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This paper focuses on the fatigue resistance properties and susceptibility to moisture damage of different bituminous mixtures used as sub-ballast layers in French railways. The analysis is made taking into account the specific working conditions and service life requirements of trackbeds. Three different road base-course mixtures used as sub-ballast layers in France were studied. A new moisture-conditioning procedure was proposed and used to induce moisture damage in the samples. Tension-compression fatigue tests were carried out on cylindrical samples at the Laboratory of Civil Engineering and Construction (LGCB) of the ENTPE, University of Lyon. All the tested mixtures were found to present satisfactory fatigue resistance properties. Low voids content and the use of polymer-modified bitumen were found to improve the resistance to moisture damage.

Moisture-induced damage is one of the most prominent distresses affecting pavement structures worldwide. As a consequence, various strategies for mitigating this phenomenon have been proposed, including the use of additives to improve bitumen-aggregate bonding, engineered to mitigate/counteract the moisture damage effects. Among these, the reported benefits of various lime forms, such as hydrated lime (HL), have propelled its use (mainly in the United States from the early 70s) as widely reported in scientific literature. However, very few studies have been conducted in the United Kingdom with locally available materials, specifications and testing methods suitable for that purpose. Therefore, this study investigates the effects of HL on the moisture damage resistance of stone mastic asphalt (SMA) mixtures designed, produced and tested under local UK conditions. A set of asphalt slabs with a target 4.0% air voids content and two bitumen contents (5.6 and 6.2%) using granite aggregates were manufactured using a roller ‘slab’ compactor consisting of control mixtures (0% HL) and those with 1, 2 and 3% HL by weight of total mixture. Characterisation of the mixtures was done via the saturated ageing tensile stiffness (SATS) test to account for both the effects of ageing and moisture damage. The SATS test results showed a positive effect of the addition of HL on the moisture damage resistance, however increasing HL contents only produced marginal additional improvements. The influence of the reduction in bitumen content was negligible. Furthermore, the results indicated an optimum dosage of 1% HL for enhanced moisture damage resistance.

Recycled plastic is now recognised as a potential bituminous binder extender and modifier, with various studies demonstrating the potential to improve asphalt mixture properties, including resistance to cracking and resistance to deformation. Many waste plastic products are intended to be dry-mixed into the asphalt production plant, but wet mixing into the bituminous binder is also possible. Laboratory tests for fracture resistance, moisture damage resistance and deformation resistance were used to compare otherwise identical wet-mixed and dry-mixed recycled plastic modified asphalt, as well as comparison to nominally identical control (unmodified) asphalt. The binder was also extracted from tested specimens and compared using common index properties, including elastic recovery, softening point and penetration. The effect of recycled plastic on the asphalt mixture properties and the binder properties was a generally significant improvement in deformation resistance, with no reduction in fracture resistance. Importantly, the wet-mixed and dry-mixed results were generally not significantly different, indicating that the two mixing processes are equally effective. Further research should focus on the practical issues of distribution and digestion of recycled plastic through the asphalt mixture during dry-mixing, as well as digestion and storage stability of wet-mixing into bituminous binder.

A considerable proportion of patients having respiratory tract or voice symptoms associated with workplace moisture damage (MD) could have multiple chemical sensitivity (MCS). MCS is characterized by symptoms of different organ systems in association with low-level chemical exposure. The objective of this study was to assess the prevalence of MCS among patients referred to secondary health care because of respiratory or voice symptoms associated with workplace MD compared to the general working-age population. Using three subscales of the QEESI© questionnaire, we assessed MCS in the study patients and 1500 controls in the same district randomly selected from the Finnish Population Information System. Study patients had significantly more often high scores in chemical intolerance (39% vs. 23%, p = 0.001), symptom severity (60% vs. 27%, p < 0.001), and life impact subscales (53% vs. 20%, p < 0.001). Asthma, chronic rhinosinusitis, laryngeal problems, and atopy were not associated with the presence of MCS. MCS is common among patients referred to secondary health care with respiratory tract and/or voice symptoms associated with workplace MD, and it considerably affects their everyday life. MCS should be considered as a possible explanatory factor for MD-associated symptoms.

