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Implementation of self-healing concrete technologies is a promising approach to enhance the durability of the transportation infrastructure. Among these technologies, bacterial concrete has the potential to seal microcracks through microbial-induced calcite precipitation (MICP). To ensure the viability of this technology, bacterial protection is essential given concrete’s harsh environment. Additionally, the success of this technology depends on the presence of an adequate mineral precursor compound and nutrient for the bacteria. As such, the main objective of this study was to optimize the healing efficiency of bacterial concrete in subtropical climates through the vacuum impregnation of bacteria into a lightweight aggregate (LWA). To achieve this objective, mortar samples were prepared while incorporating different combinations of precursors (magnesium acetate, calcium lactate, and sodium lactate) and alkali-resistant healing agent Bacillus pseudofirmus bacteria (with and without). In addition, a control sample was prepared without bacteria or precursors for comparative purposes. For each sample, three mortar cubes and three mortar beams were cast and used to evaluate the compressive strength, crack healing efficiency, and flexural strength recovery. Additionally, the morphology of healing products was observed in bacteria-containing samples under scanning electron microscopy with energy x-ray dispersive spectroscopy using a scanning electron microscope (SEM) with EDAX Pegasus energy dispersive spectroscopy (EDS). Results showed that self-healing bacterial concrete could be optimized (without significant reduction in mechanical properties) if Bacillus pseudofirmus bacteria at a concentration of 108 cells/ml and sodium lactate precursor at a concentration of 75 mM/l were impregnated into lightweight aggregate.

Extreme weather events, including inundation, are the major causes of weather-related disruption to the transportation sector. Considerable research has been conducted in recent years to evaluate the impacts of inundation on pavement functional and structural conditions. Yet, limited studies quantified how inundation may affect the long-term pavement performance and pavement life-cycle costs. As such, the main objective of this study was to quantify the impact of the 2016 inundation event in Louisiana, U.S., on the long-term pavement performance (in relation to reduction in the pavement service life [PSL]) and on pavement life-cycle costs. To achieve this objective, a total of 10 inundated pavement sections were evaluated. Pavement conditions, fatigue, and rutting indices for these sections were analyzed over a monitoring period of up to 15 years (11 years before and 4 years after inundation). Results indicated that the 2016 inundation event reduced the PSL of the inundated sections to an extent that depended on their pre-flooding pavement condition, traffic level, and asphalt concrete thickness. This reduction was attributed to the accelerated fatigue, rutting damage, or both, that resulted from prolonged water submergence and heavy traffic loading during debris hauling that took place after the inundation event. A logistic regression model with adequate accuracy was developed to predict whether an inundated pavement would experience reduction in its PSL based on the project conditions. The study findings were incorporated into a simple tool to assist transportation agencies make effective decisions for the maintenance and rehabilitation of inundated pavements.

Due to limited budget, most transportation agencies restripe their thermoplastic pavement markings based on a fixed schedule or based on visual inspection instead of monitoring the retroreflectivity and restriping when the retroreflectivity drops below a pre-determined threshold. These strategies are questionable in terms of efficiency and economy. Therefore, previous studies proposed degradation models to predict the retroreflectivity of thermoplastic markings based on key variables. Yet, most of these studies reported low R2 (as low as 0.1), which placed little confidence in these models. Therefore, the objective of this study was to evaluate and predict the field performance of thermoplastics and to propose cost-effective restriping strategies for thermoplastics used in hot and humid climate service conditions. To achieve this objective, National Transportation Product Evaluation Program (NTPEP) data were mined and analyzed. Results indicated that the service life (SL) of thermoplastics ranged between 0.4 and 12.1 years (according to the initial retroreflectivity, traffic, and surface type) with an average value of 3.4 ± 0.2 years. Four regression models with relatively high accuracy were developed to predict the SL of thermoplastics based on key variables. In addition, the genetic algorithm was used to develop a model that predicts the future retroreflectivty of these pavement markings. The predicted values were compared against actual retroreflectivity measurements collected from a field experiment at Louisiana State University. The results of this study could be used to make effective decisions related to restriping scheduling. Using the proposed models in restriping scheduling can result in considerable cost savings (up to $8,212 per lane-mile), as compared to the conventional restriping strategy., Tran-SET Project: 21BLSU11

