Full-depth Reclamation Research Articles

Assessment of the quality of full depth reclamation (FDR) using a dynamic cone penetrometer (DCP): a case study

The full-depth reclamation with no stabilization (FDR-NS) is widely used as a pavement rehabilitation technique. It is important to evaluate the on-site characteristics of FDR-NS materials to avoid short-term underperformance. The need for performance-based testing could then be supported by in-situ and non-destructive testing, such as dynamic cone penetrometer (DCP). DCP allows to estimate the bearing capacity of the pavement structure and to verify its homogeneity according to the depth. The objective of this research is to evaluate the applicability of using DCP to assess the quality of FDR-NS. Overall, DCP results showed a good reliability, allows to measure the effective depth of reclamation and to observe a significant reduction (average of 75 %), in terms of DCP values, between before and after the reclamation process. Thus, the potential of using DCP for FDR-NS rehabilitation was confirmed. The results from this research provide a rational basis for establishing specifications.

Can Geopolymer Be a Replacement for Portland Cement in Full-Depth Reclamation Projects? Short- and Long-Term Performance Analysis

The fundamental concern of the full-depth reclamation (FDR) technique using Portland cement (FDR-PC) lies in its detrimental effect on the environment. Therefore, researchers are exploring alternative binders that are comparatively greener but compatible with FDR. This study evaluates both the strength and durability aspects of FDR incorporating geopolymer binder (FDR-GP) as an alternative to conventional FDR-PC. Various blends of fly ash (FA) and ground granulated blast furnace slag (GGBS) have been experimented with as geopolymer pre-cursors, ensuring that the additive content does not exceed 20% by weight of the total mix. Sodium hydroxide (NaOH) was utilized for the alkalinization in varying molarities to enhance the performance of the mixes. The experimental design was formulated to achieve a target 7-day unconfined compressive strength (UCS) strength of 4.95 MPa. This was obtained at a lower molarity (M) of 2 M and a 70% FA, 30% GGBS binder content. The mixes performed satisfactorily in both compression and flexure, along with excellent durability properties analyzed through wetting and drying tests. Furthermore, the long-term performance of FDR-GP mixes was investigated with regard to both UCS and flexural strength after 56, 161, and 238 days of curing. Thereafter, a comprehensive microstructural analysis was conducted to understand the fundamental changes in the matrix that influence mix performance. The outcome of this research confirms the potential of using FA/GGBS-based geopolymer as an alternative binder in FDR projects of flexible pavement, the mechanical and durability properties of which adequately satisfy the requirements as stipulated in various design standards.

Microcracking Considerations in Full-Depth Reclamation with Cement

Microcracking Considerations in Full-Depth Reclamation with Cement

Evaluating the Strength of Full Depth Reclamation (FDR) Mixtures Using RAP and Virgin Aggregate

Evaluating the Strength of Full Depth Reclamation (FDR) Mixtures Using RAP and Virgin Aggregate

Strength characteristics and mix design of full-depth reclamation of asphalt pavement with cement

The research presents the strength characteristics and theoretical mix design of full-depth reclamation (FDR) with cement for road maintenance and rehabilitation. The reclaimed aggregates used in the study were pulverized and blended on the investigation site by the recycler machine. The FDR mix design covered the reclaimed asphalt pavement (RAP), reclaimed base, and reclaimed subbase courses. The unconfined compressive strength (UCS) was tested on the FDR with cement under different mix proportions, cement content, moisture content, and curing time. Two factors that affect the UCS of FDR, viz., moisture-induced packing density and moisture for cement hydration, were observed. The mix proportion with 40 % RAP required at least 6 % cement to stabilize the FDR for use as a bound base course as per the standard, while the effective limit of cement content for FDR was 9 %. The strength prediction model of FDR with cement was presented theoretically based on the modified soil-moisture/cement ratio concept. The verification of the proposed strength model was performed using 7 and 28-day UCS from another investigation site. The design recommendations for FDR with cement were summarized. This discovery could offer a cost-effective and precise method for the mix design of FDR with cement.

