Pavements

Semiflexible pavement (SFP), a composite pavement, is formed by filling into a very open porous asphalt skeleton a specifically designed water consistency fluid mortar with a very high early and 28-day strength. The amalgamation of both components will produce a SFP where it will replace the conventional wearing course. The main goal of this investigation is to study the effect of various aggregate gradations towards producing SFP. These include determining the optimum binder, volumetric properties, and durability and strength of each aggregate gradation. The final results were statistically analyzed and two factor variance analyses (ANOVA) were performed to check on the significance at certain confidence limits. The results confirmed that different aggregate gradations significantly affect the properties mentioned.

In recent years, the significant importance of solid waste management, increase in the cost of bitumen and polymer modifiers have encouraged the pavement engineers to use reusable alternative sources. Ground tire rubber (GTR) and amorphous carbon powder (ACP) are considered as two industrial waste which their using in asphalt mixture prevents their releasing in the environment. This study aims to analyze moisture sensitivity, fatigue performance, and rutting resistance of asphalt mixture influenced by using GTR (8, 12, and 16% of bitumen weight) as the modifier of bitumen properties, and ACP (25, 50, and 75% of filler weight) as filler. The results of this study shows that the ACP increases the resilient modulus and indirect tensile strength of rubberized asphalt concrete (RAC) mixtures. The results revealed that despite the negative effect of GTR on the moisture resistance of asphalt mixture, ACP improves the moisture performance. The results of fracture energy also implies that using ACP decreases the fracture energy, but using the GTR improves the fatigue resistance of asphalt mixture. Furthermore, the results of dynamic creep and wheel track tests indicates that 16GTR + 50ACP has the lowest permanent deformation and highest rutting resistance. The results of ANOVA analysis demonstrates that using GTR and ACP has a considerable effect on the performance properties of asphalt mixture. Finally, the results of this study illustrate the simultaneous use cleaner production and wasted materials decreases the environmental damages in addition to improvement of physical properties of the asphalt mixture.

The Steenbreek program is a private Dutch program which aims to involve citizens, municipalities and other stakeholders in replacing pavement with vegetation in private gardens. The Dutch approach is characterized by minimal governmental incentives or policy, which leaves a niche for private initiatives like Steenbreek, that mainly work on behavioural change. The aim of this paper is to build a model based on theory that can be used to improve and better evaluate depaving actions that are based on behavioural change. We tested this garden greening behaviour model in the Steenbreek program. The main result is that the model provides an understanding of the ‘how and why’ of the Steenbreek initiatives. Based on this we are able to provide recommendations for the improvement of future initiatives. Steenbreek covers a wide range of projects that together, in very different ways, take into account elements of the theoretical framework; either more on information factors, or on supporting ...

h i g h l i g h t s Marshall Test results show that 4.6% Gilsonite increase Marshall Stability. The indirect tensile test indicates the performance improvement of mixture made with Gilsonite. Test result indicates that the addition of Gilsonite to mixtures reduces moisture sensitivity. The specimens with Gilsonite have better performance to those made with pure bitumen 70-60. a b s t r a c t Iran-produced bitumen under the circumstances of severe temperature fluctuation, heavy traffic load and raining/freezing conditions show low efficiency; therefore, it is necessary to improve its properties accordingly. Existence of weakness in produced bitumen result in failure occurrence in asphalt pavements during service life of asphalt roads. Given the existence of considerable reserves of Gilsonite in Iran, its low costs compared with other additives and its remarkable properties, we can study asphalts modified by Gilsonite. At the present time, little research has been conducted on this modifier in the world and Iran (which its properties are still not quite evident for researchers). The most important failure in flexible pavements is permanent deformations which are known as rutting. Rutting is longitudinal depression in the wheel path in bituminous pavements. The rate and depth of rutting depend on the internal factors such as bitumen properties, aggregate, mixture properties and thickness of pavement layers. In this lab study, with regard to the technical and executive issues, common functional performance-based tests of bitumen were performed on specimens through adding Gilsonite with 0, 2, 4, 6, 8, 10 wt.% of made bitumen specimens. Then, the optimum percentage was calculated using the AHP. The specimens containing pure bitumen 60-70 and modified bitumen 60-70 with Gilsonite in two different aggregations (4 and 5) were made and the effects of adding Gilsonite in Marshall Stability and flow, indirect tensile strength and moisture sensitivity, as well as dynamic creep, and resilient modulus were evaluated by the UTM device. The research showed that adding Gilsonite to bitumen in hot asphalt mixtures considerably increases Marshall Stability and resilient modulus parameter in asphalt specimens. However, resilient modulus test indicated a significant reduction in flexibility property of asphalt mixtures made of modified bitumens. Moreover, increasing the flow number obtained from the dynamic creep test indicate the increase of rutting resistance.