In Louisiana, most districts restripe their roadways using waterborne paints every other year; this strategy is questionable in relation to efficiency and economy. Previous studies show substantial variability in paint service life throughout the U.S.A., ranging between 0.25 and 6.2 years. Shortcomings in modeling the retroreflectivity of waterborne paints appear to significantly contribute to these variations as several studies predicted these values using degradation curves with a coefficient of determination (R2) as low as 0.1. Therefore, the objective of this study was to develop new cost-effective restriping strategies using 4 in. and 6 in. wide waterborne paints (15 and 25 mils thickness) when applied on asphalt pavements in hot and humid climates. To achieve this objective, National Transportation Product Evaluation Program data were collected and analyzed to evaluate the field performance of waterborne paints commonly used in southern states of the U.S.A. and to develop a decision making model that may be used by transportation agencies to predict when to restripe their roadways. Results indicated that 4 in. wide standard paints exhibited service life up to four years depending on the line color, traffic and initial retroreflectivity, while 4 in. wide high build paints had a service life of at least three years. Based on a life-cycle cost analysis, it was concluded that Louisiana Department of Transportation and Development could restripe its district roads every three years instead of the current two-year period using the same product (4 in. or 6 in. wide) saving about $20 million or $2 million, respectively, every year when restriping a 5,000-mi network.

Pavement performance prediction models are used by state agencies to determine pavement maintenance and rehabilitation strategies. However, most performance prediction models are based on a limited number of parameters and a maximum prediction period of five years. With the ever-increasing amount of available pavement performance data, machine-learning techniques have become a promising alternative to traditional performance prediction models. The objective of this study was to develop a machine-learning-based framework for states with a hot and humid climate that can predict the long-term field performance (up to 11 years) of asphalt concrete (AC) overlays on asphalt pavements based on key project conditions. The pavement condition index (PCI) was used as the pavement performance indicator. Two machine-learning algorithms, namely, random forest (RF) and CatBoost, were examined. A total of 892 log-miles of AC overlay data were obtained from the Louisiana Department of Transportation and Development Pavement Management System database. Based on the collected data, six models were trained (for each algorithm) and validated to predict the PCI of AC overlays for up to 11 years. The results indicated that the RF algorithm yielded higher accuracy than the CatBoost algorithm. Therefore, the RF-based models were considered in the proposed decision-making framework.

The National Transportation Product Evaluation Program (NTPEP) database is a promising tool for U.S. state agencies to evaluate the performance of waterborne paint pavement markings. Out of the total 50 U.S. states, 29 states (57%) utilize the NTPEP data to assess the performance of waterborne paints to be included in the approved materials list. Yet, this dataset is based on transverse retroreflectivity (RL) measurements, which are significantly different from the longitudinal RL measurements in real-world conditions. As such, the key objective of this study was to develop a methodology that converts the transverse RL measurements of waterborne paints to the corresponding longitudinal measurements in hot and humid climate. This approach could be used by transportation agencies to predict the service life of their waterborne paints and make reliable restriping decisions. To achieve this objective, three road sections were selected in Louisiana, U.S., and four different waterborne paints were installed in the transverse and longitudinal directions. These road sections consisted of seven subsections with varying traffic levels and pavement surface types. The data collected included durability readings and longitudinal and transverse RL measurements at five time periods between October 2020 and April 2022. Based on the collected data, two non-linear regression models (for asphalt and concrete surfaces) were developed, with reasonable accuracy, to predict the longitudinal RL of waterborne paints based on the corresponding transverse RL. The predicted longitudinal RL could then be used to determine the expected service life of waterborne paints and make reliable restriping decisions.

Cement-stabilized full-depth reclamation (CSFDR) is a common rehabilitation treatment used by transportation agencies. Yet, several gaps exist in the literature regarding the long-term fiel...