Porous asphalt (PA) mixtures are designed with a high air void (AV) (i.e., 18~22%) content allowing rainwater to infiltrate into their internal structures. Therefore, PA mixtures are more sensitive to moisture damage than traditional densely graded asphalt mixtures. However, the moisture damage evolution of PA mixtures is still unclear. The objective of this study was to investigate the moisture damage evolution and durability damage evolution of PA mixtures. The indirect tensile test (ITT), ITT fatigue test, and Cantabro loss test were used to evaluate the moisture sensitivity and durability of PA mixtures, and a staged ITT fatigue test was developed to investigate the damage evolutions under dry and wet conditions. Indirect tensile strength (ITS), fatigue life, indirect tensile resilience modulus (E), and durability decreased with the increment of moisture damage and loading cycles. The fatigue life is more sensitive to the moisture damage. The largest decrements in ITS and E were found in the first 3000 loading cycles, and PA mixtures tended to fail when the decrement exceeded 60%. Damage factors based on the ITS and E are proposed to predict the loading history of PA mixtures. The durability damage evolution and damage factors could fit an exponential model under dry conditions. Moisture had a significant influence and an acceleration function on the moisture damage evolution and durability damage evolution of PA mixtures.

The present paper offers a micromechanical modeling approach to evaluate the impact of the porosity structure on the response of asphalt concrete as a viscoelastic multiphase material under...

Background Exposure to indoor moisture damage and visible mold has been found to be associated with asthma and respiratory symptoms in several questionnaire-based studies by self-report. We aimed to define the prospective association between the early life exposure to residential moisture damage or mold and fractional exhaled nitric oxide (FeNO) and lung function parameters as objective markers for airway inflammation and asthma in 6-year-old children. Methods Home inspections were performed in children's homes when infants were on average 5 months old. At age 6 years, data on FeNO (n = 322) as well as lung function (n = 216) measurements were collected. Logistic regression and generalized additive models were used for statistical analyses. Results Early age major moisture damage and moisture damage or mold in the child's main living areas were significantly associated with increased FeNO levels (>75th percentile) at the age of 6 years (adjusted odds ratios, 95% confidence intervals, aOR (95% CI): 3.10 (1.35-7.07) and 3.16 (1.43-6.98), respectively. Effects were more pronounced in those who did not change residential address throughout the study period. For lung function, major structural damage within the whole home was associated with reduced FEV1 and FVC, but not with FEV1/FVC. No association with lung function was observed with early moisture damage or mold in the child's main living areas. Conclusion These results underline the importance of prevention and remediation efforts of moisture and mold-damaged buildings in order to avoid harmful effects within the vulnerable phase of the infants and children's immunologic development.

As escórias de aciaria, como Linz-Donawitz (LD), sofrem expansões volumétricas quando submetidas ao calor e à umidade. Contudo, o ligante asfáltico pode estabilizar a expansão da LD em misturas asfálticas à quente (MAQ). Este trabalho objetiva avaliar os efeitos da expansão da LD no comportamento mecânico de MAQ sujeitas ao envelhecimento e dano por umidade. Foram avaliadas quatro MAQ, uma de referência e três misturas com 25% LD com diferentes expansões iniciais. As misturas foram submetidas ao envelhecimento de curto e longo prazo. Posteriormente, foram submetidas a ensaios de dano por umidade induzida e resistência à tração indireta. Também foi avaliada a expansão dos agregados extraídos das MAQs. As misturas com LD apresentaram resultados mecânicos satisfatórios e até superiores à mistura de referência. Não foi observada diferença significativa nos valores de expansão de agregados extraídos das misturas após condicionamento, indicando que os efeitos da expansão da LD podem ter sido estabilizados.