Engineers are often faced with construction of pavement structures over soft and highly compressible subgrade. Such conditions render the structures unable to withstand the required design loads and susceptible to high settlements with associated excessive distress, leading to pavement damage. Because using imported quality fill to improve the load-bearing capacity of the subgrade has limited benefits, an alternative construction approach is needed to ensure the required strength of the soil structure is reached. The use of geosynthetics in soil to improve bearing capacity and stability offers a better alternative to imported fill. This research was conducted to determine the degree of improvement of the load-bearing capacity and reduction in settlement as a result of the geosynthetic reinforcement of soft clay overlain by granular material. Compression tests on the unreinforced clay subgrade and geosynthetic-reinforced two-layered soil composite were conducted at bench-scale using a Universal Compression Machine at the University of Cape Town Geotechnical Engineering Laboratory. The geosynthetic products used to reinforce the soil structure in this study included geogrids and geotextiles. The reinforcement layer was placed alternatively within the layer of granular material and at the interface of the soil and a range of fill thicknesses and depths of placement were tested to determine their influence on mobilized strength. The use of these composites could potentially lead to reduced construction costs as a result of less aggregate material used, an extension in the design life of the pavement structure and, consequently, a reduced necessity for maintenance work.

This project aims to evaluate the effectiveness of the quality measures employed by the Wisconsin Department of Transportation to influence the in-service performance of flexible pavements. The study involved creating a relational geo-referenced database connecting production, placement, and routine in-service performance data collected over the years for Wisconsin Projects. The database relied on geo-referencing all the data such that each individual data point is assigned a location. This approach allows for tracking the quality of the material and construction of specific segments of the roadway to the in-service performance. A subset of the projects was also included in an in-depth study using on-site distress survey and non-destructive testing using Falling Wheel Deflectometer (FWD). In general, the thirty (30) highway projects studied in this project show that transverse and longitudinal cracking are the most common distresses. Construction joint longitudinal cracking appears to be highly common in all the on-site visits. Rutting is localized but not common. Alligator cracking takes place in multiple locations. This distress appears to relate to either soft foundation or some of the quality measures.
Deviations from the quality indicators’ targets show correlations with the distresses. Mix production air voids (Va), mix voids in mineral aggregate (VMA), and placement density (%Gmm) are correlated with in-service performance. Deviation from target Va by reduction of 0.25% or more, correlates with a reduction in performance. Accomplishing VMA higher than the target is associated with lower levels of distresses. For %Gmm, about 2% increase in the compacted density show improved performance for thicker than 2” lifts. Thin lifts are more sensitive to the increase in compaction effort than thicker pavements.

The research reported herein was performed under NCHRP Project 1-38, by
Kathleen T. Hall, Carlos E. Correa, Samuel H. Carpenter, and Robert P. Elliott.
Kathleen Hall was the contractor and principal investigator for this study. Carlos
Correa, Samuel Carpenter, and Robert Elliott were consultants to Kathleen Hall.
The authors wish to express their gratitude to Marshall Thompson of the University of
Illinois and Thomas Scullion of the Texas Transportation Institute, for their review
and helpful comments on portions of this report.

