A pure case study on moisture sensitivity assessment using tests on both loose and compacted asphalt mixture (original) (raw)
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2017
The damage due to moisture can be result in asphalt pavements either due to stripping or the softening of asphalt, both of which result in loss of ability to resist traffic- induced stresses which is mainly occur due to the loss or destruction of bond between the aggregate and the asphalt. This study is aimed to determine the effect of moisture on different graded bitumen mixture i:e open graded mixture and dense graded mixture and the effect of anti-stripping agent(lime) in hot mix asphalt(HMA). Moisture susceptibility of asphalt mixture can be determined by different tests indirect tensile strength test, Retained Marshall stability value and boiling water test with varying the percentage of lime content from 0% to 2.5%.The results indicates that the addition of hydrated lime increases the moisture resistance value to some extent and also provide larger strength as compare to the other mixes without addition of lime and more over the dense graded mix provide more effective value th...
Moisture Damage Performance Tests of Asphalt Mixtures: A Review
This paper presents a comprehensive literature on moisture damage performance tests of asphalt mixtures. The moisture damage remains to be a detriment to the durability of the Hot Mix Asplhalt (HMA) pavements. Moisture damage can be defined in form of adhesive failure between bitumen and aggregates and cohesive failure within bitumen. Aggregate mineralogy, bitumen characteristic and anti-stripping additive dominantly influence the performance of asphalt mixture towards moisture damage alongside construction methods, climate and traffic loading. Various laboratory test methods have been developed to quantify the moisture damage performance of asphalt mixtures by resembles the action in the field including qualitative test such as Boiling Water Test (ASTM D3625) and quantitative tests (Modified Lottman test AASHTO T283). Both of these types of tests consist of two phase which is conditioning phase and evaluation phase. This paper will review the effectiveness of the selected available tests based on various asphalt mixtures material.
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Moisture damage in asphalt mixtures is a complicated mode of pavement distress that results in the loss of stiffness and structural strength of the asphalt pavement layers. This paper evaluated the moisture sensitivity of different aggregate-bitumen combinations through three different approaches: surface energy, peel adhesion and the Saturation Ageing Tensile Stiffness (SATS) tests. In addition, the results obtained from these three tests were compared so as to characterise the relationship between the thermodynamic and the mechanical tests. The surface energy tests showed that the work of adhesion in dry conditions was bitumen type dependent which is in agreement with the peel test. After moisture damage, all of these three tests found that the moisture sensitivity of aggregate-bitumen combinations were mainly aggregate type dependent. Based on the peel test, the moisture absorption and mineralogical compositions of aggregate were considered as two important factors to moisture sensitivity. This phenomenon suggests that in a susceptible asphalt mixture, the effect of aggregate may be more influential than the effect of bitumen. The SATS test and the peel test showed similar moisture sensitivity results demonstrating the good correlation between these two mechanical tests. However, the surface energy tests and the mechanical tests cannot correlate in terms of moisture sensitivity evaluation.
Effects of various additives on the moisture damage sensitivity of asphalt mixtures
Construction and Building Materials, 2005
Effects of four additives, namely two fatty amine (Wetfix I, Lilamin VP 75P), one catalyst (Chemcrete) and a polymer (rubber), on the moisture damage of asphalt mixtures were studied. Rheological characteristics of the binders were measured using conventional methods both original and thin-film oven aged. Mechanical characteristics of the mixtures were evaluated with Marshall, indirect tensile and Lottman treatment tests. The additives used in this study reduced the level of damage due to moisture in asphalt mixtures. Minimum acceptable indirect tensile strength ratio (0.70) is achieved when Chemcrete and 0.2% of Wetfix I, and 0.4-0.6% of Lilamin VP 75P are used in asphalt mixtures. Indirect tensile strength ratio may decrease due to the relatively higher strength obtained in dry specimens with respect to the conditioned ones. Indirect tensile strength ratios of asphalt paving specimens were found to be less than the Marshall Stability ratios.
Effects of Various Asphalt Binder Additives/Modifiers on Moisture-Susceptible Asphaltic Mixtures
Moisture damage of asphalt concrete is defined as the loss of strength and stability caused by the active presence of moisture. The most common technique to mitigate moisture damage is using additives or modifiers with the asphalt binder or the aggregate. Various additives and modifiers are used to enhance the performance of asphalt mixtures. However, some of these additives/modifiers may affect the moisture susceptibility of the asphaltic mixtures. The objective of this study was to investigate the effect, if any, of various additives and modifiers on the moisture susceptibility of asphalt concrete. Additives and modifiers included in this study were selected as those most commonly used in Illinois: liquid anti-strip (LAS), styrene butadiene styrene (SBS), polyphosphoric acid (PPA), and hydrated lime. Two mixtures exhibiting failed tensile strength ratio (TSR) results were selected for testing. Mixture-level lab tests were conducted including modified AASHTO T283 Lottman test with five freezing and thawing (FT) cycles, the Hamburg wheel tracking test, and a fracture test using semi-circular bending (SCB) specimens. The modified AASHTO T283 Lottman tests showed that LAS and hydrated lime improved moisture damage control of the asphalt mixes. In the wheel tracking tests, mixes with SBS-modified binder and mixes with hydrated lime provided the least rutting potential. The fracture tests generally showed that mixes with either hydrated lime or LAS had the best relative performance. Component-level tests were conducted including the direct adhesion test (DAT) and contact angle test to determine surface free energy (SFE). Results of SFE values and DAT parameters were in agreement with the results of mixture-level tests: LAS and hydrated lime generally help to mitigate a mixture's susceptibility to moisture. Full-scale test sections were built and exposed to accelerated load testing. Although not all full-scale sections met the lab-mix design volumetrics, the control mix and the mixes with LAS and SBS had similar mixture composition compared with the labprepared mixes. This study found that LAS and hydrated lime might reduce moisture susceptibility of asphalt mixes. However, PPA may need to be used with another moisture control additive or modifier in order to avoid adverse effects on an asphalt mixture. The study also found that surface free energy values can be used to identify aggregate-binder compatibility with respect to moisture damage.