Background: Respiratory tract symptoms are associated with workplace moisture damage (MD). The focus of this observational clinical study was patients with workplace MD-associated symptoms, to evaluate the usefulness of different clinical tests in diagnostics in secondary healthcare with a special interest in improving the differential diagnostics between asthma and laryngeal dysfunction. Methods: In patients referred because of workplace MD-associated respiratory tract symptoms, we sought to systematically assess a wide variety of clinical findings. Results: New-onset asthma was diagnosed in 30% of the study patients. Laryngeal dysfunction was found in 28% and organic laryngeal changes in 22% of the patients, and these were common among patients both with and without asthma. Most of the patients (85%) reported a runny or stuffy nose, and 11% of them had chronic rhinosinusitis. Atopy was equally as common as in the general population. Conclusions: As laryngeal changes were rather common, we recommend proper differential diagnostics with lung function testing and investigations of the larynx and its functioning, when necessary, in cases of prolonged workplace MD-associated symptoms. Chronic rhinosinusitis among these patients was not uncommon. Based on this study, allergy testing should not play a major role in the examination of these patients. publishedVersion

The modification of asphalt mix with waste polymers provides several benefits. Among the most important is the optimization of the performance of the mix and the increase in its useful life. Not to mention a reduction in the amount of plastic waste that does not have an adequate waste management. This article shows the results obtained from a study where a blister type waste material (composed of polymers such as PVC) was incorporated into an asphalt mixture by the dry method. Method in which, prior to the asphalt adhesion, the modifier is incorporated to the mix in substitution of part of the fine aggregate. The purpose of the study was to evaluate the performance of the mix and compare its mechanical behavior with a conventional mix. For the project development, the modifier was characterized, and the appropriate percentage was selected so that the design of the modified mixture would comply with Superpave requirements. With the optimized design, the test specimens were prepared, and their performance was evaluated based on the following tests: four-point beam bending, Hamburg wheel, retained tensile strength (moisture damage) and dynamic modulus. Since an adequate behavior of the modified mix was observed, its sensitivity was evaluated in a pavement structure; identifying in which layers of the asphalt mix should the material be used. La modificación de mezclas asfálticas con polímeros de desecho brinda diversos beneficios. Entre los más importantes se encuentra la optimización del desempeño de la mezcla y el incremento en su vida útil. Esto sin considerar, una reducción en la cantidad de residuos plásticos que no poseen un adecuado manejo de desecho. El presente artículo muestra los resultados obtenidos de una investigación en donde se incorporó a una mezcla asfáltica un material de desecho tipo blíster (compuesto por polímeros como el PVC) por medio de la vía seca. Método en donde, previo a la adhesión del asfalto, se incorpora a la mezcla el modificante en sustitución de parte del agregado fino. Esto con el propósito de evaluar el desempeño de esta mezcla y comparar su comportamiento mecánico con el de una mezcla convencional. Para la ejecución del proyecto se caracterizó el modificante (blíster) y se seleccionó el porcentaje adecuado para que el diseño de la mezcla modificada cumpliera con las especificaciones de la metodología Superpave. Con el diseño definido se realizaron los especímenes de ensayo y se evaluó su desempeño con las pruebas de: fatiga a cuatro puntos, rueda de Hamburgo, resistencia retenida a la tensión diametral y módulo dinámico. Como se identificó un adecuado comportamiento de la mezcla modificada, se evaluó su sensibilidad en una estructura de pavimento; identificando en qué capas de la mezcla asfáltica sería conveniente utilizarla.

Frank Llyod Wright’s Fallingwater House designed and built for Edgar Kaugmann, Jr. is one of the most celebrated examples of design excellence, innovation, and creativity. The building is located on Bear Run in the Mill Run section of Stewart Township, Fayette County, Pennsylvania, located in the Laurel Highlands of the Allegheny Mountains, near Pittsburgh, PA. The house is partly built on a waterfall, which at the time of its construction became a source of several construction challenges including moisture damage and structural problems. How these challenges were negotiated and resolved over time and how the Fallingwater stood the test of time exemplify a unique opportunity to introduce the decision-making process of value-based design. This chapter presents a retrospective design added value analysis of Fallingwater, including key historical events that contributed to its design, construction, and emergence and resolution of its several construction challenges.