A Comprehensive Review of Life Cycle Cost Assessment of Recycled Materials in Asphalt Pavements Rehabilitation

This paper provides a comprehensive review of the use of life cycle cost assessment (LCCA) and life cycle assessment (LCA) methods for evaluating the sustainability and costs of using recycled materials in asphalt pavement rehabilitation projects. The review begins with an introduction to pavement rehabilitation strategies and the importance of choosing techniques based on thorough engineering and economic analyses. It then explores the different types of recycled materials that can be utilized, including reclaimed asphalt pavement, recycled concrete aggregate, and recycled asphalt shingles, discussing the key characteristics and properties of these materials based on previous laboratory studies. The review also examines the various rehabilitation methods that employ recycled content, such as cold in-place recycling, hot in-place recycling, and full-depth reclamation, providing a detailed breakdown of the construction, maintenance, and rehabilitation costs considered in LCCA and analyzing the environmental benefits of recycled material usage through a review of LCA techniques and criteria like carbon footprint reduction, impacts on air and water quality, and considerations of technological factors. Software tools for conducting LCA are compared and challenges to advancing the adoption of recycled materials are reviewed along with directions for future research efforts. The unique contribution of this work is its holistic assessment of LCCA and LCA methodologies to inform the sustainable and cost-effective deployment of recycled materials in asphalt pavement rehabilitation, a topic of growing importance for transportation infrastructure management. In summary, this current work provides a valuable review of how LCCA and LCA methodologies can assess the sustainability and costs of employing recycled content in asphalt pavement rehabilitation projects.

Erosion Potential of Stabilized Support Layers for Concrete Pavements and Overlays

The performance of concrete pavements and overlays is highly dependent on the uniformity, durability, and stability of the underlying support layers. Erosion of support layers can lead to pavement distresses and a reduction in pavement life. A review of existing erodibility performance tests that assessed stabilized support layers was first conducted to identify and evaluate their suitability for adaptation. The Hamburg wheel tracking device (HWTD) test was selected to assess the erosion potential of asphalt and cement stabilized support layers. Field testing with distress surveys, falling weight deflectometer, and coring was completed to obtain HWTD specimens and link laboratory results to pavement performance. The HWTD test was performed on cores obtained from in-service cement and asphalt stabilized support layers, a cold in-place recycling (CIR) mixture, and cement stabilized laboratory mixtures. As expected, an increase in cement content within cement stabilized mixtures decreases the likelihood of erosion with the HWTD. Additionally, conventional asphalt stabilized base layers were highly erosion resistant. Erosion resistant cement stabilized bases (including full-depth reclamation) should target an average HWTD erosion depth ≤2 to 4 mm (0.08 to 0.16 in.) after 10,000 load cycles based on the functional classification and expected traffic volume of the pavement section. Likewise, asphalt stabilized bases (including CIR and support layers for concrete overlays) should target an average HWTD erosion depth ≤12.5 mm (0.5 in.) after 7,500 load cycles with performance grade 64 binder.

ТЕХНОЛОГІЇ ХОЛОДНОГО РЕСАЙКЛІНГУ ДЛЯ ГЛИБОКОЇ РЕГЕНЕРАЦІЇ НЕЖОРСТКОГО ДОРОЖНЬОГО ОДЯГУ

ntroduction. In the introduction to the article, the briefly performed comparative analysis of the road asphalt concrete cold recycling technologies was adduced and also the actuality of the implementation of widened nomenclature of such technologies in the Ukraine was outlined. Problem statement. The issue of the article concerns processes and materials for technologies of the full-depth reclamation of flexible road pavements using cold recycling trough full depth of asphalt layer/layers including the underlying layers of granular materials as required. Purpose. The aim of the article is to analyze the technological parameters of processes of full-depth reclamation (FDR) and also general requirements for reclaimed materials especially those concerning the estimation of their thermorheological properties. Results. The methods of the reclaimed materials stabilization were examined which, in accordance with the FDR technologies, should be divided in mechanical and those performed with the stabilizing agents. The types of pavement defects were defined under presence of which the application of FDR technologies has been recognized highly effective. The concise analysis of general requirements for reclaimed materials was performed with setting off the materials subjected to special requirements for grading. Also, the technological particularities of processes of the full-depth reclamation were stated which should be attributed to the technical characteristics of road equipment, the road pavement condition, and reclaimed mixtures quantitative proportions as well. According to the analysis of the test methods of reclaimed materials stabilized by bitumen using foamed bitumen, the role of the thermoreological uniformity of cold recycled mixtures for their proper design was shown.