Chip seal is a preventive maintenance technique typically applied on relatively low traffic roads to reduce pavement deterioration rate and to defer the need for costly rehabilitation activities. This study aims to address the common challenges with chip seal application in hot and humid climates such as Louisiana to ensure the maximum benefits are achieved. Specifically, this study evaluated the short and long-term field performances and optimal timing of chip seal by analyzing the cracking, roughness, and overall pavement conditions of 47 flexible and composite pavement sections in Louisiana. Furthermore, potential moisture damage in asphalt concrete after chip seal application was assessed. Results indicated that chip seal extended pavement service life by 4–17 years based on the pre-treatment pavement conditions and pavement type (flexible or composite). Based on the cost benefit analysis, it is recommended to use alternating cycles of asphalt overlay and chip seal on low volume roads (less than 5,300 vehicles per day) with chip seal applied when the pavement condition index (PCI) of the pavement drops to a value between 70 and 74. In this case, significant monetary savings could be achieved when compared with adding chip seals at different time periods (outside the recommended range of PCI between 70 and 74). Results also showed that the application of chip seal does not seem to contribute to moisture damage. Instead, shallow groundwater conditions present in the State seem to contribute to moisture damage in asphalt pavements owing to moisture entrapment underneath the asphalt layer.

Preventive maintenance treatments are widely used throughout the United States to extend pavement service life (PSL), and therefore, defer costly rehabilitation activities. However, optimizing the use of these treatments faces several key challenges. First, the benefits resulting from these treatments are not well-defined. Second, there is considerable debate over the optimal timing of these treatments. Third, concerns exist that these treatments may be responsible for moisture damage if the surrounding moisture conditions are not adequately considered before installation. Although significant research has been conducted to address these challenges, few efforts have been directed toward technology transfer and implementation of the research findings. Therefore, the objective of this study was to combine the results of a comprehensive research study addressing these challenges into an enhanced decision-making tool that can be used to select the best maintenance treatment to be applied to an existing asphalt concrete (AC) overlay based on the project conditions. For a given project, this tool will predict the most cost-effective maintenance treatment (crack sealing, chip seal, microsurfacing, or do nothing) to address existing surface distresses without causing moisture damage. The tool will also provide the optimal timing of installation of the recommended treatment. To ensure that the developed tool is practical and simple to use, it was developed using macros in Microsoft Excel. The developed tool is implementation-ready and should be utilized by the relevant Department of Transportation to maximize the benefits from pavement maintenance activities.

In Louisiana, most districts restripe their roadways using waterborne paints every other year; this strategy is questionable in terms of efficiency and economy. Meanwhile, previous studies showed substantial variability in the paint service life throughout the United States ranging between 0.25 and 6.2 years. Shortcomings in modeling the retroreflectivity of waterborne paints appear to significantly contribute to these variations as several studies predicted these values using degradation curves with a coefficient of determination (R2) as low as 0.1. Therefore, the objective of this study was to (i) develop new cost-effective restriping strategies using 4-inch (15-mil thickness) and 6-inch (25-mil thickness) wide waterborne paints when applied on asphalt pavements in hot and humid climates, and (ii) employ an advanced machinelearning algorithm to develop performance prediction models for waterborne paints considering the variables that are believed to affect their performance. To achieve these objectives, National Transportation Product Evaluation Program (NTPEP) data were collected and analyzed to evaluate the field performance of waterborne paints commonly used in Southern United States. Results indicated that 4-inch wide standard paints exhibited service life up to four years depending on the line color, traffic and initial retroreflectivity, while 4-inch wide high-build paints had a service life of at least three years. Based on a life-cycle cost analysis, it was concluded that LaDOTD could restripe their district roads every three years instead of the current two-year period using the same product (4-inch or 6-inch wide) saving about $20 or $2 million, respectively, every year when restriping a 5,000-mile network. Additionally two machine-learning models were developed with an acceptable level of accuracy, and that can predict the skip and wheel retroreflectivity of waterborne paints for up to three years using only the initial measured retroreflectivity and the anticipated project conditions over the intended prediction horizon, such as line color, traffic, air temperature, etc. These models could be used by transportation agencies throughout the United States to (1) compare between different products and select the best product for a specific project, and (2) determine the expected service life of a specific product based on a specified threshold retroreflectivity to plan for future restriping activities., Tran-SET Project: 20BLSU03