Warm mix asphalt (WMA) is increasingly recognised as a green paving technology in terms of energy saving and emission reduction. The reduction in mix production temperature associated with ...

Sustainability is very important in this world at this time. One of the best materials used for sustainability in asphalt concrete pavements is the warm mix asphalt (WMA) as well as the reclaimed asphalt pavement (RAP). WMA technology has the ability to reduce production temperature to reduce the fuel usage and emissions. RAP is the old concrete asphalt mixture that is out of service and using it again leads to preservation of the virgin material. This search studied the viability of using WMA with different percentages of RAP (10%, 30%, and 50%) and compared them with control hot mix asphalt (HMA) and WMA. The Marshall properties, Tensile strength ratio (TSR), rut depth and fatigue life were determined in this work. The results showed that the tensile strength ratio (TSR) for HMA was better than that for WMA by 6%, rut depth for HMA was (4.37 mm) lower than that for WMA was (6.5mm), better fatigue life was obtained for WMA was (700 cycle) as compared to HMA was (500 cycle). In case of WMA with RAP (WMA-RAP), when the percentage of RAP increased with WMA, the moisture damage resistance improved by 2.5%, 13.3% and 15.4% for G1, G3 and G5 respectively, also the rutting resistance improved by 34.6%, 48% and 62.3% for G1, G3 and G5 respectively, but deteriorated of fatigue life by 45.8%, 74% and 88.5% for G1, G3 and G5 respectively.

Moisture-induced damage in asphalt concrete is a major concern to the transportation agencies. Existing moisture sensitivity tests are mostly conducted at the macro- or micro-level and focused on t...

Wind-driven rain is one of the most important moisture sources that may lead to moisture damage risks of building envelopes, particularly when the rainwater unintentionally infiltrates into the envelope assembly through defects of the wall components. This paper proposes a stochastic modelling approach to evaluate the impact of rain infiltration on hygrothermal performance of highly insulated wood-framed walls, including an I-joist deep cavity wall, two exterior insulated walls, and a conventional 2×6 stud wall as the baseline wall. The stochastic hygrothermal models of the walls are created based on the uncertainties of material properties and rain deposition factor under different scenarios with rain infiltration deposited at different locations of the wall assembly. The stochastic simulation results show that the rainwater deposited on a water resistive barrier does not cause any moisture damage risk, but there is a significant risk when the rainwater is directly deposited on the exterior or interior surface of wood sheathing, and the interior deposition has the highest risk.

The accumulation and crystallization of alkane acids at the interface of bitumen and siliceous aggregates are known to increase the propensity for moisture damage in bitumen-based composites such a...

Currently, many studies seek to find materials that are friendlier towards the environment. Warm mix asphalt (WMA) technology helps to decrease manufacturing temperature in traditional hot mix asphalts (HMA), which reduces emissions that are detrimental to the environment. For the case of asphalt pavements, WMA technology, which uses recycled materials such as blast furnace slag (BFS), this could be an interesting alternative technique. Reutilizing these types of industrial waste materials for roadway project constructions could help to minimize negative impacts on the environment. In this study, the coarse fraction of natural aggregate in a control HMA was replaced with BFS. Additionally, a chemical additive was used to lower mixing temperature by 30 °C, and thus manufacture WMA. Marshall, indirect tensile strength, resilient modulus and permanent deformation tests were carried out. This additive helps to reduce air void content, reduces mixing and compacting temperatures and increases asphalt stiffness. Studied WMA that has a 12.5% substitution of coarse natural aggregate fraction with BFS, results in a significant increase in stiffness (under monotonic and cyclic loads), as well as an increase in resistance to moisture damage and to permanent deformations, when compared to control HMA.