Link: https://www.amazon.com/dp/8797231703

This book introduces purely mechanistic models that are of particular relevance to the pavement engineering profession. It commences with a short recap of basic mechanics concepts, and then delves into topics such as viscoelasticity, elastic half-space solutions, and mechanics of supported plates. Given that all pavement design and analysis approaches are founded on some mechanistic logic, the text essentially offers a universal and long-lasting reference to practitioners and engineering students.

This research was carried out in the ancient palace of Ijebu-Ode, the capital of the Ijebu kingdom. Over 20 units (ranging in size from 1m x 1m to 20m x 15m) were excavated from the King's quarters, Queen's quarters, Palace gardens, and courtyards. This series of excavations yielded a diverse range of artifacts including, beads, bronze bell anklets, knife blades, etc. A notable find is the first evidence of ceramic pavements in the Ijebu kingdom. Team members unearthed two pavements at the palace complex; one is a carved pavement that is an effigy of a local deity, the other is a geometric pavement with astronomical alignments. This research showed that behind the organization of the palace complex lies a well-designed and integrated architecture, ritual/religion, astronomy, politics, governance, and commerce, all of which functioned as a system that sustained the Ijebu Kingdom.

The present study evaluates the mechanical performance of a Hot Mix Asphalt – Type II (HMA-2) modified with carbon nanotubes and carbon nanofibers (CNTF). CNTF were made by means the Catalytic Vapor Deposition (CVD) technique at 700° C using a Nickel, Copper and Aluminum (NiCuAl) catalyst with a Cu/Ni molar relation of 0,33. In order to properly assess HMA-2 performance, three different mixtures were analyzed: 1) HMA-2 modified with purified CNTF; 2) HMA-2 modified with non-purified CNTF and, 3) a Conventional HMA-2 (control). Samples manufactured in accordance with the Marshall Mix Design were tested in the laboratory to study rutting, resilient modulus (Mr) and fatigue. In addition to the aforementioned dynamic characterization, the effect of CNTF purification on the asphalt mixture’s mechanical properties was analyzed. In short, a comparative study was designed to determine whether or not CNTF should be purified before introduction into the HMA-2. This investigation responds to the growing demand for economical materials capable of withstanding traffic loads while simultaneously enhancing pavement durability and mechanical properties. Although purified CNTF increased HMA-2 stiffness and elastic modulus, non-purified CNTF increased the asphalt mixture’s elastic modulus without considerable increases in stiffness. Thus, the latter modification is deemed to help address fatigue-related issues and improve the long-term durability of flexible pavements.

Semiflexible pavement (SFP), a composite pavement, is formed by filling into a very open porous asphalt skeleton a specifically designed water consistency fluid mortar with a very high early and 28-day strength. The amalgamation of both components will produce a SFP where it will replace the conventional wearing course. The main goal of this investigation is to study the effect of various aggregate gradations towards producing SFP. These include determining the optimum binder, volumetric properties, and durability and strength of each aggregate gradation. The final results were statistically analyzed and two factor variance analyses (ANOVA) were performed to check on the significance at certain confidence limits. The results confirmed that different aggregate gradations significantly affect the properties mentioned. © 2014 Nadiah Md. Husain et al.

http://www.hindawi.com/journals/amse/2014/529305/abs/

Rutting occurs due to accumulation of incrementally small permanent deformations from each load application and it can cause irreparable problems in pavements. On the other hand, the Marshall Mix design which is known as the main method in Iran, the lack of a simple test to determine specimen resistance to permanent deformation as the major reason for asphalt rutting is noticeable. Although today many devices are used for rutting measurement, none of them have the ability to use in wider field. In addition, prevalent methods of evaluating rutting potential are usually costly and time consuming. Mentioned parameters illustrate the necessity of developing a simple method, not only having fine precision, but also are able to predict rutting performance with low cost in the short term in laboratory. In this research, after performing the main tests on specimens, IDT test results and Marshall Parameters were used to develop a mathematical model to estimate specimen rut depth. The model is validated by using ANN and makes it possible to evaluate mixtures rutting potential while OBC is being determined in laboratory. So not only is there no need to use expensive instruments of rutting test, but also a remarkable time saving in mix design procedure is achievable.