Concrete is a remarkable construction material. However, its low tensile strength makes it prone to cracking, which negatively affects its durability. To address this issue, bacterial concrete has been implemented as a self-healing alternative due to its capability to seal microcracks through microbial-induced calcium carbonate precipitation (MICCP). In this study, a bacterial strain (i.e, Bacillus Pseudiformus) was encapsulated through three different methods: encapsulation through hydrogel beads, vacuum impregnation on lightweight aggregates, and attachment to cellulose nanocrystals. Furthermore, three precursor types were used, magnesium acetate, calcium lactate, and sodium lactate were implemented. Compressive strength tests and flexural strength tests were performed on mortar specimens to characterize their mechanical properties. Once the crack was induced, samples were subjected to 28 days of wet/dry cycles in which the corresponding crack width was monitored. At the end of this period, the beams were retested to determine the strength recovery of the specimens. The results showed that the specimen groups in which calcium lactate was added to the cementitious matrix displayed the highest values in compressive strength. In terms of flexural strength, no major difference was found among the specimens. Moreover, the flexural strength recovery of the specimens did not show any significant difference as well. In terms of the healing efficiency, the sample that displayed the best results was the one containing calcium lactate as a precursor along with bacteria and yeast extract encapsulated in hydrogel beads. In addition, scanning electron microscopy (SEM) along with x-ray energy dispersive spectroscopy (EDS) was performed on the cracked specimens to characterize the healing products. Furthermore, a scale study was performed on concrete samples to determine the long-term implications of adding encapsulated bacteria along with calcium lactate and yeast extract in concrete., Tran-SET Project: 20CLSU05

Crack sealing prevents the ingress of water in the pavement structure, thus preventing the weakening of the pavement and delaying its deterioration. Earlier studies indicate that sealing pavements in areas with a high ground water table (GWT) may prevent moisture from escaping upwards through cracks in asphalt pavements, therefore, accelerating stripping. The objective of this study was to provide guidelines for using crack sealing to minimize moisture entrapment under cracks, thus reducing stripping on low volume roadways. To achieve this, a calibrated Finite Element (FE) model was used to model a field experiment consisting of cracked and crack-sealed asphalt pavement sections. Sensitivity analysis was then conducted to compare crack-sealed and unsealed sections under different GWT levels, air relative humidity, air temperatures, rain intensities, and asphalt hydraulic conductivities. Results indicate that crack sealing could be applied under common rain intensities in Louisiana and any GWT depth without potential for stripping because of moisture entrapment if the hydraulic conductivity of the original pavement does not exceed 2 × 10–6 m/s. Yet, crack sealing should be applied after a dry period to ensure that the existing moisture in the original pavement is minimal. A non-linear regression model was developed for use in the Southern United States to help determine whether crack sealing should be used to avoid moisture damage in a cracked pavement at a given site based on the GWT and air relative humidity without the need for FE simulations. This can be a useful tool when planning maintenance activities.

Generally, the use of reclaimed asphalt pavement (RAP) has been limited to asphalt mixes. Recently, this trend has changed to include using RAP in unbound pavement layers. However, the cost-effectiveness of this application is not well studied. This paper presents a methodology to conduct cost–benefit analyses for using RAP–sand blend in subgrade and subbase layers considering a general process of RAP–sand blend from different sources until it is used in construction. Eight scenarios of RAP–sand blend applications were considered. Each scenario has two pavement sections (control and alternative) and was evaluated using the mechanistic-empirical approach. The benefit of using RAP–sand blend in the alternative section was assessed in terms of saving in asphalt thickness under various equivalent single axle load (ESALs) ranging between 1 and 12 million. Four mixing options were identified, and results for Option 1 (fresh RAP and mixing at site) indicated significant saving ranging between –$ 0.48 and $9.29/m2 depending on the scenario of RAP blend utilization. The highest benefit–cost ratios were also achieved with this option. Estimated benefit–cost ratios ranged between 0.58 and 18.64 depending on the scenario and option considered in the analysis, with uneconomic situations associated with Scenario 3. In this analysis, no significant impact was found for ESALs when their values are above 1 million. Generally, the RAP–sand blend is more effective in reducing required asphalt thickness, especially when used as a subgrade or subbase layer below thinner unbound aggregate layers. The significant saving achieved may encourage future implementation of this blend.

