Moisture Damage Of Hot Mix Asphalt Research Articles

Measuring moisture damage of hot-mix asphalt (HMA) by digital imaging-assisted modified boiling test (ASTM D3625): Recent advancements and further investigation

Boiling water test (ASTM D3626) has been utilized to investigate the moisture susceptibility of asphalt mixture for decades. It was originally intended to compare the relative moisture resistance of a few mixtures, and the degree of stripping after the boiling was recorded based on visual observations. In recent years, several digital imaging-assisted modified boiling tests have been proposed, which significantly improved the accuracy of test results. This paper reviewed the recent advancements (2009–2022) in different test methods by digital imaging. The limitations and challenges of each method were also discussed and compared to each other. In addition, further experiments were performed to investigate the effect of aging, boiling time and water quality on the coating ratios. The boiling test results of sixty loose mixtures were compared to the tensile strength ratios (TSRs). Based on the results, the boiling water test with enhanced accuracy by image processing can be potentially developed as a measure of field performance. More importantly, the test should be conducted immediately after the mixing of asphalt and aggregate, and the aging of asphalt mixtures could significantly increase the results of coating ratios up to 100%, which made the boiling test unable to identify moisture susceptibility. It was found that the boiling water could not strip asphalt from aggregate after a long time of aging even though the moisture damage occurred and weakened the bond between asphalt and aggregate. In addition, the water quality could considerably influence the boiling test results, and the use of distilled water might underestimate the moisture damage of asphalt mixtures subjected to acid rain.

Evaluation of the Specific Surface Method as a Tool to Determine the Binder Content of Fine-Aggregate Matrices

AbstractStudies have shown that fine-aggregate matrices (FAM) are a good tool to assess fatigue cracking and moisture damage of hot-mix asphalt (HMA) mixtures. However, there is no consensus on the...

Effect of centrifuged latex on moisture damage of hot-mix asphalt with brick aggregate

First-class bricks and waste (i.e. overburnt) bricks can be used as a substitute for stone aggregates in asphalt concrete. However, the high porosity of brick aggregate can result in moisture damage, which results in premature distresses in asphalt pavements. In this study, the effect of centrifuged latex (Cenex) on the moisture susceptibility of asphalt mixtures made with overburnt bricks and first-class bricks as aggregate was investigated. Moisture damage tests, such as tensile strength ratio, resilient modulus ratio, retained Marshall stability, boiling water and wheel-tracking tests, were conducted. It was found that the addition of Cenex to the virgin binder improved the mixture resistance against moisture damage for both aggregate mix types. Besides the improvement of moisture damage, the addition of latex also enhanced the rutting resistance and stability of a plain asphalt concrete mix. The work shows that Cenex enhances the performance of brick aggregate asphalt concrete against moisture damage and is an efficient substitution in pavement structures.

Investigating the influence of using nano-composites on storage stability of modified bitumen and moisture damage of HMA

ABSTRACTIn this study, a composite of styrene butadiene rubber (SBR) and nano-clay was made with different ratios and used for bitumen modification. The results show that using nano-composites improves storage stability at high temperature. However, pure SBR modified bitumen is proved not to be stable at high temperature. Investigating the results of indirect tensile strength and indirect tensile strength ratio also indicates that nano-composites improve moisture sensitivity of hot mix asphalt (HMA). Further, according to the results, increasing the content of nano-clay enhances the resistant of asphalt mixtures against moisture damage.

Investigating the effects of using nanomaterials on moisture damage of HMA

In the past few years, several studies have been conducted focusing on the use of nanomaterials as additives in asphalt mixtures. Nevertheless, the effects of these additives on the moisture susceptibility of asphalt mixtures have not been studied. In this study, the effects of using nano-CaCO3 as an antistrip additive on moisture susceptibility of asphalt mixtures have been assessed using the surface free energy (SFE) method and modified Lottman test. Hot mix asphalt (HMA) samples were made with asphalt binders containing 0, 2, 4 and 6% of nano-CaCO3 and two sources of aggregate, namely limestone and granite. One, three and five freeze–thaw cycles were applied to HMA samples in a modified Lottman test to explore the effect of nanomaterials, clearly. The results of the modified Lottman test show that the wet/dry ratio values of indirect tensile strength (ITS) for mixtures containing nanomaterials were higher than those of control samples. In addition, the results of the SFE method indicate that nano-CaCO3 increases the wettability of the asphalt binder on the aggregate and promotes the adhesion between the asphalt binder and aggregate. Adding nanomaterials leads to the decrease of the acid component of SFE and increases the basic component of SFE of the asphalt binder that leads to an increase of adhesion between the asphalt binder and sensitive aggregate against moisture damage.

Estimating the moisture damage of asphalt mixture modified with nano zinc oxide

One of the main distresses of hot mix asphalt (HMA) is moisture damage. The most common method for decreasing this type of distress is using antistrip additives. In this study, the effect of nanoparticles was evaluated as an antistrip agent on the moisture damage of HMA. Two types of aggregates were evaluated in this study with different sensitivities against moisture damage (limestone and granite aggregate) and the asphalt binder with 60/70 penetration grade and nano zinc oxide (ZnO) in two different percentages by weight of the asphalt binder. The tests employed to evaluate the effects of modifying asphalt binder by nanomaterials on the moisture damage of asphalt mixture were surface free energy (SFE) and AASHTO T283. The results showed that the ratio of wet/dry values of indirect tensile strength for the mixtures containing nano ZnO for two types of aggregate were higher than the control mixtures. In addition, the results of the SFE method showed that adding nano ZnO increased the total SFE of the asphalt binder, which led to better coating of the aggregate with asphalt binder. Nano ZnO decreased the acid to base ratio of SFE of asphalt binder, while it led to improving adhesion between the asphalt binder and acidic aggregate that are prone to moisture damage.