h i g h l i g h t s Mechanical properties of RCCP slightly decreased as a result of adding waste sand. Adding nano SiO 2 improved the mechanical properties of RCCP. The optimum content of Nano SiO 2 for RCCP was determined. Increasing the waste materials' content led to an increase in skid resistance. The mixes containing glass waste showed the highest abrasion resistance. a b s t r a c t This study deals with the use of waste materials as replacement of fine aggregate in roller-compacted concrete pavement (RCCP). To achieve this, waste ceramic, waste concrete, and waste glass were initially crushed and mixed and then replaced natural fine aggregate at varying amounts in RCCP. Furthermore, to mitigate the probable negative effects of waste aggregates and also to improve the mechanical properties of cement paste, nano SiO 2 was employed in the mixes design. After preparing the mixes, Vebe time, com-pressive strength, splitting tensile strength, water absorption, abrasion resistance, and skid resistance were measured. The results show that more than 40% of sand replacement with waste materials could have a negative effect on the properties of RCCPs. However, this impact is negligible up to 10% of waste material proportions. The compressive strength of the mixes containing waste materials was lower than that of the control mix, except for the sample containing 10% ceramic waste. In terms of water absorption, mixes with waste materials had higher water absorption than the control mix. Besides, abrasion somewhat increased as a result of adding waste materials, except for the samples containing 10% glass and 10% ceramic wastes that showed a slight decrease. Moreover, mixes with waste materials had higher skid resistance than the control mix. Overall, waste ceramic mixes showed better mechanical properties and waste glass mixes had better performance in terms of water absorption. In addition, using nano SiO 2 leads to improve the mechanical properties of the RCCP; the optimum content of nano SiO 2 has determined to be 0.7% of cement weight.

Colombia es un país que tiene una red vial que en parte es antigua, sin embargo los gobiernos han tratado de promover el desarrollo y de las regiones y la comodidad de los usuarios con la construcción de nuevas rutas que han sido dadas en concesión, estas se adelantan tanto en
proyecto y ejecución con altos estándares a nivel internacional, en busca de actualizar la calidad de los corredores, para poder tener una correcta visión de la magnitud de las intervenciones viales existentes, en proyecto y en ejecución, es de vital importancia tener datos históricos,
técnicos, estadísticos y económicos actualizados a la época actual.
A continuación se desarrolla una serie de preguntas planteadas por el docente para el desarrollo de la materia.
La investigación se realizó con la asesoría de la Ingeniera Johana Bonilla Parra de la Universidad Católica de Colombia en conjunto con Shirley Stella Villarreal Sáenz.

Ver las fuentes de consulta web al final.

This paper presented an analytic investigation of pavement systems subjected to mill-and-overlay treatments-including grid reinforcement in-between the new asphalt concrete (AC) overlay and the underlying (existing) cracked and aged AC. The investigation was based on an updated version of the classic layered elastic theory capable of handling a fragmented layer. Such a layer mechanically replicates a multi-cracked AC offering considerable vertical stiffness alongside low bending rigidity. A thin high-modulus layer represented the reinforcing grid, fully bonded to the abutting AC layers. Three mill-and-overlay cases and an additional reference case were investigated for a pavement system under the loading of a dual-tire configuration. The cases differed by the milling depth (thin, medium, and thick), and by the inclusion or exclusion of a reinforcing grid. Key responses in the structure and subgrade, commonly associated with different pavement distress, were calculated and compared across the different cases. The analysis suggests that a reinforcing grid can potentially reduce bottom-up cracking and permanent deformation within the AC overlay for the medium and thick mill-and-overlay cases. For the thin mill-and-overlay case, the analysis suggests that topdown cracking is the expected distress mechanism. In this context, the inclusion of a reinforcing grid seemed to be ineffective. Finally, it is found that adding reinforcement to any of the mill-and-overlay cases produces only a marginal effect on key responses linked to the development of permanent deformation deeper in the structure and subgrade.