Laboratory Evaluation of Strength Performance of Full-Depth Reclamation with Portland Cement Material

Laboratory Evaluation of Strength Performance of Full-Depth Reclamation with Portland Cement Material

Evaluation of the Fatigue Performance of Full-Depth Reclamation with Portland Cement Material Based on the Weibull Distribution Model

The full-depth reclamation with Portland cement (FDR-PC) technology embodies an environmentally friendly approach to solving the damage to old asphalt pavement. Fatigue failure emerges as the predominant mode of degradation for FDR-PC pavement. The fatigue characteristics of the full-depth reclamation with Portland cement cold recycled mixtures were evaluated through four-point bending tests. Three contents (4%, 5%, 6%) of cement and three base-to-surface ratios (10:0, 8:2, 6:4) were utilized. The fatigue equations were derived for the mixtures using a two-parameter Weibull distribution. The results indicate that all correlation coefficients of the Weibull distribution model surpass 0.88, effectively projecting the lifespan of FDR-PC. With increases in cement contents and base-to-surface ratios, the fatigue life of the mixture extends, though with an augmentation of stress sensitivity. Comparative analysis with the fatigue equation model parameters of the current Chinese specifications for the design of highway asphalt pavement reveals that mixtures with a 4% cement content and combinations of a 5% cement content with a low base-to-surface ratio meet the requirements for inorganic-binder-stabilized soil. Additionally, mixtures with a 5% cement content and a high base-to-surface ratio, along with those with a 6% cement content, fulfill the specifications for inorganic-binder-stabilized granular materials.

Full-Scale Evaluation of Airfield Pavement Runway Reconstruction with Full-Depth Reclamation Technique

Full-depth reclamation (FDR) has been identified as a strategic in-place recycling technique that is readily available for effecting a rapid restoration of the structural capacity of abandoned airfield pavements in contingency environments. A full-scale pavement section was designed to investigate the performance of pavement sections containing an FDR layer under simulated loading conditions of a tactical heavy aircraft. The FDR materials were composed of various combinations of base material types (i.e., gravel and limestone) and different asphalt layer thicknesses (i.e., 51 mm and 102 mm). The FDR blends were stabilized with a combination of 3% asphalt emulsion and 2% Portland cement. The FDR pavement section consisted of six different test items to investigate the performance of various FDR material types, asphalt layer thicknesses (i.e., 51 mm and 76 mm), and unpaved landing zones. The performance of the existing pavement and the FDR pavement test sections was compared to assess the improvements resulting from the rehabilitation of airfield pavements using the FDR technique. The results indicated that FDR was effective in restoring the structural condition of a damaged asphalt pavement section to support additional aircraft operations. The quality of the FDR blend had a significant impact on pavement performance, whereas the impact of the asphalt layer thickness was insignificant. Finally, the unpaved FDR sections also demonstrated enough structural competency to support a low volume of aircraft traffic before further surface layers are added during pavement reconstruction in contingency environments.

Sustainability implications of lateral wander modes for autonomous trucks

Autonomous trucks can bring changes in transport infrastructure in terms of sustainability based on the type of lateral wander mode used. In this research, two lateral wander modes, a zero wander and uniform wander mode are analyzed based on their applicability for sustainability by analyzing the CO2 emissions occurred during pavements life cycle. Both lateral wander modes have been analyzed in terms of occurrence of fatigue damage by using finite element analysis in ABAQUS. The fatigue damage predictions have then been used for planning the maintenance interventions for both lateral wander modes. Life cycle analysis has been performed for the analysis period of 30 years for the pavement section of 10 km. Results show that zero wander mode generates more emissions as a result of premature fatigue damage under channelized loading. The uniform wander mode leads to 20% less emissions when compared to zero wander mode. Moreover, the use of full depth reclamation during pavement’s life cycle improves the CO2 emissions by 15% when compared to traditional removal and reconstruction methods. Therefore, the uniform wander mode is favorable for improvement of pavement sustainability in terms of CO2 emissions.

