Moisture Damage Evaluation Research Articles

Rubber tire wheel tracking to isolate the effects of moisture via wet and dry specimen pairs

In this paper, data from the PURWheel-G2, a rubber tire wheel tracker, was utilized alongside several techniques to better understand isolation of the effects of moisture on asphalt rutting. Techniques commonly used to interpret wheel tracking data, particularly to evaluate moisture damage, were summarized and used to evaluate over 150 PURWheel-G2 tests where wet and dry pairs of tests were conducted to directly isolate the effect of moisture on rutting. Among all the available wheel tracking analysis techniques and models for moisture evaluation, there lacks a consensus approach, and available approaches vary widely highlighting the need for a standard test method. The rubber tire wheel tracker presented in this paper aims to take a step towards developing test protocols to isolate moisture damage. The ability to measure the effects of moisture on rutting is a feature that other existing wheel tracking methods cannot do on their own.

Evaluating the Effect of Curing Time and Resting Time on Moisture Damage Resistance of Asphalt Mixtures Using the Pull-Off Tensile Strength (POTS) Test

This article explores the effectiveness of the Pull-off Tensile Strength (POTS) test as a tool for evaluating the moisture damage resistance of asphalt mixtures. Currently, indirect tensile strength (ITS) and the Hamburg Wheel Tracking (HWT) test are used, but they have limitations such as expensive equipment and being heavy. The POTS test is a low-cost and portable alternative. This study investigated the effect of curing time and resting time on the POTS of asphalt-aggregate systems by subjecting samples to different curing times and resting times before testing their tensile strength under dry and wet conditions. The results show that the tensile strength decreases with increasing curing time or exposure to water, indicating that the debonding process between asphalt and aggregates occurs more rapidly with aging. The tensile strength ratio (TSR) of the POTS test for all three asphalt binder types increases with resting time and curing time, with the highest values observed at a curing time of 2 h and a resting time of 5–15 min. Additionally, this study found a strong linear relationship between the tensile strength ratios of ITS and POTS tests, regardless of curing time and resting time. Overall, the POTS test is a promising alternative for evaluating moisture damage resistance in asphalt mixtures.

Evaluation of the cohesive bond strength of bitumen and mastics

The evaluation of fundamental mechanical properties of bitumen is vital to construct long-term performing pavements. This research evaluates cohesive bond strength of bitumen and mastics using compression pull-off test (CPOT). The results show problems in the common interpretation of load-displacement curves. A discussion is made on fibrillary nucleation in binder. The curing for 24 h is sufficient for the development of the cohesive bond. Furthermore, longer conditioning is needed to evaluate the moisture damage using aluminium plates. Bitumen source, grade, filler content, and loading rate affect the pull-off strength (POS). Ageing increases POS and shifts the failure mode towards brittle. The type of filler does not affect POS after short-term ageing. The moisture conditioning reduces the POS and results in a mixed to adhesive failure with increased variability in results. The aggregate plates are necessary for detailed moisture damage evaluation. The use of re-used aggregate substrate is found to be ineffective.

Twenty-Five Years of Rubber Tire Wheel Tracking of Asphalt Pavements in a Laboratory

This paper assesses the state-of-the-art for rubber tire wheel tracking of asphalt mixtures in a laboratory setting with emphasis on differentiating moisture damage from rutting. This assessment made use of a comprehensive literature review and roughly 300 experiments conducted over several years with the second generation of the Purdue Laboratory Wheel Tracker (PURWheel). The literature review revealed that direct separation of rutting from moisture damage with physical measurements taken with a rubber tire under otherwise identical conditions is not common practice. Collective analysis of these roughly 300 experiments revealed that second-generation PURWheel protocols offer two specific contributions to the asphalt mixture testing community: (1) a pneumatic rubber tire is used, which is most representative of vehicle traffic; and (2) the effects of moisture damage can be decoupled from rutting by testing under both wet and dry conditions where all other parameters are constant. The analysis was performed on data collected for other purposes, but the data did provide seven manners to evaluate moisture damage and three manners to evaluate variability in the context of standardizing protocols. These 10 evaluations clearly demonstrated the potential of rubber tire wheel tracking to improve characterization of asphalt mixtures beyond what has occurred to date. This paper works toward standardization of protocols for rubber tire wheel tracking in wet and dry conditions, and some discussion is provided on the status and needed advancements toward this eventual goal.

Evaluation of Moisture Damage in Asphalt Mixtures at Macro- and Nanoscales

AbstractThe aim of this study was to examine the effects of different additives on the moisture resistance of asphalt binders using atomic force microscopy (AFM), and to correlate the results with ...