This research focused the impact of various aggregate gradations on permanent deformation and moisture susceptibility of asphalt concrete mixtures. Five wearing course of different gradation, namely NHA-A, NHA-B, SP-1, SP-2 and MS-2, were adopted. Two paving grade bitumen i.e. 40/50 and 60/70 were used. Hamburg Wheel Tracking Test (HWTT) and Modified Lottman test were performed to assess rutting propensity and moisture damage of asphalt mixtures. The results indicated the superior performance of NRL 40/50 binder in HWTT while mixes prepared with Parco 60/70 showed better resistance against moisture. In HWTT, NHA-A performed well followed by NHA-B and SP-2 while MS-2 and SP-1 failed the minimum rut depth criteria. All the mixtures passed the minimum benchmark for Tensile Strength Ratio (TSR). Aggregate gradation SP-1 given in Superpave guidelines provided greater resistance to moisture damage due to compact nature of the blend. Rutting tendency of the mixtures increased with increasing TSR and decreasing Indirect Tensile Strength (ITS).

Rejuvenator additive primary restores aged asphalt binder properties from its oxidized state. In this study, different rejuvenators were evaluated based on the performance of asphalt mixtures containing reclaimed asphalt pavement (RAP). Through a three-point bending (TPB) test, the induction heating healing level was investigated. This observation led to further testing on three rejuvenators to evaluate its performance on moisture damage (stripping), rutting, and cracking susceptibility. The test results indicated that using rejuvenator additive substantially benefit recycled asphalt mixtures in self-healing capability. Good ranking correlation was observed between healing level and cracking resistance for late healing cycles.

Raveling, as one of the key distresses of the chip seal, affects the performance of the chip seal. A new cold-mixed ultra-thin (CMUT) chip seal consisting of modified emulsion, single particle size aggregate, and cement was designed. The wet track abrasion test (WTAT) was used to study the effects of curing conditions, submersion durations, amounts of aggregate, emulsion, and cement on both the early raveling and wet raveling resistance of the CMUT chip seal. In addition, the binder bond strength (BBS) test was also used to evaluate the moisture-induced damage with the prolonging of submersion durations. Additionally, the one-way analysis of variance was used to analyze the sensitivity of different factors. The results indicate that both temperature and curing time could significantly affect the raveling resistance of the CMUT chip seal. It is confirmed that submersion duration has significant influences on aggregate losses and pull-off strengths. With the prolonging of submersion duration, the moisture damage was severe but tending stable. Therefore, the raveling potential of specimens after being submerged for 6d was used to evaluate the wet raveling potential. According to the sensitivity analysis, it is confirmed that the emulsion dosage is the most significant factor affecting both the early and wet raveling resistance. Cement dosage is recognized to have dramatic effects on wet raveling resistance, while the effects are negligible when it comes to early raveling resistance. Furthermore, the amount of aggregate can hardly influence the raveling resistance of the CMUT chip seal.

Porous asphalt pavements have been widely used because of their advantages of drainage and noise reduction. However, these pavements are susceptible to moisture damage due to the characteristically large portion of air voids. Therefore, the maintenance of porous asphalt pavement has become one of the research hotspots. Microwave technology is generally used as a kind of high-efficiency maintenance method, but now it is also recommended as the technology to heal the micro-cracks in the pavement. However, there is little research conducted on its healing efficiency of asphalt mixture suffered from moisture damage. In this paper, the influence of ferrite content on the pavement performance, mechanical properties and heating effect was studied. Through the indirect tensile fatigue test, the effects of microwave heating time, healing time and damage degree on the self-healing efficiency of moisture-damaged asphalt mixture before and after microwave heating were studied based on the evaluation indexes of the fatigue life extension ratio and fatigue life recovery ratio. It is found that the optimal microwave heating time and optimal healing opportunity of OGFC-13 asphalt mixture with 5% ferrite are 120 s and 50% damage degree respectively. In addition, the longer the healing time, the better the healing effect, but the influence of the healing time is smaller compared with the heating time.

In this study, the effects of virgin aggregate content, such as mineral filler, machine-made sand, and coarse aggregate, on the performance of emulsified asphalt cold recycled mixtures (ECRMs) prod...