Impacts of Increased Prediction Accuracy in Management Decisions: A Study of Full-Depth Reclamation Pavements

Impacts of Increased Prediction Accuracy in Management Decisions: A Study of Full-Depth Reclamation Pavements

PERFORMANCE EVALUATION OF LATERITE AND PULVERIZED RECLAIMED ASPHALT PAVEMENT STABILIZED WITH BASE SEAL AND CEMENT

This research delves into the effectiveness of incorporating pulverized Reclaimed Asphalt Pavement (RAP), Base Seal, and cement to enhance the stability of lateritic base materials in Nigeria. Addressing a crucial gap in pavement engineering literature, particularly the underexplored use of base seals as liquid stabilizers, the study adopts a comprehensive methodology involving literature review, field evaluation, and laboratory tests. Analyzing various material mixes, from pure Laterite to combinations with RAP, Base Seal, and varying cement contents, the research reveals substantial improvements in crucial engineering properties. Enhanced particle size distribution, reduced clay content, and optimal compaction characteristics at 0% cement content for laterite materials with pulverized RAP signify the positive impact of these additives. California Bearing Ratio analysis establishes a consistent correlation between higher cement content and improved load-bearing capacity. Notably, the synergistic effects of RAP and base seal, particularly at 5% cement content, showcase the highest CBR value (91), indicating optimal conditions for strength and stability. The study concludes with practical recommendations for road maintenance authorities, advocating for innovative approaches like full-depth reclamation techniques and stabilized full-depth reclamation, exploring different RAP to base material ratios, examining curing periods' impact, assessing long-term performance, considering environmental implications, and conducting field trials for validation. Overall, these findings contribute valuable insights to pavement design practices, fostering the development of resilient infrastructure in construction projects.

Long-Term Performance and Forensic Evaluation of an Asphalt Pavement with Cold Central Plant Recycled Asphalt

In 2012 Virginia Department of Transportation constructed two test sections at the National Center for Asphalt Technology Test Track containing asphalt processed via cold central plant recycling (CCPR) with identical asphalt overlays. One section contained a stabilized base beneath the CCPR layer (Section S12), similar to a full-depth reclamation layer; the other included an unstabilized aggregate base beneath the CCPR layer (Section N4). Both sections were subjected to trafficking by loaded trucks for a total of 30 million equivalent single axle loads. Minor cracking was observed at the surface of the section with the unstabilized base; the section with the stabilized foundation exhibited no surface cracking. Furthermore, strain, pressure, and deflection measurements showed better performance for the section with the stabilized foundation than the section with the unstabilized base. Because of the relatively unchanged performance of Section S12, it was taken out of service to conduct a forensic investigation. This paper presents the analysis of the instrumentation results, coring, trenching, and mechanistic testing and modeling, to better understand and compare the performance between sections. The stabilized base was found to greatly reduce bending action in the section, exhibited no substantial rutting, but also contained what appeared to be some shrinkage cracks. However, these cracks did not propagate to the surface, indicating that the CCPR layer may be an effective crack mitigator. Further, it was found that mechanistic modeling using AASHTOWare Pavement ME design software overestimated the rutting but predicted similar international roughness index and cracking to that observed in the field.

Effective lane width analysis for autonomous trucks

Lateral wander of autonomous truck can be further improved by optimizing the uniform wander. Increase in available lane width for the autonomous trucks can increase the performance efficiency of this mode. This research is based on finding the optimum, combination of lane width increment and asphalt layer thickness reduction among different scenarios. Therefore, In this research with assumed maximum lane width of 4.35 m, difference combination of lane width and asphalt layer thickness scenarios have been analyzed using finite element modelling in ABAQUS. Considering the base pavement width of 3.75 m, increment for each scenario is 15 cm and reduction in asphalt layer thickness is at 2 cm. Performance efficiency of each scenario is conducted while considering the initial construction costs and damage assessment for each scenario. Moreover, life cycle cost analysis (LCCA) is conducted for the base scenario and selected optimum scenario. Results show that increase in pavement width beyond 4.2 m, renders the scenarios uneconomical and thus, the scenario consisting of 4.2 m lane width and 16 cm asphalt layer thickness yield a maximum performance efficiency of 20% among all other alternatives. LCCA analysis shows that a difference in salvage value of 42 million Euros exists when compared with the base scenario. By selecting the optimum lane width of 4.2 m and asphalt layer thickness of 16 cm, Pavement lifetime can be further increased by 13 years with full depth reclamation used as maintenance intervention.