Evaluating Moisture Damage Using Impact Resonance Test

Abstract Moisture damage in asphalt mixtures has been a major cause for premature failure of asphalt pavements for decades. Although a lot of research has been done and many test methods have been developed to evaluate moisture damage in asphalt mixtures, not much research has been done on the use of nondestructive testing techniques to evaluate moisture damage in asphalt mixtures. The impact resonance (IR) test is a nondestructive test that is used to determine material properties like dynamic elastic modulus. The IR test on asphalt mixtures is done on a thin-disk specimen (150-mm diameter and 25-mm thickness). In this study, the IR test was used to assess moisture damage in asphalt mixtures by determining the resonant frequency of asphalt mixture samples in the unconditioned and moisture conditioned state. The relative reduction (ER) in dynamic elastic modulus was calculated as the ratio of the resonant frequency of conditioned and unconditioned specimens from the IR test, which was used to evaluate moisture damage. Moisture sensitivity of the asphalt mixtures was also determined by the tensile strength ratio (TSR) test. Two different moisture conditioning procedures were used for both the IR test and TSR test—modified AASHTO T 283 (Standard Method of Test for Resistance of Compacted Asphalt Mixtures to Moisture-Induced Damage) and Moisture Induced Stress Tester (MIST) conditioning. Six different mixtures from three different aggregate sources were used in this study. A good correlation was observed between TSR values from the TSR test using both conditioning procedures and the ER values from the IR test using both conditioning procedures for the asphalt mixtures used in this study. This study shows that the IR test can be used to evaluate moisture damage in asphalt mixtures. This study also explored the effects of various parameters such as support condition, impact source, and impact location on the resonant frequency from the IR test.

Combined Use of Wind-Driven Rain Load and Potential Evaporation to Evaluate Moisture Damage Risk: Case Study on the Parliament Buildings in Ottawa, Canada

Parts of the building envelope that frequently receive high amounts of rain are usually exposed to a higher risk of deterioration due to moisture. Determination of such locations can thus help with the assessment of moisture-induced damage risks. This study performs computational fluid dynamics (CFD) simulations of wind-driven rain (WDR) on the Parliament buildings in Ottawa, Canada. Long-term time-varying wetting load due to WDR and potential evaporation are considered according to several years of meteorological data, and this cumulative assessment is proposed as a fast method to identify critical locations and periods. The results show that, on the Center Block of the Parliament buildings, the façades of lower towers facing east are the most exposed to WDR, together with the corners of the main tower. Periods of high WDR wetting load larger than the potential evaporation are observed, indicating that deposited rain may lead to moisture accumulation in the envelope. During these critical periods of up to several months, air temperature may repeatedly drop below freezing point, which poses a risk of freeze–thaw damage. First assessment on future freeze–thaw damage risks indicates an increase in such risks at moderate increases in temperature, but a lower risk is found for larger increases in temperature.

Evaluation of performance of hot mix asphalt contained various sizes of Reclaim asphalt pavement and polymer modified Bitumen

The present investigation intends to investigate the performance of Hot Mix Asphalt (HMA) included Reclaim Asphalt Pavement (RAP) and Polymer Modified Bitumen (PMB) binder prepared with Novolac (phenol–formaldehyde solid resin)polymer. In order to assess the mechanical properties and performance of HMA with various RAP contents, several laboratory tests such as Marshall tests, indirect tensile strength testing, moisture damage evaluation, creep compliance test, and wheel track test was performed. The substitution was conducted in two stages: the first stage includes replacing the coarse aggregate with RAP up to 40percent with an increment of 10percent and the second stage includes the substitution of fine aggregate with the same percentages. The PMB binder was prepared by testing several mixes with various percentages of Novolac and its cross-linking agent (Hexamine). The findings of experimental work showed that the use of PMB binder significantly improves the mechanical properties and performance of HMA. Also, it shows that the substitution of coarse aggregate with RAP produces a substantial improvement in mechanical properties and performance of HMA compared with the substitution of fine aggregate or with control mix.