Grouted Macadam composite pavement (GMCP) is generally a composite pavement which is manufactured by preparing a highly workable fluid mortar which is specially designed with a very high early and 28 day strength (1 day - 45 MPa, 28 day - 105 MPa) by filling the flowing fluid mortar into a very open porous asphalt skeleton (25-32% Voids in Mix - VIM). The combination of both components will produce a semi-rigid pavement or GMCP which has the best features of both rigid concrete and flexible bituminous pavement where it will replace the conventional wearing course. This paper will investigate the significance difference of GMCP produced by the 3 different aggregate gradations by Road Engineering Association of Malaysia (REAM) in volumetric properties, durability and strength. The best quality fluid grout was chosen to fill the porous asphalt skeleton and GMCP was subjected for compression test, VIM and indirect tensile test (IDT) to check on its performance. The results show that the 3 different aggregate gradations significantly affect the volumetric properties, durability and strength. Furthermore it will also help in reducing pollution and helps with the current environmental problems. © 2010 IEEE.

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5653996

Past studies developed pavement performance models using data from all or multiple states across the United States. This study hypothesized that due to variation in agency practices and work activity profiles, individual pavement performance models should be estimated for each state, using data from its own roadway network, for use in its pavement management system. To test this hypothesis, this study used condition data of Interstate flexible pavements from eight Midwestern states to estimate three models: fixed-parameters regression, randomparameters regression, and artificial neural networks (ANNs). The ANNs model was found to statistically outperform the regression counterparts when estimating pavement roughness across all states. In contrast, the random-parameters model was statistically superior to the ANNs model in some cases when exploring the performance of these models for individual states. The statistical performance of models did not have a consistent trend across all states. Therefore, the application of models, based on data from multiple jurisdictions, could lead to erroneous/nonoptimal maintenance and rehabilitation decisions. Highway agencies are recommended to rely on their own jurisdictional data when developing their pavement performance models.

Resumen: Las losas cortas son una innovación en el área de pavimentos de hormigón, que implica un cambio de paradigma respecto al diseño, donde usualmente se limita el número de juntas. En este enfoque, el tamaño de la losa se diseña de tal manera que no más de un set de ruedas del vehículo quede sobre ella, con el objetivo de reducir las tensiones. La investigación asociada a esta innovación ha estado focalizada en pavimentos urbanos e interurbanos donde se han generado ahorros económicos de hasta un 25%. Por otra parte, los pisos industriales de hormigón tienen solicitaciones distintas a los caminos y carreteras, las cargas de tráfico son diferentes y los efectos climáticos considerados no son los mismos debido a que el piso industrial se encuentra, por lo general, cubierto por una estructura. El objetivo de este artículo es analizar el estado tensional de losas cortas bajo solicitaciones de pisos industriales mediante modelación de elementos finitos para generar recomendaciones de diseño. Esto se lleva a cabo mediante un análisis factorial que considera variables como localización del pavimento, fecha de construcción, geometría de las losas y tráfico. Los resultados indican que las losas cortas si pueden generar ahorros significativos en ciertos pisos industriales, pero que no son la mejor opción en todos los escenarios analizados. Sin embargo, son una muy atractiva alternativa para pisos industriales tipo bodega de uso masivo.

Abstract: Short slabs are a concrete pavement innovation that represents a change of paradigm in the traditional design (where the number of joints is limited). In this innovative approach, the concrete slab is designed in a way that no more than one set of vehicle wheels is actually on the slab. In this way, the stresses are reduced. The research related with this innovation has been focused in urban and interurban pavements, where the costs have been reduced even until 25%. On the other hand, the traffic demands over industrial floors are different from concrete pavements of streets or highways. In addition, the weather demands are different because a roof covers industrial floors. The objective of the present article is to analyze the stresses of short slabs for industrial floors using finite elements models in order to generate design recommendations. For that, a factorial design including variables as the pavement location, time of construction, slab geometry and traffic is defined. The results show that short slabs can generate significant costs reductions in certain industrial floors, but that they are not necessarily the best option for all the analyzed scenarios. However, short slabs are an attractive alternative for industrial floors commonly used as warehouses.