Freeze-thaw damage in asphalt pavements is a complex phenomenon dependent on many parameters such as moisture infiltration, temperature and mechanical properties of the asphalt constituents as well...

This study investigated the effects of aggregate-binder adhesiveness on moisture damage and on fatigue life of four different asphalt mixtures. Adhesivemeness was assessed by: (i) qualitative observation of binder stripping from the coarse aggregate’s surface, incremented in this paper with digital image processing, and (ii) modified Lottman test. Fatigue damage modeling was performed, using tension-compression test results. The granitic aggregate produced mixtures with better moisture resistance and fatigue properties when compared to the phonolitic aggregate (same ranking as for aggregate-binder adhesiveness). The same was observed for mixtures with binder containing an anti-stripping agent. It was demonstrated that mixtures with better aggregate-binder adhesiveness have greater fatigue life.

This paper investigates the effects of Acrylonitrile Butadiene Styrene (ABS) polymer as an asphalt binder modifier on reducing the moisture susceptibility of hot asphalt mixtures. In order ...

The present study was undertaken to evaluate the effects of different warm mix asphalt (WMA) additives on bonding behaviour of asphalt binder and aggregates using two different approaches: (i) The ...

Moisture damage is one of the common distresses in pavements; it is mainly associated with failure of interfacial bonds between bitumen and the stone aggregates that form the skeleton of pavement. ...

Iron production’s waste materials include significant quantities of blast furnace slag (BFS) which could potentially be used as a substitute for natural aggregates in hot mix asphalt (HMA) used in highway projects. Although many of properties of slag are interesting, its porosity and absorption rate would lead to greater consumption of asphalt. For this study, a Portland cement (PC) paste was used to reduce the porosity of a BFS. This PC treated BFS (called BFS-C) was then used in an HMA to replace the coarse fraction of a natural aggregate. Marshall, Indirect Tensile Strength (ITS), resilient modulus and Cantabro tests were then carried out on different HMA mixtures that included BFS-C. Using BFS-C, HMA’s resistance under monotonic loading, stiffness under cyclic loading, and resistance to moisture damage increased remarkably. In addition, the Cantabro abrasion resistance of BFS-C improved was better than that of the HMA mixture produced with untreated BFS.

Implementation of Warm Mix Asphalt concrete (WMA) is getting global acceptance due to the restrictions for protecting the environment and the requirements to reduce fuel consumption. In this investigation, two WMA mixtures have been prepared in the laboratory using medium curing cutback (MC-30) and Cationic emulsion asphalt. Hot Mix Asphalt (HMA) was also prepared for comparison. The cylinder specimens (63.5mm) in height and (101.6mm) in diameter were constructed from the mixtures and subjected to indirect tensile strength test to determine the Tensile Strength Ratio (TSR). The cylinder specimens of (101.6mm) in height and (101.6mm) in diameter were also constructed from those mixtures and subjected to static compressive strength test to determine the Index of Retained Strength (IRS). It was concluded that the WMA are more prone to moisture damage than HMA, the TSR are (92 and 86) % for (emulsion and cutback) WMA respectively, both are lower than of HMA by (2.13 and 8.51) % respectively. As the asphalt content increases, the TSR also increases and reached to peak value of Optimum Asphalt Content (OAC) then decreases. The WMA has less IRS than HMA, the IRS are 70% and 78% for the WMA-emulsified asphalt and HMA respectively.

The current study was undertaken to evaluate the effect of Polyphosphoic Acid (PPA) on rheological properties of different grades of asphalt binders containing a chemical Warm-Mix Asphalt (WMA) add...