Mechanical performance and global warming potential of unaged warm cup lump modified asphalt

The use of natural rubber modified bitumen to improve pavement performance exist over a century. However, few documented research explore its mechanical performance in warm mix asphalt (WMA). This paper examined the rutting, moisture damage, tensile properties and carbon emission of cup lump rubber modified asphalt (CMA) in hot mix asphalt (HMA) and WMA. Aggregate coating and compactability tests were employed to select the production temperature of the WMA. The result shows that the warm cup lump modified asphalt (WCMA) has excellent rutting resistance of less than 2 mm rut depth at 8000 load repetitions representing 21% improvement compared with the conventional HMA. The tensile property was improved by 62% due to cup lump rubber (CLR) modification. Moisture damage evaluation shows that the WCMA retained more than 95% bitumen coating and has a tensile strength ratio (TSR) value of 99%, thus fulfilling the AASHTO T283 minimum requirement of 80%. The asphalt mixtures resistance to severe condition of stripping and rutting happening simultaneously revealed that the mixes are more sensitive to rutting than the stripping component of the APA-moisture damage test. The emission test result shows that producing WCMA at 40 °C lower than CMA reduced 5 kg of CO2 equivalent, amounting to 23% reduction in global warming potential. The multi-attribute analysis combined the mechanical performance results and environmental impact to rank WCMA as the optimum mixture for future road construction.

An Erosion Test to Evaluate Moisture Damage of Cement-Treated Base under Dynamic Water Pressure

Abstract Different kinds of testing methods were used in recent studies to evaluate the moisture damage of a cement-treated base. However, these methods were based on the condition of static water, without considering the effect of dynamic water pressure and stress conditions in the pavement, which could not truly reflect the moisture damage process of the pavement base. This study presents details of a new method of evaluating the moisture damage of a cement-treated macadam under dynamic water pressure. Specimens with different curing times (7 d, 14 d, and 28 d) were scoured by means of a self-designed dynamic water scouring system, and the compressive strength was tested after scouring. The results show that most of the damage caused by scouring occurs in the early stage (less than 10 min), which accounts for more than 80 % of the total damage. Although the scouring damage continues in the later period (10∼40 min), the damage process is relatively slow. The results of the compressive test show that both the strength loss and strength loss rate of specimens at 28 d are much smaller than that of 14 d and 7 d. Results reveal that the curing time of the specimens has an essential influence on the scouring resistance.

Effects of moisture damage on asphalt mixtures

Abstract The reduction in the ability of bitumen to bond with the aggregate surface due to the infiltration of moisture has been recognised for years, and this deterioration phenomenon is called moisture damage. In general, the loss of bonding between bitumen and aggregate shortens the service life of the top layer of the pavement. Many investigations have been conducted to understand the mechanisms of moisture damage due to the loss of bonding strength between bitumen and aggregate and to find ways to improve and strengthen the bond to mitigate the effect of moisture. This paper reviews the extensive literature on the loss of bitumen-aggregate bonding strength due to moisture damage in asphalt mixtures. The general description of the theories and mechanisms that explain the effect of the thermodynamic, chemical, physical and mechanical characteristics of the bitumen and aggregate on the bonding phenomenon are discussed in this paper. In addition, the causes of and contributing factors to moisture damage and methods to improve the bond between bitumen and aggregates are also discussed. Moreover, a description of the test methods that can be used to evaluate moisture damage in poorly bonded and compacted mixtures are also presented. Special attention is given to a well-known method, known as the pull-off test, which has been successfully used to evaluate aggregate-binder bond strength, both for laboratory and in-situ tests. This includes the test methods, the factors that affect the bonding strength results and their correlation with other test method. A review of the failure mode of bitumen under the pull-off loading test is discussed in the final section of this paper.

Multi-scale damage characterization of asphalt mixture subject to freeze-thaw cycles

This paper summarizes the results of laboratory tests including scanning electron microscopy (SEM), X-ray computed tomography (CT), a developed interfacial shear test and the indirect tensile test. These tests were performed to characterize the damage of dense-graded asphalt mixture under freeze-thaw cycles from different length scales. SEM was utilized to observe the surface of asphalt mixture samples and showed that micro-cracks occurred at the contact interface between asphalt and aggregate after cyclic freeze-thaw exposure, indicating the loss of adhesion bonds at the aggregate-mastic interface. Meanwhile, X-ray CT and a set of image processing techniques were employed to capture the evolution of three-dimensional internal structure within samples under freeze-thaw cycles from a mesoscopic-view. Three-dimensional images reconstructed from X-ray CT images illustrated that the diversification in internal structure was observed to occur mainly in three ways: (1) expansion of existing individual voids, (2) combination of two separated air voids, and (3) generation of new voids. Furthermore, a developed interfacial shear test was conducted to quantify shear bond properties between asphalt and aggregate, which revealed that the interfacial shear strength decreases with the increase of the number of freeze-thaw cycles and declines rapidly at the initial stage of freeze-thaw cycles. Finally, the indirect tensile test (IDT) was applied to evaluate the loss of tensile strength within the samples on a macro-scale. The evolution of IDT strength consisted with the variations of mesoscopic parameters such as interfacial shear strength, three-dimensional void content and void number, and then a systematic evaluation of moisture damage of asphalt mixture could be done.