This project aims to evaluate the effectiveness of the quality measures employed by the Wisconsin Department of Transportation to influence the in-service performance of flexible pavements. The study involved creating a relational geo-referenced database connecting production, placement, and routine in-service performance data collected over the years for Wisconsin Projects. The database relied on geo-referencing all the data such that each individual data point is assigned a location. This approach allows for tracking the quality of the material and construction of specific segments of the roadway to the in-service performance. A subset of the projects was also included in an in-depth study using on-site distress survey and non-destructive testing using Falling Wheel Deflectometer (FWD). In general, the thirty (30) highway projects studied in this project show that transverse and longitudinal cracking are the most common distresses. Construction joint longitudinal cracking appears ...

Various types of Markov chain methodologies have been used in past research to develop stochastic performance models for infrastructure systems-the staged-homogeneous, nonhomogeneous, homogeneous, semi-, and hidden Markov. The primary components of a Markov model are the transition probability matrix, condition states, and duty cycle. This paper hypothesizes that the number of condition states (NCS) and length of duty cycle (LDC) significantly influence the prediction accuracy of a Markov model and that the nature of such influence varies across the different Markov methodologies. In previous studies on Markovian performance modeling, not only did this hypothesis go unanswered, but also there is a lack of comparison across the different Markov methodologies. In an attempt to shed light on this issue, this paper describes the development and comparison of performance models using these Markov methodologies and empirical data. The paper also investigates the sensitivity of Markovian model prediction accuracy to NCS and LDC. The results indicate that the semi-Markov techniques yield performance models that are generally statistically superior to those of the homogeneous and staged-homogeneous Markov (except in a few cases of NCS and LDC combinations) and that the prediction accuracy of Markovian models is very sensitive to NCS and LDC: an increase in NCS improves the prediction accuracy up to a certain NCS threshold, after which the accuracy diminishes, likely due to data overfitting. In addition, an increase in LDC generally enhances prediction accuracy when the NCS is small. The results can help guide highway agencies and researchers not only in selecting the appropriate Markovian methodology for a given NCS and LDC but also in selecting the appropriate NCS and LDC for a given Markovian methodology.

The Steenbreek program is a private Dutch program which aims to involve citizens, municipalities and other stakeholders in replacing pavement with vegetation in private gardens. The Dutch approach is characterized by minimal governmental incentives or policy, which leaves a niche for private initiatives like Steenbreek, that mainly work on behavioural change. The aim of this paper is to build a model based on theory that can be used to improve and better evaluate depaving
actions that are based on behavioural change. We tested this garden greening behaviour model in the
Steenbreek program. The main result is that the model provides an understanding of the ‘how and why’ of the Steenbreek initiatives. Based on this we are able to provide recommendations for the improvement of future initiatives. Steenbreek covers a wide range of projects that together, in very different ways, take into account elements of the theoretical framework; either more on information factors, or on supporting factors, sometimes taking all elements together in a single action. This focus is sometimes understandable when just one element is needed (e.g., support), sometimes more elements could be taken into account to be more effective. If a certain element of the framework is
lacking, the change of behaviour will not (or will only partly) take place. The model also gives insight into a more specific approach aimed at the people most susceptible to changing their behaviour, which would make actions more effective.