The market for modular buildings based on prefabricated room modules made of cross-laminated timber (CLT) is rapidly growing in Europe. Short construction times combined with high construction quality due to prefabrication are highly attractive features of this construction method. While structural design aspects have been steadily improved, only little attention has been paid to mechanical, electrical and plumbing (MEP) systems so far. However, the integration of water-bearing pipes and surface seals must be done with great care, since a permanent exposure of the timber construction to moisture caused by leaks may result in biological degradation of the wooden structure. The risk of moisture damage can be reduced by decreasing the length of horizontal piping by means of intelligent pipe routing. In addition, sensor technology can be used to detect water leaks in critical areas where other measures fail to provide sufficient protection. Both aspects are addressed in this paper. First, the results of an analysis of nine completed construction projects based on CLT modules including hotels, student residences, nursing homes, and health care centers are presented. The projects were used to identify the current state of practice regarding the design of CLT room modules with respect to the integration of MEP installations. In a next step, general strategies for a safe integration of MEP installations in timber buildings are outlined. A bathroom layout with optimized pipe routing based on three individual shafts is chosen to show the application of these strategies. The approach enables a considerable reduction of horizontal pipe length while maintaining the functional and architectural requirements of the room module. Finally, a new planar sensor for detecting water leaks is presented. The results were developed in the research project SensGT and will lead to standardized solutions for a safe integration of MEP installations in CLT room modules.

One of the widely used parameters in evaluating moisture susceptibility of asphalt mixtures is tensile strength ratio (TSR). From a mechanical point of view, TSR is only appropriate at the bottom o...

In this study, it has been attempted to use thermodynamics theories and the surface free energy (SFE) method to evaluate the effect of anti-stripping additives on the asphalt binder cohesion and as...

The quantification of moisture susceptibility has been a major concern for researchers as it adversely affects the performance of asphalt pavements. Several methods have been developed to assess bond strength using asphalt mixtures in loose and compacted state. These tests lack in their ability to study fundamental properties that affect the bond between bitumen and aggregate. In this context, more fundamental techniques have been developed such as pull-off stub tests and direct tension tests. The first group only measures the maximum pull-off strength and second group has problems related to use of consistent binder film thickness and operational difficulties in test itself. This paper presents a new test to evaluate bond strength, in an attempt, to solve problems associated with traditional direct tension tests. The aim is achieved through a review of existing techniques, development of a gap assembly, fabrication of direct tension test moulds, development of Compression Pull-Off Test (CPOT) and evaluation of its results. The key parameters for bitumen and mastics were evaluated. The CPOT shows promising results for use of this technique to study cohesive as well as adhesive bond strength of binder.

Moisture damage has become one of serious distresses to reduce stability of pavement structure and service life. One of the most essential reasons for moisture damage is insufficient adhesion betwe...

Aggregate–binder adhesiveness in asphalt mixtures is affected by the physico-chemical properties of aggregates and asphalt binder. The objective of this paper is to analyse how aggregate morphologi...

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.

In this paper, the moisture susceptibility of different bituminous binders with two substrates (glass and limestone) was investigated. To that end, the tensile strength of different combinations of bituminous binder–substrate bond was measured using a pull-off test. This test was adapted from the pneumatic adhesion tensile testing instrument (PATTI) test to improve repeatability. Samples were tested in dry condition and after a 7-day conditioning in hot water bath (60 °C). An analysis of variance (ANOVA) was performed on the test results. Overall, the results show that in dry condition, the pull-off strength is a function of the bituminous binder type rather than of the substrate type. After water conditioning, an increase in the pull-off strength was observed for the bituminous binder without polymers and coupled with glass substrate. This was associated with an increase in binder stiffness. For the limestone substrate, the effect of water conditioning was significant only for one type of binder.