3D reconstruction of moisture damage resulted volumetric changes in porous asphalt mixture

Porous asphalt pavements are widely used to make moisture penetrate pavement surface faster than dense-graded mixtures, thus improving driving safety. Long-term interaction with moisture makes its moisture susceptibility deserve intensive attention. Methods currently used to detect moisture susceptibility do not factually simulate the mechanism of moisture damage in pumping action. Meanwhile, there is less concern about the variation in volumetric properties, such as air void content, distribution, interconnectivity of pores and asphalt volume after moisture damage. This study simulated field moisture damage with different hydrodynamic pressures by MIST (Moisture Induced Sensitivity Tester) to detected evolution of volumetric properties of porous asphalt mixture. X-ray Computed Tomography and Mimics software were used for acquiring internal structure, processing 3D reconstruction and analysis of asphalt mixture. Resilient modulus test was conducted to evaluate moisture damage degree and moisture resistance of SBS and HVA (high viscosity modified asphalt) mixtures were compared. The results show that distinctly growths of air voids and moisture damage degree were found when MIST-conditioning pressure increased from 276 kPa to 414 kPa for SBS mixtures. Extension of pores for SBS-414 kPa is most obvious and high-viscosity asphalt can effectively improve moisture resistance. Hydraulic pressure can significantly influence the moisture damage degree, so it should be selected according to the actual traffic conditions instead of constant default.

Moisture damage evaluation of asphalt-aggregate constituents and warm mix asphalt using imaging techniques and tensile tests

Warm Mix Asphalt (WMA) is more susceptible to adhesive failures at the asphalt-aggregate interface than Hot Mix Asphalt (HMA) due to its lower production temperature. This paper presents an innovative approach to quantify the adhesive failures of asphalt-aggregate constituents and mixtures in direct and indirect tensions, respectively. Advanced imaging techniques were utilized to compute the specimens percentage adhesive failure. A PG-64 bitumen was the conventional binder used. Hydrated Lime (HL) and Pavement Modifier (PMD) were used as anti-stripping fillers, while Evotherm (EV) was incorporated as the surfactant-WMA additive. Three moisture conditioning levels were performed namely; unconditioned, 1 freeze-thaw (F-T) and 3 F-T cycles prior to testing. The specimens percentage adhesive failure increased, while tensile strength reduced with F-T cycle. PMD specimens exhibited slightly lower percentage adhesive failure than HL specimens. The percentage failure further reduced with the incorporation of EV. The effects of incorporating EV were more pronounced when combined with PMD as shown by the higher tensile strength and lower percentage failure than HL-EV. Limestone specimens showed superior moisture resistance than granite in moist condition. The high percentage broken aggregate on the fractured surfaces of tested asphalt mixtures was found to be more related to aggregate orientation than shape.

Evaluation of Moisture Damage under Crack-Sealed Asphalt Pavements in Louisiana

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.

Stripping at the Bitumen–Aggregate Interface: A Laboratory Method To Assess the Loss of Chemical Adhesion

Moisture damage, cracking, and deformation are the three chief distresses caused by traffic and climate during the service life of an asphalt pavement. One manifestation of moisture damage is the loss of bond between bitumen and aggregate, resulting in the displacement of the bitumen in a process called stripping. While numerous tests try to evaluate moisture damage in the laboratory, most of them show poor correlation with field performance. A fuller understanding of stripping is still needed to enable paving technologists to predict and prevent the effects of moisture damage. This study aims to develop a new stripping resistance evaluation technique, wherein adhesion is measured exclusively as a function of the chemical interaction between bitumen and aggregate. A key element of the evaluation technique discussed herein uses a time-lapse image analysis method to characterize the dynamic wetting of precisely applied bitumen droplets on the surfaces of polished mineral aggregates during immersion in a the...