The present study evaluated the potential use of Blast Furnace Slag (BFS) as forming material of untreated granular layers in pavement (e.g. base, subbase and subgrade), and as stone aggregate in the manufacture of asphalt mixtures. For that purpose, tests of characterization, X-ray diffractometry (XRD), X-ray fluorescence (XRF) and imaging in a scanning electron microscope (SEM) were executed on the BFS. As a general conclusion is reported that the BFS can be used in the formation of unbound granular layers of subbase. As granular base material, its use would be recommended on roads with low traffic volumes or with thick asphalt layers and as a selected material, in tertiary roads that support light traffic. In the case of HMA is not recommended to use the coarse fraction of the BFS as a stone aggregate. However, the obtained results indicate that the fine fraction shows good characteristics to be used in the production of the mastic of such mixtures.

Here I discuss a collection of animal bones, found on the two succeeding wooden pavements of the medieval Kozmodemyanskaya Street of Novgorod the Great. The pioneering study draws attention to the bones found in wooden street pavements as a valuable source of information on the life of the medieval city.

The behavior in flexural fatigue tests of concrete containing metal fibers has not been extensively studied. Therefore, this study aims at determining the effects of incorporating metal fibers in concrete paving on flexural fatigue tests. A concrete mix was designed with modulus of rupture of 4.1 MPa at 28 days, which was added with steel fibers of 35 mm long and 0.5 mm in diameter in 3 proportions: 20 kg/m3, 40 kg/m3 and 80 kg/m3 and left to a non-corresponding control mixture addition.
Fatigue tests were performed on 68 specimens of 100 x 100 x 350 mm, at a frequency of 8 Hz, and stresses between 80% and 90% of the modulus of rupture of each mixture. The Weibull probability distribution was used to calculate the fatigue curves with different failure probabilities. For the stress ranges studied, the fatigue life did not increase in the mix with fiber content of 20 kg/m3, but it did increase by 6% to 40 kg/m3 (0.5%) and 25% to 80 kg/m3 (1%), compared with the control mixture.

This study investigated the effect of aggregate gradation on the permeability and mechanical properties of pervious concrete (PC). PC with 3 aggregate gradations was characterized by laboratory testing. Air voids distribution of PC was evaluated through conventional procedure and ...

Sometimes a pavement deflects only because of seasonal volume change of expansive soils in the pavement subgrade. Engineering practitioners expect an implementable and straightforward analysis method for a geosynthetic-reinforced pavement subjected to the swelling/shrinkage issue of expansive clayey subgrade, in an effort to find the bending moment, shear force and tension force distributions through the reinforced pavement, which are induced from the volumetric changes of subgrade soils. The virtual load method (VLM) was proposed in the past following the Timoshenko beam theory to analyze geosynthetic-reinforced pavement on expansive soils. In the VLM, the unknown virtual distributed load was obtained in the way by applying the inverse theory for the identification of material parameters of the pavement-foundation system. It was seen that the selection of the number of material parameters to obtain virtual load significantly affects the accuracy of the structural properties of the ...

The Mechanistic-Empirical Pavement Design Guide (MEPDG) includes empirical distress models that have been calibrated using national databases. It is necessary to calibrate these models using local pavement distress data, material properties, traffic information, and for local conditions. In this study, the distress models of fatigue cracking (bottom-up and top-down), rutting and roughness for flexible pavements were locally calibrated using 39 pavement sections in Arizona. Data needed were mostly obtained from the Long Term Pavement Performance (LTTP) program. The calibration (optimization) was performed by varying the local calibration coefficients in each distress model in order to reduce the sum of squared errors between predicted and measured distresses and to set the sum of standard errors to zero. Numerous trial runs of the MEPDG software with different calibration coefficients were made. The Excel Microsoft Solver was used to optimize various calibration coefficients. A compa...

This Paper describes the beneficial impact of reinforcing the sub-grade layer with a single layerof geo-grid at different positions and thereby determination of optimum position of reinforcement layer. The(best) optimum position was determined based on California Bearing Ratio (CBR value) and unconfined compression tests were conducted to decide the optimum position of geo-grid. The CBR value of a soil increases by 50-100% when it is reinforced with a single layer of geogrid. The amount of development (Improvement) depends upon the type of soil and position of geo-grid. CBR of sub-grade soil is 6.53% without reinforcement and when geo-grid was placed at 0.2H from the top, the CBR value increased to 19.66%. Soaked Condition CBR of sub-grade soil is 4.77% without reinforcement and when geo-grid was placed at 0.2H from the top, the CBR value increased to 4.46%.