Frattura ed Integrità Strutturale, 2020
Given the defects of bitumen in asphalt mixtures particularly exposed to moisture, this study mainly aims to investigate the relationship between qualitative and quantitative results of moisture susceptibility tests on asphalt mixtures modified by ZycoTherm, nanoclay, nanosilica and SBS. The Marshall stability, modulus of resilience and indirect tensile strength tests are carried out. Boiling water and SEM qualitative tests are also used. Eventually, the qualitative tests results are digitalized through image processing by MATLAB and compared with the moisture susceptibility results of indirect tensile strength test. For modulus of resilience testing, the results show that this modifier has the maximum impact on Marshall stability, improving it by about 23%. For moisture susceptibility testing, the nanosilica-modified mixture has the maximum effect among anti-stripping additives, with an improvement by about 20%. An investigation into the results of SEM images and boiling water test via MATLAB indicates the high accuracy of SEM images and their results show the most compatibility with the results of quantitative data. KEYWORDS. Modifier; Moisture susceptibility; Image processing; Scanning electron microscopy (SEM) of bitumen. Citation: Farazmand, P., Hayati, P., Shaker, H., Rezaei, S., N., Relationship between microscopic analysis and quantitative and qualitative indicators of moisture susceptibility evaluation of warm-mix asphalt mixtures containing modifiers, Frattura ed Integrità Strutturale, 51 (2020) 215-224.
Construction and Building Materials, 2012
The purpose of this study is to compare laboratory and field performances for dense graded asphalt mixtures. Control road pavement section was constructed in Black Sea Coast Highway. Marshall identical control samples produced in laboratory and core samples taken from wearing courses before the traffic opened were used. Three different moisture conditioning methods were applied to control laboratory and core samples. Mechanical properties of samples were evaluated with indirect tension, indirect tension strength and repeated creep tests. Indirect tensile strength test results for laboratory mixtures were found 1.22 and 1.30 times more in accordance with field samples at 10°C and 20°C respectively. Marshall samples gave higher resilient modulus for all control and conditioned mixtures. Repeated creep test results also proved the difference between laboratory and field sample performance. Laboratory samples protected their structural integrity along with the test duration and did not showed tertiary creep. It is concluded from this study that laboratory samples state expressly higher performance according to the core field samples.
Journal of Materials in Civil Engineering, 2023
Evaluation of a mixture's moisture sensitivity is currently the final step in the Superpave® volumetric process. This step is accomplished by using AASHTO T-283, which tolerates a range of values in the test variables of sample air voids and degree of saturation. The tensile strength ratios determined for the mixes in this study varied with the air void level and degree of saturation. Although the levels of conditioning were within the specifications for AASHTO T-283, test results both passed and failed the 80 percent criterion, depending on the severity of conditioning. An alternative to measuring indirect tensile strength is a test that evaluates a mixture's fundamental material properties. A relatively simple test is proposed that measures the cohesion and friction angle for asphalt mixtures. In addition, the Superpave shear tester (SST) was incorporated as a tool in evaluating moisture sensitivity. The proposed axial test determined the cohesion and angle of friction of the mix. The friction angle remained constant for the conditioned and unconditioned samples. Hence, conditioning of the samples had practically no effect on the mixture's internal friction. The cohesion of the mix decreased when the mix was subjected to conditioning. The reduction in cohesion was greater in the case of the Fountain aggregate, which is known to be highly moisture susceptible. The shear tests to failure performed on the SST confirmed the results of the new apparatus, which provides a simple method for determining a mixture's cohesion. The loss of cohesion due to conditioning can be used to determine a mixture's moisture susceptibility. The three antistrip additives used in this study were hydrated lime, a liquid amine, and a liquid phosphate ester.
Increasing the Durability of Asphalt Mixture Against Moisture: A Case Study in Iran
Indian Journal of Science and Technology, 2017
Background: Hydrated Lime (HL) has been known as an additive for asphalt mixture durability. It is observed to be the most effective additive when moisture damage becomes one of the most pressing pavement failure modes. Methods: The use of HL is a known technique to increase durability and decrease stripping phenomena in asphalt mixtures. In this research, we intended to study the effect of adding HL, by presenting laboratory examinations on different aggregates using with one percent of HL additive and investigating the changes in some main HMA design factors. Results: Test results have been used in Zanjan-Tabriz highway (section 9), which is the longest freeway of Iran. Texas boiling water test (ASTM D3625) was used as a primary investigation of aggregate trend to stripping and Lottman test (AASHTO T283) for testing the indirect tensile strength of asphalt mixtures. Asphalt Mixture durability against moisture was evaluated by TSR ratio, MRR and fatigue index. Conclusion: Results, wholly, confirmed beneficial effects of HL on asphalt mixture durability and stripping Phenomena, for the samples of this project.