Specimen size effect on dynamic modulus measurement of Cold recycled and full depth reclamation mixtures

Dynamic modulus was measured using large-scale (LS) and small-scale (SS) specimens of four cold recycled (CR) and one full depth reclamation mixtures. The study found emulsified mixtures showed similar and repeatable dynamic modulus (E*) results with both specimen geometries (<15% difference) and foamed mixtures showed poor agreement between specimens (>24% difference), likely due to the differences in the mix matrices. The mechanistic-empirical pavement design analysis showed that E* differences in LS and SS of CR mixtures with foam resulted in error in asphalt concrete (AC) rutting predictions for sections with a thin surface layer (25 mm [1 in.]) and did not affect rutting predictions once the surface layer thickness was above 76 mm (3.0 in.). An empirical SS to LS shift factor method is presented.

Unconfined compressive strength prediction of recycled cement-treated base mixes using soft computing techniques

ABSTRACT The study evaluates the viability of using Full-depth reclamation (FDR) as an eco-friendly approach for constructing roads. The research employs chemical stabilizers in reclaimed asphalt pavement (RAP) material to create a cement-treated base (CTB) layer. The study uses artificial neural network (ANN) models to predict the 7-days unconfined compressive strength (UCS) of RAP material-based CTB mixes. The Levenberg-Marquardt backpropagation-based ANN (LM-BP-ANN) and Scaled Conjugate Gradient backpropagation-based ANN (SCG-BP-ANN) models are used to forecast the UCS values. The models are assessed based on regression coefficient (R) and mean squared error (MSE), and the LM-BP-ANN model outperforms the SCG-BP-ANN model with an R value of 0.99556 and MSE of 0.0305. The findings suggest that the proposed models have the potential to forecast UCS values of recycled cement-treated base mixes.

Structural Performance of Foamed Asphalt Base in a Full Depth Reclaimed and Sustainable Pavement

Environmental awareness and budgetary constraints in road construction and rehabilitation require innovative and at the same time environmentally friendly solutions in favor of resource conservation, in any type of pavement intervention. In the meantime, surface interventions in severely deteriorated pavements are insufficient, increasing as such the recycling potential of existing materials in Full Depth Reclamation (FDR). This study addresses the efficiency of an FDR process in which the recycled base course of an existing semi-rigid pavement is stabilized with Foamed Asphalt (FA). The adverse effects of FA curing, which have a significant impact on pavement evaluation, particularly in the early stages of a pavement’s life cycle, prompted the conduct of a comprehensive testing campaign at two different periods, shortly after pavement rehabilitation and five years thereafter. The campaign included nondestructive testing at the aforementioned periods using Ground Penetrating Radar (GPR) and the Falling Weight Deflectometer (FWD), which facilitate the structural evaluation of the FA base. Using the collected nondestructive testing data, the principles of Multi-Layer Elastic Theory (MLET) and Genetic Algorithms (GA) are used to investigate the performance of the FA base. Both analysis tools captured the FA strength increase in the second period, but an increased variance of the FA modulus was observed mainly in the first test period, probably due to the curing effect. In addition, GA showed an advantage over other, more conventional tools for back-analysis of pavement stiffness, resulting in an interesting correlation potential of FA modulus to a deflection-based parameter reflecting the condition of the FA layer. Overall, the study contributes to the development of a practical methodology suitable for the evaluation of non-conventional and sustainable pavement structures.

Demonstrating Field Use of the Plastic Mold Device on Full-Depth Reclamation Projects in Mississippi

This paper documents the use of the 4 x 8 in. plastic mold (PM) device on two full-depth reclamation (FDR) field projects where cement-stabilized material containing large aggregates were used. PM device specimens were assessed to understand project variability as well as investigate potential in-field curing protocols for early-age roadway trafficability. Additionally, PM device specimens were compared with cores to quantify early-age mechanical properties and relationships. The density of PM device specimens and cores were, on average, within 2% of one another. In some cases, on-site curing protocols produced strengths that were not statistically different from cores. Ultimately, the PM device was successfully implemented and capable of producing reliable and repeatable results that captured project variability.