Various methodologies are being developed to build and improve probabilistic pavement performance models that have high prediction capabilities. However, the effectiveness of preventive maintenance (PM) has not been considered in such models due to the lack of historical PM data. Consequently, the predicted pavement condition is erroneous and often biased, which leads to nonoptimal maintenance and rehabilitation (M&R) decisions. This paper introduces and validates a hybrid approach to incorporate the impact of PM into probabilistic pavement performance models when historical PM data are absent. The types of PM treatments and their times of application are estimated using two approaches: (1) analysis of the state of practice of pavement maintenance through literature and expert surveys, and (2) detection of PM times from probabilistic pavement performance curves. Using a newly developed optimization algorithm, the estimated times and types of PM treatments are integrated into pavement condition data. A nonhomogeneous Markovian pavement performance model is developed by estimating the transition probabilities of pavement condition using the ordered probit method. The developed hybrid approach and performance models are validated using cross validation with out-of-sample data and through surveys of subject matter experts in pavement engineering and management. The results show that the hybrid approach and models developed predict probabilistic pavement condition incorporating PM effects with an accuracy of 87%.

Past studies developed pavement performance models using data from all or multiple states across the United States. This study hypothesized that due to variation in agency practices and work activity profiles, individual pavement performance models should be estimated for each state, using data from its own roadway network, for use in its pavement management system. To test this hypothesis, this study used condition data of Interstate flexible pavements from eight Midwestern states to estimate three models: fixed-parameters regression, random-parameters regression, and artificial neural networks (ANNs). The ANNs model was found to statistically outperform the regression counterparts when estimating pavement roughness across all states. In contrast, the random-parameters model was statistically superior to the ANNs model in some cases when exploring the performance of these models for individual states. The statistical performance of models did not have a consistent trend across all states. Therefore, the application of models, based on data from multiple jurisdictions, could lead to erroneous/nonoptimal maintenance and rehabilitation decisions. Highway agencies are recommended to rely on their own jurisdictional data when developing their pavement performance models.

h i g h l i g h t s Mechanical properties of RCCP slightly decreased as a result of adding waste sand. Adding nano SiO 2 improved the mechanical properties of RCCP. The optimum content of Nano SiO 2 for RCCP was determined. Increasing the waste materials' content led to an increase in skid resistance. The mixes containing glass waste showed the highest abrasion resistance. a b s t r a c t This study deals with the use of waste materials as replacement of fine aggregate in roller-compacted concrete pavement (RCCP). To achieve this, waste ceramic, waste concrete, and waste glass were initially crushed and mixed and then replaced natural fine aggregate at varying amounts in RCCP. Furthermore, to mitigate the probable negative effects of waste aggregates and also to improve the mechanical properties of cement paste, nano SiO 2 was employed in the mixes design. After preparing the mixes, Vebe time, com-pressive strength, splitting tensile strength, water absorption, abrasion resistance, and skid resistance were measured. The results show that more than 40% of sand replacement with waste materials could have a negative effect on the properties of RCCPs. However, this impact is negligible up to 10% of waste material proportions. The compressive strength of the mixes containing waste materials was lower than that of the control mix, except for the sample containing 10% ceramic waste. In terms of water absorption, mixes with waste materials had higher water absorption than the control mix. Besides, abrasion somewhat increased as a result of adding waste materials, except for the samples containing 10% glass and 10% ceramic wastes that showed a slight decrease. Moreover, mixes with waste materials had higher skid resistance than the control mix. Overall, waste ceramic mixes showed better mechanical properties and waste glass mixes had better performance in terms of water absorption. In addition, using nano SiO 2 leads to improve the mechanical properties of the RCCP; the optimum content of nano SiO 2 has determined to be 0.7% of cement weight.