteristics of RAP stabilized with sawdust ash (RHA) with a view to determine its suitability for use as a subbase and base material in flexible pavements. The RAP-RHA mixtures were subjected to British Standard light, BSL (standard Proctor) compactive effort to determine the compaction characteristics and California bearing ratio (CBR). Test results show that the properties of RAP improved when treated with RHA. The particle grading improved from 99.8 % coarse aggregate and 0.2 % fines, with an AASHTO classification of A-1-a for 100 % RAP to 92.5-99.5 % coarse aggregate and 0.5-7.5 % fines, with an AASHTO classification that ranges from A-1-a (granular materials) to A-3 (nonplastic fine sand) for the various RAP-RHA mix proportions to A- 4 (silty materials) for 100 % RHA. Generally, maximum dry density (MDD) decreased and optimum moisture content (OMC) increased with higher RHA content in the mixes. The CBR values decreased with higher RHA content. However, the values increased from 35 (unsoaked) and 23 % (soaked for 24 h) for 100 % RAP to peak values of 41 (unsoaked) and 34 % (soaked for 24 h) for a 70 %RAP/30 %RHA mix that can be used as a subbase material in flexible pavements.