Investigating influence of mineral filler at asphalt mixture and mastic scales

This study is devoted to understand the mechanisms of mineral fillers in asphalt at the mixture and mastic scales. To do so, the physical properties of asphalt mixtures and mastics were evaluated; in addition, a chemical investigation was presented into the mastic scale for the sake of providing insight into the possible mechanisms between asphalt binder and mineral filler. Three mineral fillers namely hydrated lime (HL), limestone (LS), and cement bypass dust (CD) were incorporated into an asphalt binder at different filler-to-binder (F/B) ratios. For the mechanistic evaluation of the mixtures, the indirect tensile strength (ITS), moisture damage evaluation, resilient modulus, and static creep-recovery tests were carried out. The fracture energies also were quantified for all the studied mixtures. The results of penetration and softening point tests, as well as their pertinent penetration index (PI), were discussed to elucidate some physical properties of the mastics. The nuclear magnetic resonance (NMR) spectroscopy was performed on the mastics to obtain information on molecular structures of the formed composites. The findings of this study emphasize that the physical properties of mixtures and mastics are highly dependent on type and concentration of mineral filler. The 1H NMR and 13C NMR results proved that the inclusion of the studied fillers did not change the molecular structure of the base asphalt binder; hereby the physical mechanisms stand behind the attained properties. It is believed that the findings of this work would contribute to growing knowledge of the mechanisms of mineral fillers in asphalt mixtures.

Investigating the mechanical properties of asphalt concrete containing waste polyethylene terephthalate

Reviewing the literature shows that limited work has been conducted on polyethylene terephthalate (PET)-modified asphaltic materials with inconsistent results, missing the investigation of some aspects such as the effect of PET particle size. This paper investigated the effects of waste PET content and particle-size distribution on some engineering properties of asphalt concrete. To this end, Marshall specimens of the mixtures containing different ground waste PET contents of 0%, 2%, 4%, 6%, 8%, and 10% (by the weight of asphalt binder) were subjected to Marshall, indirect tensile strength (ITS), moisture damage, and dynamic creep tests. Two different sizes of PET particles were used: one with particles in the range of 1.18–2.36 mm as coarse-graded PET, and the other with particles in the range of 0.297–0.595 mm, as fine-graded PET. ITS test was conducted on dry and conditioned specimens to evaluate moisture damage susceptibility. Dynamic creep tests were performed under the stress level of 300 kPa at 40°C. Results show that, for both coarse- and fine-graded PET particles, the highest Marshall quotient is achieved at 4% of PET content, after which it decreases with increasing the PET content. Furthermore, results indicate that, for both fine and coarse PET particles, the mixture containing 2% of PET content has the highest ITS and resistance against moisture damage. Based on dynamic creep test results, the resistance against permanent deformation decreases with increasing the PET content. Comparing the results for the mixtures containing coarse and fine PET particles shows that a better performance can be achieved using finer PET particles.

Moisture damage evaluation of aggregate–bitumen bonds with the respect of moisture absorption, tensile strength and failure surface

The moisture-induced deterioration of asphalt mixture is because of the loss of adhesion at the aggregate–bitumen interface and/or the loss of cohesion within the bitumen film. An experimental study was undertaken in this paper to characterise the effects of moisture on the direct tensile strength of aggregate–bitumen bonds. The aim of this paper was to evaluate the moisture sensitivity of aggregate–bitumen bonds in several different aspects, which included moisture absorption, tensile strength and failure surface examination. Moisture absorption and mineralogical compositions of aggregate were measured using gravimetric techniques and a Mineral Liberation Analyser (MLA), respectively, with the results being used to explain the moisture sensitivity of aggregate–bitumen bonds. Aggregate–bitumen bond strength was determined using a self-designed pull-off system with the capability of accurately controlling the bitumen film thickness. The photographs of the failure surface were quantitatively analysed using Image-J software. The results show that the magnitude of the aggregate–bitumen bonding strength in the dry condition is mainly controlled by bitumen. However, the retained tensile strength after moisture conditioning was found to be influenced by the mineralogical composition as well as the moisture diffusion properties of the aggregates. The linear relationship between retained tensile strength and the square root of moisture uptake suggests that the water absorption process controls the degradation of the aggregate–bitumen bond. The results also suggested that the deterioration of aggregate–bitumen bonds is linked to the decrease in cohesive failure percentage.

Studying viscosity of asphalt binders and effect of varied production temperatures on engineering properties of hot mix asphalt mixtures

The objectives of this paper are studying the viscosity characteristics of asphalt binders containing different additives, ethylene vinyl acetate, polypropylene, and hydrated lime, and the influence of varying mixing and compaction temperatures on the engineering properties of the corresponding mixtures. The engineering properties of the asphalt mixtures were investigated using the indirect tensile strength, moisture damage evaluation, and volumetric properties (in terms of the air void content). Based on the viscosity results, the non-Newtonian behavior of the asphalt binders prevails with the increase in the concentration of polymers and hydrated lime, thus the setting of the production temperatures using the equiviscous principle would be expected to be rather inaccurate. The variation in the production temperatures affected the engineering properties of the asphalt mixtures. It is recommended that a revision of the production temperatures from different methods be undertaken to satisfy the desired engineering properties for different conditions.