Backcalculation analysis of pavement layer moduli is typically conducted based on falling weight deflectometer (FWD) measurements; however, the stationary nature of FWD requires lane closure and traffic control. To overcome these limitations, a number of continuous deflection devices were introduced in recent years. The objective of this study was to develop a methodology to incorporate traffic speed deflectometer (TSD) measurements in the backcalculation analysis. To achieve this objective, TSD and FWD measurements were used to train and to validate an artificial neural network (ANN) model that would convert TSD deflection measurements to FWD deflection measurements. The ANN model showed acceptable accuracy with a coefficient of determination of 0.81 and a good agreement between the backcalculated moduli from FWD and TSD measurements. Evaluation of the model showed that the backcalculated layer moduli from TSD could be used in pavement analysis and in structural health monitoring with a reasonable level of accuracy.

One of the most common methods used to treat longitudinal and transverse cracks is crack sealing (CS), which is categorized as a preventive maintenance method. Field performance and cost-effectiveness of this treatment widely vary depending on pavement conditions and installation of the material. The objective of this study was to evaluate the field performance and cost-effectiveness of CS in flexible and composite pavements in hot and wet climates such as Louisiana, and to develop a model that would quantify the expected benefits of CS given project conditions. To achieve this objective, 28 control sections that were crack-sealed between 2003 and 2010 were monitored for at least four years. These sections included flexible and composite pavements, sealed and unsealed segments, and varying traffic levels. The performance of these sections was evaluated for the random cracking index (RCI) and roughness index (RI). Based on the results of this analysis, it was concluded that CS only has a significant impact on random cracking. When compared with untreated segments, CS extended pavement service life (PSL) by two years. When compared with the original pavement, CS extended PSL by 5.6 and 3.2 years for flexible and composite pavements, respectively, if applied at the correct time. The cost-benefit analysis indicated that CS is cost-effective whether asphalt emulsion or rubberized asphalt sealant is used. A non-linear regression model was developed to predict the extension in PSL because of CS without the need for performance data based on the average daily traffic (ADT), pavement type, and prior pavement conditions.

Interface bonding conditions between pavement layers have a major impact on pavement performance. The objective of this study was to assess interface bonding conditions between pavement layers using falling weight deflectometer deflection measurements. In addition, the effect of interface bonding conditions on the backcalculated layer moduli was investigated. To achieve these objectives, a new methodology was developed based on FWD measurements collected in 46 sections in Louisiana. These measurements were used to backcalculate the layer moduli using MODULUS 6.0 software. BISAR 3.0 software was then used in conjunction with MODULUS 6.0 to backcalculate the asphalt concrete (AC)/base bonding condition and to correct the backcalculated base layer moduli. The results of the proposed methodology were verified through evaluation of extracted cores. Based on the results of this analysis, it was found that the interface bonding conditions significantly influenced the accuracy of the backcalculation analysis. The...

Crack sealing and seal coats are used to prevent the ingress of water into the pavement, thus delaying its deterioration. Yet, earlier studies indicated that sealing pavements in areas with high ground water table (GWT) prevented moisture from escaping upwards through the cracks of asphalt pavements, therefore, accelerating stripping. The objectives of this study were to determine whether these treatments contribute to stripping in Asphalt Concrete (AC) and/or moisture accumulation in the base and to evaluate the effect of GWT, rain, and traffic on subsurface failures under these treatments. In this study, nine test sections included in the Long-Term Pavement Performance (LTPP) program and several field chip seal projects in Louisiana were analyzed. Results indicated that these treatments do not contribute to stripping. However, the cause of common stripping under these treatments in the Southern United States is moisture entrapment under the AC layer under shallow GWT conditions, which is also the key contributor to stripping under unsealed sections.

Transportation agencies often need to differentiate between top-down and bottom-up cracking in the field to set up an effective and targeted schedule and budget for the repair of these crac...

In Louisiana, 50% of the districts use microsurfacing as a maintenance treatment with yearly expenditure of $4,700,000 (about 37% of overall budget allocated to pavement preservation) throu...

Crack sealing of asphalt concrete (AC) overlays is an important component of pavement preventive maintenance. The objectives of this study were to evaluate the cost effectiveness (CE) of cr...

In Louisiana and many other states, the design pavement service life (PSL) for structural asphalt concrete (AC) overlays is typically assumed to be 20 years. However, research studies showe...