Laboratory simulation tests of effect of mechanical damage on moisture damage evolution in hot-mix asphalt pavement

Moisture damage of hot-mix asphalt (HMA) pavement is an extremely complicated mode of distress. Previous researches on moisture damage mainly focused on the performances of undamaged pavement at the initial stage of opening to traffic. So with the permeability tests and the Hamburg Wheel Tracking Device (HWTD) tests, trial works were done to study the effect of traffic-load-induced mechanical damage on the evolution of moisture damage in HMA pavement. The monotonous uniaxial compression loading method and the repetitive compression loading method were employed to make the mechanical damages of the styrene–butadiene–styrene block copolymer-modified HMA specimens, respectively. Comparisons demonstrated that there were slight differences between the damages from the two kinds of damage making methods. The damages were characterised with two kinds of nondestructive testing methods (dynamic modulus testing method and ultrasonic wave testing method), and the relationship of the characterised damages with the two methods was obtained. The permeability tests of HMA showed that the coefficient of permeability initially decreases and then increases with the damage. HWTD test results implied that the mechanical damage had a significant influence on the moisture damage, especially in hot and humid environment. In HWTD test, the mechanical damage induced by the undesirable stress state in pavement accelerates the appearance of the striping inflection point and increases the cumulative deformation of HMA specimen. Therefore, in order to reflect the performance of asphalt pavement during its life cycle, the effect of mechanical damage on the evolution of moisture damage should be considered in pavement design and construction.

Influence of using polymeric aggregate treatment on moisture damage in hot mix asphalt

Moisture damage in hot mix asphalt (HMA) occurs due to a loss of adhesion and or cohesion, resulting in the reduced strength or stiffness of the HMA and the development of various forms of pavement distress. One of the convenient approaches to decreasing moisture sensitivity in HMA is coating the aggregate surface with a suitable agent. In this research, the effects of two types of polyethylene (PE), namely high density polyethylene (HDPE) and low density polyethylene (LDPE), on moisture damage of asphalt mixtures were evaluated. Two types of aggregates representing a considerable range in mineralogy (granite and limestone) were evaluated during the course of this study. To assess the impact of PE on moisture damage of HMA, control mixtures (without PE) and mixtures containing PE in dry and wet conditions were tested using indirect tensile strength (ITS) and indirect tensile stiffness modulus (ITSM) tests. The results showed that the ratio of wet/dry values of ITS and ITSM for mixtures containing limestone was higher than those of the samples with granite aggregate. The results of the laboratory tests indicate that PE increases the wettability of asphalt binder over the aggregate and the adhesion between the asphalt binder and aggregate, especially in the mixtures containing acidic (granite) aggregate prone to moisture damage. The aggregates treated with HDPE showed better resistance against moisture damage in both aggregates that were used in this study.

Evaluating the Effect of Zycosoil on Moisture Damage of Hot-Mix Asphalt Using the Surface Energy Method

There are several approaches for improving adhesion and moisture sensitivity in asphalt mixtures, one of which is to coat the aggregate surface with a suitable agent to change the predominant electrical charges at the surface and reduce the surface energy of the aggregate. In this study, the effects of using Zycosoil as an antistripping additive on moisture susceptibility of asphalt mixtures has been evaluated by determining the mechanism that affects the adhesive bond between the aggregate and asphalt binder using the surface free energy (SFE) method and laboratory dynamic modulus test. The percentage of the aggregate surface exposed to water (P index) has also been calculated by using the measured SFE and dynamic modulus results, and evaluated as an index for the moisture susceptibility of mixtures. The results of the SFE method show that Zycosoil decrease the difference between the free energy of the adhesion of aggregate- asphalt binder in dry and wet conditions, and this difference is equal to the amount of energy released when stripping occurs. Coating of the aggregate surface with Zycosoil decreases this difference, and subsequently causes the mixture to be more resistant to moisture damage. DOI: 10.1061/(ASCE)MT.1943-5533.0000819. © 2014 American Society of Civil Engineers.

Effectiveness of Lime in Hot-Mix Asphalt Pavements

The pavement community has recognized that moisture damage of hot-mix asphalt (HMA) has been a serious problem since the early 1960s. Numerous additives have been evaluated with the objective of reducing the potential of moisture damage in HMA mixtures; lime has been one of the most common ones. The Nevada Department of Transportation has been using lime in HMA mixtures since the mid-1980s. The objective of this research was to quantify the improvements in pavement performance that have been realized through the addition of lime to HMA mixtures. The program evaluated field samples and pavement performance data from untreated and lime-treated pavements. The properties of untreated and lime-treated mixtures from field projects in the southern and northwestern parts of Nevada indicate that lime treatment of Nevada's aggregates significantly improves the moisture resistance of HMA mixtures. The study showed that lime-treated HMA mixtures become significantly more resistant to multiple freeze–thaw cycles than do the untreated mixtures. Long-term pavement performance data indicate that under similar environmental and traffic conditions, the lime-treated mixtures provide better-performing pavements with fewer requirements for maintenance and rehabilitation activities. The analysis of the impact of lime on pavement life indicates that lime treatment extends the performance life of HMA pavements by an average of 3 years. This extension represents an average increase of 38% in the expected pavement life.