Moisture induced damage can cause a progressive deterioration in the performance of asphalt pavement by the loss of adhesion between asphalt binder and aggregate surface and/or loss of cohesion within the binder in the presence of water. The objective of this paper is to improve the asphalt mixtures resistance to moisture by using hydrated lime as an anti-stripping additive. For this purpose, two types of asphalt binder were utilized; asphalt grades (40-50) and (60-70) with one type of aggregate of 19.0 mm aggregate nominal maximum size, and limestone dust as a mineral filler. Marshall method was adopted to find the optimum asphalt content. Essentially, two parameters were determined to evaluate the moisture susceptibility, namely: The Index of Retained Strength and the Tensile Strength Ratio. The hydrated lime was added by 1.0, 1.5, and 2.0 percentages (by weight of aggregate) using the saturated surface dry method. It was concluded that using hydrated lime will improve the moisture damage resistance. This was adopted as the value of tensile strength ratio increased by 24.50 % and 29.16% for AC (40-50) and AC (60-70) respectively, furthermore, the index of retained strength also increased by 14.28 % and 17.50 % for both asphalt grades. The optimum hydrated lime content founded to be 1.5 %.

The performance of asphalt concrete is severely influenced by moisture. The presence of moisture in asphalt pavement substantially reduces its designed service lifetime. Currently, the indirect tensile strength test with constant loading rate is employed to estimate the moisture damage potential to an asphalt mixture. This evaluation method is empirical in nature and, therefore, suitable for only empirically designed asphalt pavements. However, speculation exists in that the conventional testing method may inappropriately simulate actual field conditions. Therefore, this research aims to evaluate the moisture damage potential to asphalt concrete under cyclic loading using the dynamic creep testing platform. The dynamic creep test provides the flow number, which represents the number of loading cycles at the failure point of the asphalt mixture. Three different types of asphalt mixtures commonly used in Western Australia were investigated in this research. The dynamic creep test provided more reasonable evaluation results of potential moisture damage than the conventional method. The tensile strength ratio of all mixtures in this research were greater than 80%, which is the conventional design criteria. On the other hand, the dynamic creep test reveals that flow number ratio of two mixtures dropped below 80%. The flow number ratio of 14 mm mixture was 58%, while 56% was obtained from 20 mm mixture. However, high uncertainty in the dynamic creep test results was observed, due to the interpretation technique. In conclusion, based on the research findings, the dynamic creep test can be used as a complementary test of the stripping potential in asphalt concrete.

A custom enhanced and modified Rice test setup was utilised in this laboratory study to assess and quantify the moisture sensitivity of hot-mix asphalt (HMA) under hydrodynamic pressure testing. Th...

One of the major causes of premature failure in asphalt pavements is moisture damage. Asphalt mixtures designed without considering climate impacts may suffer from durability problems caused by movement of water inside the asphalt mixture. Rolling traffic over wet pavement builds up pore pressure in the mixture, which will consequently accelerate deterioration. The objective of the study was to assess the moisture damage to asphalt concrete mixtures by means of complex modulus testing of dry and moisture-conditioned asphalt specimens with various mixture compositions. The asphalt mixtures were conditioned with the Moisture Induced Sensitivity Tester (MIST), which aims to replicate pore pressure in field conditions. The results showed a decline in stiffness modulus and a reduction in elastic properties after MIST conditioning. In addition, the results indicated that binder content and air void content had a significant influence on the reduction in stiffness. To capture the relationship between air void content, binder content, and the reduction in stiffness, a relationship was developed and validated with measurements on cores extracted in the field.

To enhance the moisture damage performance of hot mix asphalt (HMA), treating the aggregate surface with a suitable additive was a more convenient approach. In this research, two types of aggregate modifiers were used to study the effect of moisture damage on HMA. Three different aggregate sources were selected based on their abundance of use in HMA. To study the impact of these aggregate modifiers on moisture susceptibility of HMA, the indirect tensile strength test and indirect tensile modulus test were used as the performance tests. Moisture conditioning of specimens was carried out to simulate the effect of moisture on HMA. The prepared samples’ tensile strength ratio (TSR) and stiffness modulus (Sm) results indicated a decrease in the strength of the HMA after moisture conditioning. After treating the aggregate surface with additives, an improvement was seen in dry and wet strength and stiffness. Moreover, an increasing trend was observed for both additives. The correlation between TSR and strength loss reveals a strong correlation (R2 = 0.7219). Also, the two additives indicate increased wettability of asphalt binder over aggregate, thus improving the adhesion between aggregate and asphalt binder.